Dinuclear [Cu2(N^N)(P^P)2][PF6]2 complexes containing bridging 2,3,5,6-tetra(pyridin-2-yl)pyrazine or 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine ligands

The dinuclear copper(I) complexes [Cu2(1)(POP)2][PF6]2, [Cu2(2)(POP)2][PF6]2, [Cu2(1)(xantphos)2][PF6]2 and [Cu2(2)(xantphos)2][PF6]2 containing bridging 2,3,5,6-tetra(pyridin-2-yl)pyrazine (1) or 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine (2) ligands and the P^P ligands bis(2- (diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) are presented. The single crystal structures of [Cu2(1)(POP)2][PF6]2 and [Cu2(2)(POP)2][PF6]2 confirm that both 1 and 2 act as bis(bidentate) ligands, bridging between two copper(I) centres; in [Cu2(1)(POP)2][PF6]2, two pyridine rings are non-coordinating, and in [Cu2(2)(POP)2][PF6]2, there is one non-coordinating pyridine. In solution and on the NMR timescale at 295 K, the four pyridine rings in coordinated 1 are equivalent; similarly, the three pyridine donors in the [Cu2(2)(P^P)2][PF6]2 complexes are equivalent. The dynamic behaviour of [Cu2(2)(POP)2][PF6]2 and [Cu2(2)(xantphos)2][PF6]2 are investigated using variable temperature 1H NMR spectroscopy. The photophysical properties of the complexes are discussed.