MOLECULAR-COMPLEXES OF NITRIC-ACID WITH N-2 - A POST-HARTREE-FOCK QUANTUM-MECHANICAL STUDY

The structure of the molecular 1:1 complexes of nitric acid with N-2 w ere optimized at the MP2/6-311G(df,pd) level of theory revealed a near ly linear planar O-H...N hydrogen bonded form and a nonplanar and non- hydrogen bonded form. The global minimum energy structure corresponds to a hydrogen-bonded species: -1.31 kcal/mol at the MP4(SDTQ)/6-311 G(df,pd)//MP2/6-311G(df,pd) and -1.27 kcal/mol at the CCSD[T] and QCIS D[T]/6-311 +G(df,pd)//MP2/6-311G(df,pd) levels. The nonplanar form is predicted to be a very weakly bonded system at both the MP4(SDTQ)/6-31 1 + G(df,pd)//MP2/6-311G(df,pd) (-0.34 kcal/mol) and at the CCSD[T]/6- 311 + G(df,pd)//MP2/6-311G(df,pd) (-0.17 kcal/mol) levels of theory. A dditionally, a decomposition of the SCF interaction energy was perform ed. (C) 1998 Published by Elsevier Science B.V. All rights reserved.