Preparation and Characterization of a Diamagnetic and Dinuclear Titanium(III) Formamidinate Complex. Evidence for the Existence of a Ti−Ti Bond?

The new diamagnetic Ti(III) complex (CyNC(H)NCy)4Ti2Cl2·2THF (1) containing a short Ti−Ti distance was prepared and crystallographically characterized. Ab initio unrestricted Hartree−Fock calculations suggested the presence of a Ti−Ti bonding interaction. Crystal data for 1 are as follows: C60H108N8Ti2Cl2O2, FW 1140.27, monoclinic Pn, a = 10.4688(9) Å, b = 14.4579(9) Å, c = 21.421(1) Å, β = 100.227(9)°, V = 3190.6(7) Å3, Z = 2, D calc = 1.187 g/cm3, F 000 = 1236, μ = 3.75 cm-1, T = −158 °C, R = 0.074, R w = 0.075, GOF = 3.64 for 540 parameters and 4630 reflections out of 5771 unique reflections observed.