2024-03-28T21:37:15Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/651132016-02-17T12:08:46Zcom_10261_31com_10261_3col_10261_284
2013-01-25T11:44:14Z
urn:hdl:10261/65113
Stoichiometric and catalytic deuteration of pyridine and methylpyridines by H/D exchange with benzene-d6 promoted by an unsaturated osmium tetrahydride species
Eguillor, Beatriz
Esteruelas, Miguel A.
García-Raboso, Jorge
Oliván, Montserrat
Oñate, Enrique
Treatment of toluene solutions of the hexahydride complex OsH 6(PiPr3)2 (1) with pyridine, 3-methylpyridine, and 4-methylpyridine affords the tetrahydride derivatives OsH4(Rpy)(PiPr3)2 (Rpy = py (3), 3-methylpyridine (4), and 4-methylpyridine (5)). In benzene-d6, these compounds release the heterocycles, and the resulting unsaturated tetrahydride OsH4(PiPr3)2 (2) promotes the stoichiometric and catalytic deuteration of pyridine, 3-methylpyridine, and 4-methylpyridine by means of H/D exchanges between the heterocycles and the solvent. The deuteration rates of the pyridinic C. - H bonds depend upon their positions in the heterocycles. For pyridine, they increase as the C. - H bonds are separated from the heteroatom. A methyl substituent has a marked negative effect on the deuteration of its adjacent C. - H bonds. The kinetic analysis of the deuteration reveals that the rate-determining step for the H/D exchanges is the C. - H activation of the bond that is deuterated. DFT calculations show that this step is formed by two elemental stages: the direct coordination of the C. - H bond and its subsequent rupture. © 2009 American Chemical Society.
2013-01-25T11:44:14Z
2013-01-25T11:44:14Z
2009
2013-01-25T11:44:14Z
artículo
Organometallics 28(13): 3700-3709 (2009)
http://hdl.handle.net/10261/65113
10.1021/om900335b
eng
closedAccess
American Chemical Society