Mono- and bis-(iminophosphoranyl)methane titanium complexes

Abstract

The reaction of the bis(iminophosphoranyl)methanes, CH₂(R₂PNSiMe₃)₂ (R = Ph 1, Me 2 or Cy 3) with two equivalents of Cp*TiCl₃ (Cp* = C₅Me₅) gave, via elimination of two moles of trimethylsilyl chloride, the air and moisture sensitive bimetallic titanium bis(iminophosphoranyl)methane complexes, [(Cp*TiCl₂)₂{μ-(NPR₂)₂CH₂-κN,N′}] (R = Ph 7, Me 8 or Cy 9). The monometallated complexes, [Cp*TiCl₂{(NPR₂)CH₂(R₂PNSiMe₃)-κN}] (R = Ph 4, Me 5 or Cy 6) were observed as intermediates in the reaction by ³¹P NMR spectroscopy but attempts to isolate the pure monosubstituted products from reactions of the bis(silyliminophosphoranyl)methane and the titanium reagent conducted under equimolar stoichiometry were not successful; instead only mixtures of the mono- and di-substituted complexes were generated. Crystal structures of 7 and 8 revealed different molecular structures; in 7 the imidotitanium groups lie in a mutual trans orientation across the molecule whereas in 8 they lie on the same side of the molecule.