Quantum chemical investigation of molecular complexes formed with bromine molecule of bicyclo[3.3.1]nonylidenebicyclo[3.3.1]nonane and its derivatives

Abstract

The strain energies and the pyramidalization parameters of bicycle [3.3.l]nonylydenebicyclo[3.3. l]nonane(BBN), <i>trans</i>(1-methyl-2-bicyclo[3.3 .1]-l-methyl bicyclo [3.3.1]nonane (DMBBN) and <i>trans</i>-(1-tert-butyl-2-bicyclo[3.3.1])-1–tertbutylbicyclo [3.3.1] nonane (DBBBN) molecules have been calculated using MM2 and AMBER molecular mechanic methods. The strain energy and the pyramidalization degree of the molecule are increased by increasing the volume of R groups at the allylic position of the double bond. The electronic structure of the molecules have been investigated by semiempirical PM3 method. The results of molecular mechanic and PM3 methods, agree with the X-ray results and shows that the double bond of BBN molecule has a planar structure. The 1: 1 π-molecular complexes of the molecules formed with Br₂ are investigated

using PM3 method and it is seen that their stable configuration has an axial structure. The electronic and the steric factors affecting the structure and the stability of the molecular complexes have been studied. It is found that the DMBBN ... Br₂ complex is more stable than the BBN ... Br₂ complex. It is determined that DBBBN ... Br₂ complex containing the bulky <i>tert-</i>butyl<i> </i>group has the lowest stabilization energy among the investigated molecular complexes.