Does PrF₅ exist? – A combined matrix isolation and quantum-chemical study
Thomas Vent-Schmidt, Sebastian Riedel – 2015
The chemistry of the lanthanides is mostly dominated by compounds in the oxidation state +III. Only few compounds of Ce, Pr, and Tb are known with the metal in the +IV oxidation state. Removal of the last f-electron on praseodymium +IV would lead to a closed-shell system with formal oxidation state V. In this work we investigated the stability of the PrF₅ molecule by theory and matrix-isolation techniques through the reaction of laser-ablated praseodymium atoms with fluorine in excess of neon, argon, krypton, or neat fluorine. Besides the known PrF₃ molecule, unreported IR bands for PrF₄ could be observed, and there is evidence for the formation of PrF and PrF₂ but not for the formation of PrF₅.