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Título

Half-sandwich complexes of rhodium containing cysteine-derived ligands

AutorCarmona, María; Rodríguez, Ricardo ; Lahoz, Fernando J. ; García-Orduña, P. ; Osante, Iñaki ; Cativiela, Carlos ; López, José A. ; Carmona, Daniel
Fecha de publicación2016
EditorRoyal Society of Chemistry (Great Britain)
CitaciónDalton Transactions 45(36): 14203-14215 (2016)
ResumenThe modified cysteine ligand, S-benzyl-α-methyl-l-cysteine (HL2), was prepared from l-cysteine hydrochloride methyl ester. The reaction of commercial S-benzyl-l-cysteine (HL1) or HL2 with the dimer, [{(η-CMe)RhCl}(μ-Cl)], gives rise to the cationic complexes, [(η-CMe)RhCl(HL)]Cl (HL = HL1 (1), HL2 (2)), in which the cysteine ligand exhibits a κN,S coordination mode. In a basic medium, HL1 or HL2 reacts with [{(η-CMe)RhCl}(μ-Cl)] to afford mixtures of two epimers at the metal centre of the neutral complexes, [(η-CMe)RhCl(κN,O-L)] (HL = HL1 (3), HL2 (4)), in which amino carboxylate adopts a κN,O mode of coordination along with variable amounts of the cationic compounds, [(η-CMe)Rh(κN,O,S-L)]Cl (HL = HL1 (6Cl), HL2 (7Cl)), which contain κN,O,S coordinated cysteine-derived ligands. However, in a basic medium, the N-Boc substituted cysteine S-benzyl-N-Boc-l-cysteine (HL3) only yields the κO,S coordinated derivative, [(η-CMe)RhCl(κO,S-L3)] (5), as a mixture of two diastereomers depending on the configuration of the metal centre. The bidentate chelate complexes 3-5 react with AgSbF to give the hexafluoroantimonates [(η-CMe)Rh(κN,O,S-L)][SbF] (HL = HL1 (6Sb), HL2 (7Sb), HL3 (8Sb)) with tridentate coordination. Compound 8Sb reacts with NaHCO to give the neutral complex [(η-CMe)Rh(κN,O,S-L3)] (9), which can also be prepared by reacting the dimer [{(η-CMe)RhCl}(μ-Cl)] with HL3 in the presence of two equivalents of NaHCO. The new compounds contain up to four stereogenic centres, namely, Rh, S, N, and C. The absolute configuration of the complexes has been established by spectroscopic and diffractometric investigations, including the crystal structure determination of [(η-CMe)RhCl(κO,S-L3)] (5), [(η-CMe)Rh(κN,O,S-L1)][SbF] (6Sb), [(η-CMe)Rh(κN,O,S-L2)][SbF] (7Sb) and [(η-CMe)Rh(κN,O,S-L3)] (9). Variable temperature H NMR studies reveal the existence of epimerization processes and theoretical calculations were used to discriminate their nature.
Versión del editorhttps://doi.org/10.1039/C6DT02411D
URIhttp://hdl.handle.net/10261/154878
DOI10.1039/C6DT02411D
Identificadoresdoi: 10.1039/C6DT02411D
e-issn: 1477-9234
issn: 1477-9226
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