X-RAY STRUCTURE DETERMINATIONS OF SOME COMPOUNDS OF INTEREST IN ANALYTICAL CHEMISTRY
INDIANA UNIV AT BLOOMINGTON CHEMICAL LABS
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A review is given of the structures of analytically important chelate complexes and chelating molecules which have been determined by x-ray diffraction methods. The dimethylglyoxime molecule first rotates 180 deg about the central short C-C bond. This bond has about 25 double-bond character and some energy is therefore required. The central bond is then stretched by 0.09 A and the C-N bond is shortened by about 0.04 A. A very strong H bond, which is believed to be symmetrical, is formed between each pair of O atoms. When proper force constants are known, energies induced by these distortions can be calculated. The structure of Zn 8-quinolinolate dihydrate was determined. When a Zn ion solution is treated with 8-quinolinol and the solution is neutralized, the dihydrate precipitates. The crystal system is monoclinic with a 11.28 A, b 5.42 A, c 13.16 A, and beta 106 deg 18 min. Observations on the effects of structure of organic molecules on the formation and stability of complexes, suggest that the distance between reacting groups may not be as important as previously supposed, because considerable distortion can occur.
- Physical Chemistry