Metal-Metal Interactions in Mixed-Valance [M 2 Cl 9 ] 2- Species: Electronic Structure of d 1 d 2 (V, Nb, Ta) and d 4 d 5 (Fe, Ru, Os) Face-Shared Systems
Date
2005
Authors
Cavigliasso, German
Stranger, Robert
Journal Title
Journal ISSN
Volume Title
Publisher
American Chemical Society
Abstract
The molecular and electronic structures of mixed-valence d 1d2 (V, Nb, Ta) and d4d5 (Fe, Ru, Os) face-shared [M2Cl9]2- dimers have been calculated by density functional methods in order to investigate metal-metal bonding in this series. General similarities are observed between d 1d2 and d4d5 systems and can be considered to reflect the electron-hole equivalence of the individual d 1-d5 and d2-d4 configurations. The electronic structures of the dimers have been analyzed using potential energy curves for the broken-symmetry and other spin states resulting from the d 1d2 and d4d5 coupling modes. In general, a spin-doublet (S = 1/2) state, characterized by delocalization of the metal-based electrons in a metal-metal bond with a formal order of 1.5, is favored in the systems containing 4d and 5d metals, namely, the Nb, Ta, Ru, and Os dimers. In contrast, the calculated ground structures for [V 2Cl9]2- and [Fe2Cl9] 2- correspond to a spin-quartet (S = 3/2) state involving weaker coupling between the metal centers and electron localization. In the case of [Ru2Cl9]2-, both the spin-doublet and spin-quartet states are predicted to be energetically favored suggesting that this species may exhibit double-minima behavior. A comparison of computational results across the (d1d1, d1d2, d2d2) [Nb2Cl9]z- and [Ta2Cl9]z- and (d4d4, d4d5, d5d5) [Ru2Cl 9]z- and [Os2Cl9]z- series has revealed that, in all four cases, the shortening of the metal-metal distances correlates with an increase in formal metal-metal bond order.
Description
Keywords
Citation
Collections
Source
Inorganic Chemistry
Type
Journal article
Book Title
Entity type
Access Statement
License Rights
Restricted until
2037-12-31