Theoretical study and atoms in molecule analysis of hydrogen bonded clusters of ammonia and isocyanic acid

Zabardasti, Abedien; Amani, Saeid; Solimannejad, Mohammad; Salehnassaj, Maryam

doi:10.1007/s11224-009-9513-1

Cited by 22 publications

(14 citation statements)

References 21 publications

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“…The existence of isocyanic acid (HNCO) in the atmosphere has been established only recently (Roberts et al, 2011;Wentzell et al, 2013) despite its molecular structure and chemical synthesis being first discovered in the 19th century (Liebig and Wöhler, 1830). HNCO can form H-bonded clusters (Zabardasti et al, 2009(Zabardasti et al, , 2010Zabardasti and Solimannejad, 2007) and in pure form appreciably polymerizes to other species (Belson and Strachan, 1982) but becomes relatively stable in the gaseous phase (ppm level) under ambient temperature conditions (Roberts et al, 2010). It is thus near-exclusively present as a monomer in the gaseous phase under ambient temperature conditions (Fischer et al, 2002;Roberts et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study

Rosanka

Nguyen

et al. 2020

Atmos. Chem. Phys.

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Abstract. Isocyanic acid (HNCO) is a chemical constituent suspected to be harmful to humans if ambient concentrations exceed ∼1 ppbv. HNCO is mainly emitted by combustion processes but is also inadvertently released by NOx mitigation measures in flue gas treatments. With increasing biomass burning and more widespread usage of catalytic converters in car engines, good prediction of HNCO atmospheric levels with global models is desirable. Little is known directly about the chemical loss processes of HNCO, which limits the implementation in global Earth system models. This study aims to close this knowledge gap by combining a theoretical kinetic study on the major oxidants reacting with HNCO with a global modelling study. The potential energy surfaces of the reactions of HNCO with OH and NO3 radicals, Cl atoms, and ozone were studied using high-level CCSD(T)/CBS(DTQ)//M06-2X/aug-cc-pVTZ quantum chemical methodologies, followed by transition state theory (TST) theoretical kinetic predictions of the rate coefficients at temperatures of 200–3000 K. It was found that the reactions are all slow in atmospheric conditions, with k(300K)≤7×10-16 cm3molecule-1s-1, and that product formation occurs predominantly by H abstraction; the predictions are in good agreement with earlier experimental work, where available. The reverse reactions of NCO radicals with H2O, HNO3, and HCl, of importance mostly in combustion, were also examined briefly. The findings are implemented into the atmospheric model EMAC (ECHAM/MESSy Atmospheric Chemistry) to estimate the importance of each chemical loss process on a global scale. The EMAC predictions confirm that the gas-phase chemical loss of HNCO is a negligible process, contributing less than 1 % and leaving heterogeneous losses as the major sinks. The removal of HNCO by clouds and precipitation contributes about 10 % of the total loss, while globally dry deposition is the main sink, accounting for ∼90 %. The global simulation also shows that due to its long chemical lifetime in the free troposphere, HNCO can be efficiently transported into the UTLS by deep convection events. Daily-average mixing ratios of ground-level HNCO are found to regularly exceed 1 ppbv in regions dominated by biomass burning events, but rarely exceed levels above 10 ppt in other areas of the troposphere, though locally instantaneous toxic levels are expected.

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Section: Introductionmentioning

confidence: 99%

Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study

Rosanka

Nguyen

et al. 2020

Atmos. Chem. Phys.

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“…AIM theory is found to be a useful tool for describing the electronic properties of a chemical bond. [49,62,63] In the AIM theory demonstrates that, when two atoms are connected by a chemical bond, a bond critical point (BCP) appears between them and the nature of chemical bonds and molecular reactivity are described by total electronic density, and its Laplacian electron density (Δ 2 ρ), and the total electronic energy density (H [r] ), and its components, the electronic potential energy density (V [r] ) and the electronic kinetic energy density (G [r] ). The calculated topological parameters for the Li +Á Á Á C bond for all cyclopropane systems are given in Table 3.…”

Section: Atoms In Molecules (Aim) Analysismentioning

confidence: 99%

Probing the bent bonds in cyclopropane systems for gas storage and separation process: A computational study

Wakchaure

Ganguly

2020

J Comput Chem

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The hydrogen, carbon dioxide, and carbon monoxide gas adsorption and storage capacity of lithium‐decorated cyclopropane ring systems were examined with quantum chemical calculations at density functional theory, DFT M06‐2X functional using 6‐31G(d) and cc‐pVDZ basis sets. To examine the reliability of M06‐2X DFT functional, a few representative systems are also examined with complete basis set CBS‐QB3 method and CCSD‐aug‐cc‐pVTZ level of theory. The cyclopropane systems can bind to one Li+ ion; however, the corresponding the methylated systems can bind with two Li+ ions. The cyclopropane systems can adsorb six hydrogen molecules with an average binding energy of 3.8 kcal/mol. The binding free energy (ΔG) values suggest that the hydrogen adsorption process is feasible at 273.15 K. The calculation of desorption energies indicates the recyclable property of gas adsorbed complexes. The same number of CO2 and CO gas molecules can also be adsorbed with an average binding energy of −14.4 kcal/mol and −10.7 kcal/mol, respectively. The carbon dioxide showed ~3–4 kcal/mol better binding energy as compared to carbon monoxide and hence such designed systems can function as a potential candidate for the separation of these flue gas molecules. The nature of interactions in complexes was examined with atoms in molecules analysis revealed the electrostatic nature for the interaction of Li+ ion with cyclopropane rings. The chemical hardness and electrophilicity calculations showed that the gas adsorbed complexes are rigid and therefore robust as gas storage materials.

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“…The existence of isocyanic acid (HNCO) in the atmosphere has been established only recently (Roberts et al, 2011;Wentzell et al, 2013) despite being first recognized in the 19 th century (Liebig and Wöhler, 1830). HNCO can form H-bonded clusters (Zabardasti et al, 2009(Zabardasti et al, , 2010Zabardasti and Solimannejad, 2007), and in concentrated/pure form appreciably polymerizes to other species, but becomes fairly stable in the presence of impurities (Belson and Strachan, 1982), such that the monomer is the near-exclusive representative especially in the gaseous phase under ambient temperature conditions (Roberts et al, 2010). The background ambient mixing ratios of HNCO vary in the range of a few pptv to tens of pptv (Young et al, 2012), while in urban regions, HNCO mixing ratio increases from tens of pptv to hundreds of pptv (Roberts et al, 2014;Wentzell et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Chemical loss processes of isocyanic acid, HNCO, in the atmosphere

Rosanka

Nguyen

et al. 2020

Preprint

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Abstract. The impact of chemical loss processes of isocyanic acid was studied by a combined theoretical and modeling study. The potential energy surfaces of the reactions of HNCO with OH and NO3 radicals, Cl atoms, and ozone, were studied using high-level CCSD(T)/CBS(DTQ)//M06-2X/aug-cc-pVTZ quantum chemical methodologies, followed by TST theoretical kinetic predictions of the rate coefficients at temperatures of 200–3000 K. It was found that the reactions are all slow in atmospheric conditions, with k(300 K) ≤ 7 × 10−16 cm3 molecule−1 s−1; the predictions are in good agreement with earlier experimental work, where available. The reverse reactions of NCO radicals, of importance mostly in combustion, were also examined briefly. The global model confirms that gas phase chemical loss of HNCO is a negligible process, contributing less than 1 %. Removal of HNCO by clouds and precipitation is a larger sink, contributing for about 10 % of the total loss, while globally dry deposition is the main sink, accounting for ~ 90 %. The global simulation also shows that due to its long chemical lifetime in the free troposphere, HNCO can be efficiently transported into the UTLS by deep convection events. Average daily concentrations of HNCO are found to rarely exceed levels considered potentially toxic, though locally instantaneous toxic levels are expected.the free troposphere, HNCO can be efficiently transported into the UTLS by deep convection events. Average daily concentrations of HNCO are found to rarely exceed levels considered potentially toxic, though locally instantaneous toxic levels are expected.

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Theoretical study and atoms in molecule analysis of hydrogen bonded clusters of ammonia and isocyanic acid

Cited by 22 publications

References 21 publications

Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study

Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study

Probing the bent bonds in cyclopropane systems for gas storage and separation process: A computational study

Chemical loss processes of isocyanic acid, HNCO, in the atmosphere

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