Syntheses, crystal structures, and magnetic properties of Ni(mnt)2-based molecular solids containing substituted isoquinolinium

Two novel ion-pair complexes, [RBzIQl]+[Ni(mnt)2]− (mnt2− = maleonitriledithiolate, [RBzIQl]+ = 4-R-benzylisoquinolinium; R = H (1), Cl (2)) have been characterized structurally and magnetically. The View the MathML sourceNi(mnt)2- anions and [BzIQl]+ cations of 1 form 1D column of alternating between cations and anions via π⋯π stacking interaction between Ni(mnt)2 plane and isoquinoline ring, and the Ni(mnt)2 anions between adjacent columns exist C⋯N, C⋯N, and N⋯N interaction. The anions and cations of 2 stack into well-segregated columns in the solid state; and the Ni(III) ions form a 1D zigzag chain in a Ni(mnt)2 column through intermolecular Ni⋯S, S⋯S, Ni⋯Ni or π⋯π interactions. The chain is uniform in 2 with the Ni⋯Ni distances of 3.784 Å. Magnetic susceptibility measurements for these complexes in the temperature range 1.8–300 K show that 1 exhibits antiferromagnetic coupling behavior, and 2 exhibits unusual magnetic phase transitions around 45 K. The overall magnetic behavior for 2 indicates the presence of antiferromagnetic interaction in the high-temperature phase (HT) and spin gap in the low-temperature phase (LT).