A dinuclear copper(I) complex bearing a mesoionic carbene ligand has been prepared from the corresponding silver analogue and its structure determined spectroscopically. The results revealed that two Cu(I) halide salt molecules were bound to the carbon atoms of the pyridine-bridged bis(triazolylidene) moieties rather than the pyridine. Cyclic voltammogram measurements revealed that the two Cu(I) centres underwent a stepwise oxidation, suggesting that both the triazolylidene rings of the ligand could be on the same expanded pi-conjugated system. The catalytic hydroboration of styrene derivatives with bis(pinacolato) diborane in the presence of this complex allowed for the beta-selective formation of the corresponding alkylboronate esters.