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 1H 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) Å, β = 104.308(2)°, Z = 8, ρ(calcd.) = 2.959 g/cm3, space group C2/c, R = 0.0779; for II, C14H30Au2O4: a = 10.3025(3), b = 15.5952(4), c = 12.6819(3) Å, β = 105.8270(10)°, Z = 4, ρ(calcd.) = 2.224 g/cm3, space group P21/c, R = 0.0229; for III, C18H22Au2O4: a = 12.8050(2), b = 19.7886(3), c = 7.60300(10) Å, Z = 4, ρ(calcd.) = 2.401 g/cm3, space group Pnma, R = 0.0144. Compounds I–III have the molecular structures; the structural units are the [(CH3)2Au(OOCR)]2 dimers (Au…Au 2.984–3.080 Å), 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 Å). The molecules in compounds I–III are united into infinite unidimensional chains connected by van der Waals interactions.