MULTIPLE BONDS BETWEEN MAIN-GROUP ELEMENTS AND TRANSITION METALS. CXXXV, TETRAMETHYLOXOOSMIUM(VI) : SYNTHESIS, GAS-PHASE MOLECULAR STRUCTURE, PHOTOELE CTRON SPECTROSCOPY, AND ELECTROCHEMISTRY

Tetramethyloxoosmium(VI) (2a), the first example of methylosmium oxides (CH 3 ) x Os y O z , has been synthesized from osmium tetraoxide (1a) and dimethylzinc (19% yield) or methyltris(isopropoxy) titanium (50% yield). A more directed synthesis (60% yield) is methylation of the glycolate osmium(VI) complex O=Os(OCH 2 CH 2 O) 2 (1b), which precursor compound is in turn accessible from 1a in quantitative yield. The thermally labile ethyl derivative tetraethyloxoosmium(VI) (2b), the first well-characterized example of its class (C 2 H 5 ) x Os y O z , is also reported