STRUCTURAL, FAR-INFRARED AND P-31 NUCLEAR-MAGNETIC-RESONANCE STUDIES OF 2-CO-ORDINATE COMPLEXES OF TRIS(2,4,6-TRIMETHOXYPHENYL)PHOSPHINE WITH GOLD(I) HALIDES

The complexes [AuX(tmpp)] [X = Cl, Br or I; tmpp = tris(2,4,6-trimethoxyphenyl)phosphine] were prepared by reaction of tmpp with [AuX(Me(2)S)] or [AuX(2)](-). The crystalline compounds are isomorphous with the corresponding complexes of Cu and Ag, with Au-P 2.253(5), 2.255(4), 2.239(7), Au-X 2.303(6), 2.413(2). 2.586(2) Angstrom and P-Au-X 176.0(2). 175.9(1), 177.7(2)degrees. The Au...O contacts involving the nearest o-methoxy oxygen atoms on the three phenyl groups in the ligand are: 3.15(1), 3.08(1), 2.92(2) (chloride); 3.13(2), 3.11(1). 2.96(1) (bromide); 3.01(2), 3.10(1), 3.09(2) Angstrom (iodide). The complexes [AuX(tmpp)] were characterized by far-IR spectroscopy [nu(Au-X) 313, 218, 183 cm(-1); X = Cl, Br, I] and by P-31 NMR spectroscopy in acetonitrile [delta(P-31) -35.9, -31.8, -23.9]. All members of the series [MX(tmpp)] (M = Cu, Ag or Au; X = Cl, Br or I) are now known (although the AgI complex has so far only been detected in solution). The M-X bond properties in this series show trends which reveal the presence of relativistic effects in the M = Au case. Reaction of [AuX(tmpp)] with tmpp in a 1:1 mole ratio in solution results in displacement of X(-) to yield [Au(tmpp)(2)](+) [delta(P-31) -24.9]. Unlike the corresponding PPh(3) complexes. [AuX(tmpp)] show no evidence of (1)J((AuP)-Au-197-P-31) spin-spin splitting in their solid-state P-31 cross polarization magic angle spinning NMR spectra. A simple one-pot synthesis of the known gold(I) complex [NBu(4)][AuI2] from metallic gold was achieved.