Mono- and bi-nuclear titanium imido complexes supported by aryloxide ligands: fine control by ortho substituents

Reaction of the titanium imido complexes [Ti(NR)Cl 2 (py) 3 ] (R = Bu t , C 6 H 3 Me 2 -2,6 or C 6 H 3 Pr i 2 -2,6; py = pyridine) with 2 equivalents of lithium aryloxide Li[OC 6 H 3 R′ 2 -2,6] (R′ = Me, Pr i or Bu t ) afforded the mononuclear four- or five-co-ordinate or binuclear four-co-ordinate complexes [{Ti(NR)(OC 6 H 3 R′ 2 -2,6) 2 (py) n } m ] (m = 1, n = 1 or 2; m = 2, n = 0) depending on the identity of R and R′. The crystal structures of [Ti 2 (µ-NBu t ) 2 (OC 6 H 3 Me 2 -2,6) 4 ] 1 and [Ti(NC 6 H 3 Me 2 -2,6)(OC 6 H 3 Me 2 -2,6) 2 (py) 2 ] have been determined. Extended-Hückel molecular orbital calculations for models of 1 showed that the deviation of the µ-imido Bu t substituents from coplanarity with the Ti 2 N 2 core in this and some related species can be attributed to a second-order Jahn–Teller distortion.