Facile 1,2-Migration of a Methyl Group on a {Dimethoxy(methyl)silyl}tungsten Complex: Formation of a Base-Stabilized (Dimethoxysilylene)(methyl) Complex

Reactions of Cp*(CO)2W(DMAP)Me [1, Cp* = η5-C5Me5, DMAP = 4-(dimethylamino)pyridine] with trialkylsilanes HSiR2Et (R = Me, Et) afforded (DMAP)(trialkylsilyl)tungsten complexes Cp*(CO)2W(DMAP)(SiR2Et) (2a, R = Me; 2b, R = Et). On the other hand, a reaction of 1 with dimethoxy(methyl)silane, HSi(OMe)2Me, gave a DMAP-stabilized (dimethoxysilylene)tungsten complex, cis-Cp*(CO)2W(Me){Si(OMe)2·DMAP} ( cis -3), through 1,2-migration of a methyl group from silicon to tungsten. Silylene complex cis -3 isomerized to its trans-isomer trans -3.