Crystal Structure of Metal Complexes with 2-Imidazoline Nitroxides and Dicyanamide

The structure of heterospin complexes[M(DCA)₂L₂ ^x]·yH₂O, where M = Mn, Co, Ni, Cu, L^x is the nitronyl nitroxide radical; DCA is the dicyanamide anion, y = 0, 1, or 2 is studied. It is found that the nature of[M(DCA)₂L₂ ^x]·yH₂O is characterized by the formation of multiple hydrogen bonds generating ribbons, layers, or frameworks in the crystals. The analysis of magnetostructural correlations by means of band calculations of the electronic structure confirms the occurrence of ferromagnetic exchange between the unpaired electrons of paramagnetic centers in solid [Cu(DCA)₂L₂ ¹]·2H₂O when the distances between the copper ion and the coordinated N-O group are short.