Synthesis, Characterization, and Chiral Behavior of S-Bridged Co^IIIPt^IICo^III Trinuclear Complexes Composed of Bis(thiolato)-Type Octahedral Units <i>cis</i>(<i>S</i>)-[Co(aet)₂(en)]⁺ and/or <i>trans</i>(<i>N</i>)-[Co(d-pen- <i>N</i>,<i>O</i>,<i>S</i>)₂]^- (aet = 2-Aminoethanethiolate, d-pen = d-Penicillaminate)

A series of linear-type CoIIIPtIICoIII trinuclear complexes composed of C2-cis(S)-[Co(aet)2(en)]+ (aet = 2-aminoethanethiolate) and/or ΛD-trans(N)-[Co(d-pen-N,O,S)2]- (d-pen = d-penicillaminate) were newly prepared, and their chiral behavior, which is markedly different from that of the corresponding CoIIIPdIICoIII complexes, is reported. The 1:1 reaction of an S-bridged CoIIINiIICoIII trinuclear complex, [Ni{Co(aet)2(en)}2]Cl4, with K2[PtCl4] in water gave an S-bridged CoIIIPtIICoIII trinuclear complex, [Pt{Co(aet)2(en)}2]Cl4 ([1]Cl4), while the corresponding 1:2 reaction produced an S-bridged CoIIIPtII dinuclear complex, [PtCl2{Co(aet)2(en)}]Cl ([2]Cl). Complex [1]4+ formed both racemic (ΔΔ/ΛΛ) and meso (ΔΛ) forms, which were separated and optically resolved by cation-exchange column chromatography. An optically active S-bridged CoIIIPtIICoIII trinuclear complex having the pseudo ΛΛ configuration, ΛDΛD-[Pt{Co(d-pen-N,O,S)2}2]0 (ΛDΛD-[3]), was also prepared by reacting ΛD-trans(N)-K[Co(d-pen-N,O,S)2] with K2[PtCl4] in a ratio of 2:1 in water. Treatment of the racemic Δ/Λ-[2]Cl with ΛD-trans(N)-K[Co(d-pen-N,O,S)2] in a ratio of 1:1 in water led to the formation of ΛΛD- and ΔΛD-[Pt{Co(aet)2(en)}{Co(d-pen-N,O,S)2}]2+ (ΛΛD- and ΔΛD-[4]2+) and ΔΔD-[Pt{Co(aet)2(en)}{Co(d-pen-N,S)2(H2O)2}]2+ (ΔΔD-[4‘]2+), besides trace amounts of ΛDΛD-[3] and ΔΔ- and ΔΛ-[1]4+. These CoIIIPtIICoIII complexes were characterized on the basis of electronic absorption, CD, and NMR spectra, along with single-crystal X-ray analyses for ΔΔ/ΛΛ-[1]Cl4, ΔΛ-[1]Cl4, and ΔΛD-[4]Cl2. Crystal data: ΔΔ/ΛΛ-[1]Cl4·6H2O, monoclinic, space group C2/c with a = 14.983(3) Å, b = 19.857(4) Å, c = 12.949(3) Å, β = 113.51(2)°, V = 3532(1) Å3, Z = 4; ΔΛ-[1]Cl4·3H2O, orthorhombic, space group Pbca with a = 14.872(3) Å, b = 14.533(3) Å, c = 14.347(2) Å, V = 3100(1) Å3, Z = 4; ΔΛD-[4]Cl2·6H2O, monoclinic, space group P21 with a = 7.3836(2) Å, b = 20.214(1) Å, c = 10.622(2) Å, β = 91.45(1)° V = 1682.0(4) Å3, Z = 2.