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

Abstract

We present two important trends in the reactivity of the titanium complex [ Me NacNacTi(Cl){η 2 -P(SiMe 3 )-P t Bu 2 }] ( Me NacNac – = [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6- i Pr 2 Ph) with nucleophilic reagents RLi (R = Ph 2 P, t BuO, (Me 3 Si) 2 N, and t Bu 2 N) 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 [ Me NacNacTi(R){η 2 -P-P t Bu 2 }] ( 1 for R = PPh 2 ), via the elimination of Me 3 SiR to afford Ti(III) complex [ Me NacNacTi(Cl){η 2 -P-P t Bu 2 }] − [Li(12-crown-4) 2 ] + ( 2 ), and via 2e – reduction process to afford new ionic complex [{ArNC(Me)CHC(Me)}Ti=NAr{η 1 -P(SiMe 3 )-P t Bu 2 }] − [Li(12-crown-4) 2 ] + ( 3 ). Quite differently, the complex [ Me NacNacTi(Cl){η 2 -P(SiMe 3 )-P t Bu 2 }] reacts with Ph 2 PLi in THF, unexpectedly yielding two new, four-coordinate Ti(IV) imido complexes 4a [{ArNC(Me)=CHC(H)(Me)-P(P t Bu 2 )}Ti=NAr(Cl)] − [Li(12-crown-4) 2 ] + ·(toluene) 2 and 4b [{ArNC(CH 2 )CH=C(Me)-P(P t Bu 2 )}Ti=NAr(Cl)] − [Li(12-crown-4) 2 ] + ·(Et 2 O). 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.

Expanding the Utility of β-Diketiminate Ligands in Heavy Group VI Chemistry of Molybdenum and Tungsten

“…Nitrene transfer reactions are commonly observed with BDI ligands, especially with low-valent early transition metals, e.g., titanium, − niobium, ,, and rhenium . Complex 17 crystallizes in the triclinic space group P 1̅ with half a molecule in the asymmetric unit.…”