302. Electron pairing

Abstract

Calculations of the electronic binding energy have shown that, between 0.6 and 1-2 A, it is only 5-10% greater for H, than for H,+ despite the fact that two electrons are involved in H, and one in H,+. This result is discussed in relation to the wide prevalence of the electron-pair bond. In addition it has been shown that for linear symmetrical H,+ the best description is in terms of two one-electron bonds.OVER the last fifty years great stress has been placed on the grouping of electrons in pairs in molecules,l and it appears that, in the minds of some, there is the belief that the " pairing of electrons '' in, for example, the chemical bond provides some special advantage energetically. This impression has been encouraged by the Heitler-London treatment of the bond in the hydrogen molecule and the interpretation of this as a so-called interchange or resonance phenomenon which demands the participation of two electrons. It is the purpose of this paper to examine in some simple cases the degree to which the " pairing of electrons '' is important. This is done by studying H,+, H,, and H3+. In the first place a comparison is made of the electronic energies of H2+ and H, as a function of