Inorganic Chemistry, Vol.41, No.8, 2229-2237, 2002
Synthesis, characterization, and chiral behavior of S-bridged (CoPtCoIII)-Pt-III-Co-II trinuclear complexes composed of bis(thiolato)-type octahedral units cis(S)-[Co(aet)(2)(en)](+) and/or trans(N)-[Co(D-pen-N,O,S)(2)](-) (aet=2-aminoethanethiolate, D-pen = D-penicillaminate)
A series of linear-type (CoPtCoIII)-Pt-III-Co-II trinuclear complexes composed of C-2-cis(S)-[Co(aet)(2)(en)](+) (aet = 2-aminoethanethiolate) and/or Lambda(D)-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 (CoPdCoIII)-Pd-III-Co-II complexes, is reported, The 1:1 reaction of an S-bridged (CoNiCoIII)-Ni-III-Co-II trinuclear complex, [Ni{Co(aet)(2)(en)}(2)]Cl-4, with K-2[PtCl4] in water gave an S-bridged (CoPtCoIII)-Pt-III-Co-II trinuclear complex, [Pt{Co(aet)(2)(en)}(2)]Cl-4 ([1]Cl-4), while the corresponding 1:2 reaction produced an S-bridged (CoPtII)-Pt-III dinuclear complex, [PtCl2{Co(aet)(2)(en)}]Cl ([2]Cl). Complex [1](4+) formed both racemic (DeltaDelta/LambdaLambda) and meso (LambdaLambda) forms, which were separated and optically resolved by cation-exchange column chromatography. An optically active S-bridged (CoPtCoIII)-Pt-III-Co-II trinuclear complex having the pseudo LambdaLambda configuration, L(D)Lambda(D)-[Pt{Co(D-pen-N,O,S)(2)}(2)](0) (Lambda(D)Z(D)-[3]), was also prepared by reacting Lambda(D)-trans(M-K[Co(D-pen-N,O,S)(2)] with K-2[PtCl4] in a ratio of 2:1 in water, Treatment of the racemic Delta/Lambda-[2]Cl with Lambda(D)-trans(N)-K[Co(D-pen-N,O,S)(2)] in a ratio of 1:1 in water led to the formation of LambdaLambda(D)- and LambdaLambda(D)-[Pt{Co(aet)(2)(en)}{Co(D-pen-N,O,S)(2)}](2+) (LambdaLambda(D)- and LambdaLambda(D)-[4](2+)) and LambdaLambda(D)-[Pt{Co(aet)(2)(en)}{Co(D-pen-N,S)(2)(H2O)(2)}](2+) (LambdaLambda(D)-[4'](2+)), besides trace amounts of Lambda(D)Lambda(D)- [3] and LambdaLambda- and DeltaLambda-[1](4+). These (CoPtCoIII)-Pt-III-Co-II complexes were characterized on the basis of electronic absorption, CD, and NMR spectra, along with single-crystal X-ray analyses for DeltaDelta/LambdaLambda-[1]Cl-4, DeltaLambda-[1]Cl-4, and DeltaLambda(D)-[4]Cl-2. Crystal data: DeltaDelta/LambdaLambda-[1]Cl-4-6H(2)O, monoclinic, space group C2/c with a = 14.983(3) Angstrom, b = 19.857(4) Angstrom, c = 12.949 (3) Angstrom, beta = 113.51 (2)degrees, V = 3532(1) Angstrom(3), Z = 4; DeltaLambda-[1]Cl-4.3H(2)O, orthorhombic, space group Pbca with a = 14,872(3) Angstrom, b = 14.533(3) Angstrom, c = 14.347(2) Angstrom, V = 3100(1) Angstrom(3), Z = 4; DeltaLambda(D)-[4]Cl-2.6H(2)O, monoclinic, space group P2(1) with a = 7.3836(2) Angstrom, b = 20.214(1) Angstrom, c = 10.622(2) Angstrom, beta = 91.45(1)degrees V = 1682.0(4) Angstrom(3), Z = 2.