Charge density distribution in small strained rings. A local hybrid overlap study

Abstract

The local hybrid orbitals obtained by the iterative maximum overlap method were used to construct electron isopycnic (isodensity) maps and deformation contours in strained cyclopropane, cyclopropene, cyclobutene and cyclopentadiene rings. The qualitative features of electron charge distributions and reorganization effects accompanying formation of chemical bonds are fairly well reproduced. The isopycnic maps and the corresponding deformation diagrams reflect the presence of bent bonds. They also indicate that the Förster—Coulson—Moffitt bent bond picture of strained rings is in principle equivalent to the Walsh model. Summarizing present results and earlier findings one can say that variable hybridization provides a simple, clear semiempirical model of covalent bonding.