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The infrared spectra of C[H.sub.3]Cl [H.sub. 2]O isolated in solid neon at low temperature are examined. High concentration studies of water and subsequent annealing lead to the formation of the ternary C[H.sub.3]Cl:[([H.sub.2]O).sub.2] complex that has a cyclic form in the ground state.

The infrared (IR) spectra of [H.sub.2]O + NO, HDO + NO, and [D.sub.2]O + NO, isolated in solid neon at low temperature is investigated by neon matrix-isolation method combined with IR absorption spectroscopy. The structure of the second observed 1:1 [H.sub.2]O-NO complex has resulted from columbic attractions between water and nitric oxide and it could be stabilized only in matrix, probably by interaction between NO, water and [(Ne).sub.n].

The infrared spectra of the CH3Cl:NO complex isolated in solid neon are investigated detecting most of the vibrational modes of the complex and on the basis of DFT calculations, different geometries are explored for the complex. The weak interaction between NO and CH3CI in CH3Cl:NO is responsible for small shifts of the vibrational mode frequencies of both CH3CI and NO molecules and the most stable structure is of C1 symmetry.

The formation and structure of the CH(sub 3)Cl:H(sub 2)O complex is investigated by neon matrix isolation technique combined with infrared absorption spectroscopy. The complex is found to have a cyclic structure, where the chlorine atom is weakly bonded to one of the hydrogen atoms of water, while the oxygen atom is weakly bonded to one of the hydrogen atoms of CH(sub 3)Cl.

The reaction of atomic titanium with nitrous oxide hasbeen reinvestigatedusing matrix isolation in solid neon coupled to infrared spectroscopyand by quantum chemical methods. Our technique of sublimation of Tiatoms from a filament heated at about 1500 °C allowed the formationof three species: one Ti–N2O pair of van der Waals(vdW) type characterized by small red shift with respect to N2O monomer, and two isomers of OTi–N2pairwhere N2is in interaction with the OTi moiety either withend-on or side-on structure. Interconversion between these structureshas been performed with several wavelengths. In the visible and near-ultravioletthe conversion vdW → OTi-N2(end-on) is observedwith characteristic times strongly varying according to the wavelength.In the near-infrared the conversion OTi–N2(end-on)→ OTi–N2(side-on) occurs, the vdW speciesremaining unchanged. These selectivities allow 8, 6, and 4 vibrationaltransitions to be assigned for vdW, 3[OTi(η1-NN)] (end-on), and 1[OTi(η2-NN)] (side-on),respectively. Electronic and geometrical structures are also investigatedwith double-hybrid functionals. It has been shown that the side-ongeometry corresponds to the ground state of 1[OTi(η2-NN)] in the singlet electronic state. The theoretical vibrationalanalysis supports well the experimental attributions. [ABSTRACT FROM AUTHOR]

Spectroscopic properties of 1:n complexes (n = 1, 2, and 3) formed between an oxirane molecule and water clusters have been evaluated using experimental techniques (FTIR spectroscopy using a new supersonic jet experiment coupled to the infrared AILES beamline of synchrotron SOLEIL and also cryogenic neon matrix device) and theoretical approaches (SAPT, ab initio, DFT, and topological analyses). From a systematic comparison between the theoretical results (obtained with both wave function based methods and several newly hydrogen bonded adapted functionals) with the available experimental results on the studied compounds, it was concluded that only the wave function based methods (particularly coupled clusters ones) are able to well describe these compounds, while the newly hydrogen bonded adapted functionals (long-range and/or dispersion-corrected ones and also double hybrids) cannot adequately describe all the spectroscopic properties in a systematic way. The MP2 method, although more expensive than DFT, still offers a reliable method to study both isolated molecules and hydrogen bonded complexes provided the contribution of the dispersion energy in total energy is properly taken into account. The nature of interaction between oxirane and water molecules has been analyzed using the symmetry adapted perturbation theory (SAPT) method. It was evidenced that the water--oxirane interaction corresponds to the hydrogen-bonded systems with a large contribution of the dispersion energy. The nature of the oxirane--water bonding has been studied using two topological methods: atoms in molecules and electron-localization function (ELF). Geometrical structures of the titled complexes were rationalized from the spatial arrangement of ELF attractors. Secondary interaction was also accounted for the bond critical points found at Hoxirane⋯Owater bond paths. [ABSTRACT FROM AUTHOR]

Carbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family. There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp³ hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm-1 region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented. [ABSTRACT FROM AUTHOR]

Thermally evaporated titanium atoms reacted with carbon monoxide and water in solid argon at 12 K to produce the HTiOH-CO and HTiOH-(CO) 2 molecules, which were characterized using infrared spectroscopy on the basis of CO, Ti, and water concentration variations and of isotopic substitutions. The insertion product, HTiOH, resulting from the reaction of a titanium atom with a water molecule reacts with CO spontaneously to give the HTiOH-CO molecule, which in turn reacts with a second CO molecule to give HTiOH-(CO) 2 The density functional theory calculations were performed to elucidate the geometrical and electronic structures and support the spectral assignments. The topological analysis of the charge density within the experimentally observed molecules allowed us to rationalize the coordination sphere as well as the electron pairing on the titanium center.

Carbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family ( Pirali , O. ; et al. J. Chem. Phys. 2012 , 136 , 024310 ). There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp(3) hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm(-1) region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented.

The reactivity of diatomic titanium with nitrous oxide has been studied in solid neon. Two molecules with the same Ti2-N2O stoichiometry are identified from concentration, temperature, and irradiation effects. The more stable one is characterized by five fundamental vibrational transitions located below 1000 cm(-1), the high frequency one at 946 cm(-1) corresponding to a pure TiO stretching mode. Its structure, a rhombus OTiNTiN with the extra O atom fixed on one Ti, is confirmed by quantum chemical calculations, at the CCSD(T) level, which predict a Cs structure in the singlet state with a Ti-O bond length close to 1.66 Å, two nonequivalent Ti-N distances close to 1.94 and 1.75 Å, and a OTiTi angle of 119.2°. The second Ti2-N2O molecule, only observed after annealing, is easily converted into the first one upon irradiation above 12 000 cm(-1) and its kinetics of photoconversion allows vibrational transitions to be identified. The strongest one located at 2123.4 cm(-1) characterizes an N-N stretching mode. Corresponding ab initio calculations complete this picture with details on the electronic structure and allow us to identify a most adequate density functional to describe the spectroscopic properties of the studied species in a simpler broken-symmetry open-shell DFT context. The theoretical results predict the existence of a metastable product OTi2N2 and correctly account for the observed spectra of the various isotopic varieties.

Two OTi-N2 complexes, experimentally observed in the TiO + N2 reaction, have been theoretically studied using several density functionals as well as ab initio approaches and various basis sets. The benchmark results calculated with coupled-cluster singles, doubles, and perturbative triples CCSD(T) and sufficiently large correlation-consistent basis set were used to assess the performance of other theoretical models, especially four density functional families, pure functional, hybrid, double-hybrid, and long-range corrected ones. It has been shown that, out of twenty-three density functionals used in this work, only three functionals, namely TPSS0, LC-TPSS, and B2PLYP, are able to reproduce the CC-reference data quantitatively. Particularly, the B2PLYP double-hybrid (with or without addition of empirical dispersion) is the most promising functional, providing the closest results to the reference ones. The nature of bonding within products has been investigated using two topological techniques and a localized orbital approach.

Spectroscopic properties of 1:n complexes (n = 1, 2, and 3) formed between an oxirane molecule and water clusters have been evaluated using experimental techniques (FTIR spectroscopy using a new supersonic jet experiment coupled to the infrared AILES beamline of synchrotron SOLEIL and also cryogenic neon matrix device) and theoretical approaches (SAPT, ab initio, DFT, and topological analyses). From a systematic comparison between the theoretical results (obtained with both wave function based methods and several newly hydrogen bonded adapted functionals) with the available experimental results on the studied compounds, it was concluded that only the wave function based methods (particularly coupled clusters ones) are able to well describe these compounds, while the newly hydrogen bonded adapted functionals (long-range and/or dispersion-corrected ones and also double hybrids) cannot adequately describe all the spectroscopic properties in a systematic way. The MP2 method, although more expensive than DFT, still offers a reliable method to study both isolated molecules and hydrogen bonded complexes provided the contribution of the dispersion energy in total energy is properly taken into account. The nature of interaction between oxirane and water molecules has been analyzed using the symmetry adapted perturbation theory (SAPT) method. It was evidenced that the water-oxirane interaction corresponds to the hydrogen-bonded systems with a large contribution of the dispersion energy. The nature of the oxirane-water bonding has been studied using two topological methods: atoms in molecules and electron-localization function (ELF). Geometrical structures of the titled complexes were rationalized from the spatial arrangement of ELF attractors. Secondary interaction was also accounted for the bond critical points found at H(oxirane)···O(water) bond paths.

A series of hydrogen bonded complexes involving oxirane and water molecules have been studied. In this paper we report on the vibrational study of the oxirane-water complex (CH(2))(2)O-H(2)O. Neon matrix experiments and ab initio anharmonic vibrational calculations have been performed, providing a consistent set of vibrational frequencies and anharmonic coupling constants. The implementation of a new large flow supersonic jet coupled to the Bruker IFS 125 HR spectrometer at the infrared AILES beamline of the French synchrotron SOLEIL (Jet-AILES) enabled us to record first jet-cooled Fourier transform infrared spectra of oxirane-water complexes at different resolutions down to 0.2 cm(-1). Rovibrational parameters and a lower bound of the predissociation lifetime of 25 ps for the v(OH)(b) = 1 state have been derived from the rovibrational analysis of the ν(OH)(b) band contour recorded at respective rotational temperatures of 12 K (Jet-AILES) and 35 K (LADIR jet).

The IR spectra of H2O+NO, HDO+NO, and D2O+NO, isolated in solid neon at low temperature have been investigated. Concentration effects and detailed vibrational analysis of deuterated and partially deuterated species allowed identification of three 1:1 HDO-NO species, two 1:1 D2O-NO species, and only one 1:1 H2O-NO complex. From comparison between the experimental spectra and the results of DFT calculations, it appeared that two different types of weakly bound complexes between water and nitric oxide can be formed in a neon matrix. The first species is a 1:1 complex where bonding occurs between water hydrogen and nitric oxide nitrogen, in which OH-N and OD-N intermolecular bonds are engaged. For this complex only DOD-NO, HOD-NO, and DOH-NO isotopic species have been experimentally detected and no IR bands of HOH-NO were observed. This result could be explained by the fact that the dissociation energy of HOH-NO is lower than those of DOD-NO, HOD-NO and DOH-NO. For the second detected 1:1 H2O-NO complex and its isotopic variants, the H2O-NO potential surface was explored systematically at the B3LYP level, but no stable species corresponding to the complex could be calculated. The structure of the second observed 1:1 H2O-NO complex results from columbic attractions between water and nitric oxide and could be stabilized only in matrix, probably by interaction between NO, water and (Ne)n.

The infrared spectra of CH3Cl + H2O isolated in solid neon at low temperatures have been investigated. The CH3Cl + H2O system is remarkable because of its propensity to form CH3Cl:H2O and CH3Cl:(H2O)n (n > or = 2) complexes. We focus here on the CH3Cl:H2O species. Low concentration studies (0.01-0.5%) and subsequent annealing lead to formation of the 1:1 CH3Cl:H2O complex with O-H. . .Cl-C or O. . .H-C intermolecular hydrogen bonds. Vibrational modes of this complex have been detected. In addition, spectra of D2O + CH3Cl and HDO + CH3Cl have also been recorded. A detailed vibrational analysis of partially deuterated species shows that HDO is exclusively D bonded to CH3Cl. This is a consequence of the preference for HDO to form a deuterium bonding complex rather than a hydrogen bonding one.