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Ion-pair complexes consisting of the [Fe(mnt)2]− anion and [RBzPy]+ cations [R = NO2(1) or Cl (2)] have been prepared and characterized by elemental analysis and i.r. spectroscopy. The single crystal structure of (1) shows that the [Fe(mnt)2]− anions are dimeric, and that the coordination geometry of each Fe atom is square pyramidal. The most significant structural feature of (1) is that anions and cations form completely separate columns and π–π interactions occur within the cation columns. Thermal variations of χmT for the complexes indicated antiferromagnetic coupling within the dimer.