Bulk weak ferromagnet in ferrimagnetic chains of organic-inorganic hybrid materials based on BDH-TTP and paramagnetic thiocyanato complex anions: (BDH-TTP)[M(isoq)₂(NCS)₄], M = Cr^III, Fe^III

The preparation, X-ray crystal structures, and magnetic properties of two new isostructural charge transfer salts, (BDH-TTP)M(isoq)₂NCS)₄ (M = Cr^III (1), Fe^III (2), BDH-TTP = 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathia-pentalene, isoq = isoquinoline), are reported. Crystal data for 1: monoclinic, space group C2/c (#15), a = 16.1363(9) Å, b = 19.0874(12) Å, c = 12.5075(6) Å, β 95.70(4)°, V = 3833.2(4) ų, Z = 4, R = 0.0516 for 2844 reflections with /> 2σ(/); for 2: monoclinic, C2/c (#15), a = 16.1938(8) Å, b = 19.1117(11) Å, c = 12.5100(10) Å, β = 94.265(3)°, V = 3861.0(4) ų, Z = 4, R = 0.0479 for 2969 reflections with /> 2σ(/). The crystal structure consists of zigzag mixed organic and inorganic layers, and each layer is formed by mixed columns of BDH-TTP radical cations and paramagnetic metal complex anions. Short intermolecular atomic contacts between donor and anion are observed within the column in the c-direction. The two compounds have weak room-temperature electrical conductivities. ESR measurements show a single signal without separating the donor and anion spins, suggesting a π interaction between the d and π electrons. For both compounds ferrimagnetic interactions are observed between the nonequivalent donor and anion spins. These materials exhibit bulk canted weak ferromagnetism below 7.6 K for both 1 and 2.