Infrared emission spectroscopy and ab initio calculations on VCl (original) (raw)
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Thermochemistry of the Gaseous Vanadium Chlorides VCl, VCl 2 , VCl 3 , and VCl 4
The Journal of Physical Chemistry A, 2008
Gaseous equilibria in the V-Ag-Cl system were studied at elevated temperatures by effusion-beam mass spectrometry, where the pertinent species were generated by reaction of Cl 2 (g) with V + Ag granules in the effusion cell source. Reaction enthalpies were derived from the equilibrium data, and the standard enthalpies of formation at 298 K of gaseous VCl, VCl 2 , and VCl 3 were found to be +49.7,-34.8, and-85.6 kcal mol-1 , respectively. The corresponding bond dissociation energies at 298 K are D(V-Cl)) 102.9 kcal, D(ClV-Cl)) 113.5 kcal, D(Cl 2 V-Cl)) 79.8 kcal, and D(Cl 3 V-Cl)) 69.5 kcal. From these data, the dissociation energy D°0(VCl)) 101.9 kcal mol-1 or 4.42 eV is obtained. An alternate value, ∆ f H°2 98 (VCl 3 ,g))-87.0 kcal mol-1 was derived from third-law analysis of literature sublimation data for VCl 3 (s). In addition, literature thermochemical data on VCl 4 (g) were re-evaluated, leading to ∆ f H°2 98)-126.1 kcal mol-1. The results are compared with various estimates in the literature.
Electronic Spectroscopy of Diatomic VC
The Journal of Physical Chemistry A, 2013
Resonant two-photon ionization spectroscopy has been applied to diatomic VC, providing the first optical spectrum of this molecule. The ground state is determined to be a 2 Δ 3/2 state that arises from the 1σ 2 1π 4 2σ 2 1δ 1 configuration. The r 0 ″ ground-state bond length is 1.6167(3) Å. The manifold of excited vibronic states in the visible portion of the spectrum is quite dense, but two possible vibrational progressions have been identified. It is noted that VC joins CrC, NbC, and MoC as species in which the metal ns-based 3σ orbital is unoccupied, resulting in large dipole moments in the ground states of these molecules. In the corresponding 5d metal carbides, however, the 3σ orbital is occupied, leading to different ground electronic states of the 5d congeners, TaC and WC.
Inorganic Chemistry, 2010
The molecular geometries of VCl 2 and VCl 3 have been determined by computations and gas-phase electron diffraction (ED). The ED study is a reinvestigation of the previously published analysis for VCl 2 . The structure of the vanadium dichloride dimer has also been calculated. According to our joint ED and computational study, the evaporation of a solid sample of VCl 2 resulted in about 66% vanadium trichloride and 34% vanadium dichloride in the vapor. Vanadium dichloride is unambiguously linear in its 4 Σ g þ ground electronic state. For VCl 3 , all computations yielded a Jahn-Tellerdistorted ground-state structure of C 2v symmetry. However, it lies merely less than 3 kJ/mol lower than the 3 E 00 state (D 3h symmetry). Due to the dynamic nature of the Jahn-Teller effect in this case, rigorous distinction cannot be made between the planar models of either D 3h symmetry or C 2v symmetry for the equilibrium structure of VCl 3 . Furthermore, the presence of several low-lying excited electronic states of VCl 3 is expected in the high-temperature vapor. To our knowledge, this is the first experimental and computational study of the VCl 3 molecule.
VUV photo-absorption spectroscopy of vinyl chloride studied by high resolution synchrotron radiation
Chemical Physics, 2006
The electronic state spectroscopy of vinyl chloride, C 2 H 3 Cl, has been investigated by high resolution VUV photo-absorption spectroscopy in the wavelength range 115-300 nm (10.8-4.2 eV). New assignments are proposed for Rydberg series converging to the four lowest ionisation energies and their associated vibrational excitation is observed for the first time. Absolute cross-section values have been obtained allowing photolysis lifetimes to be derived in the Earth's troposphere and stratosphere.
An angle-resolved photoemission study of the (100) surface of VC
Surface Science, 1991
Angle-resolved photoemission investigations of the (100) surface of a VC,,,, single crystal using synchrotron radiation in the energy range 17-48 eV are reported. The experimental results are interpreted using the bulk band structure and theoretical photoemission spectra calculated for VC,,,. It is shown that most of the features in the recorded spectra can be explained as originating from direct bulk band transitions. A mapping of the bulk band structure is presented and compared with the calculated LAPW band structure. Contributions from a surface state, a vacancy induced state and density of states (DOS) are discussed.
Electronic states of vanadium(III) in trans-VCl 2(H 2O) 4 + chromophore
Journal of Alloys and Compounds, 2008
The polarized absorption spectra of vanadium(III) in Cs 3 VCl 6 ·4H 2 O complex are presented in the UV-vis region and correspond to the transition from the ground state 3 T 1g ( 3 F) to the excited states 3 T 2g ( 3 F), 3 T 1g ( 3 P) and 3 A 2g ( 3 F). Semiempirical calculations of the crystal-field levels of the vanadium(III) with D 4h point group symmetry in Cs 3 VCl 6 ·4H 2 O chromophore are carried out, leading to a good agreement between the theoretical and experimental energy levels.
The crystal structures and properties of [VCL3(THF)2(H2O] and [VCl3(THF)2(H2O)]·THF
Polyhedron, 1996
The structure of the products formed between [mer-VCl3(THF)3] and water in tetrahydrofuran (THF) or dichloromethane were investigated. Two different crystalline species were isolated: [VCl3(THF)2(H2O)] (1) and [VCl3(THF)2(H2O)]·THF (2). Their structures were determined by means of X-ray analysis. In both compounds the vanadium (III) ions are in a distorted octahedral environment surrounded by three mer-chlorine atoms, two trans-situated THF molecules and a water molecule.
The Journal of Chemical Physics, 2014
Six electronic states (X 4 − , A 4 , B 4 , 2 , 2 , 2 + ) of the vanadium monochloride cation (VCl + ) are described using large basis set coupled cluster theory. For the two lowest quartet states (X 4 − and A 4 ), a focal point analysis (FPA) approach was used that conjoined a correlationconsistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through pentuple (CCSDTQP) excitations. FPA adiabatic excitation energies (T 0 ) and spectroscopic constants (r e , r 0 , B e , B 0 ,D e , H e , ω e , v 0 , α e , ω e x e ) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, and spin-orbit coupling. Due to the delicate interplay between dynamical and static electronic correlation, single reference coupled cluster theory is able to provide the correct ground electronic state (X 4 − ), while multireference configuration interaction theory cannot. Perturbations from the first-and second-order spin orbit coupling of low-lying states with quartet spin multiplicity reveal an immensely complex rotational spectrum relative to the isovalent species VO, VS, and TiCl. Computational data on the doublet manifold suggest that the lowest-lying doublet state ( 2 ) has a T e of ∼11 200 cm −1 . Overall, this study shows that laboratory and theoretical rotational spectroscopists must work more closely in tandem to better understand the bonding and structure of molecules containing transition metals.
Vanadium Oxide in the Spectra of Mira Variables
Astrophysical Journal, 2000
As a preliminary step in deducing and log (g) of Mira variables as a function of phase, a compari-T eff son is made between spectra synthesized from LTE stellar atmosphere models and observed spectra. The observed spectra show obvious vanadium oxide (VO) absorption bands. However, the molecular line list used to produce the synthetic spectra does not include the bound-bound VO opacities. The wavenumbers, line oscillator strengths, and lowest energy levels are needed to calculate these opacities. The equations, constants, and experimentally determined factors required to calculate the line oscillator strengths and lowest energy levels from experimentally determined wavenumbers are presented. The e †ect of including the wavenumbers, line oscillator strengths, and lowest energy levels of the VO BÈX (0, 0) band are calculated and show the expected absorption features observed in the spectra of Mira variables. In the VO BÈX (0, 0) band the line oscillator strengths range from about 0.05 to 3.
Journal of Molecular Spectroscopy, 2007
High-resolution Fourier-transform infrared spectra between 1235 and 1680 cm À1 and subterahertz spectra between 250 and 630 GHz of monoisotopic 13 CH 3 35 Cl have been recorded and analyzed simultaneously, with all Coriolis, a-resonance, and l-type interactions in the polyad of the v 2 = 1, v 5 = 1, and v 3 = 2 levels taken into account. Several a-resonances (Dk = ±2, Dl = «1) generating perturbationallowed transitions have been assigned in the rovibrational spectra. These resonances enabled us to determine accurately and independently the ground state rotational and centrifugal distortion parameters A 0 = 5.205 746 9 (55) cm À1 and D 0 K ¼ 8:4404ð84Þ Â 10 À5 cm À1. Even H 0 K ¼ 8:527ð39Þ Â 10 À9 cm À1 , which is, however, correlated to higher-order a-resonance terms, was determined. With 51 upper state parameters varied, about 5800 rovibrational wavenumbers and more than 550 rotational frequencies pertaining to the excited vibrational states were fitted within their experimental accuracy.