13C, 15N and 31P NMR study of the disproportionation of cyanogold(I) complexes:: [R3PAu13C15N]

The disproportionation of cyanogold(I) complexes of general formula [(R3PAuCN)-C-13-N-15] forming [(R3P)(2)Au](+) and [Au((CN)-C-13-N-15)(2)](-) ions has been investigated using C-13, N-15 and P-31 NMR spectroscopy for a series of phosphines with R=cyclohexyl, i-propyl, Et, Me, cyclohexyl/diphenyl, o-tolyl, p-tolyl, m-tolyl, p-tolyl/diphenyl, allyl/diphenyl, phenyl, tri(cyanoethyl) CEP, and I-naphthyl. The C-13 NMR of the (CN)-C-13-N-15 group in these complexes exhibited two distinct resonances, one due C-13 in the starting [(R3PAuCN)-C-13-N-15] complex and the second in the [Au((CN)-C-13-N-15)(2)](-) anion. The P-31 NMR spectra revealed two P-31 resonances due to [(R3PAuCN)-C-13-N-15] complex, and the [(R3P)(2)Au](+) cation. The N-15 NMR revealed only an averaged resonance due to [(R3PAuCN)-C-13-N-15] and [Au((CN)-C-13-N-15)(2)](-) anion, except in the cases of [(Me3PAuCN)-C-13-N-15] and [(Et3PAuCN)-C-13-N-15] where two resonances were observed. The coupling constants, (1)J(C-13-N-15), (2)J(P-31-C-13) and (3)J(O-31-N-15) were obtained for all complexes and the free energies of activation for ligand disproportionation were determined using P-31-{H-1} NMR band shape analysis. (C) 1999 Elsevier Science Ltd. All rights reserved.