Abstract Dinuclear copper(I) complexes with bridging bis(dicyclohexylphosphino)methane (dcpm) or bis(diphenylphosphino)methane (dppm) and 2,2′-bipyridine or 2-[ N-(2-pyridyl)methyl]amino-5,7-dimethyl-1,8-naphthyridine (L), [Cu 2(bpy) 2(dppm) 2](BF 4) 2 ( 1), [Cu 2(bpy) 2(dcpm)](BF 4) 2 ( 2), [Cu 2(L)(dppm)](BF 4) 2 ( 3) and [Cu 2(L)(dcpm)](BF 4) 2 ( 4) were prepared, and their structures were determined by X-ray crystal analysis. Two-, three-, and four-coordinate copper(I) centers are found in these complexes. Compounds 3 and 4 show close Cu I⋯Cu I separations of 2.664(3) and 2.674(1) Å, respectively, whereas an intramolecular copper–copper distance of 3.038 Å is found in 2 having only dcpm as an additional bridge. Powdered samples of 1, 3, and 4 display intense and long-lived phosphorescence with λ max at 533, 575, and 585 nm at room temperature, respectively. In the solid state, 2 exhibits only a weak emission at 555 nm. The time-resolved absorption and emission spectra of these complexes were investigated. The difference in the emission properties among complexes 1– 4 suggests that both Cu I⋯Cu I distances and coordination environment of the copper(I) centers affect the excited-state properties.