Sulfur-Bridged Co^IIIPt^IICo^III Trinuclear Complexes with Mixed Aliphatic and Aromatic Thiolate Ligands:  Effect of Nonbridging Ligands on the Homochiral Linkage of Cobalt(III) Octahedrons by Platinum(II)

Abstract

The reaction of [Ni[Co(aet)(2)(pyt)](2)](2+) (aet = 2-aminoethanethiolate, pyt = 2-pyridinethiolate) with [PtCl(4)](2)(-) gave an S-bridged Co(III)Pt(II)Co(III) trinuclear complex composed of two [Co(aet)(2)(pyt)] units, [Pt[Co(aet)(2)(pyt)](2)](2+) ([1](2+)). When a 1:1 mixture of [Ni[Co(aet)(2)(pyt)](2)](2+) and [Ni[Co(aet)(2)(en)](2)](4+) was reacted with [PtCl(4)](2)(-), a mixed-type S-bridged Co(III)Pt(II)Co(III) complex composed of one [Co(aet)(2)(pyt)] and one [Co(aet)(2)(en)](+) units, [Pt[Co(aet)(2)(en)][Co(aet)(2)(pyt)]](3+) ([2](3+)), was produced, together with [1](2+) and [Pt[Co(aet)(2)(en)](2)](4+). The corresponding Co(III)Pt(II)Co(III) trinuclear complexes containing pymt (2-pyrimidinethiolate), [Pt[Co(aet)(2)(pymt)](2)](2+) ([3](2+)) and [Pt[Co(aet)(2)(en)][Co(aet)(2)(pymt)]](3+) ([4](3+)), were also obtained by similar reactions, using [Ni[Co(aet)(2)(pymt)](2)](2+) instead of [Ni[Co(aet)(2)(pyt)](2)](2+). While [Pt[Co(aet)(2)(en)](2)](4+) formed both the deltalambda (meso) and deltadelta/lambdalambda (racemic) forms in a ratio of ca. 1:1, the preferential formation of the deltadelta/lambdalambda form was observed for [1](2+) (ca. deltalambda:deltadelta/lambdalambda = 1:3) and [2](3+) (ca. delta(en)lambda(pyt)/lambda(en)delta(pyt):deltadelta/lambdalambda = 1:2). Furthermore, [3](2+) and [4](3+) predominantly formed the deltadelta/lambdalambda form. These results indicate that the homochiral selectivity for the S-bridged Co(III)Pt(II)Co(III) trinuclear complexes composed of two octahedral [Co(aet)(2)(L)](0 or +) units is enhanced in the order L = en < pyt < pymt. The isomers produced were separated and optically resolved, and the crystal structures of the meso-type deltalambda-[1]Cl(2).4H(2)O and the spontaneously resolved deltadelta-[4](ClO(4))(3).H(2)O were determined by X-ray analyses. In deltalambda-[1](2+), the delta and Lambda configurational mer(S).trans(N(aet))-[Co(aet)(2)(pyt)] units are linked by a square-planar Pt(II) ion through four aet S atoms to form a linear-type S-bridged trinuclear structure. In deltadelta-[4](3+), a similar linear-type trinuclear structure is constructed from the delta-mer(S).trans(N(aet))-[Co(aet)(2)(pymt)] and delta-C(2)-cis(S)-[Co(aet)(2)(en)](+) units that are bound by a Pt(II) ion with a slightly distorted square-planar geometry through four aet S atoms.

A novel heterometallic dinuclear compound:rac-pentaaqua-1κ5O-(μ-2-sulfidoacetato-1:2κ3O:O′,S)bis(2-sulfidoacetato-2κ2O,S)manganese(II)tin(IV)

“…Since the establishment of Werner's coordination theory by his pioneering research on the optical resolution of chiral cobalt(III) complexes, chirality has been one of the most important and fascinating subjects in coordination chemistry (Werner, 1911(Werner, , 1912Hirotsu et al, 2004). During the past few decades, a great deal of attention has been focused on the design and creation of well organized clusters or polymers, the overall structures of which can be controlled by the chirality of their building units (Leininger et al, 2000;Swiegers & Malefetse, 2000).…”

Separation and Optical Resolution of a Pair of atrop Diastereomers of the Octahedral Rhodium(III) Complex with a Nine-Membered S,S-Chelate Ring

“…30 × 10 3 cm −1 , suggestive of an appreciable CD contribution from the axial chirality. Assuming that the CD contributions from the central and axial chiralities are additive, the CD curves calculated from the equations 1 2 [ Δ ε { Λ R R ( R ax ) − [ 1a ] 2 + } + Δ ε { Λ R R ( S ax ) − [ 1b ] 2 + } ] and 1 2 [ Δ ε { Λ R R ( S ax ) − [ 1b ] 2 + } − Δ ε { Λ R R ( R ax ) − [ 1a ] 2 + } ] would represent the CD contribution from the Λ configurational Rh III center having two R configurational S donors (Λ RR ) and the CD contribution from the S ax configurational biphenyl moiety, respectively. From the calculated CD curves illustrated in Figure…”