Luminescent organometallic gold(I) complexes. Structure and photophysical properties of alkyl-, aryl- and μ-ethynylene gold(I) complexes

Abstract

The complexes [Au(PPh3)Ph] 1, [Au2(dppm)Me2] 2, [Au2(dppm)Ph2] 3 and [{Au[P(C6H4OMe-p)3]} 2(μ-C≡C)] 4 were prepared by literature methods. The structures of 1-3 have been established by X-ray crystallography: 1, triclinic, space group P1, a = 8.524(2), b = 15.227(2), c = 15.525 Å, α = 91.07(1), β = 92.06(1), γ = 94.28(1)°; 2, monoclinic, space group P21/n, a = 12.201(3), b = 13.014(5), c = 16.329(4) Å, β = 94.11(2)°; 3, monoclinic, space group C2/c, a = 16.688(3), b = 10.468(1), c = 17.899(2) Å, β = 97.70(1)°. The intramolecular Au ⋯ Au distances in 2 and 3 are 3.251(1) and 3.154(1) Å respectively. Extended-Hückel molecular orbital calculations showed that the highest occupied molecular orbital of 3 is a combination of dσ* and dδ*, whereas its lowest unoccupied molecular orbital is the π* of the co-ordinated phenyl group. The UV/VIS absorption spectra of 2 and 3 show intense absorptions at around 290-300 nm, which are assigned as Au(dσ*, dδ*) → π* (Ph, dppm) in nature. Both 2 and 3 show luminescence in fluid solution at room temperature. The emission properties of 3 have been examined in detail. Complex 4 shows a well resolved vibronic structured emission at 400-600 nm in dichloromethane at room temperature, arising from the 3[ππ*] excited state of C2 2-. © Copyright 1994 by the Royal Society of Chemistry.