Separation and Optical Resolution of a Pair of atrop Diastereomers of the Octahedral Rhodium(III) Complex with a Nine-Membered S,S-Chelate Ring
journal contributionposted on 01.09.2008, 00:00 by Nobuto Yoshinari, Takumi Konno
Treatment of fac-[Rh(aet)3] (aet = 2-aminoethanethiolate) with 2,2′-bis(bromomethyl)-1,1′-biphenyl gave a mononuclear rhodium(III) complex with a nine-membered S,S-chelate ring, fac-[Rh(aet)(L)]2+ (2+, L = 2,2′-bis(2-aminoethylthiomethyl)-1,1′-biphenyl). Complex 2+ afforded a pair of atrop diastereomers, ΔSS(Sax)/ΛRR(Rax)-2+ ([1a]2+) and ΔSS(Rax)/ΛRR(Sax)-2+ ([1b]2+), which involves the axial chirality (Rax/Sax) about a biphenyl moiety of L, besides the central chirality (Δ/Λ) about a RhIII ion bound by two asymmetric (R/S) thioether donors. The atrop diastereomers ([1a]2+ and [1b]2+) were successfully separated, isolated, and optically resolved, and the circular dichroism (CD) contribution from the axial chirality was evaluated by CD spectral analyses.