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

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Two novel ion-pair complexes, [RBzIQl] +[Ni(mnt) 2] − (mnt 2− = maleonitriledithiolate, [RBzIQl] + = 4-R-benzylisoquinolinium; R = H ( 1), Cl ( 2)) have been characterized structurally and magnetically. The Ni ( 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).