Resolution of the chiral η 6-methyl- o-toluate complex [RuCl 2(η 6- o-MeC 6H 4CO 2Me)] 2. Crystal structure and absolute configuration of the (+)-neomenthyldiphenylphosphine (NMDPP) complex RuCl 2(η 6- o-MeC 6H 4CO 2Me)-[(+)-NMDPP

Abstract

The planar chiral η 6-methyl- o-toluate-ruthenium(II) complex [RuCl 2(η 6- o-MeC 6H 4CO 2Me)] 2 ( 1) was found to react with (+)-neomenthyldiphenylphosphine (NMDPP) ( 2) to give monomeric diastereomers [RuCl 2(η 6- o-MeC 6H 4CO 2Me)-(NMDPP)] ( 3a and 3b), which were separated by fractional crystallization. Crystals of the less soluble diastereomer 3a belong to the space group P2 12 12 1, with a 11.998(3), b 16.178(4), c 17.171(4) Å, Z = 4, at 293 K. The structure has been solved by Patterson and Fourier techniques and refined by full-matrix least squares analysis to R = 0.0607, R w = 0.0624 for 1398 unique reflections with F o > 2σ( F o). The ruthenium atoms is pseudo-octahedrally coordinated by η 6-methyl- o-toluate, NMDPP and two chloride ligands (RuP 2.357(5), RuCl 2.423(6), 2.381(6) Å). The arene ring is planar within experimental error but it is coordinated unsymmetrically: the RuC distances to the unsubstituted carbon atoms are 2.11(3)–2.17(2) Å, whereas those to the carbon atoms bearing the methoxycarbonyl and methyl groups are 2.26(2) Å and 2.30(2) Å, respectively. The absolute configuration at the chiral planar centre of 3a is R. 3a and 3b have been converted into ( R)- and ( S)-Ru(η 6- o-MeC 6H 4CO 2Me)(η 4-1,5-cyclooctadiene) ( 6a and 6b respectively), from which the ( R, R)- and ( S, S)-[RuCl 2(η 6- o-MeC 6H 4CO 2Me)] 2 have been obtained in enantiomeric purities of 90 and 60%, respectively.