Ferromagnetic interaction in mu1,3-cyanamido-derived copper(II) cryptates

The reaction of dinuclear copper(II) cryptates with calcium cyanamide, CaNCN, and sodium dicyanamide, NaN(CN)(2)] results in dinuclear compounds of formulae Cu(2)(HNCN)(R3Bm)](ClO(4))(3) (1), Cu(2)(dca)(R3Bm)](ClO(4))(3)4H(2)O (2), and Cu(2)(NCNCONH(2))(R3Bm)](CF(3)SO(3))(3) (3), in which R3Bm=N(CH(2))(2)NHCH(2)(C(6)H(4)-m)CH(2)NH(CH(2))(2)](3)N and dca=dicyanamido ligand (NCNCN(-)). The X-ray diffraction analysis reveals for both 1 and 3 a dinuclear entity in which the copper atoms are bridged by means of the -NCN- unit. The molar magnetic susceptibility measurements of 1-3 in the 2-300 K range indicate ferromagnetic coupling. The calculated J values, by using theoretical methods based on density functional theory (DFT) are in excellent agreement with the experimental data. Catalytic hydration of a nitrile to an amide functional group is assumed responsible for the formation of 3 from a mu(1,3)-dicyanamido ligand.