Reactions of Lithiated Diphosphanes R2P-P(SiMe3)Li (R = tBu and iPr) with [MeNacnacTiCl2•THF] and [MeNacnacTiCl3]. Formation and Structure of TitaniumIII and TitaniumIV β-Diketiminato Complexes Bearing the Side-on Phosphanylphosphido and Phosphanylphosphinidene Functionalities

beta-Diketiminate complexes of Ti-III-containing phosphanylphosphido ligands [(Me)NacnacTi(Cl){eta(2)-P(SiMe3)-PR2}] ((Me)Nacnac- = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr(2)C(6)H(3)) were prepared by reactions of [(Me)NacnacTiCl(2)center dot THF] with lithium derivatives of diphosphanes R2P-P(SiMe3)Li (R = tBu, iPr) in toluene solutions. Surprisingly, reactions of [(Me)NacnacTiCl2 center dot THF] with R2P-P(SiMe3)Li in THF solutions led to Ti-IV complexes containing phosphanylphosphinidene ligands [(Me)NacnacTi(Cl)(eta(2)-P-PtBu2)] via an autoredox path involving a migration of a nitrene NAr from the Nacnac skeleton to the Ti centers. Solid-state structures of [(Me)NacnacTi(Cl){eta(2)-P(SiMe3)-PtBu2}] (1a) and [(Me)NacnacTi(Cl)(eta(2)-P-PtBu2)] (two isomers 2a1, 2a2) together with [(Me)NacnacTi(Cl){eta(2)-P(SiMe3)-PiPr(2)}] (1b) and [(Me)NacnacTi(Cl)(eta(2)-P-PiPr(2))] (2b) were established by the single-crystal X-ray diffraction and display clearly side-on geometry of the (Me3Si)P-PR2 and P-PR2 moieties in the solid state. Phosphanylphosphinidene complexes [(Me)NacnacTi(Cl)(eta(2)-P-PR2)] indicate that the P-31 NMR resonances of phosphinidene P atoms appear at a very low field in solution and in the solid state.