Activation of metal-carbonyl clusters by their encapsulation within alumina sol-gel matrices

TY - JOUR

T1 - Activation of metal-carbonyl clusters by their encapsulation within alumina sol-gel matrices

AU - Eliau, Nino

AU - Avnir, David

AU - Eisen, Moris S.

AU - Blum, Jochanan

N1 - Funding Information: We gratefully acknowledge the financial support of this study from the Israel Science Foundation through Grant No. 177/03 and the Ministry of Science for support under the Tashtiot project.

PY - 2005/8

Y1 - 2005/8

N2 - Entrapment of Ru3(CO)12 and Os3(CO) 12 within alumina sol-gel matrices, (obtained by hydrolysis and polycondensation of a THF solution of aluminum isopropoxide) converts these clusters into highly active, leach-proof and recyclable hydrogen transfer catalysts. Likewise Rh2Co2(CO)12 which, in its silica sol-gel entrapped form, neither promotes the isomerization of allylbenzene nor the disproportionation of dihydroarenes, becomes upon its entrapment in an alumina sol-gel matrix, an efficient and recyclable catalyst for these reactions. While the entrapped osmium cluster promotes at 100-110°C and 20 bar only the hydrogenation of alkenes, the ruthenium analog catalyzes also the saturation of the aromatic C-C bonds. The hydrogenations take place via the hydride mechanism. XPS and TEM studies revealed that the carbonyl clusters do not decompose to give detectable amounts of (entrapped) metal particles during the encapsulation as well as during the catalytic processes.

AB - Entrapment of Ru3(CO)12 and Os3(CO) 12 within alumina sol-gel matrices, (obtained by hydrolysis and polycondensation of a THF solution of aluminum isopropoxide) converts these clusters into highly active, leach-proof and recyclable hydrogen transfer catalysts. Likewise Rh2Co2(CO)12 which, in its silica sol-gel entrapped form, neither promotes the isomerization of allylbenzene nor the disproportionation of dihydroarenes, becomes upon its entrapment in an alumina sol-gel matrix, an efficient and recyclable catalyst for these reactions. While the entrapped osmium cluster promotes at 100-110°C and 20 bar only the hydrogenation of alkenes, the ruthenium analog catalyzes also the saturation of the aromatic C-C bonds. The hydrogenations take place via the hydride mechanism. XPS and TEM studies revealed that the carbonyl clusters do not decompose to give detectable amounts of (entrapped) metal particles during the encapsulation as well as during the catalytic processes.

KW - Catalysis

KW - Doped alumina sol-gel

KW - Hydrogen-transfer reactions

KW - Metal carbonyls

UR - http://www.scopus.com/inward/record.url?scp=23844545554&partnerID=8YFLogxK

U2 - 10.1007/s10971-005-1403-4

DO - 10.1007/s10971-005-1403-4

M3 - 文章

AN - SCOPUS:23844545554

SN - 0928-0707

VL - 35

SP - 159

EP - 167

JO - Journal of Sol-Gel Science and Technology

JF - Journal of Sol-Gel Science and Technology

IS - 2

ER -