Titanium Imido Complexes with Tetradentate Schiff Base Ligands

New mono- and binuclear titanium imido complexes supported by tetradentate, dianionic N₂O₂-donor Schiff base ligands were prepared in good yield from the readily available [Ti(NBu^t)Cl₂(py)₃] (1a). Thus treatment of 1a with Na₂[substituted-salen] gave monomeric [Ti(NBu^t)(substituted-salen)] where substituted-salen = Et₂salen (2) or Bu^t₄salen (4). In contrast, the binuclear complex [Ti(NBu^t){μ-(MeO)₂salen}]₂ (5) was obtained from 1a and Na₂[(MeO)₂salen]. The less sterically crowded compounds 2 and 5 undergo tert-butyl imide/arylamine exchange reactions to form [Ti(N-2,6-C₆H₃Me₂)(Et₂salen)] (3) and [Ti(N-2,6-C₆H₃Me₂){μ-(MeO)₂salen}]₂ (6), respectively, whereas 4 does not exhibit this kind of reactivity. The compound 3 can also be obtained directly from Na₂[Et₂salen] and [Ti(N-2,6-C₆H₃Me₂)Cl₂(py)₃] (1b). Crystal data for 3:  triclinic, P1̄, a = 12.216(4) Å, b = 12.312(11) Å, c = 17.246(2) Å, α = 90.352(12)°, β = 102.59(2)°, γ = 104.96(2)°, V = 2440.3(8) ų, Z = 4, R = 0.051, R_w = 0.066 for 7011 data with I > 2σ(I). Crystal data for 5·CH₂Cl₂:  orthorhombic, Pbca, a = 14.747(4) Å, b = 17.042(4) Å, c = 20.545(3) Å, V = 5163.5(13) ų, Z = 4, R₁ = 0.096, wR₂ = 0.086 for 3765 data with I > 2σ(I). Crystal data for 6:  monoclinic, C2/c, a = 17.902(5) Å, b = 12.411(4) Å, c = 21.068(5) Å, β = 90.27(2)°, V = 4681(2) ų, Z = 4, R = 0.034, R_w = 0.039 for 3633 data with I > 2σ(I).