Olefin strain energies and platinum complexes of highly pyramidalised alkenes

Density functional theory has been used to investigate the platinum complexes of a series of 16 highly pyramidalised alkenes. Olefin pyramidalisation strain energies (OPSE) were calculated at the B3LYP level for the free alkenes. The geometries and binding energies of the platinum complexes are reported. The charge decomposition analysis procedure was used to quantitatively investigate the nature of the bonding in these complexes. This showed that the metal–alkene bond in 14 of the complexes could be interpreted in terms of the Dewar model of donation and back donation. For two series of alkenes, the back donation becomes more important as the degree of pyramidalisation increases. For these two series of alkenes, it was found that a useful correlation exists between the binding energies of the platinum complexes and either the donation/back donation ratio, the pyramidalisation angle, or the OPSE of the free alkene.