Knowledge Bank

Minimal basis LCAO-SCF calculations on diimide were carried out using a Gaussian expansion of Slater atomic orbitals. Results predict the trans isomer ($rNN=1.28\backslash AA,rNH=1.13\backslash AA,\angle NNH=104\circ$) to be about 7 kcal/mole lower in energy than the cis ($rNN=1.28\backslash AA,rNH=1.13\backslash AA,\angle NNH=112\circ$). The computed free energy change for the reaction $N2H2⟶N2+2H$ at $298\circ K$ with various $N2H2$ geometries indicates that both cis and trans isomers are stable with respect to this decomposition, but that intermediates in cis-trans conversion are not.