Study of the structural and thermodynamic stability of pentacoordinated nitrogen compounds NF2X3 (X = H, Cl, Br): Ab initio calculations

摘要

Quantum chemical calculations of compounds with a pentacoordinated nitrogen atom such as NF2H3 (in the CCSD(Full)/6-311++G(d,p) approximation), NF2Cl3 and NF2Br3 (in the B3LYP/6-311+G(d) approximation) are carried out. It is found that NF2Cl3 and NF2Br3 molecules are structurally stable, but thermodynamically unstable, and are isomerized to NFCl2...FCl and NFBr2...FBr molecular complexes respectively. The total energy of NFCl2...FCl and NFBr2...FBr complexes is lower than the total energy of NF2Cl3 and NF2Br3 molecules by 62 kcal/mol and 64 kcal/mol respectively. The trigonal bipyramidal form of the NF2H3 molecule of D (3h) symmetry is structurally unstable: a first-order saddle point corresponds to it on the potential energy surface of the system. A second-order saddle point is found on the reaction path of NF2H3 isomerization.