Abstract
The reaction of fac(S)-[Rh(aet)3] with Ni2+ at room temperature gave a linear-type S-bridged RhIIINiIIRhIII trinuclear complex, [Ni{Rh(aet)3}2]2+ (1). A similar reaction of ΔLLL-fac(S)-[Rh(L-cys-N,S)3]3− with Ni2+ produced the corresponding trinuclear complex with L-cys ligands, ΔLLLΔLLL-[Ni{Rh(L-cys-N,S)3}2]4− (ΔLLLΔLLL-2), retaining the ΔLLL configuration of the starting complex. The crystal structure of 1(NO3)2 was determined by X-ray diffraction. [Ni{Rh(aet)3}2](NO3)2·2H2O, chemical formula C12H40N8S6O8NiRh2, crystallizes in the triclinic space group with a = 12.249(3), b = 13.366(4), c = 10.260(2) Å, α = 108.76(1), β = 102.46(1), γ = 101.21(1)°, V = 1488.7(7) Å3, Z = 2, and R = 0.024. In 1 the central NiII atom is situated in a distorted octahedral geometry, coordinated by six thiolato sulfur atoms from the two octahedral fac(S)-[Rh(aet)3] units. The two fac(S)-[Rh(aet)3] units have the same absolute configuration to form the racemic (ΔΔ/ΛΛ) isomer. The optically active ΔΔ and ΛΛ isomers of 1 were derived from ΔΔΔΔ- and ΛΛΛΛ-[{Rh(aet)3}4Zn3(HO)]5+ respectively, by adding excess Ni2+. The electronic absorption spectral behavior of 1 indicated that the intermolecular exchange of the fac(S)-[Rh(aet)3] units occurs in solution, which results in the formation of the ΔΛ (meso) isomer from a 1 : 1 mixture of the ΔΔ and ΛΛ isomers. The chemical properties of the present RhIIINiIIRhIII complexes are discussed in comparison with those of the corresponding CoIIINiIICoIII and RhIIICoIIIRhIII complexes.

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