Synthesis,Crystal Structure and Ferromagnetic Properties of a New Dicyanamide Bridged Dicopper(Ⅱ) Complex with IM-1′-MeBzIm-κ2 N,O Mode

A new dinuclear copper(Ⅱ) complex with imino nitroxide radicals [Cu2(NO3)2(IM-1′-MeBzIm)2(dca)2] (IM-1′-MeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimi-dazoline-1-oxyl, dca = dicyanamide anion) has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group P1, with a = 9.440(5), b = 10.124(6), c = 11.603(7), α = 102.904(7), β = 94.033(6), γ = 104.299(7)°, C34H40Cu2N16O8, Mr = 927.90, V = 1038.2(10) 3, Z = 1, Dc = 1.484 g/cm3, μ(MoKα) = 1.093 mm-1, F(000) = 478, R = 0.0609 and wR = 0.1512 for 2889 observed reflections with I > 2σ(I). X-ray analysis reveals that two Cu(Ⅱ) atoms are bridged by two dicyanamides to form a centrosymmetric Cu(Ⅱ)-Cu(Ⅱ) dinuclear entity. Every Cu(Ⅱ) ion is five-coordinated with a distorted square pyramidal coordination geometry and IM-1′-MeBzIm ligand coordinates to the metal ion with the κ2 N(1′-MeBzIm), O(IM) mode to avoid steric hindrance with the methyl group in the complex. Meanwhile, the molecules are linked by intermolecular hydrogen bonds, leading to a 1-D chain structure. Moreover, such chains are further linked by π-π stacking interactions to form a 2-D network structure. Magnetic measurement demonstrates that the intramolecular exchange couplings between Cu(Ⅱ) ion and the IM-1′-MeBzIm are ferromagnetic with J = 12.46 cm-1, where the spin Hamitonian is defined as■ = -2J12 within the complex.