Synthesis and X-ray structure of [Ag₂(Ph₂X₂)4][AsF₆]₂(X = S or Se); six-membered silver–sulphur and silver–selenium rings

The reaction of diphenyl disulphide with AgAsF6 in liquid SO2 leads to [Ag2(Ph2S2)4][AsF6]2- The X-ray structure [space group P, a= 10.902(4), b= 10.976(6), c= 13.308(7)Å, α= 112.82(4), β= 92.43(3), γ= 107.69(3)°, Z= 1, and R= 0.041 for 5 139 unique observed reflections] shows a centrosymmetric six-membered ring, in which two silver atoms are connected by two bridging Ph2S2 ligands; further unidentate sulphur ligands complete irregular three-co-ordination at silver. The analogous reaction with diphenyl diselenide leads to the isostructural [Ag2(Ph2Se2)4][AsF6]2[space group P, a= 10.676(3), b= 11.253(3), c= 13.625(4)Å, α= 66.40(2), β= 89.67(2), γ= 71.40(2)°, Z= 1, and R= 0.044 for 4 439 reflections].