Selective inclusion of DMF molecules within non-covalent cavity

[Me4P]4[Cu4(mnt)4]·2CH3CN (1), [Me4P]4[Cu4(mnt)4]·2CH3NO2 (2), [Me4P]4[Cu4(mnt)4]·2DMF (3) and [Me4P]4[Cu4(mnt)4]·2C3H3N (4) (mnt = maleonitriledithiolate, [S2C2(CN)2]2−) clusters are readily synthesized in several solvents like acetonitrile, nitromethane, N,N-dimethylformamide and acrylonitrile to provide respective solvent as guest within the non-covalent cavity of the cluster ion. The guest species is accommodated within non-covalent cavity that is generated by two adjacent {Cu4(mnt)4} cores bridging with tetramethylphosphonium cation through hydrogen bonding. These hydrogen bonds are not strong and when mixed solvents were used selective DMF binding takes place to yield only complex 3 over other complexes.