Copper(I) Complexes of Anionic Tridentate CNC Pincer Ligands

Nickel(II) carbonyl, ammonia, and aceto-nitrile complexes supported by a pyridine dipyrrolide pincer ligand

The synthesis, isolation and crystal structures of nickel(II) carbonyl, aceto-nitrile and ammonia complexes supported by a dianionic, pyridine dipyrrolide pincer ligand [pyrr2py]2-, namely, carbonyl[2,2'-(pyridine-2,6-di-yl)bis-(3,5-di-p-tolyl-pyrrolido-κN)]-nickel(II), [Ni(C41H33N3)(CO)], ammine[2,2'-(pyridine-2,6-di-yl)bis-(3,5-di-p-tolyl-pyrrolido-κN)]nickel(II), [Ni(C41H33N3)(NH3)], and (aceto-nitrile-κN)[2,2'-(pyridine-2,6-di-yl)bis-(3,5-di-p-tolyl-pyrrolido-κN)]nickel(II), [Ni(C41H33N3)(CH3CN)], as well as the free ligand 2,6-bis-(3,5-di-p-tolyl-pyrrol-2-yl)pyridine, C41H35N3 or [pyrr2py]H2 are reported. The nickel complexes are four-coordinate and adopt a square-planar geometry. The CO stretch of the nickel-bound carbon monoxide ligand of [pyrr2py]Ni(CO) has been observed at 2101 cm-1. The ammonia and aceto-nitrile complexes, [pyrr2py]Ni(NH3) and [pyrr2py]Ni(NCMe) feature all-nitro-gen coordination spheres around nickel consisting of different N-donor ligand types.

Mercury(II) Complexes of Anionic N-Heterocyclic Carbene Ligands: Steric Effects of the Backbone Substituent

Mercury(II) complexes (Me-maloNHC_Dipp)HgCl (1b), (t-Bu-maloNHC_Dipp)HgCl (2b) and (t-Bu-maloNHC_Dipp)HgMe (2c) supported by anionic N-heterocyclic carbenes have been obtained in good yields from the reaction of the potassium salt of N-heterocyclic carbene ligand precursors and mercury(II) salts, HgCl₂ and MeHgI. These molecules have been characterized by ¹H-NMR, ¹³C-NMR and IR spectroscopy and elemental analysis. X-ray crystal structures of 1b and 2b are also presented. Interestingly, complex 1b is polymeric {(Me-maloNHC_Dipp)HgCl}_n in the solid state, as a result of inter-molecular Hg-O contacts, and features rare three coordinate mercury sites with a T-shaped arrangement, whereas the (t-Bu-maloNHC_Dipp)HgCl (2b) is monomeric and has a linear, two-coordinate mercury center. The formation of T-shaped structure and the aggregation of complex 1b is attributable to the reduced steric demand of the N-heterocyclic carbene ligand backbone substituent.