Reactivity of titanium imidazolin-2-iminato complexes with 2,6-diisopropylaniline and 2-{(2,6-diisopropylphenyl)-iminomethyl}pyrrole

Abstract

We report the reactions of imidazolin-2-iminato titanium complexes [(ImRN)Ti(NMe2)3] (R = Mes, 2b; R = Dipp, 2c; Mes = mesityl, Dipp = 2,6-diisopropylphenyl) with 2,6-diisopropylaniline in a 1:3 molar ratio to yield the titanium imido complexes of composition [(ImRNH)Ti = N(Dipp)(HNDipp)2] (R = Mes, 3b; R = Dipp, 3c) in good yield by the Ti-Niminato bond cleavage at 60 °C. In contrast, the reaction of [(ImRN)Ti(NMe2)3] with 2,6-diisopropylaniline in a 1:1 molar ratio afforded mono-substituted products [(ImRN)Ti(NMe2)2(HNDipp)] (R = Mes, 4b; R = Dipp, 4c) in good yield. The reaction of [(ImRN)Ti(NMe2)3] with the iminopyrrole ligand [2-(2,6-iPr2C6H3-N = CH)C4H3NH] (NDippPyH) in a 1:1 ratio afforded mixed ligands, titanium complexes [(ImRN)Ti(NMe2)2(NDipp-Py)] (R = tBu, 5a; R = Dipp, 5c) with imidazolin-2-iminato and iminopyrrolide ligands. Molecular structures of 3b, 3c, 4c, 5a, and 5c were determined by single-crystal X-ray analysis. The solid-state structures of 3b and 3c clearly indicate the formation of true Ti = N double bonds, measuring 1.730(2) Å and 1.727(1) Å, respectively. The solid-state structures of 5a and 5c reveal the formation of five-coordinate titanium complexes.