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75 Publikation(en)

Taming the High Reactivity of Gold(III) Fluoride: Fluorido Gold(III) Complexes with N-based Ligands

Mathias A. Ellwanger, Simon Steinhauer, Paul Golz, Helmut Beckers, Anja Wiesner, Beatrice Braun-Cula, Thomas Braun, Sebastian Riedel

Erschienen in: 2017, submitted

Thema: Fluorine Chemistry, Fluorides, Gold(III), Fluorido Organo Gold Compound, Fluoride Complexes, Goldtrifluoride

Tricyanomethane and its Ketenimine Tautomer Generated from Different Precursors and Analyzed in Solution, Argon Matrix, and Single Crystal

Klaus Banert, Madhu Chityala, Manfred Hagedorn, Helmut Beckers, Tony Stüker, Sebastian Riedel, Tobias Rüffer, and Heinrich Lang

Erschienen in: Angew. Chem. Int. Ed. 2017, DOI 10.1002/anie.201704561

DOI: 10.1002/anie.201704561

Thema: Azides, Cyanides, Cyanoform, Ketenimines, Reactive Intermediates

From Square-planar [ICl4]- to Novel Chloroiodates(III)? A Systematic Experimental and Theoretical Investigation of their Ionic Liquids.

Benedikt Burgenmeister, Karsten Sonnenberg, Sebastian Riedel, Ingo Krossing

Erschienen in: Chem. Eur. J. accepted

Thema: Halogens, Ionic Liquids, Iodine, Chlorine

Group 11 Oxo fluorides: Terminal Oxo Ligand gives rise to Intriguing Oxidation States

Lin Li, Tony Stüker, Stefanie Kieninger, Dirk Andrae, Tobias Schlöder, Yu Gong, Lester Andrews, Helmut Beckers and Sebastian Riedel

Erschienen in: submitted

Thema: SupeOxidefluorides, Matrix-Isolation Spectroscopy, Caoinage Metals

Novel Superacids: Formation of Pentafluoro-orthotellurate Derivatives of Aluminium

Anja Wiesner, Thomas W. Gries, Simon Steinhauer, Helmut Beckers and Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed.

DOI: 10.1002/anie.201702807

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: Superacids, Lewis Acids, Bronsted Acids, Weakly Coordinating Anions, Carbocations

Formation and Characterization of [BrC(NMe2)2)][Br3] and [BrC(NMe2)2)]2[Br8] in Ionic Liquids

Karsten Sonnenberg, Patrick Pröhm, Simon Steinhauer, Anja Wiesner, Carsten Müller, Sebastian Riedel

Erschienen in: Z. Anorg. Allg. Chem. 2017, 643, 101–105

DOI: 10.1002/zaac.201600337

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: Bromine, Polyhalogen Anions, Dianions

[NMe4][I4Br5] – A new Iodobromide from an Ionic Liquid with Halogen-Halogen Interactions

Lisa Mann, Patrick Voßnacker, Carsten Müller, and Sebastian Riedel

Erschienen in: Chem. Eur. J. 2017, 23, 244 – 249.

DOI: 10.1002/chem.201605421

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: Bromine, iodine, Polyhalogen Anions, Nonahalides

Structural Proof for the First Dianion of a Polychloride: Investigation of [Cl8]2–

Robin Brückner, Patrick Pröhm, Anja Wiesner, Simon Steinhauer, Carsten Müller, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed, 2016, 55, 10904–10908

DOI: 10.1002/anie.201604348

http://onlinelibrary.wiley.com/wol1/doi/ ...

Thema: Chlorine, Polyhalogen Anions, Halogen-Halogen Bonding

Are There Molecular Manganese Fluorides Beyond MnF3? – A Quantum-Chemical And Matrix-Isolation Investigation

Felix Brosi, Tobias Schlöder, Alexei Schmidt, Helmut Beckers, Sebastian Riedel

Erschienen in: Dalton Transactions, 2016, 45, 5038 - 5044

DOI: 10.1039/C5DT04827C

http://pubs.rsc.org/en/Content/ArticleLa ...

Thema: Fluorine, Manganese, Matrix-Isolation Spectroscopy, Coupled-Cluster Calculations

A matrix isolation and computational study of molecular palladium fluorides: does PdF6 exist?

Antony Wilson, Tim Nguyen, Felix Brosi, Xuefeng Wang, Lester Andrews, Sebastian Riedel, Adam Bridgeman, Nigel Young

Erschienen in: Inorg. Chem. 2016, 55, 1108-1123.

http://pubs.acs.org/doi/abs/10.1021/acs. ...

Thema: High Oxidation States, Matrix-Isolation Spectroscopy, Fluorine

Extending the Row of Lanthanide Tetrafluorides - A combined Matrix-Isolation and Quantum-Chemical Study

Thomas Vent-Schmidt, Zongtang Fang, Zachary Lee, David Dixon, Sebastian Riedel

Erschienen in: Chemistry - A European Journal, 2016, 22, 2406-2416.

DOI: 10.1002/chem.201504182

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: Matrix Isolation, High Oxidation State, Fluorine Chemistry, Lanthanide Fluorides, Electronic Structure Calculation

Ultraviolet Photolysis Studies of XeO4 in Noble-Gas and F2 Matrices and the Formation and Characterization of a New Xe(VIII) Oxide, (n2-O2)XeO3

Thomas Vent-Schmidt, James T. Goettel, Gary J. Schrobilgen, Sebastian Riedel

Chem. Eur. J. | 2015

Erschienen in: Chemistry - A European Journal 2015, 21, 11244 – 11252.

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: High Oxidation States, Matrix-Isolation Spectroscopy, Xenon, Oxides, Noble Gas Compounds

A 2D Polychloride Network Glued by Halogen-Halogen Interaction

Robin Brückner, Heike Haller, Simon Steinhauer, Carsten Müller, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed. 2015, 54, 15579-15583. (Angew. Chem. 2015, 127, 15800 –15804.)

DOI: 10.1002/ange.201507948

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: Chlorine, Polychlorides, Ionic Liquids

Does PrF5 exist? – A combined matrix isolation and quantum-chemical study

Thomas Vent-Schmidt, Sebastian Riedel

Erschienen in: Inorg. Chem. 2015, 54, 11114-11120.

DOI: 10.1021/acs.inorgchem.5b01175

http://pubs.acs.org/doi/full/10.1021/acs ...

Thema: Praseodym, Matrix-Isolation Spectroscopy, Coupled-Cluster Calculations

Reaction of laser ablated uranium and thorium atoms with H2Se: A rare example for selenium multiple bonding

Thomas Vent-Schmidt, Lester Andrews, K. Sahan Thanthiriwattec, David Dixon, Sebastian Riedel

Erschienen in: Inorg. Chem. 2015, 54, 9761-9769.

DOI: 10.1021/acs.inorgchem.5b01383

http://pubs.acs.org/doi/abs/10.1021/acs. ...

Thema: Uranium, Thorium, Matrix-Isolation Spectroscopy, Coupled-Cluster Calculations

Polyfluorides and Neat Fluorine as Host Material in Matrix Isolation Experiments

Felix Brosi, Thomas Vent-Schmidt, Stefanie Kieninger, Tobias Schlöder, Helmut Beckers, Sebastian Riedel

Erschienen in: Chemistry - A European Journal 2015, 21, 16455-16462.

DOI: 10.1002/chem.201502849

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: High Oxidation States, Matrix-Isolation Spectroscopy, Fluorine, Polyfluorides

Fluorine Rich Fluorides – New insights into the chemistry of polyfluoride anions

Thomas Vent-Schmidt, Felix Brosi, Jens Metzger, Tobias Schlöder, Xuefeng Wang, Lester Andrews, Carsten Müller, Helmut Beckers, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed. 2015, 54, 8279–8283 (Angew. Chem. 2015, 127, 8397 – 8401. VIP Paper

http://onlinelibrary.wiley.com/doi/10.10 ...

Thema: Fluorine, Polyfluorides, Matrix-Isolation Spectroscopy, Coupled-Cluster Calculations

Investigation of Alkali Metal Polyfluorides by Matrix-Isolation Spectroscopy

Frenio A. Redeker, Helmut Beckers, Sebastian Riedel

Erschienen in: RSC Adv. 2015,5, 106568-106573.

DOI 10.1039/c5ra24227d

http://pubs.rsc.org/en/content/articlela ...

Thema: Polyfluorides, Alkalimetals, Matrix-Isolation Spectroscopy, Fluorine

Matrix-isolation and computational study of the HKrCCH...HCCH complex

Knut Willmann, Thomas Vent-Schmidt, Markku Räsänen, Sebastian Riedel, Leonid Khriachtchev

Erschienen in: RSC Adv. 2015, 5 (45), 35783-35791

DOI: 10.1039/C5RA01880C

http://pubs.rsc.org/en/Content/ArticleLa ...

Thema: Matrix-Isolation Spectroscopy, Krypton, Noble Gas Compounds

Investigation of Thorium Hydride Fluorides by Matrix-Isolation Spectroscopy and Quantum-Chemical Calculations

Thomas Vent-Schmidt, Jens Metzger, Lester Andrews, Sebastian Riedel

Erschienen in: J. Fluorine Chem. 2015, 174, 2-7.

DOI:10.1016/j.jfluchem.2015.02.001

http://dx.doi.org/10.1016/j.jfluchem.201 ...

Following the successful preparation of HUF through the reaction of laser ablated uranium atoms with HF in excess noble gases, we continue the investigation of actinide atom reactions with HF. Herein we report the reaction products of laser ablated thorium atoms with HF as well as supporting quantum chemical calculations and a discussion of the bonding in HThF and higher oxidation state molecules. The results of this study are compared to previous results obtained in similar uranium reactions.

Reactions of Laser-ablated U Atoms with HF: Infrared Spectra and Quantum Chemical Calculations of HUF, UH, and UF in Noble Gas Solids

Thomas Vent-Schmidt, Lester Andrews, Sebastian Riedel

Erschienen in: Journal of Physical Chemistry A 2015, 119 (11), 2253-2261.

DOI: 10.1021/jp5055827

http://pubs.acs.org/doi/full/10.1021/jp5 ...

Reactions of laser-ablated U atoms with HF produce HUF as the major product and UH and UF as minor products, which are identified from their argon and neon matrix infrared spectra. Our assignment of HUF is confirmed by the observation of DUF and close agreement with observed and calculated vibrational frequencies and deuterium shifts in the vibrational frequencies. Our previous observation of the UH diatomic molecule from argon matrix experiments with H2, HD, and D2 as reagents is confirmed through its present observation with HF and DF, and with recent higher level quantum chemical calculations. The HF reaction provides a lower concentration of F in the system and thus simplifies the fluorine chemistry relative to similar U atom reactions with F2, and the new matrix identification of UF here is consistent with recent high level calculations on UF. In addition, we find evidence for the higher oxidation state secondary reaction products UHF2, UHF3, and UH2F2.

Recent discoveries of polyhalogen anions – from bromine to fluorine

Heike Haller, Sebastian Riedel

Erschienen in: Z. Anorg. Allg. Chem. 2014, 640, 1281.

DOI: 10.1002/zaac.201400085

http://onlinelibrary.wiley.com/doi/10.10 ...

In this review we discuss the recent discoveries in polyhalide anion chemistry with the main focus on polybromide, -chloride, and -fluoride anions. Based on novel synthetic strategies either in ionic liquids or in neat halogens several new polyhalides of bromine and chlorine were synthesized. Beyond these discoveries the chemistry of polyfluoride monoanions is reviewed. Such species were investigated under cryogenic conditions at 4 K in conjunction with quantum-chemical calculations. In addition to these bonding and structural discussions, an overview of possible applications of such polyhalide anions is provided.

New evidence in an old case – The question of chromium hexafluoride reinvestigated

Tobias Schlöder, Felix Brosi, Benjamin J. Freyh,Thomas Vent-Schmidt, Sebastian Riedel

Erschienen in: Inorganic Chemistry 2014, 53, 5820-5829.

DOI: 10.1021/ic500651r

http://pubs.acs.org/doi/abs/10.1021/ic50 ...

The question of whether or not the chromium hexafluoride molecule has been synthesized and characterized has been widely discussed in the literature and cannot, in spite of many efforts, yet be answered beyond doubt. New matrix-isolation experiments can now show, together with state-of-the-art quantum-chemical calculations, that the compound previously isolated in inert gas matrixes, was CrF5 and not CrF6. New bands in the matrix IR spectra can be assigned to the Cr2F10 dimer, and furthermore evidence was found in the spectra for a photodissociation or reversible excitation of CrF5 under UV irradiation. However, even if CrF6 is not stable at ambient conditions, its formation under high fluorine pressures in autoclave reactions cannot be excluded completely.

Identification of an iridium-containing compound with a formal oxidation state of IX

Guanjun Wang, Mingfei Zhou, James T. Goettel, Gary J. Schrobilgen, Jing Su, Jun Li, Tobias Schlöder, Sebastian Riedel

Erschienen in: Nature, 2014, 514, 475–477.

doi:10.1038/nature13795

NatureChemical & Engineering NewsChemistryWorldBioPortfolioPressemitteilung FU BerlinScinexxWirtschaft.comForschung & WissenAnalytik NewsChemie.deScienceNewsHighlight Angew. Chem.Canadian Chemical News (accn)Nachrichten aus der Chemie

One of the most important classifications in chemistry and within the periodic table is the concept of formal oxidation states. The preparation and characterization of compounds containing elements with unusual oxidation states is of great interest to chemists. The highest experimentally known formal oxidation state of any chemical element is at present VIII, although higher oxidation states have been postulated. Compounds with oxidation state VIII include several xenon compounds (for example XeO4 and XeO3F2) and the well-characterized species RuO4 and OsO4. Iridium, which has nine valence electrons, is predicted to have the greatest chance of being oxidized beyond the VIII oxidation state. In recent matrix-isolation experiments, the IrO4 molecule was characterized as an isolated molecule in rare-gas matrices. The valence electron configuration of iridium in IrO4 is 5d1, with a formal oxidation state of VIII. Removal of the remaining d electron from IrO4 would lead to the iridium tetroxide cation ([IrO4]+), which was recently predicted to be stable and in which iridium is in a formal oxidation state of IX. There has been some speculation about the formation of [IrO4]+ species, but these experimental observations have not been structurally confirmed. Here we report the formation of [IrO4]+ and its identification by infrared photodissociation spectroscopy. Quantum-chemical calculations were carried out at the highest level of theory that is available today, and predict that the iridium tetroxide cation, with a Td-symmetrical structure and a d0 electron configuration, is the most stable of all possible [IrO4]+ isomers.

Thema: High Oxidation States, Iridium, Spectroscopy

On the Oxidation of the Three-Dimensional Aromatics [B₁₂X₁₂]₂⁻ (X = F, Cl, Br, I)

René T. Boeré, Janis Derendorf, Carsten Jenne,* Sylwia Kacprzak, Mathias Keßler, Rainer Riebau, Sebastian Riedel, Tracey L. Roemmele, Monika Rühle, Harald Scherer, Jonas Warneke, Thomas Vent-Schmidt, Stefan Weber

Erschienen in: Chemistry - A European Journal, 2014, 20, 4447-4459.

DOI: 10.1002/chem.201304405

http://onlinelibrary.wiley.com/doi/10.10 ...

The perhalogenated closo-dodecaborate dianions [B12X12]2− (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6X6 (X=H, F, Cl, Br, I). Whereas oxidation of the parent compounds [B12H12]2− and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions [B12X12]2− with the strong oxidizer AsF5 in liquid sulfur dioxide (lSO2) yielded the corresponding radical anions [B12X12]⋅− (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12Cl12 and [Na(SO2)6][B12Br12]⋅B12Br12. Sublimation of the crude reaction products that contained B12X12 (X=Cl, Br) resulted in pure dark blue B12Cl12 or decomposition to red B9Br9, respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the [B12X12]2− dianions by going from fluorine to bromine as halogen substituent. The oxidation of all [B12X12]2− dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions [B12X12]2− (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For [B12X12]2− (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1.68 and +2.29 V (lSO2, versus ferrocene/ferrocenium (Fc0/+))), the second process is irreversible (with oxidation potentials ranging from +2.63 to +2.71 V (lSO2, versus Fc0/+)). [B12I12]2− showed a complex oxidation behavior in cyclic voltammetry experiments, presumably owing to decomposition of the cluster anion under release of iodide, which also explains the failure to isolate the respective radical by chemical oxidation.

Properties of ThFx from Infrared Spectra in Solid Argon and Neon with Supporting Electronic Structure and Thermochemical Calculations

Kanchana Thanthiriwatte, Xuefeng Wang, Lester Andrews, David Dixon, Jens Metzger, Thomas Vent-Schmidt, Sebastian Riedel

Erschienen in: The Journal of Physical Chemistry, 2014, 118, 2107-2119.

DOI: 10.1021/jp412818r

http://pubs.acs.org/doi/full/10.1021/jp4 ...

Laser-ablated Th atoms react with F2 in condensing noble gases to give ThF4 as the major product. Weaker higher frequency infrared absorptions at 567.2, 564.8 (576.1, 573.8) cm–1, 575.1 (582.7) cm–1 and 531.0, (537.4) cm–1 in solid argon (neon) are assigned to the ThF, ThF2 and ThF3 molecules based on annealing and photolysis behavior and agreement with CCSD(T)/aug-cc-pVTZ vibrational frequency calculations. Bands at 528.4 cm–1 and 460 cm–1 with higher fluorine concentrations are assigned to the penta-coordinated species (ThF3)(F2) and ThF5–. These bands shift to 544.2 and 464 cm–1 in solid neon. The ThF5 molecule has the (ThF3)(F2) Cs structure and is essentially the unique [ThF3+][F2–] ion pair based on charge and spin density calculations. Electron capture by (ThF3)(F2) forms the trigonal bipyramidal ThF5– anion in a highly exothermic process. Extensive structure and frequency calculations were also done for thorium oxyfluorides and Th2F4,6,8 dimer species. The calculations provide the ionization potentials, electron affinities, fluoride affinities, Th–F bond dissociation energies, and the energies to bind F2 and F2– to a cluster as well as dimerization energies.

Brominations with Pr₄NBr₉ as a solid reagent with high reactivity and selectivity

Thorsten Beck, Heike Haller, Jan Streuff, Sebastian Riedel

Erschienen in: Synthesis 2014, 46, 740-747

DOI: 10.1055/s-0033-1340705

https://www.thieme-connect.de/DOI/DOI?10 ...

Tetrapropylammonium nonabromide (Pr4NBr9) is introduced as a room-temperature solid reagent for rapid bromination reactions of various substrates. The reagent exhibits reactivity similar to that of elemental bromine, but shows higher selectivity and it is easier and safer to store and to handle.

Iodine-iodine bonding makes tetra(diiodine)chloride, [Cl(I₂)₄]⁻, planar

Christine Walbaum, Mark Richter, Ulf Sachs, Ingo Pantenburg, Sebastian Riedel, Anja-Verena Mudring, Gerd Meyer

Erschienen in: Angew. Chem. Int. Ed. 2013, 52, 12731–12735 (Angew. Chem. 2013, 125, 12965–12968)

10.1002/ange.201305412

http://onlinelibrary.wiley.com/doi/10.10 ...

Planar statt tetraedrisch! Das Polyinterhalogenid [Cl(I₂)₄]⁻ , das in der Gasphase tetraedrisch wäre, nimmt in den Kristallen von [(H₅O₂)(I₂b15c5)₂][Cl(I₂)₄] eine planare Struktur ein (I₂b15c5=Diiodbenzo-15-Krone-5). Neben anderen Effekten wie elektrostatischer Anziehung zwischen kationischen und planaren anionischen Schichten spielen auch Iod-Iod-Bindungen mit σ-Loch-Wechselwirkungen eine wichtige Rolle.

Beyond state I

Sebastian Riedel, Peter Schwerdtfeger

Erschienen in: Nature Chemistry 2013, 5, 815-816

http://www.nature.com/nchem/journal/v5/n ...

Five-Coordinate Silicon(II) Compounds with Si–M Bonds (M = Cr, Mo, W, Fe): Bis[N,N-diisopropyl-benzamidinato(–)]silicon(II) as a Ligand in Transition-Metal Complexes

Konstantin Junold, Johannes A. Baus, Christian Burschka, Thomas Vent-Schmidt, Sebastian Riedel, Reinhold Tacke

Erschienen in: Inorg. Chem. 2013, 52, 11593-11599

http://pubs.acs.org/doi/abs/10.1021/ic40 ...

Reaction of the donor-stabilized silylene 1 with [Cr(CO)6], [Mo(CO)6], [W(CO)6], or [Fe(CO)5] leads to the formation of the transition-metal silylene complexes 2−5, which contain five-coordinate silicon(II) moieties with Si−M bonds (M = Cr, Mo, W, Fe). These compounds were characterized by NMR spectroscopic studies in the solid state and in solution and by crystal structure analyses. According to computational studies, the Si−M bonds are best described as single bonds.

[HMIM] [Br₉]: a Room Temperature Ionic Liquid Based on a Polybromide Anion

Heike Haller, Michael Hog, Franziska Scholz, Harald Scherer, Ingo Krossing, Sebastian Riedel

Erschienen in: Z. Naturforsch B. 2013, 68b, 1103-1107

http://www.znaturforsch.com/ab/v68b/ga68 ...

[HMIM][Br₉]: a Room-temperature Ionic Liquid Based on a Polybromide Anion

Formation and Characterization of HUF and DUF in Solid Argon

Thomas Vent-Schmidt, Rodney Dale Hunt, Lester Andrews, Sebastian Riedel

Erschienen in: Chem. Comm. 2013, 49, 3863–3865.

http://pubs.rsc.org/en/content/articlela ...

Reactions of laser-ablated U atoms with HF and DF in condensing and solid rare gas produce HUF and DUF as the major new products based on close agreement between observed and calculated vibrational frequencies and deuterium shifts for U–H and U–F stretching modes at 1383 and 544 cm⁻¹, respectively.

The highest oxidation states of the periodic table

Sebastian Riedel

Erschienen in: Chem. Rev. 2013, submitted

Structural Proof of Undecabromide [Br₁₁]⁻

Heike Haller, Jan Schröder, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed. 2013, 52, 4937–4940 (Angew. Chem. 2013, 125, 5037–5040)

http://onlinelibrary.wiley.com/doi/10.10 ...

Verteilte Ladung: Außer für Iod wurden bisher nur wenige der bekannten Polyhalogenanionen strukturell charakterisiert. Es ist deshalb bemerkenswert, dass das bisher höchste Element/Ladung-Verhältnis nun in dem neuen Undecabromid [Br₁₁]⁻ gefunden wurde. Dieses neue Polybromid-Monoanion wurde in reinem Halogen hergestellt und mithilfe von Einkristallstrukturanalyse, Raman-Spektroskopie (siehe Bild) und quantenchemischen Methoden charakterisiert.

Matrix Infrared Spectroscopy and Quantum-Chemical Calculations for the Coinage-Metal Fluorides:  Comparisons of Ar-AuF, Ne-AuF, and Molecules MF₂ and MF₃

Xuefeng Wang, Lester Andrews, Felix Brosi, Sebastian Riedel

Erschienen in: Chem. Eur. J. 2013, 19, 1397–1409

http://onlinelibrary.wiley.com/doi/10.10 ...

The reactions of laser-ablated Au, Ag, and Cu atoms with F₂ in excess argon and neon gave new absorptions in the MF stretching region of their IR spectra, which were assigned to metal-fluoride species. For gold, a NgAuF bond was identified in mixed neon/argon samples. However, this bonding was much weaker with AgF and CuF. Molecules MF₂ and MF₃ (M=Au, Ag, Cu) were identified from the isotopic distribution of the Cu and Ag atoms, comparison of the frequencies for three metal fluorides, and theoretical frequency calculations. The AuF₅ molecule was characterized by its strongest stretching mode and theoretical frequency calculations. Additional evidence was observed for the formation of the Au₂F₆ molecule.

Investigation of Gold Fluorides and Noble Gas Complexes by Matrix-Isolation Spectroscopy and Quantum-Chemical Calculations

Xuefeng Wang, Lester Andrews, Knut Willmann, Felix Brosi, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed. 2012, 51, 10628–10632 (Angew. Chem. 2012, 124, 10780–10784)

http://onlinelibrary.wiley.com/doi/10.10 ...

Noble with a difference: Matrix-isolation experiments and quantum-chemical calculations have led to the characterization of two new compounds, namely first open-shell binary gold fluoride, AuF₂, and a NeAuF complex. Moreover, ArAuF, AuF₃, Au₂F₆, and monomeric AuF5 have been produced and identified under cryogenic conditions in neon and argon matrices.

Polyhalogenanionen - Überraschende Vielfalt

Heike Haller, Sebastian Riedel

Erschienen in: Nachrichten aus der Chemie, 2012, 9, 865–868

Beyond Iron Trifluoride: A Matrix-Isolation and Quantum-Chemical Investigation of FeF₄

Tobias Schlöder, Thomas Vent-Schmidt, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed. 2012, 51, 12063–12067 (Angew. Chem. 2012, 124, 12229–12233)

http://onlinelibrary.wiley.com/doi/10.10 ...

Beyond iron trifluoride: Matrix-isolation IR spectroscopy and state-of-the-art quantum-chemical calculations have led to the characterization of iron tetrafluoride, a previously unknown species. FeF4 has been prepared by co-deposition of laser-ablated iron atoms with fluorine under excess of noble gases (neon and argon) at cryogenic temperatures.

Spectroscopic Observation of a Group 12 Oxyfluoride: A Matrix-Isolation and Quantum-Chemical Investigation of Mercury Oxyfluorides

Lester Andrews, Xuefeng Wang, Yu Gong, Tobias Schlöder, Sebastian Riedel, Marvin J. Franger

Erschienen in: Angew. Chem. Int. Ed. 2012, 51, 8235–8238 (Angew. Chem. 2012, 124, 8359–8363

http://onlinelibrary.wiley.com/doi/10.10 ...

Hg auf den Zahn gefühlt: Experimente mit Amalgamen als Quelle für laserablatierte Hg-Atome als Reaktionspartner für OF₂ ergaben starke HgF₂-Infrarotabsorptionen und neue Banden im Hg-F-Streckschwingungsbereich, die den in festem Argon und Neon isolierten Molekülen zugeordnet wurden. Die Zuordnung dieser neuen Banden zum ersten Quecksilberoxyfluorid, OHgF, und zum Insertionsprodukt FOHgF wurde durch quantenchemische Rechnungen gestützt.

Can zinc really exist in its oxidation state +III?

Tobias Schlöder, Martin Kaupp, Sebastian Riedel

Erschienen in: J. Am. Chem. Soc. 2012, 134, 11977–11979

http://pubs.acs.org/doi/abs/10.1021/ja30 ...

Very recently, a thermochemically stable ZnIII complex has been predicted by Samanta and Jena ( J. Am. Chem. Soc. 2012, 134, 8400−8403). In contrast to their conclusions we show here by quantum chemical calculations that (a) Zn(AuF₆)₃ is not a thermochemically feasible compound, and (b) even if it could be made, it would not represent a ZnIII oxidation state by any valid definition.

Exploring new ¹²⁹Xe chemical shift ranges in HXeY compounds: hydrogen more relativistic than xenon

Perttu Lantto, Stanislav Standara, Sebastian Riedel, Juha Vaara, Michal Straka

Erschienen in: Phys. Chem. Chem. Phys. 2012, 14, 10944–10952

http://pubs.rsc.org/en/content/articlela ...

Among rare gases, xenon features an unusually broad nuclear magnetic resonance (NMR) chemical shift range in its compounds and as a non-bonded Xe atom introduced into different environments. In this work we show that ¹²⁹Xe NMR chemical shifts in the recently prepared, matrix-isolated xenon compounds appear in new, so far unexplored ¹²⁹Xe chemical shift ranges. State-of-the-art theoretical predictions of NMR chemical shifts in compounds of general formula HXeY (Y = H, F, Cl, Br, I, –CN, –NC, –CCH, –CCCCH, –CCCN, –CCXeH, –OXeH, –OH, –SH) as well as in the recently prepared ClXeCN and ClXeNC species are reported. The bonding situation of Xe in the studied compounds is rather different from the previously characterized cases as Xe appears in the electronic state corresponding to a situation with a low formal oxidation state, between I and II in these compounds. Accordingly, the predicted ¹²⁹Xe chemical shifts occur in new NMR ranges for this nucleus: ca. 500–1000 ppm (wrt Xe gas) for HXeY species and ca. 1100–1600 ppm for ClXeCN and ClXeNC. These new ranges fall between those corresponding to the weakly-bonded Xe0 atom in guest–host systems (δ < 300 ppm) and in the hitherto characterized Xe molecules (δ > 2000 ppm). The importance of relativistic effects is discussed. Relativistic effects only slightly modulate the ¹²⁹Xe chemical shift that is obtained already at the nonrelativistic CCSD(T) level. In contrast, spin–orbit-induced shielding effects on the 1H chemical shifts of the H1 atom directly bonded to the Xe center largely overwhelm the nonrelativistic deshielding effects. This leads to an overall negative 1H chemical shift in the range between −5 and −25 ppm (wrt CH4). Thus, the relativistic effects induced by the heavy Xe atom appear considerably more important for the chemical shift of the neighbouring, light hydrogen atom than that of the Xe nucleus itself. The predicted NMR parameters facilitate an unambiguous experimental identification of these novel compounds.

Infrared Spectroscopic and Theoretical Investigations of the OUF₂ and OThF₂ Molecules with Triple Oxo Bond Character

Yu Gong, Lester Andrews, Xuefeng Wang, Tobias Schlöder, Sebastian Riedel

Erschienen in: Inorg. Chem. 2012, 51, 6983-6991

http://pubs.acs.org/doi/abs/10.1021/ic30 ...

The terminal oxo species OUF₂ and OThF₂ have been prepared via the spontaneous and specific OF₂ molecule reactions with laser ablated uranium and thorium atoms in solid argon and neon. These isolated molecules are characterized by one terminal M-O and two F–M–F (M = U or Th) stretching vibrational modes observed in matrix isolation infrared spectra, which are further supported by density functional frequency calculations and CASPT2 energy and structure calculations. Both molecules have pyramidal structures with singlet (Th) and triplet (U) ground states. The molecular orbitals and metal–oxygen bond lengths for the OUF₂ and OThF₂ molecules indicate triple bond character for the terminal oxo groups, which are also substantiated by NBO analysis at the B3LYP level and by CASPT2 molecular orbital calculations. Dative bonding involving O₂p → Th₆d and Udf interactions is clearly involved in these oxoactinide difluoride molecules. Finally, the weak O–F bond in OF₂ as well as the strong U–O, U–F and Th–O, Th–F bonds make reaction to form the OUF₂ and OThF₂ molecules highly exothermic.

Iron(II) and nickel(II) complexes of N-alkylimidazoles and 1-methyl-1H-1,2,4-triazole: X-ray studies, magnetic characterisation and DFT calculations

Timo Huxel, Sebastian Riedel, Jochen Lach, Julia Klingele

Erschienen in: Z. Anorg. Allg. Chem. 2012,  638, 925–934

http://onlinelibrary.wiley.com/doi/10.10 ...

Using the ligands N-methylimidazole (MeIm), N-ethylimidazole (EtIm), N-propylimidazole (PrIm), and 1-methyl-1H-1, 2, 4-triazole (MeTz) three series with a total of 13 iron(II) complexes were isolated. The series comprise of the following complexes: (a) [Fe(MeIm)₆](ClO₄)₂ (1), [Fe(EtIm)₆](ClO₄)₂ (2), [Fe(PrIm)₆](ClO₄)₂(3), [Fe(MeTz)₆](ClO₄)₂ (4), [Fe(MeIm)₆](MeSO₃)₂ (5), [Fe(EtIm)₆](MeSO₃)₂ (6), and [Fe(MeTz)₆](BF₄)2 (10); (b) [Fe(MeIm)₄(MeSO3)2](7), [Fe(EtIm)₄(MeSO₃)₂] (8), and [Fe(PrIm)₄(MeSO₃)₂] (9); (c) [Fe(MeIm)4(NCS)₂] (15), [Fe(EtIm)₄(NCS)₂ ] (16), and [Fe(MeTz)₄(NCS)2] (17). Single crystal X-ray diffraction studies were performed on 7–10 and 15–17. Temperature dependent magnetic susceptibility measurements were performed on selective examples of all series, and confirmed them to be in the HS state over the range 6–300 K. DFT calculations were performed at BP86/def-SV(P) and TPSSh/def2-TZVPP level on all [FeL₆]²⁺ complex cations and the neutral complexes 7–9 and 15–17. Additionally the four homoleptic nickel(II) complexes [NiL₆](ClO₄)₂ (11: L = MeIm; 12: L = EtIm; 13: L = PrIm; 14: L = MeTz) were synthesized and compounds 11–13 structurally characterized. UV/Vis/NIR spectroscopic measurements were carried out on all homoleptic iron(II) and nickel(II) complexes. The 10Dq values were determined to be in the range of 11547–11574 and 10471–10834 cm⁻¹ for the iron(II) and nickel(II) complexes, respectively.

Polychloride Monoanions from [Cl₃]- to [Cl₉]-: A Raman-Spectroscopic and Quantum-Chemical Investigation

Robin Brückner, Heike Haller, Mathias Ellwanger, Sebastian Riedel

Erschienen in: Chem. Eur. J. 2012, 18, 5741-5747

http://onlinelibrary.wiley.com/doi/10.10 ...

Polychloride monoanions stabilized by quaternary ammonium salts are investigated using Raman spectroscopy and state-of-the-art quantum-chemical calculations. A regular V-shaped pentachloride is characterized for the [N(Me)₄][Cl₅] salt, whereas a hockey-stick-like structure is tentatively assigned for [N(Et)₄][Cl₂⋅⋅⋅Cl₃⁻]. Increasing the size of the cation to the quaternary ammonium salts [NPr₄]⁺ and [NBu₄]⁺ leads to the formation of the [Cl₃]⁻ anion. The latter is found to be a pale yellow liquid at about 40 °C, whereas all the other compounds exist as powders. Further to these observations, the novel [Cl₉]⁻ anion is characterized by low-temperature Raman spectroscopy in conjunction with quantum-chemical calculations.

Synthesis of the Smallest Axially Chiral Molecule by Asymmetric Carbon-Fluorine Bond Activation

Moritz F. Kuehnel, Tobias Schlöder, Sebastian Riedel, Belén Nieto-Ortega, Francisco J. Ramírez, Juan T. López Navarrete, Juan Casado, Dieter Lentz

Erschienen in: Angew. Chem. Int. Ed. 2012, 51, 2218–2220 (Angew. Chem. Int. Ed. 2012, 124, 2261–2263

http://onlinelibrary.wiley.com/doi/10.10 ...

Enantioselect-DeFluor: Die Spaltung einer Kohlenstoff-Fluor-Bindung durch einen chiralen Zirconiumkomplex ermöglichte die erste Synthese von optisch aktivem 1,3-Difluorallen. Die absolute Konfiguration wurde durch Schwingungs-Circulardichroismus-Spektroskopie (VCD) in der Gasphase bestimmt (siehe Diagramm).

Investigation of heterodimeric and homodimeric radical cations of the series: [F₂O₂]⁺, [F₂Cl₂]⁺ [Cl₂O₂]⁺, [F₄]⁺, and [Cl₄]⁺

Tobias Schlöder, Sebastian Riedel

Erschienen in: RSC Adv., 2012, 2, 876-881

http://pubs.rsc.org/en/Content/ArticleLa ...

In this state-of-the-art quantum-chemical investigation we report structures, thermochemical stabilities, Born-Fajans-Haber cycles as well as vibrational data of heterodimeric and homodimeric radical cations of the series [F2O₂]⁺, [F₂Cl₂]⁺, [Cl₂O₂]⁺, [F₄]⁺, and [Cl₄]⁺. The so far experimentally unknown species [F₄]⁺, [F₂O₂]⁺ and [F₂Cl₂]⁺ are predicted to be thermochemically stable and could be possible targets for gas-phase or matrix-isolation experiments. Furthermore, their stabilities as homodimeric [X₄]⁺ or heterodimeric [X₂Y₂]⁺ radical cation salts in the solid state have been estimated by Born-Fajans-Haber cycles.

Investigation of Polybromide Monoanions of the series [NAlk4][Br9] (Alk = Methyl, Ethyl, Propyl, Butyl)

Heike Haller, Matthias Ellwanger, Alexander Higelin, Sebastian Riedel

Erschienen in: Z. Anorg. Allg. Chem. 2012, 638, 553-558

http://onlinelibrary.wiley.com/doi/10.10 ...

Polybromide monoanions of the series [NAlk₄][Br₉] (Alk = methyl, ethyl, propyl, butyl) have been investigated. The corresponding salts were characterized by Raman spectroscopy, single-crystal X-ray diffraction and state-of-the-art quantum-chemical calculations. Comparisons between their crystal structures and the gas-phase calculations have been made whereas the latter shows regular tetrahedral arrangement. Usually the nonabromides contain one central Br⁻ anion at which all other four Br₂ molecules are coordinated. The only exception is [NBu₄][Br₉] where also a [Br₃]⁻ unit is found.Quantum-chemical calculations show that dispersion as well as spin-orbit corrections alter the results only marginally and can be neglected. Conductivity measurements show a surprisingly high conductivity of these polybromide monoanions. It is found that the tetraalkylammonium nonabromide salts (alkyl = methyl, ethyl, propyl, and butyl) show decreasing conductivity as the size of the cation increases. Making thesepolybromide monoanions possible electrolytes in batteries or dye-sensitized solar cells.

Structural proof for a higher polybromide monoanion. Investigation of [N(C₃H₇)₄][Br₉]

Heike Haller, Matthias Ellwanger, Alexander Higelin, Sebastian Riedel

Erschienen in: Angew. Chem. Int. Ed. 2011, 50, 11528 (Angew. Chem. 2011, 123, 11732)

http://onlinelibrary.wiley.com/doi/10.10 ...

Bromine's nine: The first crystal structure of a higher polybromide monoanion, [NPr₄][Br₉] is reported along with its IR and Raman spectra (see picture). Owing to its low melting point and vapor pressure, this substance can be classified as an ionic liquid. It shows surprisingly high conductivity which may enable its applications as electrolyte in batteries.

In-between Complex and Cluster: A 14-Vertex Cage in [Ag₂Se1₂]²⁺

Tobias Köchner, Nils Trapp, Tobias A. Engesser, Anna J. Lehner, Carolin Röhr, Sebastian Riedel, Carsten Kanpp, Harald Scherer, Ingo Krossing

Erschienen in: Angew. Chem. Int. Ed. 2011, 50, 11253 (Angew. Chem. 2011, 123, 11449)

http://onlinelibrary.wiley.com/doi/10.10 ...

Upon treatment of red, amorphous selenium with the silver salts of two large weakly coordinating anions (WCA), the thermodynamically driven formation of [Ag₂Se₁₂]²⁺ occurred. The structure of the dication is an unprecedented D₃d-symmetric 14-vertex cage built from six six-membered rings in a boat conformation that includes a weak argentophilic Ag–Ag bond.

Is rhodium tetroxide in the formal oxidation state VIII stable? a quantum chemical and matrix isolation investigation of rhodium oxides

Yu Gong, Mingfei Zhou, Lester Andrews, Tobias Schlöder, Sebastian Riedel

Erschienen in: Theoretical Chemistry Accounts - Special Issue for Prof. Pekka Pyykkö 2011, 129, 667-676.

http://link.springer.com/article/10.1007 ...

The structures and reactions of different rhodium oxides and dioxygen complexes with RhO₄ stoichiometry were investigated by matrix isolation infrared spectroscopy and quantum chemical calculations. The inserted RhO₂ molecule reacted with dioxygen upon sample annealing to form the [(η¹-O₂)RhO₂] complex, which can further isomerize to the known [(η²-O₂)RhO₂] complex via infrared irradiation. Both experimental and theoretical studies suggest that the [(η¹-O₂)RhO₂] complex has a doublet ground state with non-planar C s symmetry in which the O₂ ligand is end-on bonded to the rhodium centre. Although rhodium tetroxide is predicted to be a stable molecule with D ₂d symmetry at different level of theory, no evidence is found for the formation of this Rh(VIII) species in noble gas matrices. Our experiments also suggest the formation of a new peroxo [Rh(η²-O₂)₂] complex, which is calculated to have a doublet ground state with D ₂d symmetry. This peroxo complex undergoes isomerization to the known superoxo [Rh(η²-O₂)₂] complex via the rotation of the dioxygen ligand under infrared irradiation.

Oxidation of closo-[B₁₂Cl₁₂]²⁻ to the radical anion [B₁₂Cl₁₂]•⁻ and to neutral B₁₂Cl₁₂

René T. Boeré, Sylwia Kacprzak, Mathias Keßler, Carsten Knapp, Rainer Riebau, Sebastian Riedel, Tracey L. Roemmele, Monika Rühle, Harald Scherer, Stefan Weber

Erschienen in: Angew. Chem. Int. Ed. 2011, 50, 549–552 (Angew. Chem. 2011, 123, 572–575)

http://onlinelibrary.wiley.com/doi/10.10 ...

Analysis of Tertiary Phosphanes, Arsanes and Stibanes as Bridging Ligands in Dinuclear Group 9 Complexes

Sandra Schinzel, Robert Müller, Sebastian Riedel, Helmut Werner, Martin Kaupp

Erschienen in: Chem. Eur. J. 2011, 7, 7228–7235

http://onlinelibrary.wiley.com/doi/10.10 ...

The unusual bridging and semi-bridging binding mode of tertiary phosphanes, arsanes, and stibanes in dinuclear low-valent Group 9 complexes have been studied by density functional methods and bonding analyses. The influence of various parameters (bridging and terminal ligands, metal atoms) on the structural preferences and bonding of dinuclear complexes of the general composition [A¹ M¹(μ-CH₂)₂(μ-EX₃)M² A²] (M¹, M²=Co, Rh, Ir; A¹, A²=F, Cl, Br, I, κ²-acac; E=P, As, Sb, X=H, F, CH₃) has been analyzed. A number of factors have been identified that favor bridging or semi-bridging modes for the phosphane ligands and their homologues. A more symmetrical position of the bridging ligand EX₃ is promoted by more polar EX bonding, but by less electronegative (softer) terminal anionic ligands. Among the Group 9 metal elements Co, Rh, and Ir, the computations clearly show that the 4d element rhodium exhibits the largest preference for a {M¹(μ-EX₃)M²} bridge, in agreement with experimental observation. Iridium complexes should be valid targets, whereas cobalt does not seem to support well a symmetric bridging mode. Analyses of the Electron Localization Function (ELF) indicate a competition between a delocalized three-center bridge bond and direct metal–metal bonding.

The Reaction of White Phosphorus with NO⁺/NO₂⁺[Al(ORF)₄]⁻: The [P₄NO]⁺ Cluster Formed by an Unexpected Nitrosonium Insertion

Tobias Koechner, Sebastian Riedel, Anna J. Lehner, Harald Scherer, Ines Raabe, Tobias A. Engesser, Franziska W. Scholz, Urs Gellrich, Philipp Eiden, Roberto A. Paz Schmidt, Dietmar A. Plattner, Ingo Krossing

Erschienen in: Angew. Chem. 2010, 44, 8316–8320 (Angew. Chem. Int. Ed. 2010, 49, 8139-8143)

http://onlinelibrary.wiley.com/doi/10.10 ...

Polyfluoride Anions, a Matrix-Isolation and Quantum-Chemical Investigation

Sebastian Riedel, Tobias Köchner, Xuefeng Wang, Lester Andrews

Erschienen in: Inorg. Chem., 2010, 49, 7156 - 7164.

http://pubs.acs.org/doi/abs/10.1021/ic10 ...

Laser-ablation experiments with metals provide a source of electrons for capture processes, which are codeposited with solid argon and neon containing molecular fluorine. New argon and neon matrix absorptions at 510.6 and 524.7 cm−1, respectively, are photosensitive upon irradiation at >290 nm, which is consistent with their assignment to an isolated anion. These bands are below the [M]+[F3]− antisymmetric trifluoride stretching frequency of 550 cm−1 in an argon matrix, which is the typical relationship for cation−anion complexes and matrix-isolated anions. Thus, we report the isolated [F3]− anion in solid argon and neon environments. Moreover, we have carried out quantum-chemical calculations up to and including the CCSD(T) method to investigate the stabilities of polyfluoride anions higher than the [F3]− anion.

How far we can go? Quantum-chemical investigations of oxidation state +IX

Daniel Himmel, Carsten Knapp, Michael Patzschke, Sebastian Riedel

Erschienen in: ChemPhysChem, 2010, 11, 865 - 869

Formation and Characterization of the Iridium Tetraoxide Molecule with Iridium in the Oxidation State +VIII

Yu Gong, Mingfei Zhou, Martin Kaupp, Sebastian Riedel

Erschienen in: Angew. Chem. 2009, 121, 8019 - 8023 (Angew. Chem. Int. Ed. 2009, 48, 7879 - 7883).

The Highest Oxidation States of the Transition Metal Elements

Sebastian Riedel, Martin Kaupp

Erschienen in: Coordination Chemistry Reviews, 2009, 253, 606 - 625.

Is Allred's [Hg(cyclam)]³⁺ a True MercuryIII Complex?

Peter Hrobárik, Martin Kaupp, Sebastian Riedel

Erschienen in: Angew. Chem. 2008, 120, 8759 - 8761 (Angew. Chem. Int. Ed. 2008, 47, 8631 - 8633).

Behaviour of BrO₃F and ClO₃F Toward Strong Lewis Acids and the Characterization of [XO₂][SbF₆] (X = Cl, Br) by Single Crystal X-ray Diffraction, Raman Spectroscopy, and Computational Methods

John F. Lehmann, Sebastian Riedel, Gary J. Schrobilgen

Erschienen in: Inorg. Chem. 2008, 47, 8343 - 8356

The interactions of BrO₃F and ClO₃F with the strong Lewis acids AsF₅ and SbF₅ were investigated. Although ClO3F is unreactive toward AsF₅ and SbF₅, BrO₃F undergoes fluoride ion abstraction and O₂ elimination, accompanied by central halogen redn., to form [BrO₂][SbnF₅n₊₁] (n 1), rather than simple fluoride ion abstraction to form BrO₃⁺ salts. The geometric parameters of the BrO₂+ cation have been obtained in the solid state for the first time by a single-crystal X-ray diffraction study of [BrO₂][SbF6] at -173 C and are compared with those of ClO₂⁺ salts. Quantum-chem. calcns. have been used to arrive at the geometries and vibrational frequencies of XO₂⁺ and XO₃⁺ (X = Cl, Br) and have been compared with the exptl. values for XO₂⁺. The calcns. have also been used to account for the contrasting behaviors of ClO₃F and BrO₃F toward central halogen redn. in the presence of liq. SbF₅. The thermochem. stabilities of ClO₃⁺ and BrO₃+ salts of the AsF₆⁻, SbF₆⁻, Sb₂F₁₁⁻, and Sb3F₁₆⁻ were also investigated, which provided the fluoride ion affinities of AsF5, SbF5, Sb₂F₁₀, and Sb₃F₁₅ up to and including the CCSD(T) level of theory. These values are compared with the current literature values. Thermochem. studies indicate that XO₃⁺ formation by fluoride ion abstraction from XO₃F is not spontaneous under std. conditions whereas a concerted fluoride abstraction and O₂ elimination to give the XO₂⁺ cations is spontaneous to near thermally neutral. Failure to observe reactivity between ClO₃F and any of the aforementioned Lewis acid fluoride ion acceptors is attributed to a significant kinetic barrier to fluoride ion abstraction.

Theoretical mapping of new L-(N +)-L family of species with donor-acceptor bonding between N+ and ligand L

Sebastian Riedel, Michal Straka, Pekka Pyykkö

Erschienen in: Journal of Molecular Structure: THEOCHEM 2008, 860, 128 - 136.

We perform a computational mapping study of a family of new inorganic species, based on idea of donor–acceptor type bonding between N⁺ and a ligand L with a terminal electron lone pair. The nitrogen ion is seen as being in an atomic ¹D state, with empty 2p acceptor orbitals [I.S.K. Kerkines., A. Papakondylis, A. Mavridis, J. Phys. Chem. A, 2002, 106, 4435]. We consider a series of small ligands, such as PN, CCH⁻, CCCN⁻, NH2⁻, and others. Chemical bonding analysis confirms the suggested bonding picture as characteristic for experimentally known N₅⁺ and N(CO)₂⁺ as well as for most of the predicted species. A number of these new compounds is found to be thermodynamically stable with respect to the existing N₅⁺ or N(CN)₂⁻. They are candidates for new synthetic targets.

Quantum chemical study of trivalent group-12 fluorides

Sebastian Riedel, Martin Kaupp, Pekka Pyykkö

Erschienen in: Inorg. Chem. 2008, 47, 3379 - 3383.

In view of the recent experimental observation of the existence of tetravalent HgIV in HgF4, a quantum chemical study of various trivalent group 12 MIII fluoride complexes has been carried out. The M-F bonds in neutral MF3 are relatively weak, making these species unlikely targets. Some additional stability can be obtained by dimerizing HgF3 to Hg2F6, which has a doubly fluorine-bridged triplet ground state. Anionic [MF4]- and [MF5]2- species are found to be more stable toward F2 elimination and M-F bond breaking than neutral MF3.

Unusual Silicon Coordination Polyhedra: Non-VSEPR Structures of Zwitterionic l⁵Si -Silicon(IV) Complexes with an SiS₂N₂C or SiS2O2C Skeleton

Dennis Troegel, Christian Burschka, Sebastian Riedel, Martin Kaupp, Reinhold Tacke

Erschienen in: Angew. Chem. 2007, 119, 7131 - 7135 (Angew. Chem. Int. Ed. 2007, 46, 7001 - 7005)

High-Valent technetium fluorides. Does TcF₇ exist?

Sebastian Riedel, Manuel Renz, Martin Kaupp

Erschienen in: Inorg. Chem. 2007, 46, 5724 - 5738.

The structures and stabilities of technetium fluorides in high oxidation states have been studied quantum-chemically at density functional theory (B3LYP) and coupled-cluster (CCSD(T)) levels. The calculations indicate clearly that technetium heptafluoride, TcF₇, has a good chance of existence and preparation, thus providing the first heptafluoride in the 4d series. The [TcF₆]⁺ cation, a potential precursor, is also computed to be thermochemically stable against gas-phase elimination reactions. The problem with such highly fluorinated complexes appears thus to be mainly in difficult synthetic access under typical condensed-phase conditions. Matrix-isolation techniques or gas-phase experiments appear to be better suited as starting points.

After 20 Years, Theoretical Evidence that “AuF₇“ is Actually AuF₅·F₂

Daniel Himmel, Sebastian Riedel

Erschienen in: Inorg. Chem. 2007, 46, 5338 - 5342.

Quantum chemical calculations at DFT (BP86, B3LYP, BHLYP), MP2, CCSD, and CCSD(T) levels have been carried out on various fluoro complexes of gold in oxidation states +V through +VII, to evaluate the previously claimed existence of AuF₇. The calculations indicate clearly that elimination of F₂ from AuF₇ is a strongly exothermic reaction, with a low activation barrier. This is inconsistent with the reported stability of AuF7 up to room temperature. A reported experimental vibrational frequency at 734 cm⁻¹ for AuF₇ could not be verified computationally. It is concluded that the reported observation of AuF₇ was probably erroneous. As the calculations indicate also an extremely large electron affinity and little stability for AuF₅, Au⁺V remains the highest well-established gold oxidation state.

Platinum fluorides beyond PtF₆?

Sebastian Riedel

Erschienen in: J. Fluorine Chem. 2007, 128, 938 - 942.

Quantum-chemical calculations at DFT B3LYP and ab initio MP2, CCSD, and CCSD(T) levels have been performed on various binary fluorides of platinum up to formal oxidation state +VIII, to evaluate the stability of these species. The calculations indicate clearly that elimination of F₂ from PtF₈ is a strongly exothermic reaction, with a moderate activation barrier. An exothermic decay is also observed for the homolytic bond breaking. Furthermore, our investigations suggest that both decomposition channels of PtF₇ are exothermic. The existence of platinum fluorides higher than PtF₆ is therefore highly unlikely.

Mercury is a Transition Metal: The First Experimental Evidence for HgF₄

Xuefang Wang, Lester Andrews, Sebastian Riedel, Martin Kaupp

Erschienen in: Angew. Chem. 2007, 119, 8523 - 8527 (Angew. Chem. Int. Ed. 2007, 46, 8371 - 8375).

Although the Group 12 elements are generally considered to be post-transition metals with filled d shells, quantum chemical calculations predict a stable HgF₄ square-planar d8 complex due to relativistic stabilization of HgIV relative to HgII. In its tetravalent oxidation state, mercury is a true transition metal that utilizes 5d orbitals fully in bonding. The first experimental evidence is reported for HgIVF₄ in solid neon by IR spectroscopy, after reaction of mercury with excess fluorine under mercury arc irradiation and subsequent annealing. Assignment of the new bands to HgF₄ is supported by coupled-cluster and density functional calculations of structures and vibrational frequencies.

Has AuF7 been made?

Sebastian Riedel, Martin Kaupp

Erschienen in: Inorg. Chem. 2006, 45, 1228 - 1234

Quantum chemical calculations at DFT (BP86, B3LYP, BHLYP), MP2, CCSD, and CCSD(T) levels have been carried out on various fluoro complexes of gold in oxidation states +V through +VII, to evaluate the previously claimed existence of AuF₇. The calculations indicate clearly that elimination of F₂ from AuF₇ is a strongly exothermic reaction, with a low activation barrier. This is inconsistent with the reported stability of AuF₇ up to room temperature. A reported experimental vibrational frequency at 734 cm-1 for AuF₇ could not be verified computationally. It is concluded that the reported observation of AuF₇ was probably erroneous. As the calculations indicate also an extremely large electron affinity and little stability for AuF₆, Au⁺V remains the highest well-established gold oxidation state.

Revising the highest oxidation states of the 5d elements: The case of iridium(+VII)

Sebastian Riedel, Martin Kaupp

Erschienen in: Angew. Chem. 2006, 118, 3791-3794 (Angew. Chem. Int. Ed. 2006, 45, 3708 - 3711)

Our computational study suggests thus that the highest iridium oxidation state that has a realistic chance of experimental observation is Ir⁺VII. The experimentally known highest 5d oxidation states for groups 9, 10, and 11 are Os+VIII, Pt⁺VI, and Au⁺V, respectively. Adding the computational predicted Hg+IV and Ir⁺VII states suggests that the trend for the later 5d metals should become a linear decrease. All in all there is a linear increase up to Os and after Os there is a linear decrease down to Hg. This trend is a new observation for the 5d transition metals.

Where is the limit of highly fluorinated high oxidation state osmium species?

Sebastian Riedel, Martin Kaupp

Erschienen in: Inorg. Chem. 2006, 45, 10497 - 10502

The structures and stabilities of various osmium fluorides and oxyfluorides in high oxidation states have been studied by quantum-chemical calculations at DFT (B3LYP), MP2, CCSD, and CCSD(T) levels. The calculations indicate that the homoleptic fluorides all the way up to OsF8 may exist, even though OsF₈ will be difficult to prepare. The last missing osmium oxyfluoride, OsOF₆, is computed to be thermochemically stable against mononuclear gas-phase elimination reactions. The problem with the nonexistence of such highly fluorinated complexes appears thus to be mainly in difficult synthetic access under typical condensed-phase conditions. Matrix-isolation techniques might provide a means to characterize the highly fluorinated OsVIII and OsVII species.

Triple-bond covalent radii

Pekka Pyykkö, Sebastian Riedel, Michael Patzschke

Erschienen in: Chem. Eur. J. 2005, 12, 3511 - 3520

http://onlinelibrary.wiley.com/doi/10.10 ...

The aim of this page is to collect and validate triple-bond covalent radii for the whole periodic table. Involving elements from Be to E112 (Eka-Mercury). The elements in the 1 Group, the elements Zn-Hg in Group 12 and Ne in Group 18 are completely excluded.

Comparative calculations for the A-frame molecules [S(MPH3)2] (M=Cu,Ag,Au) at levels up to CCSD(T)

Sebastian Riedel, Pekka Pyykkö, Ricardo A. Mata, Hans-Joachim Werner

Erschienen in: Chem. Phys. Lett. 2005, 405, 148 - 152

The geometries of the A-frame mols. S(MPH₃)₂ (M = Cu, Ag, Au) are optimized at the HF, MP2, MP3, MP4, CCSD, and CCSD(T) levels using 19-valence-electron pseudopotentials. The M-M distances show oscillations which increase in the order Ag < Au < Cu. This result qual. parallels recent findings for the metallophilic bond strength by O'Grady and Kaltsoyannis. Local MP2 and local CCSD calcns. were also performed for comparison. These methods allow to partition the correlation contributions to the M-M interaction energy into dispersion and ionic terms. The latter were found to be unprecedently important for M = Cu.

Can Weakly Coordinating Anions Stabilize Mercury in its Oxidation State +IV?

Sebastian Riedel, Michal Straka, Martin Kaupp

Erschienen in: Chem. Eur. J. 2005, 9, 2743 - 2755

http://onlinelibrary.wiley.com/doi/10.10 ...

In view of the recent experimental observation of the existence of tetravalent HgIV in HgF₄, a quantum chemical study of various trivalent group 12 MIII fluoride complexes has been carried out. The M-F bonds in neutral MF₃ are relatively weak, making these species unlikely targets. Some additional stability can be obtained by dimerizing HgF₃ to Hg₂F₆, which has a doubly fluorine-bridged triplet ground state. Anionic [MF₄]⁻ and [MF5]²⁻ species are found to be more stable toward F₂ elimination and M-F bond breaking than neutral MF₃

[Pb₅{Mo(CO)₃}₂]⁴⁻ The first Complex Containing a Planar Pb₅ Unit

Li Yong, Stephan D. Hoffmann, Thomas F. Fässler, Sebastian Riedel, Martin Kaupp

Erschienen in: Angew. Chem. 2005, 117, 2129 - 2133 (Angew. Chem. Int. Ed. 2005, 44, 2092 - 2096)

http://onlinelibrary.wiley.com/doi/10.10 ...

On the Lack of Correlation between Bond Lengths, Dissociation Energies and Force Constants. The Fluorine-Substituted Ethane Homologues

Martin Kaupp, Sebastian Riedel

Erschienen in: Inorg. Chim. Acta 2004, 6, 1865 - 1872

http://onlinelibrary.wiley.com/doi/10.10 ...

Accurate ab initio coupled-cluster (CCSD) calculations have been used to evaluate systematically the E–E bond lengths, homonuclear dissociation energies, and force constants of a series of fluorine-substituted ethane homologues H₃−nFnE–EH₃−₃Fn (n=0–3), H₃E–EF₃, and H₃E–EH₂F (E=C, Si, Ge, Sn) in their staggered ethane-like conformations. The pronounced lack of correlation between bond lengths, dissociation energies, and force constants observed previously with E=Sn has also been found for the lighter group 14 homologues. However, each element in the group exhibits a different behavior. Attempts are made to interpret the findings in the context of electronegativity, hybridization defects, as well as negative and geminal hyperconjugation.

Validation of Density Functional Methods for Computing Structures and Energies of Mercury(IV) Complexes

Sebastian Riedel, Michal Straka, Martin Kaupp

Erschienen in: Phys. Chem. Chem. Phys. 2004, 6, 1122 - 1127

http://onlinelibrary.wiley.com/doi/10.10 ...

While quantum chemical predictions have strongly suggested a decade ago the existence of mercury in its oxidation state +IV, no experimental evidence has been found yet. To enable the search for alternative targets and preparation routes by quantum chemical methods, the present work has validated density functional methods against accurate CCSD(T) results for structures, reaction energies and activation barriers for X₂-elimination, and atomization energies for three HgXx systems (X=F, Cl, H). Hybrid functionals with ca. 20% Hartree–Fock exchange like B3LYP, B1LYP or MPW1PW91 have provided the best energetics, whereas local or gradient-corrected pure functionals overestimate, and the BHandHLYP hybrid functional underestimates the stability of the HgIV state. Basis sets are suggested that provide a reasonable compromise between accuracy and computational effort in calculations on larger systems.