tantalum(V) complexes. X-ray crystal structure of [TaCp*Cl, ( CN-2,6-Me,C,HJ]

[TaCp’Cl,] (Cp* = n5-CsMe,) reacts with isocyanides and amines to give the pseudo-octahedral adducts [TaCp*CI,L] (L = 2,6-Me,C,H,NC, 1; 2,4,6-Me,C,H,NC, 2; ‘BuNC, 3; or C,H,NH,, 4). Reduction of 1, or alternatively of [TaCp*Cl,l in the presence of stoichiometric amounts of isocyanide, with two equivalents of Na/Hg gives the diamagnetic pseudo-octahedral tantaIum(II1) complex, [TaCp*Cl,(CN-2,6-Me,C,H,)s], 5. Reaction of 4 with two equivalents of LiNEt, affords the pseudo-oc-tahedral imido complex [TaCp’Cl,(N-C,H,)]. 6. All the complexes were characterized by usual IR and NMR spectroscopic methods and the molecular structure of 1 was confirmed by X-ray diffraction methods