An S4-symmetric mixed-valent decacopper cage comprised of [Cu(II)(L-S2N2)] complexes bridged by Cu(I)(MeCN)n (n = 1 or 2) cations.

Oxidative addition of 1,2,11,12-tetrathia-5,8,15,19-tetra(N-methylamino)cycloicosane, the bis(disulfide) form of N,N'-dimethyl-N,N'-bis(2-mercaptoethyl)ethylenediamine (L-N2S2) to [Cu(MeCN)4][BF4] (2.5 eq.) in MeCN produces good yields of the decacopper cage compound [(Cu(II)(L-N2S2))4(µ2-Cu(I)(MeCN)2)2(µ3-Cu(I)(MeCN))4][BF4]6·2.25MeCN, [1][BF4]6·2.25MeCN. This mixed-valent hexacation shows idealized S4 point group symmetry and is composed of four [Cu(II)(L-N2S2] centers held in distorted four-coordinate environments and joined by µ2-Cu(I)(MeCN)2/µ3-Cu(I)(MeCN) ions that bridge their thiolate sulfur atoms. Each four-coordinate [Cu(II)(L-N2S2)] center is related to the other three by successive executions of the S4 operation. A dark violet color is observed for [1](6+) and attributed to a combination of metal-to-ligand (S), ligand (S)-to-metal, and, at lower energy, intermetal charge transfer transitions, as found for Cu5 cage compounds with a compositional relationship to [1](6+).