Molecular conductors from bis(ethylenedithio)tetrathiafulvalene with tris(oxalato)gallate and tris(oxalato)iridate

We present the synthesis, crystal structures and conducting properties of six new BEDT-TTF radical-cation salts with the tris(oxalato)gallate or -iridate anion. The use of halobenzenes gives 4 : 1 β′′ metallic or superconducting salts with tris(oxalato)gallate - fluorobenzene (PhF) or chlorobenzene (PhCl) as a guest molecule gives a metal, whilst the larger bromobenzene (PhBr) or iodobenzene (PhI) gives a superconductor. A 4 : 1 pseudo-κ semiconducting salt is obtained with benzonitrile as the guest molecule for tris(oxalato)iridate, and a novel 5 : 1 metal-insulator phase with tris(oxalato)iridate is also reported.