Synthesis and characterization of perhalogenated diazaphosphametalletidines containing transition metals from group 4 and 5

Abstract

The preparation and characterization of the novel perhalogenated diazaphosphametalletidines, Cl₃M[N(SiMe₃)PCl₂N(SiMe₃)]·THF, M = Ti, Zr and Hf 2–4 and Cl₄Nb[N(SiMe₃)PCl₂N(SiMe₃)] 5 are reported. In addition, a new high yield preparation of the previously synthesized metallacycle Cl₃Ti[N(SiMe₃)PCl₂N(SiMe₃)] 1 is described. All reported complexes were synthesized by [3 + 1] cyclocondensation reactions involving the aminoiminophosphorane, (Me₃Si)₂NPCl₂NSiMe₃, and corresponding metal halides in dichloromethane. When 2.5 equivalents of (Me₃Si)₂NPCl₂NSiMe₃ were reacted with NbCl₅ a complex series of products was identified by ³¹P{¹H} NMR spectroscopy; crystals of the unusual heterocycles [Cl₃Nb{N(SiMe₃)PCl₂N}₂Cl₂Nb{N(SiMe₃)PCl₂N(SiMe₃)}] 6 and [Cl₂Nb{N(SiMe₃)PCl₂N(SiMe₃)}]₂-μ-Cl(NPCl₂N) 7 were isolated. Complex 7 contains the first example of a ClNbNPNNb six-membered ring. Structural characterization by single-crystal X-ray diffraction is also reported for metallacycles 2, 3, and 5–7.