Abstract
RhL2Cl(CO) (1; L = PMe3), a known catalyst for the photodehydrogenation of alkanes, is found to catalyze the highly efficient thermal (nonphotochemical) transfer-dehydrogenation of alkanes under high-pressure hydrogen atmosphere. The proposed mechanism involves addition of H2, loss of CO, and transfer of H2 to a sacrificial acceptor, thereby generating RhL2Cl, the same catalytically active fragment formed by photolysis of 1. Consistent with this proposal, we report that photochemically inactive species, RhL2ClL′ (L′ = P'Pr3, PCy3, PMe3) and [RhL2Cl]2, are also thermochemical catalyst precursors. These species demonstrate much greater catalytic activity than RhL2Cl(CO), particularly under moderate hydrogen pressures (ca. 500 times greater under 800 Torr of H2 at 50°C). The dependence of the turnover rates on hydrogen pressure is consistent with the proposed role of hydrogen, i.e., displacement of L′ from the four-coordinate complexes or fragmentation of H2Rh2L4Cl2, giving H2RhL2Cl, which is dehydrogenated by olefin to give RhL2Cl. Selectivity studies provide further support for the characterization of the active fragment.
| Original language | English |
|---|---|
| Pages (from-to) | 9492-9498 |
| Number of pages | 7 |
| Journal | Journal of the American Chemical Society |
| Volume | 114 |
| Issue number | 24 |
| Publication status | Published - 1992 |
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Efficient transfer-dehydrogenation of alkanes catalyzed by rhodium trimethylphosphine complexes under dihydrogen atmosphere. / Maguire, John A.; Petrillo, Angelo; Goldman, Alan S.
In: Journal of the American Chemical Society, Vol. 114, No. 24, 1992, p. 9492-9498.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Efficient transfer-dehydrogenation of alkanes catalyzed by rhodium trimethylphosphine complexes under dihydrogen atmosphere
AU - Maguire, John A.
AU - Petrillo, Angelo
AU - Goldman, Alan S
PY - 1992
Y1 - 1992
N2 - RhL2Cl(CO) (1; L = PMe3), a known catalyst for the photodehydrogenation of alkanes, is found to catalyze the highly efficient thermal (nonphotochemical) transfer-dehydrogenation of alkanes under high-pressure hydrogen atmosphere. The proposed mechanism involves addition of H2, loss of CO, and transfer of H2 to a sacrificial acceptor, thereby generating RhL2Cl, the same catalytically active fragment formed by photolysis of 1. Consistent with this proposal, we report that photochemically inactive species, RhL2ClL′ (L′ = P'Pr3, PCy3, PMe3) and [RhL2Cl]2, are also thermochemical catalyst precursors. These species demonstrate much greater catalytic activity than RhL2Cl(CO), particularly under moderate hydrogen pressures (ca. 500 times greater under 800 Torr of H2 at 50°C). The dependence of the turnover rates on hydrogen pressure is consistent with the proposed role of hydrogen, i.e., displacement of L′ from the four-coordinate complexes or fragmentation of H2Rh2L4Cl2, giving H2RhL2Cl, which is dehydrogenated by olefin to give RhL2Cl. Selectivity studies provide further support for the characterization of the active fragment.
AB - RhL2Cl(CO) (1; L = PMe3), a known catalyst for the photodehydrogenation of alkanes, is found to catalyze the highly efficient thermal (nonphotochemical) transfer-dehydrogenation of alkanes under high-pressure hydrogen atmosphere. The proposed mechanism involves addition of H2, loss of CO, and transfer of H2 to a sacrificial acceptor, thereby generating RhL2Cl, the same catalytically active fragment formed by photolysis of 1. Consistent with this proposal, we report that photochemically inactive species, RhL2ClL′ (L′ = P'Pr3, PCy3, PMe3) and [RhL2Cl]2, are also thermochemical catalyst precursors. These species demonstrate much greater catalytic activity than RhL2Cl(CO), particularly under moderate hydrogen pressures (ca. 500 times greater under 800 Torr of H2 at 50°C). The dependence of the turnover rates on hydrogen pressure is consistent with the proposed role of hydrogen, i.e., displacement of L′ from the four-coordinate complexes or fragmentation of H2Rh2L4Cl2, giving H2RhL2Cl, which is dehydrogenated by olefin to give RhL2Cl. Selectivity studies provide further support for the characterization of the active fragment.
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M3 - Article
VL - 114
SP - 9492
EP - 9498
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 24
ER -