Nitric Acid Molecules Research Articles

Crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo [8.8.8]hexacosane nitrate-hydrogen nitrate perchlorate semihydrate

An adduct of 2.2.2-cryptand with nitric and perchloric acids of the [H2(Crypt-222)· 0.52H2O]2+·ClO 4 − ·NO 3 − ·HNO3 composition (I) is prepared and characterized by single crystal X-ray diffraction. The triclinic structure of I (space group $$P\overline 1 $$ , a = 10.176 A, b = 11.272 A, c = 12.870 A, α = 78.61°, β = 76.62°, γ = 79.88°, Z = 2) is solved by a direct method and refined in the full-matrix anisotropic approximation to R = 0.062 for all 3642 measured independent reflections (CAD-4 automated diffractometer, λMoK α). The structure of I contains a dication of 2.2.2-cryptand in the endo-endo conformation, two hydrogen atoms at the protonated N atoms are directed inside the cavity which also includes a water molecule with a site occupation factor of 0.52. Tetrahedral ClO 4 − anion in I is disordered. In I, the H atom of the NO 3 − ·HNO3 dimer is split over two close positions with occupation factors of 0.33 and 0.67; this dimer is joined by a very strong single disordered hydrogen bond N-O-H⋯O = N between the molecule of nitric acid and its anion.

4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]-hexacosane Bis(nitrate-hydrogennitrate): Synthesis and crystal structure

A crystalline adduct of 2.2.2-cryptand and nitric acid, [H2(Crypt-222)]2+·2(NO 3 − ·HNO3) (I), is synthesized and studied using X-ray diffraction analysis. The monoclinic structure of compound I (space group C2/c, a = 13.326 A, b = 15.262 A, c = 15.020 A, β = 98.96°, Z = 4) is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.067 for 2647 independent reflections (CAD4 automated diffractometer, λMoK α radiation). In the structure of compound I, the 2.2.2-cryptand dication lies on an axis 2 and has an endo-endo conformation, for which two H atoms at two protonated N atoms are directed inside the cavity. One of the NO 3 − ·HNO3 dimers is situated in the inversion center, and the other dimer lies on another axis 2 and is disordered over three orientations. All H atoms in the NO 3 − ·HNO3 dimers are equiprobably disordered over two close sites. Each of the two NO 3 − ·HNO3 dimers is formed by the very strong disordered N-O-H···O=N hydrogen bond between the nitric acid molecule and nitrate anion.

Cr3O(CH3COO)6(H2O)3]NO3⋅HNO3⋅H2O, Triaqua-Hexakis(Μ- Acetato)-Μ3-Oxo-Trichromium(III) Nitrate Nitric Acid Solvate Monohydrate

Reaction in methanol solution of the trinuclear ‘basic’ chromium(III) acetate with Pr(NO3)3⋅5H2O and further extraction by chloroform-acetone mixture led to the formation of novel unusual [Cr3O(CH3COO)6(H2O)3]NO3⋅HNO3⋅H2O (1) cluster with one “free” molecule of nitric acid. Complex 1 crystallizes in the monoclinic space group P21/c with, at room temperature, a = 13.624(2), b = 15.032(2), c = 15.180(2) Å, β = 112.98(3) °, Z = 4, and V = 2862.09 Å3. The obtained crystalline compound has been synthesized and characterized by IR and UV/Vis methods.

Theoretical study of hydrogen bonded complexes of dimethyl disulfide or dimethyl peroxide with nitric acid

Ab initio and DFT calculations performed on the title systems revealed two types of structures for both DMDS–HNO 3 and DMDO–HNO 3 complexes. In both structures two hydrogen bonds are formed between the OH group interacting with one of sulfur (or oxygen) atoms and methyl CH group being a proton donor to one of the oxygen atoms of the NO 2 group of nitric acid. Depending on the location of the interacting methyl group with respect to the S or O acceptor of the main O–H⋯S(O) bond, the seven or eight-membered ring structures are formed. For all the structures, the most pronounced changes in geometric parameters upon interaction are observed for the proton donor molecule. The calculated binding energies Δ E ZPE CP are between −20.86 and −29.95 kJ/mol at MP2 and between −17.52 and −27.47 kJ/mol at B3LYP using the 6-311++G(2d,2p) basis set. The complexes involving disulfide are slightly weaker by ca. 6.7–8.6 kJ/mol than the corresponding peroxide complexes. The performed NBO analysis reveals that the charge transferred to σ*(OH) orbital of the nitric acid molecule comes mainly from the high p-character lone pair orbital of sulfur or oxygen atom being the hydrogen bond acceptor site in the disulfide or peroxide molecule.

Synthesis and crystal structure of a new zinc diphosphonate

A new zinc diphosphonate [NH3CH(CH3)CH2NH3]2Zn2(edbbp)2(HNO3)2·4H2O [eddbp = O3PCH(Ph)NH(CH2)2NHCH(Ph)PO3] was hydrothermally synthesized with Zn(NO3)2·6H2O, ethane-1,2-diamino-N,N′-bis(benzylphosphonic acid) (H4edbbp) and 1,2-propyldiamine. It consists of a centro-symmetric dimeric unit [Zn2(edbbp)2], in which each zinc ion adopts a distorted square-pyramidal coordination geometry. Hydrogen bonds formed between phosphonate groups and protonated 1,2-propyldiamine molecules link the dimeric units into one-dimensional chains. The doubly protonated 1,2-propyldiamine molecules serve not only as charge compensating counter ions, but also as bridging groups. Hydrogen-bonding interactions among the phosphonate oxygen atoms, water molecules, nitric acid molecules and protonated 1,2-propyldiamine result in the formation of a three-dimensional supramolecular network.

Ground‐based nitric acid measurements at Arrival Heights, Antarctica, using solar and lunar Fourier transform infrared observations

Nitric acid plays an important role in processes leading to stratospheric ozone loss in polar regions. Spectroscopic absorption measurements of nitric acid have been made during the sunlit part of the Antarctic year at Arrival Heights (78°S, 167°E) since the late 1980s. This paper presents the first extension of these nitric acid measurements through the winter, using the Moon as a light source. Both solar and lunar measurements for the years 1998–2003 are presented. For the lunar measurements, additional corrections owing to emission of the atmosphere and the instrument must be made. The measurements show that the column amount of nitric acid within the polar vortex continues to increase after polar sunset reaching values of ∼2.5 × 1016 molecules cm−2 ∼1 month after sunset. When temperatures become low enough for the condensation of water and nitric acid molecules, polar stratospheric clouds form, and rapid depletion of the gaseous nitric acid column is observed. The measurements have captured this event particularly well in 2002. At the time of the polar sunrise the column amounts of nitric acid are extremely depleted and are as low as 0.5 × 1016 molecules cm−2. During the spring period the site can sample air from both inside and outside the polar vortex. Inside the vortex the observed gradual recovery of HNO3 in the spring and summer months is consistent with predictions of denitrification occurring during the Antarctic winter. For measurements outside the vortex, higher HNO3 columns are observed.

Effects of Hydration on the Properties of Protonated-Water−Nitric Acid Clusters

The uptake of nitric acid by protonated water (hydronium cation, H3O+) clusters and the characteristic structures of the resulting mixed aggregates, H+·(H2O)n·(HNO3)m, have been studied theoretically. As baseline simulations, B3LYP/6-311++G(d,p) geometry optimizations and energy calculations for n = 1−9 and m = 0−1 have been employed. To establish the mechanism of nitric acid uptake by hydronium ion−water clusters, the energetics of the various reaction pathways involving H3O+·(H2O)n and HNO3 are evaluated. In the presence of hydronium ion−water clusters, protonated nitric acid forms by a charge exchange reaction involving H3O+ and HNO3. Successive hydration of H+·HNO3 is an energetically favorable phenomena resulting in the formation of the mixed clusters containing one nitric acid molecule. However, when the number of water ligands on the clusters is less than about five, water binds more strongly to protonated water aggregates than to the mixed clusters. Accordingly, water will preferentially react with hydrated hydronium ions. Attachment reactions of nitric acid to the hydronium ion−water clusters are also found to be exothermic across the spectrum of sizes considered. However, switching reactions, involving H2O and H+·(H2O)n·(HNO3) for n = 2−7, are found to reestablish the hydronium ion−water cluster series. Above five water molecules, the binding energy of water to the mixed clusters containing one nitric acid molecule becomes comparable to that of the equivalent water aggregates; hence, the concentration of the former is expected to grow. Similar behavior has been experimentally observed by Castleman and co-workers [Zhang, X.; Mereand, E. L.; Castleman, A. W., Jr. J. Phys. Chem. 1994, 98, 3554. Gilligan, J. J.; Castleman, A. W., Jr. J. Phys. Chem. A 2001, 105, 5601].1,2 The structural arrangement of the optimized mixed clusters has also been investigated. The results show that isomeric configurations exist and that, depending on the degree of hydration of the ionic clusters, the most stable structures are the hydronium ion (H3O+), H5O2+ or the nitronium ion (NO2+). For low levels of hydration (i.e., n = 0, 1), the nitronium ion−water structures appear to be the most stable. These results agree with experimental investigations [Cao, Y.; Choi, J.-H.; Haas, B.-M.; Johnson, M. S.; Okumura, M. J. Chem. Phys. 1993, 99, 9307. Cao, Y.; Choi, J.-H.; Haas, B.-M.; Okumura, M. J. Phys. Chem. 1994, 98, 12176. Choi, J.-H.; Kuwata, K. T.; Cao, Y.-B.; Haas, B.-M.; Okumura, M. J. Phys. Chem. A 1997, 101, 6753].3-5 The geometry optimized structures also show that, depending on the cluster arrangement, the nitric acid molecule can dissociate into NO3- and H3O+ when the number of water ligands in the cluster is greater than about seven.

Theoretical study of the structure, stability and vibrational spectrum of the hydrogen-bonded nitric acid trimer

The structure, stability and vibrational spectrum of the hydrogen-bonded nitric acid trimer have been investigated using ab initio MP2/6-31G(d,p) and B3LYP/6-31G(d,p) calculations. Full geometry optimization was performed for the complex studied. It was established that the hydrogen-bonded nitric acid trimer has a planar cyclic structure. As a result of the hydrogen bonding a charge rearrangement occurs. The hydrogen and oxygen atoms, participating in the hydrogen bonding are the most sensitive to the complexation. The oxygen atoms act as acceptors of electric charge. The hydrogen bonding between three nitric acid molecules leads to the substantial changes in the vibrational characteristics of the stretching O–H vibrations. In the complex studied these vibrations are shifted to lower wave numbers. The calculated frequency shifts with the MP2/6-31G(d,p) are −88, −107 and −224 cm −1 and with the B3LYP/6-31G(d,p) calculations are −157, −198 and −274 cm −1. The magnitudes of the wavenumber shifts are indicative of O–H⋯O hydrogen-bonded interactions with a medium strength. The intensities of these vibrations increase dramatically upon hydrogen bonding. The calculated increase at the MP2 level is up to 12 times and with the B3LYP/6-31G(d,p) calculations is up to 13 times.

Hydrogen bonding and proton transfer in small hydroxylammonium nitrate clusters: A theoretical study

Structures and energies of gas-phase hydroxylammonium nitrate (HAN), HONH3NO3, are determined using density functional theory and the 6-311++G(d,p) basis set. Three stable configurations are found for HAN which involve strong hydrogen bonding between hydroxylamine and nitric acid molecules. In the most stable configuration, both the oxygen and the nitrogen of hydroxylamine are hydrogen bonded to sites on the nitric acid molecule. In the less stable HAN structures only the oxygen or the nitrogen of hydroxylamine are hydrogen bonded. Two stable structures for the (HAN)2 complex are investigated. The more stable structure is ionic, with the nitric acid proton having transferred to the nitrogen of hydroxylamine. Strong electrostatic and hydrogen-bonding interactions stabilize this structure. The other stable form of (HAN)2 has fewer hydrogen bonds and is composed of interacting neutral nitric acid and hydroxylamine molecules. Binding energies are determined for all structures along with corrections for basis set superposition errors in the HAN molecules. Proton exchange reaction paths are studied for the HAN configurations. The saddle points for the proton exchange process are ionic forms of HAN with interacting HONH3+ and NO3− moieties. These ionic structures are 13.5 and 13.6 kcal/mol higher in energy than the neutral hydrogen-bonded complexs of HONH2 and HNO3 from which they are formed. The electrostatic attractions between the ions are sufficient to stabilize the ionic form of (HAN)2, whereas in the HAN “monomer” the interaction energy for single HONH3+ and NO3− ions is not sufficient to compensate for the energy required for proton transfer from nitric acid to the hydroxylamine group. A correlation based on the bond-valence theory which describes the bond lengths of the hydrogen bonds is examined for the complexes. All the hydrogen bonds follow the correlation well.

Calculated OH-Stretching Vibrational Transitions of the Water−Nitric Acid Complex

We have calculated fundamental and overtone OH-stretching vibrational band frequencies and intensities of the water−nitric acid complex. The calculations use the simple harmonically coupled anharmonic oscillator (HCAO) local-mode model with local-mode parameters obtained from scaled ab initio calculations and ab initio-calculated dipole moment functions. The ab initio calculations were performed at the HF, B3LYP, and QCISD levels of theory predominantly with the 6-311++G(2d,2p) basis set. We have compared our results for the water−nitric acid complex with results for the water dimer and the nitric acid and water molecules. The results show that the water−nitric acid complex is more strongly bound, and the changes in spectroscopic properties compared to the individual molecules are more significant than those for the water dimer. The total OH-stretching intensity of the water−nitric acid complex is significantly higher than the sum of the intensities for the individual molecules in the fundamental and higher overtone regions. The transitions associated with the hydrogen-bonded OH bond show a very large red shift compared to the OH-stretching transitions of the nitric acid molecule. These red-shifted bands provide likely spectral regions for the detection of the water−nitric acid complex in the near-infrared. The effect of the water−nitric acid complex on atmospheric OH radial productions and absorption of solar radiation is discussed.

Experimental study of sticking probabilities for condensation of nitric acid — water vapor mixtures

In the present study condensational droplet growth rates in the binary vapor system HNO 3–H 2O were measured over a relatively wide range of vapor activitiesin order to investigate the mass accommodation coefficients in binary vapor mixtures. The measurements on condensational droplet growth rates were performed in an expansion chamber with a sensitive time of the order of 10 s . Droplet growth rates and the corresponding droplet number concentrations were determined by the Constant angle mie scattering (CAMS) method. In the present study the droplet radii cover a range from 0.5 to about 4 μm . The experiments were performed at constant temperature and total pressure near atmospheric conditions. The experimental growth curves determined in the binary vapor system HNO 3–H 2O are compared to corresponding model calculations. Thereby the mass and thermal accommodation coefficients can be determined. It can be concluded from the experiments that in binary supersaturated vapor mixtures of HNO 3–H 2O the sticking probability for nitric acid molecules is between 1.0 and 0.3 for the case of the sticking probability for the water molecules is set to unity. Especially at very low relative humidities below 75% very good agreement between experiment and theory can be established when the sticking probability of water as well as of nitric acid is regarded to be unity.

Diffusion and Intercalation of Nitric Acid into Highly Oriented Pyrolytic Graphite: An in situ Conduction ESR Study

Results of an in situ conduction ESR (CESR) study of HNO3 molecule intercalation into narrow highly oriented pyrolytic graphite (HOPG) slabs are presented. The changes in the graphite CESR signal line shape, intensity and linewidth and the step-wise changes both of intensity and linewidth of the CESR signal from the intercalated sample have been clearly detected during this reaction. Under the assumption that the graphite CESR signal evolution is caused by the advance of a boundary separating the intercalated and non-intercalated HOPG, the constant of two-dimensional diffusion of nitric acid molecules into HOPG and the average value of the spin reorientation probability during the collision of current carriers with this interface have been extracted from the experimental data.

Diffusion and Intercalation of Nitric Acid into Highly Oriented Pyrolytic Graphite: An in situ Conduction ESR Study

Results of an in situ conduction ESR (CESR) study of HNO 3 molecule intercalation into narrow highly oriented pyrolytic graphite (HOPG) slabs are presented. The changes in the graphite CESR signal line shape, intensity and linewidth and the step-wise changes both of intensity and linewidth of the CESR signal from the intercalated sample have been clearly detected during this reaction. Under the assumption that the graphite CESR signal evolution is caused by the advance of a boundary separating the intercalated and non-intercalated HOPG, the constant of two-dimensional diffusion of nitric acid molecules into HOPG and the average value of the spin reorientation probability during the collision of current carriers with this interface have been extracted from the experimental data.

Graphite intercalation by nitric acid: conduction ESR and theoretical studies

Results of an in situ conduction ESR (CESR) study of HNO 3 molecules intercalation into narrow highly oriented pyrolytic graphite (HOPG) slab are presented. The changes in the graphite CESR signal line shape, intensity and line width and the stepwise changes both of intensity and line width of CESR signal from intercalated sample have been clearly detected during this reaction. Under the assumption that the graphite CESR signal evolution is caused by the advance of a boundary separating the intercalated and non-intercalated HOPG, the average probability value of spin reorientation during the collision of current carriers with this interface and the constant of two-dimensional diffusion of nitric acid molecules into HOPG were extracted from experimental data. Using the dependence of chemical potential on exposure time of graphite in HNO 3 atmosphere offered by the authors for the experimental conditions, the stepwise evolution of CESR signal intensity from intercalated HOPG was calculated theoretically.

Tunneling dynamics of internal rotation in the nitric acid molecule

The Hamiltonian of internal rotation about theC2 axis in the HNO3 molecule and its H/D-, O18/O16-, and N15/N14-isotopomers was reconstructed using the results of quantumchemical calculations. The Fermi resonance between the torsional (2v9) and ONO bending (v5) vibrations is a characteristic feature of the molecule. Tunneling splittings in the ground and excited states were calculated using the perturbative instanton approach. Abnormally large changes in the splittings upon isotope substitution of heavy atoms are predicted.

Measurement of inorganic acids with rotating ball inlet mass spectrometry

Using a new acid resistant inlet we have evaluated the use of rotating ball inlet mass spectrometry (ROBIN-MS) as a tool for the measurement of inorganic acids in aqueous solution. EI-spectra of sulfuric, sulfurous, nitric, perchloric, bromic, iodic and boric acids were recorded and interpreted with respect to preionization decomposition and electron impact fragmentation. With the exception of sulfuric acid the detection limits for these acids were in the order of 1 mM and the response times are in the order of 1 s. Sulfuric acid had a significantly higher detection limit and response time than the other acids. No mass spectrum of phosphoric acid could be detected. High concentrations of phosphoric acid reduced the signals of other acids. HCl formed by decomposition of perchloric acid caused a strong and slowly recovering decrease of the sensitivity of the mass spectrometer. Sodium sulfate or sodium nitrate in neutral solution did not yield any mass spectrum. The intensity of the sulfuric acid peak of acid solutions of sodium sulfate was measured at different molar ratios of sodium and sulfate. The results indicate that the evaporation of such samples leaves a remnant containing three molecules of sulfuric acid per sodium ion. Similar measurements on acid solutions of sodium nitrate indicate that the remnant contains one molecule of nitric acid per sodium ion.

Stratospheric chemical ionization mass spectrometry: nitric acid detection by different ion molecule reaction schemes

Detailed height profiles of stratospheric nitric acid mixing ratios have been derived with a baloon borne chemical ionization mass spectrometer by applying several ion molecule reaction schemes, each associated to a specific and selective ion source. These ions (CO 3 −, Cl n −, CF 3O −, and CF 3O −H 2O) give rise to specific product ions (mainly CO 3 −HNO 3, NO 3 −HCl, NO 3 −HF, and CF 3O −HNO 3) upon reaction with ambient nitric acid molecules. This paper reports on the instrumental details as well as on the results obtained during two balloon flights with the instrument. Within the accuracy of the measurements, the nitric acid height profiles obtained with the three different ion sources are in good agreement with one another as well as with literature data.

Structure and stability of the nitric acid–ammonia complex in the gas phase and in water

The nitric acid–ammonia system is studied by high level ab initio calculations. The equilibrium structure, vibrational frequencies, and binding energy of the system in the gas phase are calculated at the second-order Mo/ller–Plesset perturbation level with the extended basis set 6-311++G(d,p). The potential energy surface along the proton transfer pathway is investigated by calculations at the same level of theory, and the effect of water as a solvent on the structure and stability of the system is investigated using self-consistent reaction field theory. It is found that the equilibrium structure contains a strong hydrogen bond with nitric acid acting as the hydrogen bond donor and ammonia as the acceptor. The binding energy is calculated to be D0=12.25 kcal/mol (De=14.26 kcal/mol), which is about three times greater than the binding energy for the water dimer. The OH stretching frequency of nitric acid in the hydrogen-bonded complex is found to be red shifted by over 800 cm−1, with an enhancement of over an order of magnitude in the infrared intensity from the isolated nitric acid molecule. The structure of ammonium nitrate corresponding to the product of a proton transfer reaction is found to be highly unstable on the potential energy surface. The most energetically favorable gas phase reaction of nitric acid and ammonia in the absence of a solvent results in proton exchange, not proton transfer from acid to base. The structure and stability of the system change drastically in the water solvent medium. In the water solvent, the hydrogen-bonded structure is no longer stable and the system exists as an ammonium nitrate ion pair resulting from the completed transfer of a proton from nitric acid to ammonia. On the basis of these results, we conclude that it is unlikely to form gaseous ammonium nitrate from nitric acid and ammonia, and that the formation of particulate ammonium nitrate most likely involves a heterogeneous mechanism.

Ab Initio Study of Pernitric Acid: Comparison with Experimental Spectra

A high-level ab initio theoretical study has been performed on the spectra and bond energies of pernitric acid, HO2NO2. Excellent agreement with experimental rotational constants, 15N NMR chemical shifts, HO2 + NO2 reaction enthalpy, and vibrational frequencies are obtained. Slight revisions of low-frequency normal modes have been made. Vertical excitations are computed by CASPT2 for comparison with future high-resolution UV−visible spectra and match the low resolution UV−visible spectra of pernitric acid in solution. The optimized geometries reported are superior to previous microwave structures because assumptions of bond lengths and angles from the analogous nitric acid and hydrogen peroxide molecules introduce significant errors.

Reactions of Water Cluster Ions with Nitric Acid

Reactions of D + (D 2 O) n (n=1-30) with DNO 3 were investigated under thermal conditions in a fast-flow reactor operated over a range of temperatures extending from 298 K down to 140 K. The results reveal that the reactions take place only for clusters exceeding a specific size at low temperature; the observed products are D + (D 2 O) n (DNO 3 ) (n≥5). The incorporation of a second and third nitric acid molecule into water clusters is found to occur only for ones having a considerably higher degree of solvation. The reactions are observed to be independent of pressure, and a switching rather than an association reaction mechanism is found to be operative