RETRACTED: Terminal gold-oxo complexes (Retracted Article)

In contradiction to current bonding paradigms, two terminal Au-oxo molecular complexes have been synthesized by reaction of AuCl3 with metal oxide-cluster ligands that model redox-active metal oxide surfaces. Use of K-10[alpha(2)-P2W17O61]-20H(2)O and K2WO4 (forming the [A-PW9O34](9-) ligand in situ) produces K15H2[Au(O)(OH2)P2W18O68]center dot 25H(2)O (1); use of K-10[P2W20O70(OH2)(2)]center dot 22H(2)O (3) produces K7H2[Au(O)(OH2)P2W20O70(OH2)(2)]center dot 27H(2)O (2). Complex 1 crystallizes in orthorhombic Fddd, with a = 28.594(4) angstrom, b = 31.866(4) angstrom, C = 38.241(5) angstrom, V = 34844(7) angstrom(3), Z = 16 (final R = 0.0540), and complex 2 crystallizes in hexagonal P6(3)lmmc, with a = 16.1730(g) angstrom, b = 16.1730(g) angstrom, c = 19.7659(15) angstrom, V = 4477.4(5) angstrom(3), Z = 2 (final R = 0.0634). The polyanion unit in 1 is disorder-free. Very short (similar to 1.76 angstrom) Au-oxo distances are established by both X-ray and 30 K neutron diffraction studies, and the latter confirms oxo and trans aqua (H2O) ligands on Au. Seven findings clarify that Au and not W is present in the Au-oxo position in 1 and 2. Five lines of evidence are consistent with the presence of d(8) Au(III) centers that are stabilized by the flanking polytungstate ligands in both 1 and 2: redox titrations, electrochemical measurements, 17 K optical spectra, Au L-2 edge X-ray absorption spectroscopy, and Au-oxo bond distances. Variable-temperature magnetic susceptibility data for crystalline 1 and 2 establish that both solids are diamagnetic, and P-31 and O-17 NMR spectroscopy confirm that both remain diamagnetic in solution. Both complexes have been further characterized by FT-IR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and other techniques.