Photochromic dihetarylethenes 9. Dithienylperfluorocyclopentenes: a quantum-chemical study

MN DO calculations of the open and cyclic forms of the molecules of three p hotochromic 1,2-di(3-thienyl)perfluorocyclopentene derivatives were carried out. Structural parameters as well as electronic and thermodynamic charact eristics of the compounds studied were analyzed. The optimized geometric pa rameters of the open forms of the three molecules under study are in satisf actory agreement with the results of X-ray diffraction studies. Analysis of the effect of substituents on the electronic characteristics of the centra l fragment and on the composition of the frontier MOs suggests that it is m ore appropriate to use cyclic rather than open forms of the molecules for c orrelation analysis and for prediction of photochromism of dithienylperfluo rocyclopentenes.