A late-transition metal oxo complex: [K.sub.7] [Na.sub.9][O=[Pt.sup.IV]([H.sub.2]O)[L.sub.2]], L = [[P[W.sub.9][O.sub.34]].sup.9-]

Terminal mono-oxo complexes of the late transition metal elements have long been considered too unstable to synthesize because of repulsion between the oxygen electrons and the mostly filled metal d orbitals. A platinum(IV)-oxo compound flanked by two polytungstate ligands, [K.sub.7][Na.sub.9][O=Pt([H.sub.2]O)[L.sub.2]], L = [[P[W.sub.9][O.sub.34]].sup.9-], has now been prepared and isolated at room temperature as air-stable brown crystals. X-ray and neutron diffraction at 30 kelvin revealed a very short [1.720(18) angstrom] Pt-O bond and no evidence of a hydrogen atom at the terminal oxygen, ruling out a better precedented Pt-OH complex. Density functional theory and spectroscopic data account for the stability of the Pt(IV)-oxo unit by electron withdrawal into delocalized orbitals of the polytungstates.
Despite the high electronegativity of oxygen, the terminal oxo ligand is a strong π electron donor. Lone oxygen atoms therefore bind most stably to high valent early transition metals, such [...]