Synthesis and crystal structures of three four-membered ring compounds containing PN2Ti skeletons

Abstract

Depending on the reaction conditions, Ph₂P(NSiMe₃)[N(SiMe₃)₂]reacts with TiCl₄ to form the titanadiazaphosphetidines Ph₂P[µ-N(SiMe₃)]₂TiCl₃MeCN (1) and Ph₂P[µ-N(SiMe₃)]₂TiCl₂,[NPPh₂N(SiMe₃)₂](2). Compound (1) dimerises slowly in solution with elimination of Me₃SiCl to yield a tricyclic system containing a central Ti₂N₂ ring (3). X-Ray analyses of these compounds show (1) and (3) to be monoclinic, space group P2₁/n, while (2) is triclinic, space group P. Compound (2) has a Ti–N–P angle of 170.3(7)° and a short exocyclic Ti–N bond of 179.2(9) pm.