Theoretical prediction regarding structural and thermodynamical characteristics of stable CH3PO2 isomers and unimolecular decomposition mechanisms of species CH3P(=O)2, CH3O-P=O, and CH2=P(=O)OH.

The detailed isomerization and dissociation reaction potential energy profile of the CH(3)PO(2) system was established at the UCCSD(T)/6-311++G(3df,2p)//UB3LYP/6-311++G(d,p) level of theory. Seventy minimum isomers were located and connected by 93 optimized interconversion transition states. Furthermore, 32 isomers with high kinetic stability were predicted to be possible candidates for further experimental detection. The bonding nature of the suggested stable isomers was analyzed while their molecular properties including heats of formation, adiabatic ionization potentials, and adiabatic electronic affinities were calculated at the G2, G2(MP2), G3, and CBS-Q levels. Based on the isomerization and dissociation potential energy surface, possible unimolecular decomposition mechanisms and pathways of the low-lying molecules CH(3)P(=O)(2), CH(3)O-P=O, and CH(2)=P(=O)OH were discussed. Furthermore, the transition state theory rate constants of the primary unimolecular dissociation channels were also calculated.