Complexes of zinc halides with amide ligands having a high dipole moment

Complexes [Zn(C6H5CONH2)2Br2] and [Zn((NH2)2CO)2Br2] were synthesized and characterized by elemental analysis, IR spectroscopy, and X-ray diffraction and compared to other complexes of zinc halides with benzamide and urea. In all complexes, the zinc ion has a tetrahedral coordination environment of two halide ligands and two oxygen atoms of two amide ligands. The structure of [Zn(C6H5CONH2)2Br2] (orthorhombic, Pna21, a = 29.207(6), b = 7.5826(14), c = 14.753(3) Å, Z = 8) is not isostructural to the chloride and iodide compounds. The [Zn((NH2)2CO)2Br2] complex (triclinic, P-1, a = 6.4435(9), b = 7.096(1), c = 11.7079(18) Å, α = 88.119(9)°, β = 77.005(9)°, γ = 66.320(8)°, Z = 2) is isostructural to [Zn((NH2)2CO)2Cl2], and they both differ from [Zn((NH2)2CO)2I2]. Dipole moments of complexes of various zinc halides with benzamide, urea, and dimethylformamide were calculated; they vary in the 9–13 D range. Complexes of zinc halides with amides were used to prepare films with the use of cellulose diacetate as a polymer matrix. Dielectric measurements showed the presence of a pronounced electret effect.