Infrared Spectra and Structures of the Neutral and Charged CrCO₂ and Cr(CO₂)₂ Isomers in Solid Neon

The reactions from codeposition of laser-ablated chromium atoms with carbon dioxide in excess neon are studied by infrared absorption spectroscopy. The species formed are identified by the effects of isotopic substitution on their infrared spectra. Density functional calculations are performed to support the spectral assignments and to interpret the geometric and electronic structures of the experimentally observed species. Besides the previously reported insertion products OCrCO and O₂Cr­(CO)₂, the one-to-one Cr­(CO₂) complex and the one-to-two Cr­(CO₂)₂ complex as well as the CrOCrCO and OCCrCO₃ complexes are also formed. The Cr­(CO₂) complex is characterized to be side-on η²-C,O-coordinated. The Cr­(CO₂)₂ complex is identified to involve a side-on η²-C,O-coordinated CO₂ and an end-on η¹-O-coordinated CO₂. OCCrCO₃ is a carbonate carbonyl complex predicted to have a planar structure with a η²-O,O-coordinated carbonate ligand. The CrOCrCO complex is predicted to be linear with a high-spin ground state. Besides the neutral molecules, charged species are also produced. The Cr­(CO₂)⁺ and Cr­(CO₂)₂⁺ cation complexes are characterized to have linear end-on η¹-O-coordinated structures with blue-shifted antisymmetric CO₂ stretching vibrational frequencies. The OCrCO^– anion is bent with the Cr–O and CO stretching frequencies red-shifted from those of OCrCO neutral molecule

Carbon Dioxide Activation by Scandium Atoms and Scandium Monoxide Molecules: Formation and Spectroscopic Characterization of ScCO₃ and OCScCO₃ in Solid Neon

The reactions of carbon dioxide with scandium monoxide molecules and scandium atoms are investigated using matrix isolation infrared spectroscopy in solid neon. The species formed are identified by the effects of isotopic substitution on their infrared spectra as well as density functional calculations. The results show that the ground state ScO molecule reacts with carbon dioxide to form the carbonate complex ScCO₃ spontaneously on annealing. The ground state Sc atom reacts with two carbon dioxide molecules to give the carbonate carbonyl complex OCScCO₃ via the previously reported OScCO insertion intermediate on annealing. The observation of these spontaneous reactions is consistent with theoretical predictions that both the Sc + 2CO₂ → OCScCO₃ and ScO + CO₂ → ScCO₃ reactions are thermodynamically exothermic and are kinetically facile, requiring little or no activation energy

Experimental and Theoretical Studies of the Infrared Spectra and Bonding Properties of NgBeCO₃ and a Comparison with NgBeO (Ng = He, Ne, Ar, Kr, Xe)

The novel neon complex NeBeCO₃ has been prepared in a low-temperature neon matrix via codeposition of laser-evaporated beryllium atoms with O₂ + CO/Ne. Doping by the heavier noble gas atoms argon, krypton and xenon yielded the associated adducts NgBeCO₃ (Ng = Ar, Kr, Xe). The noble gas complexes have been identified via infrared spectroscopy. Quantum chemical calculations of NgBeCO₃ and NgBeO (Ng = He, Ne, Ar, Kr, Xe) using <i>ab initio</i> methods and density functional theory show that the Ng–BeCO₃ bonds are slightly longer and weaker than the Ng–BeO bonds. The energy decomposition analysis of the Ng–Be bonds suggests that the attractive interactions come mainly from the Ng → BeCO₃ and Ng → BeO σ donation

Covalent Bonding Between Be⁺ and CO₂ in BeOCO⁺ with a Surprisingly High Antisymmetric OCO Stretching Vibration

The cationic complex BeOCO+ is produced in a solid neon matrix. Infrared absorption spectroscopic study shows that it has a very high antisymmetric OCO stretching vibration of 2418.9 cm–1, which is about 71 cm–1 blue-shifted from that of free CO2. The quantum chemical calculations are in very good agreement with the experimental observation. Depending on the theoretical method, a linear or quasi-linear structure is predicted for the cation. The analysis of the electronic structure shows that the bonding of Be+ to one oxygen atom induces very little charge migration between the two moieties, but it causes a significant change in the σ-charge distribution that strengthens the terminal C–O bond, leading to the observed blue shift. The bonding analysis reveals that the Be+ ← OCO donation results in strong binding due to the interference of the wave function and a charge polarization within the CO2 fragment and hybridization to Be+ but only negligible charge donation

Adjusted odds ratio of pet keeping for asthma and allergy among children when an avoidance behavior is adjusted^a.

<p>Adjusted odds ratio of pet keeping for asthma and allergy among children when an avoidance behavior is adjusted<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197274#t004fn001" target="_blank">^a</a>.</p

Demographic information, health outcomes and exposure to pets of the investigated population, n (%).

<p>Demographic information, health outcomes and exposure to pets of the investigated population, n (%).</p

Adjusted odds ratios of pet keeping for asthma and allergies among children^a.

<p>Adjusted odds ratios of pet keeping for asthma and allergies among children<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197274#t003fn001" target="_blank">^a</a>.</p

The dose-response relationship between pets keeping in home and allergies among children.

<p>¹Odds ratios are adjusted for gender, age, total household income, family allergic history, home location, home dampness and avoidance behavior. ² Furry pet: cats, dogs, rodents and birds.</p

Prevalence (n, %) of asthma and allergy among children with different pets keeping status.

<p>Prevalence (n, %) of asthma and allergy among children with different pets keeping status.</p