Synthesis, Characterization, and Structures of Copper(II)-Thiosulfate Complexes Incorporating Tripodal Tetraamine Ligands

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• 作者：Adam J. Fischmann ; Andrew C. Warden ; Jay Black ; and Leone Spiccia
• 刊名：Inorganic Chemistry
• 出版年：2004
• 出版时间：October 18, 2004
• 年：2004
• 卷：43
• 期：21
• 页码：6568 - 6578
• 全文大小：523K
• 年卷期：v.43,no.21(October 18, 2004)
• ISSN：1520-510X

文摘

The reaction of [Cu(L)(H₂O)]²⁺ with an excess of thiosulfate in aqueous solution produces a blue to green colorchange indicative of thiosulfate coordination to Cu(II) [L = tren, Bz₃tren, Me₆tren, 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 ofthiosulfate to polythionates. Products suitable for single-crystal X-ray diffraction analyses were obtained for threethiosulfate complexes, namely, [Cu(tren)(S₂O₃)]·H₂O, [Cu(Bz₃tren)(S₂O₃)]·MeOH, and (H₃Me₃tren)[Cu(Me₃tren)(S₂O₃)]₂(ClO₄)₃. Isolation of [Cu(Me₆tren)(S₂O₃)] was prevented by its reactivity. In each complex, the copper(II) center isfound in a trigonal bipyramidal (TBP) geometry consisting of four amine nitrogen atoms, with the bridgehead nitrogenin an axial position and an S-bound thiosulfate in the other axial site. Each structure exhibits H bonding (involvingthe amine ligand, thiosulfate, and solvent molecule, if present), forming either 2D sheets or 1D chains. The structureof [Cu(Me₃tren)(MeCN)](ClO₄)₂ was also determined for comparison since no structures of mononuclear Cu(II)-Me₃tren complexes have been reported. The thiosulfate binding constant was determined spectrophotometricallyfor each Cu(II)-amine complex. Three complexes yielded the highest values reported to date [K_f = (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 forMe₆tren, the binding constant was much smaller (40 ± 10 M^-1).