title: Is it True That the Normal Valence-Length Correlation Is Irrelevant for Metal-Metal Bonds?
abstract: The most intriguing feature of metal-metal bonds in inorganic compounds is an apparent lack of correlation between the bond order and the bond length. In this study, we combine a variety of literature data obtained by quantum chemistry and our results based on the empirical bond valence model (BVM), to confirm for the first time the existence of a normal exponential correlation between the effective bond order (EBO) and the length of the metal-metal bonds. The difference between the EBO and the formal bond order is attributed to steric conflict between the (TM)n cluster (TM=transition metal) and its environment. This conflict, affected mainly by structural type, should cause high lattice strains, but electron redistribution around TM atoms, evident from the BVM calculations, results in a full or partial strain relaxation.
authors.affiliation: Department of Chemistry and, the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Vijay
authors.initials: V
authors.lastname: Singh
authors.affiliation: Department of Chemistry and, the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Mudit
authors.initials: M
authors.lastname: Dixit
authors.affiliation: Department of Chemistry and, the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Monica
authors.initials: M
authors.lastname: Kosa
authors.affiliation: Department of Chemistry and, the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Dan Thomas
authors.initials: DT
authors.lastname: Major
authors.affiliation: Department of Chemistry and, the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Elena
authors.initials: E
authors.lastname: Levi
authors.affiliation: Department of Chemistry and, the Lise Meitner-Minerva Center of Computational Quantum Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Doron
authors.initials: D
authors.lastname: Aurbach
keywords: bond length; bond order; bond strains; cluster compounds; computational chemistry; metal-metal bonds