Synthesis,Crystal Structure and Ferromagnetic Properties of a New Dicyanamide Bridged Dicopper（Ⅱ） Complex with IM-1＇-MeBzIm-k2 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′-（1′-methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl, dca = dicyanamide anion） has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group P 1^-, with α = 9.440（5）, b = 10.124（6）, c = 11.603（7） A, α = 102.904（7）, β = 94.033（6）,γ = 104.299（7）°, C34H40Cu2N16O8, Mr = 927.90, V= 1038.2（10） A^3, Z = 1, Dc = 1.484 g/cm^3, 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′-MeBzlm ligand coordinates to the metal ion with the k^2 N（1 ′-MeBzlm）, 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 H^ = -2JS^1S^2 within the complex.