Syntheses, crystal structures and magnetic properties of three new molecular solids based on bis(maleonitriledithiolate)copper(II) anion and 2-substituted benzyl triphenylphosphonium

• Three molecular solids containing [Cu(mnt)2]2− anion were synthesized and characterized.
• There are weak CH⋯X, CH⋯S, CH⋯N, CH⋯Cu, CH⋯π and X⋯X interactions.
• Three molecular solids form a 3D network structure, and show weak ferromagnetic coupling at 2.0–300 K.

Syntheses, crystal structures and magnetic properties of three molecular solids, [2RBzTPP]2[Cu(mnt)2] (mnt2− = maleonitriledithiolate; [2RBzTPP]+ = 1-(2′-R-benzyl)triphenylphosphonium, R = F(1), Cl(2) and Br(3)) are investigated. All three molecular metals crystallize in the triclinic space group P-1. The change of the molecular topology of the counteraction when the o-substituted group in the benzyl ring has changed from F to Cl and Br, results in the difference in the dihedral angles, the stacking mode and the weak interactions of the cations and anions of 1, 2 and 3. The effect of weak intramolecular interactions such as CH⋯X(X = F, Cl, Br), CH⋯S, CH⋯N, CH⋯Cu, CH⋯π hydrogen bonds and the short X⋯X interactions generates a 3D network structure. The magnetic susceptibilities of these molecular metals measured in the temperature range 2.0–300 K show that the overall magnetic behaviors of 1–3 correspond to a paramagnetic system with a very weak ferromagnetic coupling interaction with θ = 0.013 K for 1, 0.019 K for 2 and 0.025 K for 3.

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