Hemilabile Phosphonate−Phosphane−Rh Catalysts for Homogeneous and Heterogeneous Carbonylation

Autor:	Bernhard Lücke, and H. Miessner, Stefan Bischoff, Axel Weigt
Rok vydání:	1996
Předmět:	Ethylene Chemistry Ligand General Chemical Engineering Energy Engineering and Power Technology chemistry.chemical_element Photochemistry Phosphonate Medicinal chemistry Catalysis Rhodium chemistry.chemical_compound Fuel Technology Catalytic cycle Methanol Carbonylation
Zdroj:	Energy & Fuels. 10:520-523
ISSN:	1520-5029 0887-0624
Popis:	New rhodium complexes with phosphonate−phosphane ligands (RO)2P(O)−X−PPh2 (1a−d), a, X = CH2; b, X = (CH2)2; c, X = (CH2)3; d, X = p-C6H4, have been synthesized and characterized. Both, open-chain structures [ClRh(cod)PPh2−X−P(O)(OR)2] (2a−d) and cyclic complexes [(cod)Rh(PPh2−X−P(O)(OR)2)]A (3a−c, A = BF4, PF6) were isolated after stoichiometric reactions at mild conditions. FTIR investigations of 2b supported on silica at temperatures between 150 and 250 °C suggest that the phosphonate−phosphane ligand stabilizes rhodium monocarbonyl species and allows also the formation of free coordination sites to form dicarbonyl species, which is in accord with the proposed hemilabile behavior of the complexes in methanol carbonylation. During the catalytic cycle, the phosphane group is assumed to be strongly coordinated to the rhodium, while the phosphoryl oxygen of the phosphonate group is supposed to change between a free and a coordinated state, thus vacating or occupying a coordination site. This is supported b...
Databáze:	OpenAIRE
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