Titanium and zirconium complexes with sterically hindered aryl-substituted iminophosphoranato ligands

Abstract

The benzyliminophosphorane 4-Bu^tC₆H₄CH₂P(Ph)₂NC₆H₂Me₃-2,4,6 reacted with TiCl₄ or ZrCl₄ to give the N-donor adducts, MCl₄{4-Bu^tC₆H₄CH₂P(Ph)₂NC₆H₂Me₃-2,4,6}. Whereas the zirconium compound proved unreactive, solutions of the titanium analogue at 10–20 °C slowly underwent C–H activation to give the phosphoranato complex TiCl₃{4-Bu^tC₆H₄CHP(Ph)₂NC₆H₂Me₃-2,4,6}. The trichloro complexes MCl₃{4-Bu^tC₆H₄CHP(Ph)₂NC₆H₂Me₃-2,4,6} were also accessible from Li[4-Bu^tC₆H₄CHP(Ph)₂NC₆H₂Me₃-2,4,6] and MCl₄ (M = Ti or Zr). The reaction of 4-Bu^tC₆H₄CH₂P(Ph)₂NC₆H₂Me₃-2,4,6 with Zr(NMe₂)₄ in refluxing toluene led to Zr(NMe₂)₃{4-Bu^tC₆H₄CHP(Ph)₂NC₆H₂Me₃-2,4,6}. The compound is fluxional in solution. Treatment with an excess of Me₃SiCl led to silylation of the ligand to give ZrCl₄{4-Bu^tC₆H₄CH(SiMe₃)P(Ph)₂NC₆H₂Me₃-2,4,6}. The structures of 4-Bu^tC₆H₄CH₂P(Ph)₂NC₆H₂Me₃-2,4,6 and Zr(NMe₂)₃{4-Bu^tC₆H₄CHP(Ph)₂NC₆H₂Me₃-2,4,6} were determined by X-ray diffraction.