Synthesis, structure, and stereochemistry of some cysteine- and penicillaminecobalt(III) complexes

Abstract

The synthesis, characterization, and properties of salts of A-and A-N,S-C~(en)~[(R)-cysteinato]"+ and Co(en)Z[(S)-penicillaminato]& are described. The less stable A-cysteine isomer can be prepared in 295% yield by a second-order asymmetric transformation. Both OH-and Co(I1) effect mutarotation about cobalt, and the homogeneous equilibria have been measured: (R)cysS, 70 f 2% A, 30 f 2% A; (S)penS, 70 f 2%,30 & 2%. The configurations of the A and A N,S bound (R)-cysteine isomers, as established by single-crystal X-ray crystallographic analysis, are consistent with those deduced from equilibrium data and spectroscopic and rotatory dispersion measurements. Crystals of A-[C0(en)~(R)cysS]C10~~H~0 and A-[Co-(en)Z(R)cysS]C104 are orthorhombic, space group P212121 with cell dimensions 15.000 (4), 12.411 (3), 8.492 (2) ts and 13.870 (l), 11.7415 ( 8 ) , 8.9907 (7) A, respectively. The structures consist of discrete Co(en),(R)cysS+ cations, in which the cysteine residues are bound by N and S and perchlorate anions and water molecules of hydration. The Co-S bond lengths are 2.252 (2) and 2.234 (1) A for the A and A complexes, respectively. The Co-N bonds trans to sulfur are lengthened relative to the average cis Co-N(en) bond lengths by 0.04 8, (A) and 0.05 8, (A).

XAS examination of glutathione–cobalt complexes in solution

“…In Co:GSH pH12 , the Co-N1 distance (Table 1) was probably lengthened due to the same effect. Averaged Co(III)-S terminal bond lengths in mononuclear octahedral Co(III) complexes holding aliphatic aminothiols and/or aminothiols containing carboxylates are within 2.23-2.27 Å range [64][65][66]. Co(III)-S distance average in tris(dithiolato) Co(III) complexes is 2.27 Å [67].…”

A Multinuclear Coordination System of L‐Cysteine and L‐Penicillamine That Induce Opposite Chiralities at Metal Centers

“…[13][14][15][16][17][18][19][20][21][22][23][24][25][26] Although a difference in coordination behavior between cysteine and penicillamine toward a given metal ion has been observed in some cases, [18,19] dpenicillamine commonly induces a chiral effect at a metal center opposite to that induced by l-cysteine, [20][21][22][23][24][25][26] which is consistent with their opposite d and l configurations. [13][14][15][16][17][18][19][20][21][22][23][24][25][26] Although a difference in coordination behavior between cysteine and penicillamine toward a given metal ion has been observed in some cases, [18,19] dpenicillamine commonly induces a chiral effect at a metal center opposite to that induced by l-cysteine, [20][21][22][23][24][25][26] which is consistent with their opposite d and l configurations.…”

Zn(II)–D-(−)penicillamine complexes in aqueous solution. Zn-67 nuclear magnetic resonance study

“…is a powerful ligand for transition metal cations (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). It acts as a bidentate or tridentate ligand, taking advantage of the coordination ability of its amino, sulfhydryl, and carboxylic groups.…”