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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

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posted on 2017-01-13, 12:33 authored by Ł. 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.

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