Related Experiment Video
Updated: Jun 13, 2026

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Synthesis and structure of early transition metal NHC complexes
Christian Lorber1, Laure Vendier
1CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077, Toulouse, France. lorber@lcc-toulouse.fr
Abstract:
The synthesis and structure of several new early transition metal (Ti, Zr, Hf, and V) NHC complexes supported by one or two IMes ligands is described. Reaction of M(NMe2)4 with IMes.HCl gives compounds VCl2(NMe2)(IMes)2 (2), and MCl2(NMe2)2(IMes) (M = V (3), Zr (4), Hf (5)). Treatment of TiCl3(THF)3 with 2 equiv. of IMes and 1 equiv. of LiNMe2 affords the titanium(III) compound TiCl2(NMe2)(IMes)2. Reaction of VCl3(THF)3 with 2 equiv. of IMes in toluene produces the trivalent complex VCl3(IMes)2 (6), while VCl2(Py)4 gives the divalent compound VCl2(IMes)(Py)3 (7), and ZrCl4(THF)2 leads to ZrCl4(IMes)2 (8). Imido compounds M(N-2,6-iPr2-C6H3)Cl2(NHMe2)(IMes) (M = V (9), Zr (10)) are prepared from V(NR)Cl2(NHMe2)2 or ZrCl2(NMe2)2(IMes) synthons. Ionic imido complexes [M(N-2,6-iPr2-C6H3)Cl3(IMes)]-[HIMes]+ (M = V (12), Ti (13)) are obtained in modest yields from the treatment of [M(NR)Cl2(NHMe2)2] with 2 equiv. of IMes. Treatment of a toluene solution of V(NMe2)4 and an amide RC(O)NH2 (R = tBu, Ph) in the presence of an excess of Me3SiCl produces the terminal oxo complex V(O)Cl2(NHMe2)2 (13), which reacts with two equiv. of IMes to give the bis-NHC oxo-complex V(O)Cl2(IMes)2 (14). All new compounds have been characterised by various spectroscopic techniques, elemental analyses, and magnetism studies for paramagnetic compounds. The solid-state structure of 12 of these complexes and of IMes.HCl have further been confirmed by X-ray diffraction analyses.
Related Concept Videos
Coordination Number and Geometry
Coordination Compounds and Nomenclature
Valence Bond Theory
Ladder Diagrams: Complexation Equilibria
The formation constant, K1, for the formation of Cd(NH3)2+ complex from cadmium and ammonia is 3.55 × 102. Log K1 (i.e. pNH3) is 2.55, and...
Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...

