Dinuclear Titanium(IV) Complexes Bearing Phenoxide‐Tethered N‐Heterocyclic Carbene Ligands with cisoid Conformation through Control of Hydrolysis

Abstract

AbstractIn situ generated N‐heterocyclic carbene salt derivative Na2(L) of 1,3‐bis(4,6‐di‐tert‐butyl‐2‐hydroxybenzyl)imidazolium bromide, [H3(L)]Br, reacted with 1 equiv. of TiBr4 at –78 °C to give a titanium complex of the composition [(L)TiBr2(thf)] (1), while the reaction in a 2:1 ratio under the same conditions afforded bisligand titanium complex [(L)2Ti] (2). Two oxygen‐bridged titanium dimers, {[(L)TiBr]2(μ‐O)} (4) and {[(L)Ti(μ‐O)]2} (5), were obtained by control of hydrolysis of 1 and [(L)Ti(CH2Ph)2] (3) in tetrahydrofuran and diethyl ether. The molecular structures of 2, 4, and 5 have been confirmed by X‐ray single‐crystal analysis. The phenoxide‐functionalized NHC ligand adopts transoid conformation in mononuclear complex 2 but rare cisoid conformation in dinuclear complexes 4 and 5. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)