Hydrazido(2–)-complexes of tungsten-(V) and -(VI) and a bis(diazenido)-complex of tungsten(IV). X-Ray crystal structure of cis-[WCl3(NNH2)(PMe2Ph)2]

Abstract

The hydrazido(2–)–hydride complexes [WX₂H(NNH₂)(PMe₂Ph)₃]X (1; X = Cl or Br), [WCI₃H(NNH₂)(PMe₂Ph)₂](2), and [WCl₃H(NNHPh)(PR₃)₂](3)(PR₃= PMe₂Ph, PMePh₂, or PPh₃) have been prepared by treatment of [WX₂(NNH₂)(PMe₂Ph)₃] with HX in tetrahydrofuran and of [WCl₄(PR₃)₂] with PhNHNH(SiMe₃) respectively. The complexes (1; X = Cl) and (3; PR₃= PMe₂Ph) convert into the hydrazido(2-) complexes cis-[WCl₃(NNH₂)(PMe₂Ph)₂](4) and trans-[WCl₃(NNHPh)(PMe₂Ph)₂](5) respectively on slow recrystallisation. The X-ray structure of (4)(space group Pnma, R= 0.055) in which the N-H atoms have been located, shows the hydrazido(2-) ligand to have a planar N–NH₂ group [d(WN)= 1.752(10), d(NN)= 1.300(17), d(NH)= 1.08 and 0.78 Å; N–N–W = 178.7(9)°]. The preparation of the complexes [WCL₄L₂](L = pyridine, 2-, 3-, or 4-methylpyridine, or quinoline) from [WCl₄(PPh₃)₂] is also described. [WCl₄(C₅H₅N)₂] reacts with PhNHNH-(SiMe₃) to give the bis(diazenido)-complex [WCl₂(NNPh)₂(C₅H₅N)₂](6). Spectroscopic data for all new complexes are discussed in terms of their structures.