Proton transfers in hydrogen-bonded systems. 2. Electron correlation effects in (N/sub 2/H/sub 7/)/sup +/

Journal Article · Wed May 06 04:00:00 EDT 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00399a005· OSTI ID:6206610

Scheiner, S; Harding, L B

Potentials for transfer of the central proton between the NH/sub 3/ units of (H/sub 3/NHNH/sub 3/)/sup +/ are calculated via ab initio methods ar several levels of sophistication. Double-well potentials are obtained for all internitrogen distances studied which vary between 2.73 and 3.15 A. All methods indicate that the energy barrier to proton transfer increases as the two NH/sub 3/ molecules are further removed from one another. Treatment of electron correlation via the polarization configuration interaction (POL-CI) method leads to barriers substantially smaller than those obtained by restricted Hartree-Fock calculations with use of a basis set of double zeta plus polarization function (RHF/DZP) quality. Inclusion of only intrapair correlations involving the two nitrogen lone pairs with use of the generalized valence bond (GVB) method leads to no decreases in the barriers relative to the DZP Hartree-Fock estimates. Use of the smaller split valence 4-31G basis produces barriers intermediate between the RHF/DZP and POL-CI results. Proton transfers in (N/sub 2/H/sub 7/)/sup +/ in the gas phase are studied using both a rigid model and one which includes relaxation of the R(NN) distance during proton motion. The latter relaxation results in a lowering of the POL-CI barrier from 3.5 to 1.5 kcal/mol. 2 figures, 4 tables.

• Research Organization: Southern Illinois Univ., Carbondale
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6206610
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:9; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AMMONIA
BARYONS
BINDING ENERGY
BOND LENGTHS
CORRELATIONS
DATA
DIMENSIONS
ELECTRON CORRELATION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
EXPERIMENTAL DATA
FERMIONS
HADRONS
HARTREE-FOCK METHOD
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN TRANSFER
INFORMATION
LENGTH
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
NUCLEONS
NUMERICAL DATA
POTENTIALS
PROTONS