Influence of L-type ligands on teh relative stability and interconversoin of cis-trans-[Ru(phen)_2L_2]~(n+) type complexes.A theoretical study

摘要

Polipyridine complexes of type [Ru(N-NhL2]2 + are useful for the conversion of light into usable energy for which the tran.l geometry would be preferable. In this paper ,the effect of distortion on trans structure stability was studied theoretically. A formal separation of the cOntributions was carried out, and it explained why the hydrogen repulsions are an important factor. A study o(the main aspects related to the cis~transisomers and also their mutual interconversionwas analyzed. Calculations were carried out at the PM3, ZINDO and ab initio level.. Energy differences between trans and cis isomers after full geometry optimizations for different L-Iigands show a dependence on .the L-Iigand Jorgensen field strength parameter f A driving coordinate ';.as performed in order to determine the kinetic preferences for isomer formation. The analysis showed that the entrance of the second phenanthroline is favoured for the cis geometry in regard to the trans geometry .TIJ:e activation barrier is alsodepertdent on the L-Iigand strength. The th~rmal trans-cis interconversion seems to be very improbable adiabatically (considering only one potential energy surface).