Bonding properties of chlorine oxides ClOx (x=1–4) in the density functional theory

Theoretical investigations on mechanisms and pathways of CH2ClO2/CHCl2O2 with ClO reactions in the atmosphere

A global and systematic theoretical research on the singlet and triplet potential energy surfaces (PESs) of the CH₂ClO₂/CHCl₂O₂ with ClO reactions are done at the CCSD(T)//B3LYP level and accompanied with RRKM computations to forecast the mechanism and distribution of products. The simulation results revealed that, on the singlet PES, products P1 (CHClO + HO₂ + Cl)/P1 (CCl₂O + HO₂ + Cl) from IM1 (CH₂ClOOOCl)/IM1 (CHCl₂OOOCl) are forecasted to the primary products of the CH₂ClO₂/CHCl₂O₂ + ClO reactions, which are initiated by the oxygen atom of ClO radical addition to the terminal-O atom of CH₂ClO₂/CHCl₂O₂ barrierlessly, while other product channels contribute less to the whole reactions owing to higher barriers. Two other isomers, including IM2 (CH₂ClOOClO) and IM3 (CH₂ClOClO₂) for the CH₂ClO₂ + ClO reaction, and three other isomers, including IM2 (CHCl₂OOClO), IM3 (CHCl₂OClO₂), and IM4 (CHCl₂ClO₃) for the CHCl₂O₂ + ClO reaction, could be produced as less significant products. RRKM calculations presented that the initial adducts IM1 (CH₂ClOOOCl)/IM1 (CHCl₂OOOCl) are the primary products at T < 400 K and T < 600 K, respectively, and products P1 (CHClO + HO₂ + Cl)/P1 (CCl₂O + HO₂ + Cl) are dominant the reactions at T ≥ 400 K and T ≥ 600 K, respectively. The atmospheric lifetime of CH₂ClO₂ and CHCl₂O₂ in ClO is around 4.61 and 3.24 h, respectively.

An ab initio investigation on the ground electronic state of chlorine monoxide and its singly charged cation and anion

The MRCI method has been utilized to calculate the equilibrium structure of the ground electronic state for the ClO radical and its singly charged cation and anion, ClO(+) and ClO(-). The augmented correlation-consistent basis sets up through sextuple-zeta quality are used to derive equilibrium structural parameters, potential energy curves and spectroscopic constants of the systems. Two extrapolating schemes enable us to remove the basis set truncation error and to estimate the complete basis set limit. Corrections of core-valence correlation and relativistic effect are included in our calculations. By solving the radial Schrödinger equation of nuclear motion, the vibrational energy levels as well as rotational and centrifugal distortion constants of the ground electronic states for the three species are obtained. Ionization potentials and the electron affinities are also obtained on the RCCSD(T)/AV6Z level. The knowledge extracted from this work are anticipated to extend our understanding on molecular characteristics of the ClO(n) (n=-1, 0, +1) systems and can serve as guidelines for further experimental or theoretical researches.

Theoretical studies on vibrational spectra of some halides of group IVB elements

The vibrational spectra of group IVB elements halides MX4 (M=Ti(IV), Zr(IV), Hf(II); X=F, Cl, Br and I), have been investigated by ab initio RHF, MP2 and density functional theory B3LYP method with LanL2DZ basis sets. The optimized geometries, calculated vibrational frequencies and Far-IR intensities of MX4 are evaluated via comparison with experimental data. The vibrational frequencies, calculated by these methods, are compared to each other. The results indicate that B3LYP method is more reliable than RHF and MP2 methods for the frequencies calculations for these compounds. With this method, some vibrational frequencies of M2X6(2+)(M=Ti(IV), Zr(IV) and Hf(II); X=F, Cl, Br and I) are also predicted.

Chlorine oxide radicals ClOx (x = 1-4) studied by matrix isolation spectroscopy

Low pressure flash thermolysis of different precursor molecules containing-ClO, -ClO3 or -OClO3 yield, when highly diluted in Ne or O2 and subsequent quenching of the products in a matrix at 5 or 15 K, ClOx (x = 1, 3, 4) radicals, respectively. If Ne or O2 gas is directed over solid ClO2 at -120 degrees C and the resulting gas mixtures are immediately deposited as a matrix, a high fraction of (OClO)2 is trapped. This enables recording of IR and UV spectra of weakly bonded (OClO)2 dimers and detailed studying of their photochemistry. For Ne or O2 matrix isolated ClO radicals the vibrational wavenumbers and electronic transitions are only slightly affected compared with the gas phase. In this study strong evidence is found for long lived ClO in the electronically excited 2 [symbol: see text] 1/2 state. A comprehensive IR study of Ne matrix isolated ClO3 (fundamentals at 1081, 905, 567, 476 cm-1) yield i) a reliable force field; ii) a OClO bond angle of alpha e = 113.8 +/- 1 degrees and iii) a ClO bond length of 148.5 +/- 2 pm in agreement with predicted data from quantum chemical calculations. The UV/Vis spectrum of ClO3 isolated in a Ne matrix (lambda max at 32,100 and 23,150 cm-1) agrees well with the photoelectron spectrum of ClO3- and theoretical predictions. The origin of the structured high energy absorption is at 22,696 cm-1 and three fundamentals (794, 498, 280 cm-1) are detected in the C2E state. By photolysis of ClO3 with visible light the complex ClO.O2 with ClO in the 2 [symbol: see text] 1/2 state is formed. In an extended spectroscopic study of the elusive ClO4 radical, isolated in a Ne or O2 matrix, three additional IR bands, a complete UV spectrum and a strong interaction with O2 are found. This leads to the conclusion that ClO4 exhibits C2v or Cs symmetry with a shallow potential minimum and forms with O2 the previously unknown peroxy radical O3ClO-O2. All these results are discussed in the context of recent developments in the chemistry and spectroscopy of the important and interesting ClOx (x = 1-4) family of radicals.