Four- and eight-membered cyclic phosphazene derivatives of zirconium, titanium and vanadium. Crystal structures of the complexes [ZrCl3(Me3SiNPPh2NSiMe3)]·MeCN and [{TiCl2(OPPh2N)}2]·4MeCN

Abstract

The reaction of ZrCl₄ with (Me₃Si)₂NPPh₂NSiMe₃1 yields the four-membered heterocycle [[graphic omitted]SiMe₃)]. An improved synthesis of the aminoiminophosphorane 1 is described. The compound TiCl₄ reacts with Me₃SiOPPh₂NSiMe₃ unexpectedly with elimination of all Me₃Si groups to yield the eight-membered heterocycle [{TiCl₂(OPPh₂N)}₂]. A vanadium-containing dimetallacyclophosphazene [{VCl₂(NPPh₂N)}₂] has been synthesised from [VCl₃(NSiMe₃)] and CiPPh₂NSiMe₃. The X-ray structures of [[graphic omitted]SiMe₃)]·MeCN and [{TiCl₂(OPPh₂N)}₂]·4MeCN have been determined. While the cyclic Zr–N distances in the former have to be considered as single bonds, the short Ti–N of the latter (almost planar) suggest double-bond character.