Syntheses, crystal structures and magnetic properties of three new molecular metals based on bis(maleonitriledithiolate)copper(II) anion and substituted benzyl isoquinolinium cations

•Three molecular solids containing [Cu(mnt)2]2− anion were synthesized and characterized.•The cations stack into a one-dimensional column through C–H⋯π and π⋯π interactions.•The anions and cations are arranged alternatively into a column.•These molecular show a change of magnetic exchange upon the temperature is lowered. Syntheses, crystal structures and magnetic properties of three novel molecular metals, [4RBzIQl]2[Cu(mnt)2] (mnt2−=maleonitriledithiolate; [4RBzIQl]+=1-(4′-R-benzyl)isoquinolinium, R=H(1), Cl(2) and NO2(3)) are systemically investigated. The crystal structural analysis reveals that three molecular metals crystallize in the triclinic space group P-1, and the [4RBzIQl]+ cations stack into a one-dimensional column through C–H⋯π and π⋯π interactions. The anions (A) and cations (C) are arranged alternatively into a column in the sequence of ···A-CC-A-CC··· for 1 and ···AA-CC-AA-CC··· for 2 and 3 though Cu⋯N, C⋯N, C⋯O, C–H⋯π or/and π⋯π interactions. The magnetic susceptibilities measured in the temperature range 2.0–300K reveals that these molecular show a change of magnetic exchange from weak ferromagnetic to antiferromagnetic around 20K, 19K and 47.6K for 1, 2 and 3.