3D molecular network and magnetic ordering, formed by multi-dentate magnetic couplers, bis(benzene)chromium(I) and [1,2,5]thiadiazolo[3,4-c][1,2,5] thiadiazolidyl

The reaction between bis(benzene) chromium(0), Cr-0(C6H6)(2), and [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (abbreviated as TDTD) formed single crystals of the 1 : 1 salt, [Cr-I(C6H6)(2)]+[TDTD](-). The crystal structure of [Cr(C6H6)(2)][TDTD] belongs to the monoclinic P2(1)/c space group, and involves a CdSO4-type network (or quartz dual net), which is formed by CH center dot center dot center dot N hydrogen bonds between [Cr(C6H6)(2)](+) (S = 1/2) and [TDTD](-)( S = 1/2). In addition to this network, the two components form an alternating chain crystal with a pi-pi overlap along the [110] and [1 (1) over bar 0] directions. The theoretical calculations for the pairwise intermolecular magnetic exchange interactions in [Cr(C6H6)(2)][TDTD] reveal the presence of 3D interactions, ranging from an antiferromagnetic interaction of -8.96 cm(-1) to a ferromagnetic one of 1.70 cm(-1). The temperature dependence of the paramagnetic susceptibility chi(p) indicates the dominance of an antiferromagnetic interaction with a negative Weiss constant of -4.8 K and a magnetic ordering at 8 K, which can be characterized in terms of weak ferromagnetism.