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-CC)]4 were prepared by literature methods. The structures of 1–3 have been established by X-ray crystallography: 1, tnclinic, space group P, 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 C22–.