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Chiral modification of trinuclear ruthenium clusters with proline and cysteine derivatives. Synthesis, crystal structure, and catalytic properties of [(μ2-H)Ru3(CO)10- (μ2,η2-OCHCH2OCH3)] and [(μ2-H)Ru3(CO)9(μ3,η2-HCH2OCH3)]

1989; Elsevier BV; Volume: 379; Issue: 3 Linguagem: Inglês

10.1016/0022-328x(89)85171-x

1872-8561

Georg Süß‐Fink, Thomas Jenke, Heike Heitz, María Angela Pellinghelli, António Tiripicchio,

Cyclopropane Reaction Mechanisms

Proline and cysteine derivatives have been used for the chiral modification of the trinuclear ruthenium cluster system. Whereas proline derivatives yield carbamoyl Ru3 clusters by NH activation, the cysteine derivatives react by SH activation to give mercapto Ru3 clusters. The chiral methoxymethyl pyrrolydine carbamoyl clusters catalyse the enantioselective isomerization of nerol to give citronellal with an enantiomeric excess of 12.4%. The structures of [(μ2-H)Ru3(CO)10(μ2,η2- OCNCH2CH2CH2CHCH2OCH3)] (R-2) and [(μ2-H)Ru3(CO)9(μ3,η2- NCCH2CH2CHCH2OCH3)] (S-3) have been determined by X-ray diffraction methods. Crystals of R-2 are monoclinic, space group P21 with Z = 2, in a unit cell of dimensions a = 8.662(4), b = 18.234(4), c = 7.662(2) Å, β = 94.87(2)°. Crystals of S-3 are monoclinic, space group P21 with Z = 2 in a unit cell of dimensions a = 8.881(4), b = 16.720(6), c = 7.567(3) Å, β = 112.15(2)°. Both structures have been solved by direct and Fourier methods and refind by full-matrix least-squares to R = 0.0581 (R-2) and R = 0.0239 (S-3) for 2366 (R-2) and 2454 (S-3) observed reflections. The structure of R-2 consists of a ruthenium triangle of unequal edges with both the hydride and carbamoyl ligands bridging the longest edge; the carbamoyl ligand interacts through the carbon and oxygen atoms. The structure of S-3 shows a metal triangle of unequal edges in which the dehydrogenated substituted pyrrolidine ligand interacts with all three Ru atoms through the C and N atoms of the imine group to form two σ-bonds with the two metals defining the longest edge (bridged also by the hydride ligand) and a π-bond with the third one.