Synthesis and characterization of osmium polyhydrides. X-ray crystal structures of (C5Me5)OsH5 and (C 5Me5)2Os2H4

Christopher L. Gross, Gregory S. Girolami

Research output: Contribution to journalArticle

Abstract

Treatment of (C5Me5)2Os2Br 4 with LiAlH4 in Et2O followed by addition of MeOH at -78°C affords two products: the osmium(VI) pentahydride (C 5Me5)OsH5 and the dinuclear osmium(III) tetrahydride (C5Me5)2Os2H 4. The X-ray crystal structures reveal that (C5Me 5)OsH5 adopts a pseudo-octahedral geometry with one axial and four equatorial hydride ligands, whereas all four hydride ligands in (C 5Me5)2Os2H4 bridge the osmium-osmium axis. Treatment of (C5Me5)OsH5 with HBF4·Et2O affords the osmium-(VIII) hexahydride [(C5Me5)OsH6][BF4], which evidently adopts a classical polyhydride structure, as judged from variable-temperature T1 studies. Treatment of (C5Me 5)OsH5 with tert-butyllithium in the presence of N,N,N′,N″,N″-pentamethyldiethylenetriamine (pmdeta) affords the osmium(IV) tetrahydride salt [Li(pmdeta)][(C5Me 5)OsH4], which is proposed to adopt a four-legged piano stool geometry. IR and NMR studies of the Os-D analogues of these new osmium hydrides are also discussed.

Original languageEnglish (US)
Pages (from-to)160-166
Number of pages7
JournalOrganometallics
Volume26
Issue number1
DOIs
StatePublished - Jan 1 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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