An S4-symmetric mixed-valent decacopper cage comprised of [CuII(L-S2N2)] complexes bridged by CuI(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 [(CuII(L-N2S2))(4)(mu(2)-CuI(MeCN)(2))(2)-( mu(3)-CuI(MeCN))(4)][BF4](6)center dot 2.25MeCN, [1][BF4](6)center dot 2.25MeCN. This mixed-valent hexacation shows idealized S-4 point group symmetry and is composed of four [CuII(L-N2S2] centers held in distorted four-coordinate environments and joined by mu(2)-CuI(MeCN)(2)/mu(3)-CuI(MeCN) ions that bridge their thiolate sulfur atoms. Each four-coordinate [CuII(L-N2S2)] center is related to the other three by successive executions of the S-4 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 Cu-5 cage compounds with a compositional relationship to [1](6+).