title: Nickel complexes of a bis(benzimidazolin-2-ylidene)pyridine pincer ligand with four- and five-coordinate geometries.
abstract: The four- and five-coordinate complexes [(CNC)NiX(2)] (X = Cl, Br, I), [(CNC)NiX]PF(6) (X = Cl, Br) and [(CNC)NiCl]Cl·H(2)O have been isolated, where CNC is the bis(N-butylbenzimidazolin-2-ylidene)-2,6-pyridine pincer ligand. A five-coordinate geometry is rare for this class of complex. Where amenable, the complexes have been structurally characterised by single crystal X-ray diffraction studies and in solution by NMR, UV-vis and MS studies. The five-coordinate dibromo complex [(CNC)NiBr(2)] is readily prepared on the gram-scale from the benzimidazolium salt precursor and Ni(OAc)(2)·4H(2)O in DMSO without the exclusion of air. Halide exchange and salt metathesis reactions using [(CNC)NiBr(2)] afford the other four- and five-coordinate complexes. [(CNC)NiBr(2)] displays very low solubility, and upon dissolution affords solutions of the four-coordinate [(CNC)NiBr](+). Factors that influence the formation of four- or five-coordinate complexes with this ligand class are discussed.
authors.affiliation: Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA 6845, Australia. d.h.brown@curtin.edu.au
authors.forename: David H
authors.initials: DH
authors.lastname: Brown
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D001562:Benzimidazoles; D008024:Ligands; D009942:Organometallic Compounds; D011725:Pyridines; D009532:Nickel; C023666:pyridine