Syntheses, crystal structures and properties of dinuclear copper(I) complexes

Two dinuclear molecule-bridged Cu(I) complexes, (μ-bpym)[Cu(PPh3)Cl]2 (1), [(μ-bpym)(CuL)2](ClO4)2·(CH3CN)2(H2O) (2) (bpym = 2,2′-bipyrimidine, L = (R)-(+)-2,2′-bis(diphenylphospho)-1,1′-dinaphthalene) have been synthesized and characterized. The molecular structures of the two new dinuclear compounds exhibit bridging of two copper(I) centers by the symmetrically bis-chelating bpym ligand. Intriguingly, compound 1 features a remarkable “intramolecular organic sandwich” configuration where the central 2,2′-bipyrimidine bridging ligand interacts in π/π/π fashion with two phenyl rings from the coligands above and below the central plane, while chiral compound 2 exhibits second-order nonlinear optical effect and temperature-dependent luminescence. Upon decreasing the temperature from 298 to 10 K, compound 2 shows a red light emission.