Magnetic molecular charge-transfer salts containing layers of water and tris(oxalato) ferrate(III) anions

We describe the synthesis, crystal structure and conducting properties of two new BEDT-TTF charge transfer salts of tris(oxalato)ferrate(III) containing slightly different numbers of water molecules, (BEDT-TTF)12[Fe(C2O4)3]2·xH2O [x = 15 ( I) and 16 ( II)]. I crystallizes in the monoclinic space group C2/c, a = 36.017(10), b = 30.880(10), c = 36.183(15) Å, = 90, = 93.66(3), = 90°, V = 40161(23) Å3, T = 120(2) K, Z = 8, R1 = 0.0842 [F2 > 2(F2)]; II crystallizes in the same space group, a = 17.9695(15), b = 15.4988(13), c = 36.115(3) Å, = 90, = 93.720(2), = 90°, V = 10037.1(14) Å3, T = 150(2) K, Z = 4, R1 = 0.0673 [F2 > 2(F2)]. Electrical resistivity measurements show that I and II are semiconductors below 275 K