Quantum chemical study of the thermodynamics, kinetics of formation and bonding of H2CN: Relevance to prebiotic chemistry
SummaryUsing the Iterative Extended Huckel Theory (IEHT), energy-conformation studies have been carried out for H2CN (I),trans-HCNH (IIA), andcis-HCNH (IIB), three possible isomers formed by addition of a hydrogen atom to hydrogen cyanide. Calculations show that the order of decreasing thermodynamic stability is I
$$ > $$
 IIA > IIB.Results of a series of calculations designed to simulate the stepwise addition of a hydrogen atom to hydrogen cyanide to form both I and IIA indicate that formation of I is also kinetically favored over IIA. Calculated properties of the minimum energy conformers of I and IIA and the nature of the bonding in them are described. The calculated distribution of the unpaired electron density in I compares favorably with results obtained empirically from the ESR spectra of a radical formed by addition of H atoms to HCN. The potential role of H2CN (I) as a reactive intermediate in prebiotic organic synthesis and its possible relevance to interstellar organic chemistry are discussed.