Novel photocatalysts based on ruthenium complexes with NHC (N-heterocyclic carbene)-type bridging ligands have been prepared and structurally and photophysically characterised. The identity of the NHC-unit of the bridging ligand was established unambiguously by means of X-ray structural analysis of a heterodinuclear ruthenium-silver complex. The photophysical data indicate ultrafast intersystem crossing into an emissive and a non-emissive triplet excited state after excitation of the ruthenium centre. Exceptionally high luminescence quantum yields of up to 39% and long lifetimes of up to 2 μs are some of the triplet excited state characteristics. Preliminary studies into the visible light driven photocatalytic hydrogen formation show no induction phase and constant turnover frequencies that are independent on the concentration of the photocatalyst. In conclusion this supports the notion of a stable assembly under photocatalytic conditions.

Bromo-functionalized precursor molecules are essential for generating desired target compounds through crosscoupling reactions. Herein we show an improved synthetic route, feasible at low temperatures and affording high yields, to the ligands 5-bromo-1,10-phenanthroline (1) and 5,6-dibromo-1,10-phenanthroline (2). The corresponding ruthenium complexes, containing various equivalents of ligand 2, are easily accessible in high yields, including the analogue of tris-homoleptic [Ru(bpy) 3 ] 2+ (bpy = 2,2′-bipyridine), [Ru (2) 3 ] 2+ . X-ray dif- [a]