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
posted on 2017-01-13, 12:33authored byŁ. Ponikiewski, A. Ziółkowska, J. Pikies
β-Diketiminate
complexes of TiIII-containing phosphanylphosphido ligands
[MeNacnacTi(Cl){η2-P(SiMe3)-PR2}] (MeNacnac– = [Ar]NC(Me)CHC(Me)N[Ar];
Ar = 2,6-iPr2C6H3) were prepared by reactions of [MeNacnacTiCl2·THF] with lithium derivatives of diphosphanes R2P–P(SiMe3)Li (R = tBu, iPr) in toluene solutions. Surprisingly, reactions of [MeNacnacTiCl2·THF] with R2P–P(SiMe3)Li in THF solutions led to TiIV complexes containing
phosphanylphosphinidene ligands [MeNacnacTi(Cl)(η2-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 [MeNacnacTi(Cl){η2-P(SiMe3)-PtBu2}] (1a) and [MeNacnacTi(Cl)(η2-P-PtBu2)] (two isomers 2a1, 2a2) together with [MeNacnacTi(Cl){η2-P(SiMe3)-PiPr2}] (1b) and [MeNacnacTi(Cl)(η2-P-PiPr2)] (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
[MeNacnacTi(Cl)(η2-P-PR2)] indicate that the 31P NMR resonances of phosphinidene
P atoms appear at a very low field in solution and in the solid state.