PREPARATION AND RESOLUTION OF CHIRAL ARENERUTHENIUM(II) COMPLEXES

The synthesis of the chiral complexes [{RuCl2(eta(6)-C(6)H(5)CHMeR)}(2 )], (R = Et, 1, (t)Bu, 2), is reported. 1 was prepared from RuCl3.3H(2 )O and 1-(2-butyl)-1,4-cyclohexadiene, whereas 2 was obtained starting from [Ru(eta(6)-naphthalene)(eta(4)-COD)] (COD = 1,5-cyclooctadiene) and 2,2-dimethyl-3-phenylbutane, which gives [Ru(eta(6)-C(6)H(5)CHMe(t )BU)(eta(4)-COD)] and subsequent reaction with HCl. Complexes 1 and 2 react with (+)-neomenthyldiphenylphosphine (NMDPP) to give monomeric. diastereomers [RuCl2(eta(6)-C(6)H(5)CHMeEt)(NMDPP)] (3a, 3b), and [RuC l2(eta(6)-C(6)H(5)CHMe(t)Bu)(NMDPP)], (4a, 4b), which were separated b y HPLC. The structure of compound 3a was solved by Patterson and Fouri er techniques and refined by full-matrix least-squares analysis to R = 0.053, R(w) = 0.061. The arene is eta(6)-bonded to the ruthenium with the phosphorus and the two chlorine atoms arranged as a three legs pi ano stool. The absolute configuration of the chiral centre of the arom atic ligand in 3a is R. The monomeric diastereomers 3a, 3b, 4a and 4b, were reconverted into their dimeric precursors (R,R)-1a, (S,S)-1b, (R ,R)-2a and(S,S)-2b as pure enantiomers. The CD spectra of (R,R)-1a and (S,S)-2b are also reported.