| Sumario: | α-Hydrogen abstraction and α-hydrogen migration reactions yield novel titanium(IV) complexes bearing terminal phosphinidene ligands. Via an α-H migration reaction, the phosphinidene (nacnac)TiP[Trip](CHBu) (nacnac = [Ar]NC(Bu)CHC(Bu)N[Ar], Ar = 2,6-(CHMe)CH, Trip = 2,4,6-PrCH) was prepared by the addition of the primary phosphide LiPH[Trip] to the nucleophilic alkylidene triflato complex (nacnac)TiCHBu(OTf), while α-H abstraction was promoted by the addition of LiPH[Trip] to the dimethyl triflato precursor (nacnac)Ti(CH)(OTf) to afford (nacnac)TiP[Trip](cH). Treatment of (nacnac)TiP[Trip](CH) with B(CF) induces methide abstraction concurrent with formation of the first titanium(lV) phosphinidene zwitterion complex (nacnac)TiP[Trip]{CHB(CF)} Complex (nacnac)-TiP[Trip]{CHB(CF)} [2 + 2] cycloadds readily PhCCPh to afford the phosphametallacyclobutene [(nacnac)Ti(p[Trip]PhCCPh)][CHB(CF)]. These titanium(IV) phosphinidene complexes possess the shortest TiP bonds reported, have linear phosphinidene groups, and reveal significantly upfielded solution P NMR spectroscopic resonances for the phosphinidene phosphorus. Solid state P NMR spectroscopic data also corroborate with all three complexes possessing considerably shielded chemical shifts for the linear and terminal phosphinidene functionality. In addition, high-level DFT studies on the phosphinidenes suggest the terminal phosphinidene linkage to be stabilized via a pseudo TiP bond. Linearity about the TiPC linkage is highly dependent on the sterically encumbering substituents protecting the phosphinidene. Complex (nacnac)TiP[Trip]{CHB(CF)} can catalyze the hydrophosphination of PhCCPh with HPPh to produce the secondary vinylphosphine HP[Ph]PhCCHPh. In addition, we demonstrate that this zwitterion is a powerful phospha-Staudinger reagent and can therefore act as a carboamination precatalyst of diphenylacetylene with aldimines.
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