Synthesis and catalytic properties of polynuclear molybdenum silicon-containing carbene complexes

The molybdenum silicon-containing carbene complexes PhMe2Si—CH=Mo(NAr)(OR)2 (1), Ph2Si[CH=Mo(NAr)(OR)2]2 (2), and (RO)2(ArN)Mo=CH—(SiMe2)2—CH=Mo(NAr)(OR)2 (Ar = 2,6-Pri 2C6H3; R = CMe2CF3) were synthesized by the reaction of the R′— CH=Mo(NAr)(OR)2 compounds (R′ = But or PhMe2C) with silicon-containing vinyl reagents. The structures of complexes 1 and 2 and the known PhMe2C—CH=Mo(NAr)(OCMe2CF3)2 compound were established by X-ray diffraction. The catalytic properties of the silicon-containing carbene complexes in homometathesis of hex-1-ene and metathesis polymerization of cyclooctene were studied. The catalytic activity of these complexes and the stereoregularity of the resulting polyoctenamers substantially depend on the nature of the substituent at the carbene carbon atom.