The shortened transition metal-tellurium bonds in organometallic clusters

Abstract

The shortening of partly multiple M-Te (M = Mn, Fe, Co, Cr or W) bonds is observed for two classes of organometallic compounds: (1) formally electron-deficient species with additional donor-acceptor interaction between Te lone pairs and half-occupied d-orbitals of M; (2) formally electron-saturated species having additional dative interaction between M lone pairs and LUMO of Te. These compounds could be prepared by two main methods: (a) interaction of [CpMn(CO)₂PhC(O)⁻]Li⁺ with Te proceeds via formation of intermediate {[CpMn(CO)₂]₂Te}²⁻ which is further transformed into binuclear complex [CpMn(CO)₂]₂Te(CH₂Ph)₂ or into trinuclear ditelluride cluster [CpMn(CO)₂]₃Te₂ on one hand or to mixed-metal monotelluride clusters [CpMn(CO)₂]₂TeM(CO)₅ on another hand. (b) treatment of Fe(CO)₅, CpMn(CO)₂(THF) or Me₄C₄Co(CO)₂I with [PhTeI]₄, PhTeI₃ or PhTeI₂HC = CPhI results in different PhTeI-containing complexes of Fe, Mn or Co. The molecular structures of all new compounds were studied by means of X-ray diffraction analyses and the mechanism of M-Te bond shortening is discussed.