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

Abstract

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.

Graphical Abstract

Keywords:

• Zinc bromide
• benzamide
• urea
• dimethylformamide
• dipole moment

Acknowledgements

Instrumental chemical analysis was performed in the Center for Collective Use (Instrumental chemical analysis and complex research of substances and materials) at the Lomonosov Institute of Fine Chemical Technologies, RTU MIREA. The XRD experiments were carried out at the Center for Collective Use of Physical Methods of Investigation of the Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences. Electret films were prepared and studied in the Ivanovo State University of Chemistry and Technology.

Additional information

Funding

This work was supported by the Russian Foundation for Basic Research [20-03-00244].