Three ion–pair complexes containing bis(maleonitriledithiolate)copper(II) anion and substituted 2-aminopyridinium cations: Syntheses, crystal structures, and magnetic properties

Abstract Three new ion–pair complexes, [2-ClBz-2′-NH 2 Py] 2 [Cu(mnt) 2 ]( 1 ), [2-Cl-4-ClBz-2-NH 2 Py] 2 [Cu(mnt) 2 ]( 2 ) and [2-Cl-4-BrBz-2′-NH 2 Py] 2 [Cu(mnt) 2 ]·C 2 H 5 OH( 3 ) ([2-Cl-4-RBz-2′-NH 2 Py] +  = 1-(2′-chloro-4′-Rbenzyl)-2-aminopyridinium, R = H, Cl, Br; mnt 2−  = maleonitriledithiolate), were synthesized and characterized by elemental analyses, IR, UV–visible, single crystal X−ray diffraction and magnetic measurements. Both 1 and 2 crystallize in the monoclinic space group P 2(1)/ c , and the [Cu(mnt) 2 ] 2− anions and the cations form a 1D network structure through the N–H⋅⋅⋅N hydrogen bonds. While the anions in 3 form a ladder-like chain through the C–H⋅⋅⋅N interactions between the [Cu(mnt) 2 ] 2− anions and CH 3 CH 2 OH molecules. Some weak interactions such as π⋅⋅⋅π, Cu⋅⋅⋅N, Cl⋅⋅⋅C, and C–H⋅⋅⋅Cl, O–H⋅⋅⋅Cl, C–H⋅⋅⋅S, N–H⋅⋅⋅O, N–H⋅⋅⋅N and C–H⋅⋅⋅N hydrogen bonds in three molecular solids generate further a 3D network structure. The magnetic measurement reveals that 1 shows a very weak ferromagnetic interaction, and 2 exhibits a transition from ferromagnetic to antiferromagnetic coupling about 15 K, while 3 shows an antiferromagnetic coupling feature with θ  = −12.51 K when the temperature is lowered.