Silver and Palladium Complexes of a Bis(benzimidazolin-2-ylidene)pyridine Pincer Ligand

Abstract

Reaction of 2,6-bis(3-butylbenzimidazol-1-ium)pyridine dibromide with silver oxide affords a dinuclear complex of the type [L 2 Ag 2 ] 2+ [L = 2,6-bis(3-butylbenzimidazolin-2ylidene)pyridine]. 1 H NMR spectroscopic studies suggest that the dinuclear structure is also present in solution. Transmetallation of the silver-NHC complex with PdCl 2 (CH 3 CN) 2 yields a mononuclear palladium complex of the type [LPdCl] + , with a chelating C,N,C-pincer ligand.

Trinuclear copper(I) complex of 1,3-bis(2-pyridinylmethyl)imidazolylidene as a carbene-transfer reagent for the preparation of catalytically active nickel(II) and palladium(II) complexes

“…Selected bond lengths ( A) and angles (deg): Cu(1)eC(37) 2.024(2), Cu(1)e C(7) 2.030(2), Cu(1)eN(1) 2.117(2), Cu(1)eN(9) 2.125(2), Cu(2)eC(50) 2.022(2), Cu(2)e C(7) 2.025(2), Cu(2)eN(5) 2.135(2), Cu(2)eN(4) 2.139(2), Cu(3)eC(37) 2.041(3), Cu(3)e C(50) 2.055(3), Cu(3)eN(8) 2.129(2), Cu(3)eN(12) 2.139(2), Cu(1)eCu(3) 2.475(1), Cu(1)eCu(2) 2.512(1), Cu(2)eCu(3) 2.506(1), Cu(3)eCu(1)eCu(2) 60.305(14), Cu(3)e Cu(2)eCu(1) 59.117(14), Cu(1)eCu(3)eCu(2) 60.577(14).…”

Synthesis, Solid-state Structures, Solution Behaviour and Catalysis Studies of Nickel Complexes of Bis(benzimidazolin-2-ylidene)pyridine Pincer Ligands

“…The syntheses reported here are derived from the previously reported procedures for the synthesis of 2 (X = Br), 3•PF 6 (X = Br) and the bis(benzimidazolium) dibromide salt used as the ligand precursor. [10,13] Treatment of 5,6-dimethoxybenzimidazole [24] with sodium hydride and then reaction of the resulting benzimidazolate anion with 2,6-dichloropyridine in DMF at 70°C for 24 hours and then 140 °C for a further 24 hours affords 1,3-bis(5,6-dimethoxybenzimidazol-1-yl)yridine (4) in good yield (Scheme 1). Alkylation of 4 with a large excess of 1-bromobutane affords the bis(benzimidazolium) salt 5•2Br.…”

“…[1,2,[4][5][6][7][8] By comparison, complexes of the benzimidazole-based 2,6-bis(benzimidazolin-2-ylidene)pyridine ligand system have only been reported with Pd, Ag, Os and recently Ni. [4,[9][10][11][12][13][14] In our recent exploration of nickel complexes of the 2,6-bis(benzimidazolin-2ylidene)pyridine ligand system we identified the formation of the five-coordinate [(CNC)NiX 2 ] complexes 2 (X = Cl, Br), [13] an unusual coordination geometry for this CNC ligand system. Other studies of nickel complexes with 2,6-bis(imidazol-2-ylidene)pyridine ligands have predominantly identified only four-coordinate [(CNC)NiX] + geometries, [7,[15][16][17] with one example of a sixcoordinate nickel complex.…”

Potentially Hemilabile N-Heterocyclic Carbene Palladium Complexes: Synthesis and Catalytic Applications

“…A palladium complex 71 of bis(benzimidazolin-2-ylidene)-2,6-pyridine is also known to be prepared through carbene transfer route from the corresponding silver-NHC complex in moderate yield (Scheme 22). The structure of the cation of complex 71 has a slightly distorted square-planar geometry around the central Pd atom [57].…”