Chemical reactivity and catalytic of homo- and hetero- metallic carbonyl clusters
Chemical reactivity and catalytic of homo- and hetero- metallic carbonyl clusters
Catalytic studies have been carried out to investigate the activation of H4Ru4(CO)12 by a heterometal centre towards the homogeneous catalysis of alkene isomerisation under mild conditions. Trends in the activity and selectivity through the cluster series H3Ru4(CO)12MPR3 (M = Cu, Ag, Au; R = Me, Ph, p-MeC6H4, Cy, o-MeC6H4) are examined. Kinetic studies, using H3Ru4(CO)12AuPPh3 as catalyst precursor, suggest that the catalytically active species is formed via cluster fragmentation. The reactivity of H3Ru4(CO)12MPPh3 (M = Cu, Au) with CO, H2, alkenes and phosphines is compared with that of H4Ru4(CO)12, the products being identified by i.r. and n.m.r. spectroscopies. Isolated from the carbonylation reaction of H3Ru4(CO)12CuPPh3 was HRu5Cu(CO)18PPh3, shown by an X-ray crystallographic study to contain a puckered 'ladder-like' arrangement of metal atoms based on triangular units. Detailed kinetic studies indicated that the introduction of the heterometal moieties promotes ligand exchange via an associative mechanism, and cluster fragmentation. High pressure i.r. spectroscopic studies of a ruthenium carbonyl based catalytic system for ethylene hydroformylation have been performed to identify species present under catalytic conditions. The effects of alkali metal cation, halide anion, iodine, and group VI metal carbonyl promoters are presented. The roles of these promoters are proposed by consideration of the species observed in the i.r. spectra of the reaction mixtures. Attention is focused on the synergic effect between ruthenium and tungsten in the Reppe system, and in particular the possible formation of any mixed-metal species. The structure of one of the isomeric forms of (H)(O2CMe)Os3(CO)9PPh3 has been confirmed by a single crystal analysis and compared with the structure of (H)(O2CMe)Os3(CO)10, which has been redetermined. A normal probability plot analysis of error has been performed on the two analyses of the latter tri-osmium cluster. Although only random error has been found in the positional parameters of the independent sets of crystallographic data, systematic error was detected in some of the thermal parameters of the heavy atoms.
University of Southampton
1987
Street, Andrew Charles
(1987)
Chemical reactivity and catalytic of homo- and hetero- metallic carbonyl clusters.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Catalytic studies have been carried out to investigate the activation of H4Ru4(CO)12 by a heterometal centre towards the homogeneous catalysis of alkene isomerisation under mild conditions. Trends in the activity and selectivity through the cluster series H3Ru4(CO)12MPR3 (M = Cu, Ag, Au; R = Me, Ph, p-MeC6H4, Cy, o-MeC6H4) are examined. Kinetic studies, using H3Ru4(CO)12AuPPh3 as catalyst precursor, suggest that the catalytically active species is formed via cluster fragmentation. The reactivity of H3Ru4(CO)12MPPh3 (M = Cu, Au) with CO, H2, alkenes and phosphines is compared with that of H4Ru4(CO)12, the products being identified by i.r. and n.m.r. spectroscopies. Isolated from the carbonylation reaction of H3Ru4(CO)12CuPPh3 was HRu5Cu(CO)18PPh3, shown by an X-ray crystallographic study to contain a puckered 'ladder-like' arrangement of metal atoms based on triangular units. Detailed kinetic studies indicated that the introduction of the heterometal moieties promotes ligand exchange via an associative mechanism, and cluster fragmentation. High pressure i.r. spectroscopic studies of a ruthenium carbonyl based catalytic system for ethylene hydroformylation have been performed to identify species present under catalytic conditions. The effects of alkali metal cation, halide anion, iodine, and group VI metal carbonyl promoters are presented. The roles of these promoters are proposed by consideration of the species observed in the i.r. spectra of the reaction mixtures. Attention is focused on the synergic effect between ruthenium and tungsten in the Reppe system, and in particular the possible formation of any mixed-metal species. The structure of one of the isomeric forms of (H)(O2CMe)Os3(CO)9PPh3 has been confirmed by a single crystal analysis and compared with the structure of (H)(O2CMe)Os3(CO)10, which has been redetermined. A normal probability plot analysis of error has been performed on the two analyses of the latter tri-osmium cluster. Although only random error has been found in the positional parameters of the independent sets of crystallographic data, systematic error was detected in some of the thermal parameters of the heavy atoms.
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Published date: 1987
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Local EPrints ID: 461867
URI: http://eprints.soton.ac.uk/id/eprint/461867
PURE UUID: 92e2ce52-375d-4886-ae7f-63df12a3ed68
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Date deposited: 04 Jul 2022 18:57
Last modified: 04 Jul 2022 18:57
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Author:
Andrew Charles Street
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