Aggregation of Dinuclear Cations [{Au(PR3)}2(μ‐OH)]+ into Dimers Induced by Polyoxometalate (POM) Template Effects

Abstract

AbstractIntercluster compounds, [{(Au{P(p‐XPh)3})2(μ‐OH)}2][α‐SiMo12O40(Au{P(p‐XPh)3})2]·nEtOH [X = F (1), Cl (2)] were synthesized by polyoxometalate (POM)‐mediated clusterization, and were unequivocally characterized by X‐ray crystallography, elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared (FT‐IR), solid‐state cross‐polarization magic‐angle‐spinning (CPMAS) 31P nuclear magnetic resonance (NMR), and solution (1H, 31P{1H}) NMR spectroscopy. The “dimer‐of‐dinuclear phosphanegold(I) cation”, i.e., [{(Au{P(p‐XPh)3})2(μ‐OH)}2]2+ was formed by the self‐assembly of dinuclear phosphanegold(I) cations, i.e., [(Au{P(p‐XPh)3})2(μ‐OH)]+, through inter‐cationic aurophilic interactions as the crossed‐edge arrangement (or tetrahedral Au4 structure) for 1, while as the parallel‐edge arrangement (or rectangular Au4 structure) for 2. The latter arrangement was first attained only by assistance of the POM. The POM anions in 1 and 2 contained two mononuclear phosphanegold(I) cations, i.e., [Au{P(p‐XPh)3}]+, linked to the OMo2 oxygen atoms of edge‐sharing MoO6 octahedra. In the solution 31P{1H} NMR of 1 and 2, we observed single signals due to the rapid exchange of the phosphanegold(I) units. This shows that the OMo2 oxygen atoms of edge‐sharing MoO6 octahedra in the Keggin POM act as multi‐centered active binding sites for the formation of [{(Au{P(p‐XPh)3})2(μ‐OH)}2]2+.