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 ′ 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- semiconducting salt is obtained with benzonitrile as the guest molecule for tris(oxalato)iridate, and a novel 5:1 metalinsulator phase with tris(oxalato)iridate is also reported. Six new BEDT-TTF salts with tris(oxalato)gallate or -iridate anions including two new superconductors β′-(BEDT-TTF) 4 [(H 3 O)Ga(C 2 O 4 ) 3 ]·guest (bromobenzene or iodobenzene) and a novel 5: 1 metal-insulator β-(BEDT-TTF) 5 Ir(C 2 O 4 ) 3 ethanol.