Synthesis of chloro and methyl imido cyclopentadienyl molybdenum and tungsten complexes. X-ray molecular structures of [WCp*C13(NtBu)], [MoCp*C1Mez(NtBu) ] and [WCp*C1Mez(NtBu) ] 1

Alternative methods to prepare [MCp'C14], [MCp'CL(N'Bu)] and [MCp'CI~(N'Bu)] [M=Mo, Cp'="qs-C~Me ~ (Cp*); M=W, Cp ' = r/5-CsH5 (Cp), r/5-CsMe5 (Cp*) ] in high yields are reported. Alkylation of [MCp'CI3(N'Bu) ] with stoichiometric amounts of LiMe or MeMgC1 under appropriate conditions leads to the dimethyl [MCp'CIMe2(N'Bu)] and trimethyl [MCp'Me~(N'Bu)], (M=Mo, Cp ' = Cp*; M = W, Cp ' = Cp, Cp * ) complexes. The 18-electron trimethyltungsten complex [WCp*Me~(N'Bu) ] reacts very slowly with CN(2,6-Me2C~,H3) to give the insertion product [WCp*{C(Me) = N(2,6-Me2C6H3)}Me2(N'Bu)]. All of the new compounds reported were characterized by elemental analyses, IR and NMR spectroscopy and the X-ray molecular structures of [WCp*CI~(N'Bu)]