Solvent Impact on the Diversity of Products in the Reaction of Lithium Diphenylphosphide and a Ti(III) Complex Supported by a tBu2P-P(SiMe3) Ligand.

We present two important trends in the reactivity of the titanium complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] (MeNacNac- = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-iPr2Ph) with nucleophilic reagents RLi (R = Ph2P, tBuO, (Me3Si)2N, and tBu2N) depending on the reaction medium. Reaction in nonpolar solvent (toluene) leads to three main products: via an autoredox process and nucleophilic substitution at the Ti-atom to afford the Ti(IV) complex [MeNacNacTi(R){η2-P-PtBu2}] (1 for R = PPh2), via the elimination of Me3SiR to afford Ti(III) complex [MeNacNacTi(Cl){η2-P-PtBu2}]-[Li(12-crown-4)2]+ (2), and via 2e- reduction process to afford new ionic complex [{ArNC(Me)CHC(Me)}Ti═NAr{η1-P(SiMe3)-PtBu2}]-[Li(12-crown-4)2]+ (3). Quite differently, the complex [MeNacNacTi(Cl){η2-P(SiMe3)-PtBu2}] reacts with Ph2PLi in THF, unexpectedly yielding two new, four-coordinate Ti(IV) imido complexes 4a [{ArNC(Me)═CHC(H)(Me)-P(PtBu2)}Ti═NAr(Cl)]-[Li(12-crown-4)2]+·(toluene)2 and 4b [{ArNC(CH2)CH═C(Me)-P(PtBu2)}Ti═NAr(Cl)]-[Li(12-crown-4)2]+·(Et2O). Complex 2 dissolved in THF converts to 4a and 4b. 1, 2, 3, 4a, and 4b were characterized by X-ray diffraction. 1, 4a, and 4b were also fully characterized by multinuclear NMR spectroscopy.