EMISSION SPECTROSCOPIC PROPERTIES OF 1,2-BIS(DICYCLOHEXYLPHOSPHINO)ETHANE COMPLEXES OF GOLD(I)

The photophysics of [Au2(dcpe)2](PF6)2, [AU2(dcpe)3](PF6)2, and [Au(dcpe)2]PF6 (dcpe = bis(dicyclohexylphosphino)ethane) show that the ligand environment about the gold atom plays a crucial role in generating long-lived Au(I) excited states. The [Au2(dcpe)2](PF6)2 complex, which has a Au-Au distance of 2.936 angstrom, exhibits emission at 489 nm at 77 K. The AuP3 units in [Au2(dcpe)3][Au(CN)2]2 are isolated (Au-Au = 7.0501 angstrom), and the emission (508 nm; see figure) from the triplet d-sigma*(d(xy), d(x2-y2))p-sigma(p(z)) excited state of Au2(dcpe)3(2+) has a lifetime of 21.1-mu-s and a strikingly high quantum efficiency (0.80) at room temperature in acetonitrile solution.