Reactions of Vanadium Dioxide Molecules with Acetylene: Infrared Spectra of VO₂(η²‑C₂H₂)_<i>x</i> (<i>x</i> = 1, 2) and OV(OH)CCH in Solid Neon

Reactions of vanadium dioxide molecules with acetylene have been studied by matrix isolation infrared spectroscopy. Reaction intermediates and products are identified on the basis of isotopic substitutions as well as density functional frequency calculations. Ground state vanadium dioxide molecule reacts with acetylene in forming the side-on-bonded VO₂(η²-C₂H₂) and VO₂(η²-C₂H₂)₂ complexes spontaneously on annealing in solid neon. The VO₂(η²-C₂H₂) complex is characterized to have a ²B₂ ground state with <i>C</i>_2<i>v</i> symmetry, whereas the VO₂(η²-C₂H₂)₂ complex has a ²A ground state with <i>C</i>₂ symmetry. The VO₂(η²-C₂H₂) and VO₂(η²-C₂H₂)₂ complexes are photosensitive. The VO₂(η²-C₂H₂) complex rearranges to the OV­(OH)­CCH molecule upon UV–vis light excitation

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

Formation and Infrared Spectroscopic Characterization of Three Oxygen-Rich BiO₄ Isomers in Solid Argon

The reactions of bismuth atoms and O₂ have been investigated using matrix isolation infrared spectroscopy and density functional theory calculations. The ground state bismuth atoms react with dioxygen to form the BiOO and Bi­(O₂)₂ complexes spontaneously on annealing. The BiOO molecule is characterized to be an end-on bonded superoxide complex, while the Bi­(O₂)₂ molecule is characterized to be a superoxo bismuth peroxide complex, [Bi³⁺(O₂^–)­(O₂^2‑)]. Under UV–visible light irradiation, the Bi­(O₂)₂ complex rearranges to the more stable OBiOOO isomer, an end-on bonded bismuth monoxide-ozonide complex. The end-on-bonded OBiOOO complex further rearranges to a more stable side-on bonded OBiO₃ isomer upon sample annealing. In addition, the bent bismuth dioxide anion is also formed and assigned

Photoassisted Homocoupling of Methyl Iodide Mediated by Atomic Gold in Low-Temperature Neon Matrix

Infrared spectroscopy and density functional theory calculations showed that the gold complexes [CH₃–Au–I] and [(CH₃)₂–Au–I₂], in which one and two CH₃I molecule(s), respectively, are oxidatively adsorbed on the Au atoms, are formed in a solid neon matrix via reactions between laser-ablated gold atoms and CH₃I. Global reaction route mapping calculations revealed that the heights of the activation barriers for the sequential oxidative additions to produce [CH₃–Au–I] and [(CH₃)₂–Au–I₂] are 0.53 and 1.00 eV, respectively, suggesting that the reactions proceed via electronically excited states. The reductive elimination of ethane (C₂H₆) from [(CH₃)₂–Au–I₂] leaving AuI₂ was hindered by an activation barrier as high as 1.22 eV but was induced by visible-light irradiation on [(CH₃)₂–Au–I₂]. These results demonstrate that photoassisted homocoupling of CH₃I is mediated by Au atoms via [(CH₃)₂–Au–I₂] as an intermediate

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

Infrared Photodissociation Spectroscopy of the Ni(O₂)_<i>n</i>⁺ (<i>n</i> = 2–4) Cation Complexes

The infrared spectra of mass-selected Ni­(O₂)_<i>n</i>⁺ (<i>n</i> = 2–4) and their argon-tagged complexes are measured by infrared photodissociation spectroscopy in the gas phase. The experimental spectra provide distinctive patterns allowing the determination of their geometric and electronic structures by comparison with the simulated vibrational spectra from density functional theory calculations. The [Ni­(O₂)₂Ar₂]⁺ cation complex was determined to have <i>D</i>_2<i>h</i> symmetry involving a Ni­(O₂)₂⁺ core ion with two equivalent superoxide ligands side-on bound to a Ni³⁺ cation center. The higher Ni­(O₂)₃⁺ and Ni­(O₂)₄⁺ cation complexes were determined to have structures with a chemically bound Ni­(O₂)₂⁺ core ion that is weakly coordinated by neutral O₂ molecule(s)