Hexacarbonyldiplatinum(I). Synthesis, spectroscopy, and density functional calculation of the first homoleptic, dinuclear platinum(I) carbonyl cation, [{Pt(CO)3}2]2+, formed in concentrated sulfuric acid

Qiang Xu, Brian T. Heaton, Chacko Jacob, Koichi Mogi, Yuichi Ichihashi, Yoshie Souma, Kan Kanamori, Taro Eguchi

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    Abstract

    The dissolution of PtO2 in concentrated H2SO4 under an atmosphere of CO results in the formation of hexacarbonyldiplatinum(I), [{Pt(CO)3}2]2+ (1), the first homoleptic, dinuclear, cationic platinum carbonyl complex, of which a prolonged evacuation leads to reversible disproportionation to give cis-[Pt(CO)2]2+((solv)) (2) and Pt(0). 1 has been completely characterized by NMR ((13)C and (195)Pt), IR, Raman, and EXAFS spectroscopy. The structure of 1 is rigid on the NMR time scale at room temperature. NMR: δ(13C(A)) 166.3, δ((13)C(B)) 158.7, δ((195)Pt) -211.0 ppm; 1J(Pt-C(A)) = 1281.5 Hz, 1J(Pt-C(B)) = 1595.7 Hz, 1J(Pt-Pt') = 550.9 Hz. The strongly polarized, sharp Raman band at 165 cm-1 (ρ = ca. 0.25) indicates the presence of a direct Pt-Pt bond. The IR and Raman spectra in the CO stretching region are entirely consistent with the presence of only terminal CO's on a nonbridged Pt-Pt bond with D2(d) symmetry, ν(CO)(IR): 2174 (E), 2187 (B2), and 2218 cm-1 (B2); ν(CO)(Raman): 2173 (E), 2194 (B2), 2219 (B2), 2209 (A1) and 2233 cm-1 (A1). EXAFS measurements show that the Pt - Pt bond is 2.718 Å and the mean length of the Pt-C bonds is 1.960 Å. The geometric optimization for 1 by a density functional calculation at the B3LYP level of theory predicts that the dinuclear cation contains two essentially planar tricarbonyl platinum(I) units that are linked via a Pt-Pt bond about which they are twisted by exactly 90.0° with respect to each other.

    Original languageEnglish
    Pages (from-to)6862-6870
    Number of pages9
    JournalJournal of the American Chemical Society
    Volume122
    Issue number29
    DOIs
    Publication statusPublished - Jul 26 2000

    All Science Journal Classification (ASJC) codes

    • Catalysis
    • Chemistry(all)
    • Biochemistry
    • Colloid and Surface Chemistry

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