Coordination complexes of TiX4 (X = F, Cl) with a bulky N-heterocyclic carbene: Syntheses, characterization and molecular structures

Reactions of the sterically encumbered N-heterocyclic carbene IPr (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, [:C{[N(2,6-iPr(2)C(6)H(3))]CH}(2)]) (1) with TiX4 (X = Cl, F) in diethyl ether or THF afford the metal halide mono- and bis-carbene complexes, [Cl4Ti-C{N(2,6-(Pr2C6H3)-Pr-i)CH}(2)] (2), [Cl4Ti{C{N(2,6-(Pr2C6H3)-Pr-i)CH}(2)}(2)] (3) and [F4Ti{C{N(2,6-(Pr2C6H3)-Pr-i)CH}(2)}(2)] (4). Compounds 2-4 have been completely characterized by elemental analysis, NMR spectroscopic methods (H-1, C-13 and F-19 NMR) and single crystal X-ray structure determination. Furthermore, the reaction of [Cl4Ti-C{N(2,6-(Pr2C6H3)-Pr-i)CH}(2)] (2) with ZnMe2 yields monomeric [ZnCl2 center dot IPr] (5), involving the transfer of carbene and chlorido ligands from Ti (IV) to Zn(II). (C) 2012 Elsevier Ltd. All rights reserved.