TY - JOUR
T1 - Synthesis and characterization of osmium polyhydrides. X-ray crystal structures of (C5Me5)OsH5 and (C 5Me5)2Os2H4
AU - Gross, Christopher L.
AU - Girolami, Gregory S.
PY - 2007/1/1
Y1 - 2007/1/1
N2 - 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.
AB - 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.
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U2 - 10.1021/om060920b
DO - 10.1021/om060920b
M3 - Article
AN - SCOPUS:33846263427
SN - 0276-7333
VL - 26
SP - 160
EP - 166
JO - Organometallics
JF - Organometallics
IS - 1
ER -