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

Abstract

3 ) were synthesized by the reaction of the R´-CH=Mo(NAr)(OR) 2 compounds (R´ = Bu t or PhMe 2 C) with silicon containing vinyl reagents. The structures of complexes 1 and 2 and the known PhMe 2 C-CH=Mo(NAr)(OCMe 2 CF 3 ) 2 compound were established by X ray dif fraction. 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 de pend on the nature of the substituent at the carbene carbon atom.

Synthesis and structures of bimetallic silicon-containing imido alkylidene complexes of tungsten (R′O)2(ArN)WCH–SiR2–CHW(NAr)(OR′)2 (R=Me, Ph) and (R′O)2(ArN)WCH–SiMe2SiMe2–CHW(NAr)(OR′)2

“…The values of W-C-Si angles in 1 (138.52(18)°and 138.82(14)°) are almost equal whereas these angles in 2 are essentially different (147.4(5)°, 137.7(5)°). A similar feature was observed in molybdenum analog 2a (Mo-C-Si angles are 146.0(1) and 137.4(1)°) [7]. Apparently, the nonequivalence of the Mo-C-Si angles in 2 and 2a is caused by different conformation of these molecules in comparison with 1.…”

“…1 and 2, Table 1). Complex 2 is isostructural with the earlier described bimetallic molybdenum complex (R 0 O) 2 (ArN)Mo@CH-SiPh 2 -CH@Mo(NAr)(OR 0 ) 2 (2a) [7]. In complexes 1 and 2 the silicon and tungsten atoms have a distorted tetrahedral coordination environment.…”