784182-17-8Relevant academic research and scientific papers
Synthesis, characterization, and structures of copper(II)-thiosulfate complexes incorporating tripodal tetraamine ligands
Fischmann, Adam J.,Warden, Andrew C.,Black, Jay,Spiccia, Leone
, p. 6568 - 6578 (2004)
The reaction of [Cu(L)(H2O)]2+ with an excess of thiosulfate in aqueous solution produces a blue to green color change indicative of thiosulfate coordination to Cu(II) [L = tren, Bz3tren, Me 6tren, and Me3tren; tren = tris(2-aminoethyl)amine, Bz3tren = tris(2-benzylaminoethyl)amine, Me6tren = tris(2,2-dimethylaminoethyl)amine, and Me3tren = tris(2- methylaminoethyl)amine]. In excess thiosulfate, only [Cu(Me6tren) (H2O)]2+ promotes the oxidation of thiosulfate to polythionates. Products suitable for single-crystal X-ray diffraction analyses were obtained for three thiosulfate complexes, namely, [Cu(tren)(S 2O3)]·H2O, [Cu(Bz3tren) (S2O3)]·MeOH, and (H3Me 3tren)[Cu(Me3tren)(S2O3)] 2-(CIO4)3. Isolation of [Cu(Me 6tren)(S2O3)] was prevented by its reactivity. In each complex, the copper(II) center is found in a trigonal bipyramidal (TBP) geometry consisting of four amine nitrogen atoms, with the bridgehead nitrogen in an axial position and an S-bound thiosulfate in the other axial site. Each structure exhibits H bonding (involving the amine ligand, thiosulfate, and solvent molecule, if present), forming either 2D sheets or 1D chains. The structure of [Cu(Me3tren)(MeCN)](CIO4)2 was also determined for comparison since no structures of mononuclear Cu(II)-Me 3tren complexes have been reported. The thiosulfate binding constant was determined spectrophotometrically for each Cu(II)-amine complex. Three complexes yielded the highest values reported to date [Kf = (1.82 ± 0.09) × 103 M-1 for tren, (4.30 ± 0.21) × 104 M-1 for Bz3tren, and (2.13 ± 0.05) × 103 M-1 for Me3tren], while for Me6tren, the binding constant was much smaller (40 ± 10 M-1).
