The formation and crystal and molecular structures of hexa(μ-organothiolato)tetracuprate(I) cage dianions: bis-(tetramethylammonium)hexa-(μ-methanethiolato)tetracuprate(I) and two polymorphs of bis(tetramethylammonium)hexa-(μ-benzenethiolato)-tetracuprate(I)

X-Ray analysis shows that the crystalline compounds (Me₄N)₂[Cu₄(SMe)₆] (1), (Me₄N)₂[Cu₄(SPh)₆] (2) and (Me₄N)₂[Cu₄(SPh)₆]EtOH (3) all contain the [tetrahedro-Cu^I₄-octahedro-(SR)₆]^2? molecular cage. Very well developed pale yellow crystals of (2) and (3) can be obtained directly from a mixture of copper(II) salt and excess benzenethiol with tertiary amine in alcohol. The substituents R of the [Cu₄(SR)₆]^2? cage remove the high symmetry of the Cu₄S₆ core, and allow three configurational isomers for the cage. All known instances of this cage structure occur as the isomer which minimises the number of close contacts of substituents over the surface of the cage. Despite this, there remain intra-cage repulsive interactions between substituents, greater for RPh than for RMe, which cause distortions primarily in the SCuS angles which range from 105–144°. CuS distances are coupled, apparently electronically, to opposite SCuS angles. The stereo-chemical analysis is extended to all known Cu₄(SR)₆ cages, and to alternative cage structures.