A new organic-inorganic hybrid salt [TM-TTF][Cr(NCS)(4)(isoquinoline)(2)] (1) (TM-TTF = Tetramethyltetrathiafulvalene) has been synthesized. Compound P (1) over bar crystallizes in the triclinic P (1) over bar space group with a = 8.269(1), b = 10.211(2), and c = 11.176(2) Angstrom, alpha = 89.244(9), beta = 88.114(6), and gamma = 74.277(7)degrees, V = 907.6(3) A(3), and Z = 1. The crystal structure was resolved in the temperature range between 223 and 123 K, showing that changes in the crystal structure at low temperature result in stronger interactions between anions and cations. The packing of 1 consists of mixed anion-cation layers in the bc plane containing (SS)-S-... and pi-pi anion-cation interactions, the layers being connected by very short S... S contacts between anions and cations. Magnetic measurements in a small external field show bulk spontaneous magnetization with a T-c of 6.6 K consistent with the presence of weakly coupled ferrimagnetic order in compound 1. The EPR measurements also demonstrate the interaction between the d and pi electrons and the presence of an internal magnetic field brought about by the magnetic ordering.