Natural bond orbital analysis of molecular interactions: Theoretical studies of binary complexes of HF, H2O, NH3, N2, O2, F2, CO, and CO2 with HF, H2O, and NH3

Abstract

The binary complexes of HF, H2O, NH3, N2, O2, F2, CO, and CO2 with HF, H2O, and NH3 have been studied by ab initio molecular orbital theory and natural bond orbital (NBO) analysis. Most of the complexes involving N2, O2, F2, CO, and CO2 are found to have both hydrogen-bonded and non-hydrogen-bonded structures. The NBO analysis provides a consistent picture of the bonding in this entire family of complexes in terms of charge transfer (CT) interactions, showing the close correlation of these interactions with the van der Waals penetration distance and dissociation energy of the complex. Contrary to previous studies based on the Kitaura–Morokuma analysis, we find a clear theoretical distinction between H-bonded and non-H-bonded complexes based on the strength of CT interactions. Charge transfer is generally stronger in H-bonded than in non-H-bonded complexes. It plays an intermediate role in non-H-bonded CO2 complexes which have been studied experimentally. However, the internal rotation barrier (1 kcal mol−1) of the H2O⋅⋅⋅CO2 complex is found to be primarily of electrostatic origin with only a small (π-type) CT contribution. The role of electrostatic interactions, effect of electron correlation, and comparison of theory with experiment are also discussed.

Combined quantum chemical and modeling study of CO hydrogenation on water ice

“…For the 1:1 water-carbon monoxide system, the two possible structures were experimentally identified (Lundell & Rasanen 1995), with the conclusion that the two complexes coexist. Results based on highly-correlated quantum chemical calculations agree with experiments (Reed et al 1986;Parish et al 1992;Lundell 1995;Sadlej et al 1995;Lundell et al 1997). We here predict that the C-attached complex is the most stable one from the computed potential interaction energies for the W3-carbon monoxide complex at L1.…”

“…The C−O bond strengthening (weakening) for the O-attached (C-attached) complexes have indeed been observed by FTIR matrix isolation spectroscopy (Lundell & Rasanen 1995), as the CO fundamental frequency is bathochromic (hypsochromic) shifted from the value of the gas CO. These effects have been described in the literature (Reed et al 1986;Lundell 1995;Lundell & Latajka 1997) and are related to the bonding/antibonding character of the CO electron lone pair engaged in the H-bond interaction.…”

Studies on Interactions between Sulfadiazine and Peptide Amides

“…To acquire deeper insight into the nature of complexes system interactions, Atoms In Molecules (AIM) analysis is performed by using AIM 2000 (Bader, 1990). In addition, analyses of the charge distribution and charge transfer processes are performed by using Natural Bond Orbital (NBO) partitioning scheme (Reed et al, 1986).…”

Estudo das ligações de hidrogênio para dímeros formados pelas moléculas de H2O, NH3, HF, HCl e HBr através de cálculos baseados em primeiros princípios

“…1,2 Existe na literatura, entretanto, um amplo intervalo 1 no qual estão situadas energias associadas às ligações de hidrogênio. Há uma série de estudos baseados em métodos computacionais ab initio [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] e em métodos semiempíricos e DFT (Density Functional Theory), [18][19][20][21] que visam compreender de forma mais clara e objetiva as ligações de hidrogênio. Desses estudos computacionais, vários se referem às interações químicas existentes na estrutura dos dímeros que contêm moléculas de água, [1][2][3]19,20,[22][23][24] amônia 20,21 e haletos de hidrogênio (exceto iodetos) 1,18,20,[25][26][27][28] em sua estrutura.…”