The ³(<i>ππ</i>*) Emission of Cy₃PAu(C⋮C)<i>_n</i>AuPCy₃ (<i>n</i> = 3, 4). Effect of Chain Length upon Acetylenic ³(<i>ππ</i>*) Emission

The Cy3PAu(C⋮C)nAuPCy3 (n = 3 (3) , 4 (4)) complexes were prepared by the reaction of Me3Si(C⋮C)nSiMe3 (n = 3, 4) with Cy3PAuCl in the presence of NaOH. The molecular structure of 3·CH2Cl2 was determined by X-ray crystallography. Complexes 3 and 4 show vibronically structured acetylenic 3(ππ*) emission with ν0-0 values of 19 920 and 17 420 cm-1, respectively; hence, ν0-0 for Cy3PAu(C⋮C)∞AuPCy3 can be estimated at ∼11 000 cm-1 from the plot of ν0-0 versus 1/n.