Pentamethylcyclopentadienyl Halfsandwich Complexes of Vanadium and Tantalum with Amido‐, Imido‐ Nitrido‐ and Azido Ligands

Lithium bis(trimethylsilyl)amide, LiN(SiMe 3 ) 2 , reacts with Cp*V(O)Cl 2 and Cp*TaCl 4 to give trimethylsilylimido complexes such as [Cp*V(NSiMe 3 )(μ‐NSiMe 3 )] 2 ( 7 ) and Cp*Ta(Cl)(NSiMe 3 )[N(SiMe 3 ) 2 ] ( 19 ), respectively. Substitution of the chloro ligand in 19 by anionic groups leads to complexes with 3 different N‐containing ligands, Cp*Ta(X)(NSiMe 3 )[N(SiMe 3 ) 2 ] (X = N 3 ( 20 ) or NPEt 3 ( 21 )). Complex 7 is air‐ and moisture‐sensitive, and several derivatives containing oxo and trimethylsiloxy ligands have been identified. Trimethylsilyl azide, Me 3 Si‐N 3 , is able to replace the oxygen‐containing ligands for azido ligands. The two complete series of bis(azido)‐bridged complexes, [Cp*VCl n (N 3 ) 2‐n (μ‐N 3 )] 2 (n = 2, 1, 0) and [Cp*TaCl n (N 3 ) 3‐n (μ‐N 3 )] 2 (n = 3, 2, 1, 0), are accessible from the reactions of Cp*VCl 3 and Cp*TaCl 4 , respectively, with trimethylsilyl azide. A bis(nitrido)‐bridged azido‐vanadium complex, [Cp*V(N 3 )(μ‐N)] 2 ( 18 ), has also been obtained and structurally characterized.