Electron-Transfer Kinetics and Thermodynamic Characterization of Copper(II/I) Complexes with Acyclic Tetrathiaethers in Aqueous Solution.

The kinetics of a series of Cu(II/I)−acyclic tetrathiaether complexes reacting with several oxidizing and reducing reagents have been examined in aqueous solution at 25 °C. This investigation has included a re-examination of CuII/I(Me2-2,3,2-S4) (Me2-2,3,2-S4 = 2,5,9,12-tetrathiatridecane = L12a), containing the ethylene−trimethylene−ethylene bridging sequence, plus three newly synthesized ligands containing an alternate bridging sequence of trimethylene−ethylene−trimethylene:  2,6,9,13-tetrathiatetradecane (Me2-3,2,3-S4 = L12b) and two cyclohexanediyl-substituted derivatives, viz., cis-1,2-bis[(3-methylthiopropyl)thio]cyclohexane (cis-cyhx-Me2-3,2,3-S4 = L14) and trans-1,2-bis[(3-methylthiopropyl)thio]cyclohexane (trans-cyhx-Me2-3,2,3-S4 = L15). The corresponding phenylene derivative, 1,2-bis[(3-(methylthio)propyl)thio]benzene (bz-Me2-3,2,3-S4 = L13), was also synthesized but did not form a measurable copper complex. The conditional stability constants for CuIIL (KCuIIL‘) and CuIL (KCuIL‘) and the CuII/I...