The shortened transition metal-tellurium bonds in organometallic clusters

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.