Far-infrared Spectra of Zinc Halide Complexes with Acetonitrile

Abstract

Abstract The infrared spectra of zinc halide complexes with acetonitrile, ZnX2·2CH3CN (X=Cl, Br, I), in the solid state were recorded in the region from 4000 to 96 cm−1. The Zn–N stretching bands for the chloride and bromide were observed, at 210 and 212 cm−1 respectively, as composite bands of the A1 and B1 species. For the iodide, the Zn–N stretching band of the B1 species was observed at 219 cm−1, while the A1 mode was coupled with the Zn–I stretching mode and was absorbed at 252 and 179 cm−1. The N–Zn–N bending bands were observed at 163, 162, and 153 cm−1 and the Zn–N≡C bending bands, at 125, 128, and 132 cm−1, for the chloride, bromide, and iodide respectively. The normal coordinate analysis was carried out by the use of the Urey-Bradley force field, and the Zn–N stretching force constant was obtained as 0.56 mdyn/Å. The force constant is much smaller than the corresponding ones in complexes containing nitrogen donors in the sp3 and the sp2 valency states.