文摘
Homoleptic ruthenium complexes [Ru(Ln)2]2+ bearing unsymmetric pyridine-based bisN-heterocyclic carbene (NHC) pincer ligands are synthesized and structurally characterized. These complexes feature the coexistence of a five-membered and a six-membered ruthenacycle within the same ligand framework, allowing an ideally octahedral CNHC鈥揜u鈥揘Py bite angle close to 90掳. In the solid state, impressive 3MLCT lifetimes of microsecond regime were detected in all of the complexes, of which [Ru(L4)2]2+, featuring four benzimidazol-2-ylidene donors, exhibited the longest values. Electronic properties of all of the ruthenium complexes are investigated by cyclic voltammetry and spectroscopic techniques. Density functional theory results were used to support the experimental observations.