Solvent effect on the conformational behavior of substituted spiro[4.5]decanes and spiro[5.5]undecanes

Abstract

Abstract:We studied the relatively complex polar systems 6-substituted-l,4-dioxospiro[4.5]decanes and 7-substituted-l,5-dioxospiro[5.5]undecanes with substituents X = CH,, F, C1, CN, OH, OCH,, and NOz. Solvent effects on theequilibrium have been analysed by means of a Self-Consistent-Reaction-Field model and the PM3 method. Complete geometry optimizations have been carried out for all the structures in the gas phase and in solution. For some substituents, a set of rotamers have been separately optimized. The discussion of the results is focussed on the effects arising from structural aspects and from steric and electrostatic interactions on the axial/equatorial relative stability. The role played by multipole moment is considered. In general, good agreement with available experimental data and with previous theoretical studies has been obtained. Though the use of semiempirical methods and simple solvent models prevents us from reaching definitive conclusions, this approach seems to be very useful in predicting the main role of solute-solvent interactions in conformational equilibria of complex systems for which ab initio calculations cannot be performed.

A computational study on heterodimerization of charged porphyrins

“…In this model, the solvent is simplified as a dielectric continuum and the solute is subjected to self-consistent field (SCF) calculations. An ellipsoidal cavity shape was employed since it was extensively tested and known to be suitable for many molecules [52][53][54][55][56]. The stable gas-phase structures of TCP and TAP were used as starting geometries in solvent effect calculations.…”