Transition metal halide complexes of 4-aminoacetophenone: Syntheses, structures, and magnetic behavior

A family of eight compounds of the general formula [(C8H9NO)(2)MX2] or [(C8H9NO)(2)(H2O)(2)MX2], (M = Ni, Co, Cu, Zn; X = Cl, Br) has been prepared and the compounds characterized by combustion analysis, IR, single-crystal X-ray diffraction and variable temperature magnetization measurements. [[(C8H9NO)(2)(H2O)(2)MX2], (1, n = 0, M = Cu, X = Cl; 2, n = 0, M = Cu, X = Br; 3, n = 2, M = Ni, X = Cl; 4, n = 2, M = Ni, X = Br; 5, n = 2, M = Co, X = Cl; 6, n = 2, M = Co, X = Br; 7, n = 0, M = Zn, X = Cl; 8, n = 0, M = Zn, X = Br.) The eight compounds crystallize in three distinct space groups and have coordination number of either four (compounds 1, 2, 7, and 8) or six (compounds 3-6). Compounds 1 and 2 are slightly distorted square planar, compounds 3-6 are slightly distorted octahedral, and compounds 7 and 8 are slightly distorted tetrahedral. All eight compounds form chains either through bihalide interactions (1 and 2) or systems of hydrogen bonds (3-8). Chains are linked into layers through short halide...halide (1, 2, 7) and both traditional and non-traditional hydrogen bonds. The complexes have also been studied via variable temperature magnetic susceptibility measurements. Data for Cu(II) com-plexes 1 and 2 the 1D-Heisenberg uniform chain model with J/kB of-13.4(6) K and-14.3(4) K, respectively, with antiferromagnetic interchain interactions (theta =-4.1(5) K,-2.5(5) K, respectively) following the H = -J n-ary sumation si center dot sj Hamiltonian. The Ni(II) and Co(II) compounds showed temperature dependent moments which were well-modeled as arising due to single-ion anisotropy.