Cyclic voltammetry (CV) experiments on LL(AuSR∗)2
complexes [LL = diphenylphosphinomethane
(dppm), diphenylphosphinopentane (dpppn); R* = p-SC6H4CH3] show anodic sweeps that broaden by
about 25 mV on going from the longer (dpppn) to the shorter (dppm) bidentate phosphine ligand.
Changing concentrations had no effect on the shape of the waveform. The result suggests a weak
intramolecular metal-metal interaction in dppm(AuSR∗)2
that correlates well with rate acceleration
occurring in the reaction of dppm(AuSR∗)2
with organic disulfides. Quantum yields for cis-dppee(AuX)2
[dppee = 1,2-bis(diphenylphosphino)ethylene; X = Cl, Br, I] complexes, (disappearance)Φ, are significantly
higher in complexes with a softer X ligand, a trend that correlates well with aurophilicity. This result also
suggests that electronic perturbation caused by Au(I)-Au(I) interactions is important in explaining the
reactivity of some dinuclear gold(I) complexes. The crystal structure for cis-dppee(Aul)2
shows short
intramolecular Au(I)-Au(I) interactions of 2.9526 (6) A°, while the structure of trans-dppee(AuI)2
, shows intermolecular Au(I)-Au(I) interactions of 3.2292 (9) A°. The substitution of .As for P results in a ligand, cis-diphenylarsinoethylene
(cis-dpaee), that is photochemically active, in contrast to the cis-dppee ligand.
The complexes, cis-dpaee(AuX)2, are also photochemically active but with lower quantum yields than the
cis-dppee(AuX)2
complexes.
