PHOSPHOLE COMPLEXES OF GOLD(III) HALIDES - SYNTHESIS, STRUCTURE, ELECTROCHEMISTRY AND LIGAND REDISTRIBUTION REACTIONS

The complexes LAuCl3 [L = 1-phenyl-3,4-dimethylphosphole(DMPP), 1-phenyldibenzophosphole(DBP) and triphenylphosphine], LAuBr3 (L = DBP, Ph3P) and LAuClBr2 (L = DBP, Ph3P) were prepared and characterized by physical properties, cyclic voltammetry, far IR, P-31{H-1} and CP/MAS P-31{H-1} NMR spectroscopy. Ligand redistribution reactions of the types: LAuCl + L'AuBr half-arrow-right-over-half-arrow-left L'AuCl + LAuBr; LAuCl3 + LAuBr3 half-arrow-right-over-half-arrow-left LAuClnBr3-n; L'AuCl3 + L'AuBr3 half-arrow-right-over-half-arrow-left LAuClnBr3-n + L'AuClnBr3-n; and LAu Cl + L'AuBr3 half-arrow-right-over-half-arrow-left LAuBr + L'AuCl + L'AuBr + LAuClnBr3-n + L'AuClnBr3-n all occur rapidly and have been studied by P-31{H-1} NMR spectroscopy. These reactions all appear to proceed by way of halide-bridged intermediates. The solid state identities of LAuClBr2 were established by a combination of far IR and CP/MAS P-31{H-1} NMR spectroscopies and single crystal X-ray crystallography for Ph3PAuBr2Cl. The R3PAuBr2Cl complexes are substitutionally disordered, probably with two-thirds bromine and one-third chlorine in each site. Ph3PAuBr2Cl crystallized in the monoclinic space group P2(1)/c with a = 9.086(2), b = 11.410(2), c = 18.734(4) angstrom beta = 95.01-degrees(2), and Z = 4. The structure was solved by least-squares methods with R(F) = 0.074 for 1919 unique reflections with I/sigma(I) greater-than-or-equal-to 3.0. The gold atom has nearly regular square-planar coordination with Au-P = 2.314(6) A-degrees and Au-X = 2.399(3), 2.413(3) and 2.415(4) A-degrees.