Complexes of nitric oxide with water and imidazole

Abstract

NO-Imi-H 2 O complexes can be used as a model to investigate the interactions of histidine with nitric oxide and water in biological systems like myoglobin. We discuss here the water-imidazole, water-nitric oxide dimers and the trimolecular complexes of nitric oxide with water and imidazole from the donor-acceptor point of view using the Natural Bond Orbitals (NBO) and Energy Decomposition Analysis (EDA) schemes. The comparison between trimolecular and bimolecular complexes shows that in general, the stabilization energies are more sensitive to changes in the interactions of imidazole with water than to changes in the interactions with nitric oxide. The effect of imidazole ring protonation on the geometry and stabilization of the complexes is also investigated. We found that cooperative effects are more relevant in charged complexes and planar structures than in neutral species and non-planar complexes. The driving forces governing the interactions between open and closed shell systems are also discussed with special emphasis on the role of lone pairs and unpaired electrons.

Reactive quenching of NO (A2Σ+) with H2O leads to HONO: a theoretical analysis of the reactive and nonreactive electronic quenching mechanisms

“…Finally, several additional theoretical studies have attempted to develop insights into the physical origin of the intermolecular interactions in the NO + H 2 O complex, as well as map out the D 0 and D 1 PESs. 29–31 Outside of the CASSCF calculations reported by Umemoto and co-workers, the photochemistry of NO (A 2 Σ + ) + H 2 O has not yet been explored.…”

Interplay of Hydrogen, Pnicogen, and Chalcogen Bonding in X(H2O)n=1–5 (X = NO, NO+, and NO–) Complexes: Energetics Insights via a Molecular Tailoring Approach

“…15 Several theoretical analyses, like the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO), were used to characterize and quantify the nature of interactions in the NO(H 2 O) complex. 11,16,17 Despite the importance of NO and water interactions in several research areas, the microhydration of NO has not been explored well at the molecular level.…”

“…Atomistic-level insights into hydrated NO and identification of the nature of noncovalent interactions among them have received immense attention in recent years. − Several research groups confirmed the hydrogen bond (HB) interaction between neutral NO and water with the help of infrared spectrum, mass spectrometry, and laser techniques. − The potential energy surface of NO­(H 2 O) complexes at the ab initio level was initially reported by Myszkiewicz and Sadlej . Several theoretical analyses, like the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO), were used to characterize and quantify the nature of interactions in the NO­(H 2 O) complex. ,, Despite the importance of NO and water interactions in several research areas, the microhydration of NO has not been explored well at the molecular level.…”

“…21 Such an interaction is noted in neutral NO(H 2 O) complexes as well; the characteristics of these types of noncovalent interaction are not detailed in previous studies but are indicated as an electron donor− acceptor interaction. 11,26 It is obvious that noncovalent interactions other than HBs are present in the NO + (H 2 O) and NO(H 2 O) complexes.…”