Syntheses, structures and photophysical properties of binuclear copper(I) complexes bridged by diphosphine ligands

Reaction of [Cu(NCCH3)(4)]ClO4 with 5,5'-dibromo-2,2'-bipyridine (BrbpyBr) and diphosphine ligands Ph2P(CH2)(x)PPh2 (x = 1, 4, 5, 6) in dichloromethane gives good yields of a series of binuclear copper(I) complexes [Cu-2(BrbpyBr)(2)(Ph2P(CH2)(x)PPh2)(2)](ClO4)(2), where x is 1, 4, 5 and 6 in complexes 1-4, respectively. The crystallographic data and the space-filling drawings of complexes 1 and 3 show that the Cu(I) centers, N atom centers and P atoms centers are well protected by the close contact of BrbpyBr and diphosphine ligands, which may be the reasons why complexes 1-4 are so stable to air and moisture in the solid state. The ESI-MS result through changing the collision cell energy from 0 to 15 eV suggests that the binding energies between Cu(I) ions and Ph2P(CH2)(x)PPh2 ligands are much larger than that between Cu(I) and BrbpyBr ligand in the [Cu-2(BrbpyBr)(2)(Ph2P(CH2)(x)PPh2)(2)](2+) cations, confirming that the corresponding [Cu-2(Ph2P(CH2)xPPh(2))(2)](2+) cations are the thermodynamically stable products in DCM solutions. All the complexes 1-4 display good phosphorescent emission in the solid state. (C) 2013 Elsevier B.V. All rights reserved.