Reduction of [Cp*2Mo2O5] in Aqueous Medium: Structure and Properties of a Triangular Mixed Oxo-Hydroxo-Bridged Product, [Cp*3Mo3(μ-O)2(μ-OH)4](X)2 (X = CF3CO2 or CF3SO3)
Résumé
The reduction of [Cp*2Mo2O5] with Zn in a MeOH/H2O solution acidified with either CF3COOH or CF3SO3H leads to the formation of the [Cp*3Mo3(μ‐O)2(μ‐OH)4]2+ ion as its trifluoroacetate or trifluoromethanesulfonate salt. The structure of the compound was confirmed by X‐ray analyses. The anions establish hydrogen‐bonding interactions with all four bridging OH groups. Density functional calculations afford bonding parameters in close agreement with the observed structure and indicate that the cluster is best described as a valence‐delocalized Mo313+ species. The five metal electrons are distributed among an a‐type (z2) orbital, which accounts for most of the metal–metal attraction, and two essentially metal–metal nonbonding e‐type (xy) orbitals with a slight Mo‐(μ‐O) π*‐type contribution. Because of the C2 symmetry, the latter orbitals are not degenerate. The calculations show that the unpaired electron is located in a molecular orbital with equal contribution from two Mo atoms, in agreement with the experimental observation of coupling of the unpaired electron to two Mo atoms in the isotropic EPR spectrum.
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