Novel charge transfer salts of BEDT-TTF with metal oxalate counterions

The preparation, crystal structures and properties of three new BEDT-TTF, bis(ethylenedithio)tetrathiafulvalene, (ET for short), charge transfer salts β″(ET).[(HO)Cr(C O)].CHNOI, β″(ET).[(HO)Fe(C O)].CHNO II and (ET).[Fe(CO)] III are reported. The structures of I and II consist of alternating layers of ET and an approximately hexagonal network formed by HO and the metal with the solvent molecule, CHNO, occupying hexagonal cavities in the anion layer. Both CHNO salts are superconducting, the iron salt having a T of 6.2 K and the chromium salt having a T of 5.8 K. The structure of (ET)[Fe(CO)] consists of an iron oxalate bridged dimer, (Fe-Fe distance 5.472 Å), interspersed with ET in a "checker board" arrangement. It is monoclinic and crystallises in the P2/n space group. At 150 K a = 16.8068 (3) Å, b = 10.9556 (2) Å, c = 19.4109 (3) Å, β = 102.1593 (9)° and V = 3493.92 (10) Å. Squid measurements show short range antiferromagnetic ordering