Bipyridyl/carbazolate silver(I) and gold(I) N-heterocyclic carbene complexes: A systematic study of geometric constraints and electronic properties

Abstract

A series of silver(I) and gold(I) carbene complexes of the type [M(L)(2,2 '-bipyridine)][PF6] (L = 1-benzyl-3-(2-pyridylmethyl)benzimidazolylidene; M = Ag (1); M = Au (3)) and [M(L)(carbazole)] (M = Ag (2); M = Au (4)) were synthesized and analyzed using a range of spectroscopic and crystallographic techniques. Inspection of the solid-state structures of 1, 2 and 4 revealed a number of intermolecular noncovalent interactions. In the solid-state structure adopted by 1, pi-pi and Ag-Ag interactions directed the complexes to orient in a head-to-tail fashion. The photophysical properties were found to be influenced by the ancillary ligands in solution as well as in the solid-state. Calculations were performed to support the aforementioned structural and optoelectronic assignments.