Thione complexes of Rh(I): A first comparison with the bonding and catalytic activity of related carbene and imine compounds

Date
2005
Authors
Neveling A.
Julius G.R.
Cronje S.
Esterhuysen C.
Raubenheimer H.G.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Heterocyclic mono(thione), trans-bis(thione), cis-bis(thione), trans-(carbene-thione), cis-(carbene-thione), trans-(phosphine-thione) and mono(imine) complexes of rhodium(I) have been prepared and fully characterised. Chloro(η4-1,5-cyclooctadiene)(L)rhodium(I) (1a, L = 1,3-diisopropyl-4,5-dimethyl-2,3-dihydro-1H-imidazol-2-thione; 1b, L = 1,3,4,5-tetramethyl-2,3-dihydro-1H-imidazol-2-thione) appear as isomers at room temperature due to slow coordination exchange on the S-donor atom. In the three structures determined, the substituent on the sulfur appears syn to Cl. Hindered rotation about the Rh-carbene bond is revealed in the NMR spectra of seven new complexes with isopropyl substituents on the heterocyclic carbene ligands. The trans influence of the thione ligands is smaller than that of carbenes but larger than that shown by imines and chloride. Thione complexes are better catalyst precursors than the carbene complexes for the hydroformylation of 1-hexene under the chosen reaction conditions: 80°C, 8 MPa CO-H2 (1 : 1), 16 h, 1 : 1000 catalyst to 1-hexene ratio.
Description
Keywords
Catalysis, Catalyst activity, Chemical bonds, Complexation, Crystal structure, Nuclear magnetic resonance spectroscopy, Carbene, Imine compounds, Thione complexes, Rhodium
Citation
Dalton Transactions
1