On the Lack of Correlation between Bond Lengths, Dissociation Energies and Force Constants. The Fluorine-Substituted Ethane Homologues
Martin Kaupp, Sebastian Riedel – 2004
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.