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

The preparation, crystal structures and properties of three new BEDT-TTF, b is(ethylenedithio)tetrathiafulvalene, (ET for short), charge transfer salts beta " (ET)(4).[(H3O)Cr(C2O4)(3)].C6H5NO2 I, beta " (ET)(4).[(H3O)Fe(C2O4) (3)].C6H5NO2 II and (ET)(4). Fe-2(C2O4)(5)] III are reported. The structure s of I and II consist of alternating layers of ET and an approximately hexa gonal network formed by H3O+ and the metal with the solvent molecule, C6H5N O2, occupying hexagonal cavities in the anion layer. Both C6H5NO2 salts are superconducting, the iron salt having a T-c of 6.2 K and the chromium salt having a T-c of 5.8 K. The structure of(ET)(4)Fe-2(C2O4)(5)] consists of a n iron oxalate bridged dimer, (Fe-Fe distance 5.472 Angstrom), interspersed with ET in a "checker board" arrangement. It is monoclinic and crystallise s in the P2(1)/n space group. At 150 K a = 16.8068 (3) Angstrom, b = 10.955 6 (2) Angstrom, c = 19.4109 (3) Angstrom, beta = 102.1593 (9) degrees and V = 3493.92 (10) Angstrom (3). Squid measurements show short range antiferro magnetic ordering.