First geometrical isomerization of [Co(D-pen-N,O,S)2]- induced by forming S-bridged structure with AuI or AgI:: Crystal structure of a CoIII3AuI3 hexanuclear metallacycle [Au3{Co(D-pen-N,O,S)2}3] (D-pen = D-penicillaminate)

The reactions of trans(N)-[Co(D-pen-N,O,S)(2)](-) with Au-I or Ag-1 in water led to the formation of novel S-bridged (Co3M3)-M-III hexanuclear metallacycles [M-3 {Co(D-pen-N,O,S)(2)}(3)] (M = Au-I (1), Ag-1 (2)), in which [Co(D-pen-N,O,S)(2)](-) units adopt a trans(O) geometry. The molecular structure of 1 was determined by X-ray crystallography.