Direct Electrochemical Synthesis of an Unusual Complex Salt: Almost Structural Identity - Different Charge.

The electrochemical synthesis is an underestimated synthesis protocol, which can lead to unexpected results. We obtained an unusual Cu^I complex salt with a pentanuclear anion and a heptanuclear cation. The anion [Cu₅(S tBu)₆]^- features a trigonal prism coordination motif with a twisted arrangement. The cation [Cu₇(S tBu)₆(bipy)₃]⁺ is structurally almost identical to the anion and shares therefore basic building principles. These Cu-S skeletons with additional N donor functions in the cation have relevance to biological copper proteins. Besides structural discussion and analysis, a theoretical study was performed to determine stabilizing effects. This is accomplished by means of DFT with a triple-zeta basis set and the TPSSh functional in order to highlight bonding interactions and to understand d¹⁰-d¹⁰ interactions, which are assigned a major stabilizing part. This is realized through Wiberg bond analysis and frontier orbital analysis of both ions. [ABSTRACT FROM AUTHOR]