Ab‐Initio studies on π‐nonbonded and through‐bonds interactions in n‐alkanes, n‐alkyl radicals, and polymethylene diradicals

Abstract

AbstractAb‐initio studies were conducted on quantitative aspects of π‐nonbonded, σ–σ*, n–σ*, and throughbond interactions in R1CH2(CH2)N–1 CH2 R2, where R1 and R2 are H and/or nonbonding AO, n, and N = 2, 3, and 4. Geometrical preferences were found to depend both on π‐nonbonding and bond–antibonding interactions, the latter being more important. Level orderings and energy splittings involved in the through‐bond interactions of diradicals can be qualitatively predicted by examining the signs of the overlap between the n orbitals and a common vicinal σ* bond orbital, using simple orbital patterns and paying special attention to the “backside” tails of bond orbitals.