PATHWAYS OF THE REACTION OF NUCLEOPHILIC-ADDITION OF AMMONIA TO FORMALDEHYDE IN THE GAS-PHASE AND IN THE COMPLEX WITH FORMIC-ACID - AB-INITIO CALCULATIONS

The gradient pathways of the reaction of nucleophilic addition of ammo nia to formaldehyde were calculated for free molecules and in the NH3- H2CO-HC(O)OH complex by the ab initio RHF/6-31G*, MP2(fc)/6-31G**, an d MP2(full)/6-311++G* methods. Both reactions proceed concertedly. In the first case, the reaction successively passes through two transiti onal states with an energy barrier exceeding 35 kcal mol(-1). In the c ase of the complex with formic acid, the reaction follows a convention al pathway, although its activation barrier calculated by the RHF/6-31 G* and MP2(fc)/6-31G** methods decreases to 12.6 and 3.8 kcal mol(-1) , respectively.