Benzimidazole-based N-heterocyclic carbene silver complexes as catalysts for the formation of carbonates from carbon dioxide and epoxides

•A series of novel mononuclear and dinuclear Silver(I)-NHC complexes are synthesized and characterized.•Very low catalyst loading (0.1 mol%) is required for the carbon dioxide insertion into epoxides.•No solvent and co-catalyst are required using the Ag-compounds.•Catalysts are highly robust demonstrating excellent conversions selectivity > 99 %.•The novel catalyst is highly active amongst the reported silver catalysts for CO2/epoxides couplings.