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

Abstract

A family of eight compounds of the general formula [(C8H9NO)2MX2] or [(C8H9NO)2(H2O)2MX2], (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)nMX2], (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) complexes 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 (θ = −4.1(5) K, −2.5(5) K, respectively) following the H=-J∑si∙sj Hamiltonian. The Ni(II) and Co(II) compounds showed temperature dependent moments which were well-modeled as arising due to single-ion anisotropy.