[CPMO(MU-SE)(MU-SEPH)]2 - A QUADRUPLE CHA LOGENATE-BRIDGED DIMOLYBDENUM COMPLEX WITH UNUSUAL STRUCTURE

The metal-metal triple bond of [Cp(CO)2Mo=Mo(CO)2Cp] (1) reacts with P hSeMgBr or PhSeLi to give the doubly-bridged complex [CpMo(CO)2(mu-SeP h)]2 (2b), containing no metal-metal bond. Compound 2b decarbonylates by reaction with selenium powder to produce fourfold-bridged [CpMo(mu- Se)(mu-SePh)]2 (3), containing a formal metal-metal double bond. The s tructures of 2b and 3 have been analysed by X-ray diffraction.