Volatile Imido−Hydrazido Compounds of the Refractory Metals Niobium, Tantalum, Molybdenum, and Tungsten

Volatile 1,1-dimethyl-2-(trimethylsilyl)hydrazido(1−) complexes of niobium, tantalum, molybdenum, and tungsten
have been synthesized and fully characterized for use as precursors in their chemical vapor deposition to metal
nitrides. Different reaction patterns were observed in the hydrazinolysis of imido complexes of those four metals
with (trimethylsilyl)dimethylhydrazine HN(SiMe3)NMe2 (H-TDMH). [Ta(NtBu)Cl3Py2] gave [Ta(TDMH)2Cl3] (1) with
loss of the imido functionality, and [M(NtBu)2Cl2Py2] gave [M(NtBu)2(TDMH)Cl] (M = W, 8a; Mo, 8b). Reactions of
both types of metal imido complexes with magnesium hydrazides produced [M(NtBu)(TDMH)2X] (M = Ta, X = Cl,
2a; X = Br, 3a; M = Nb, X = Cl, 2b; X = Br, 3b) and [M(NtBu)2(TDMH)X] (M = W, X = Cl, 8a; X = Br, 9a;
M = Mo, X = Cl, 8b; X = Br, 9b). Halogen substitution reactions at 2 and 3 by −NMe2, −NHtBu, and CH2Ph
groups as well as imido ligand replacement reactions have been investigated. The results of crystal structure
determinations of 1, 4a, 5a, 6a, 7b, and 9b are presented.