Synthesis and crystal structure of dimethylgold(III) carboxylates

Three novel carboxylate complexes were synthesized: dimethylgold(III) trifluoroacetate [Me2Au(Tfa)](2) (I), trimethylacetate (pivalate) [Me2Au(Piv)](2) (II), and benzoate [Me2Au(OBz)](2) (III). The starting reagent was [Me2AuI](2). The procedure of its synthesis provides 60% product yield. Dimethylgold(III) carboxylates were identified from the IR and H-1 NMR data. The title compounds were studied by X-ray diffraction. The unit cell parameters for I, C8H12Au2F6O4: a = 15.5522(13), b = 12.9398(11), c = 15.6555(14) angstrom, beta = 104.308(2)degrees, Z = 8, rho(calcd.) = 2.959 g/cm(3), space group C2/c, R = 0.0779; for II, C14H30Au2O4: a = 10.3025(3), b = 15.5952(4), c = 12.6819(3) angstrom, beta = 105.8270(10)degrees, Z = 4, rho(calcd.) = 2.224 g/cm(3), space group P2(1)/c, R = 0.0229; for III, C18H22Au2O4: a = 12.8050(2), b = 19.7886(3), c = 7.60300(10) angstrom, Z = 4, rho(calcd.) = 2.401 g/cm(3), space group Pnma, R = 0.0144. Compounds I-III have the molecular structures; the structural units are the [(CH3)(2)Au(OOCR)](2) dimers (Au...Au 2.984-3.080 angstrom), R = CF3, tert-Bu, Ph. The gold atoms have the square coordination with two carbon atoms and two oxygen atoms (Au-O 2.120-2.173 angstrom). The molecules in compounds I-III are united into infinite unidimensional chains connected by van der Waals interactions.