NEW SYNTHETIC METHODOLOGY LEADING TO 16-ELECTRON ASYMMETRIC COMPLEXES OF TUNGSTEN - CP(STAR)-W(NO)(CH2SIME3)R (R = ALKYL OR ARYL)

An unprecedented three-step synthetic route leading from Cp*W(NO)(CH2SiMe3)2 [Cp* = (eta(5)C5Me5)] to the asymmetric species Cp*W(NO)(CH2SiMe3)R (R = alkyl or aryl), is described. The three steps are (1) exposure of Cp*W(NO)(CH2SiMe3)2 to H2 (1 atm) in acetonitrile to afford Cp*W(NO)(CH2SiMe3)(N = C(H)CH3) (1), probably via hydrotungstation of CH3CN by the initially formed hydrido complex, Cp*W(NO)(CH2SiMe3)H, (2) treatment of 1 with 2 equiv of HCI in Et2O to form Cp*W(NO)(CH2SiMe3)CI (2), and (3) metathesis reactions of 2 with organomagnesium reagents, R2Mg, to produce the mixed alkyl and alkyl-aryl complexes, Cp*W(NO)(CH2SiMe3)R (3a, R = o-tolyl; 3b, R = CH2CMe2Ph; 3c, R = Me).