Matrix isolation study of the vacuum ultraviolet photolysis of allene and methylacetylene. Vibrational and electronic spectra of the species C3, C3H,C3H2, and C3H3

Upon hydrogen-discharge photolysis of normal or deuterium-substituted allene or methylacetylene in an argon or a nitrogen matrix at 14°K, infrared absorptions of all of the C₃H_n species with n < 4 appear. A hydrogen-deformation fundamental of C₃H₂ has been identified in the far infrared. Infrared studies of the partially deuterium- substituted methylacetylenes indicate that extensive photoisomerization occurs. The observed products are consistent with those predicted using the previously postulated gas-phase photolysis mechanism. The ultraviolet spectrum of C₃H₃ corresponds closely with that characteristic of the gas-phase molecule. Comparison of the spectrum between 1900 and 4000 A of photolyzed methylacetylene with that of matrix-isolated graphite vapor has indicated that any new electronic transition of C₃ in this region must be weak.     

Multiphoton ultraviolet photochemistry

Multiphoton photodissociation has been observed in C₂N₂, C₂H₂, C₂H₄, CH₃OH, and C₂H₅OH. In all of these molecules fluorescence from small free radicals such as CN, CH, and OH has been observed. None of the observed fluorescence can result from the absorption of a single 193 nm photon. Arguments are presented which suggest that the observed results are best explained by invoking a sequential absorption scheme where the excited molecule absorbs a second laser photon rather than predissociating. Emissions have also been observed when H₂O is photolyzed with the ArFlaser. In H₂O the evidence suggest that this emission arises from collisional dissociation of two excited H₂O molecules.     

The first ruthenium(II) complex with benzotriazole and pyridylcarboxylato ligands

The reaction of [RuCl₂(PPh₃)₃] with 1-(2-pyridylcarbonyl)benzotriazole has been examined. A new ruthenium(II) complex–[RuCl(PPh₃)₂(C₆H₅N₃)(C₅H₄NCO₂)] has been obtained and characterized by IR and UV–Vis measurements. The crystal structure of the complex has been determined. The electronic spectrum of the complex has been calculated by TDDFT method.     

Synthesis and Characterization of Single-Phase Cubic ZrO2 Spherical Nanocrystals by Decomposition Route

A simple thermal decomposition route has been developed to prepare single-phase cubic ZrO₂ nanospheres by [Zr(sal)₃(H₂O)₂](NO₃) as the new precursor. The ZrO₂ nanocrystals have been prepared by bis-aqua, tris-salicylaldehydato zirconium(IV) nitrate; [Zr(sal)₃(H₂O)₂](NO₃), as precursor in oleylamine (C₁₈H₃₇N) and triphenylphosphine (C₁₈H₁₅P). To control the particle size, combination of C₁₈H₃₇N and C₁₈H₁₅P were applied as surfactants. The C₁₈H₃₇N and C₁₈H₁₅P play an important role in preventing aggregation of ZrO₂ nanocrystals. The products were characterized by X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy to depict the phase and morphology. The FT-IR spectrum showed the purity of obtained ZrO₂ nanocrystals with cubic phase.     

Comparison of collisional activation spectra of some positive ions produced both by charge reversal of negative ions and by decomposition of positive ions

The charge reversal collision induced decomposition mass analyzed ion kinetic energy spectrum of allyl anion has been compared with the collision induced dissociation mass analyzed ion kinetic energy spectrum of allyl cation and found to be identical except for the presence of +2 ions formed by charge stripping in the spectrum of the [C₃H₅]⁺ ion. Likewise, the collision induced dissociation mass analyzed ion kinetic energy charge reversal spectrum of [CH₃Se]^? has been compared with the collision induced dissociation mass analyzed ion kinetic energy spectrum of [CH₃Se]⁺ and found to be identical. A study of the pressure dependence of the collision induced dissociation mass analyzed ion kinetic energy spectrum of [C₃H₅]⁺ and [C₃H₅]^? showed increasing fragmentation with increasing collision gas pressure, and suggests that a greater mean number of collisions converts more energy to internal modes in the collision induced dissociation mass analyzed ion kinetic energy experiment even at low pressures.     

The decomposition of a triply-charged metastable positive ion of biphenyl

The transition, [C12H10]⁺³→[C₁₁H₇]⁺² + [CH₃]⁺, has been detected both in the ion kinetic energy spectrum and in the mass spectrum of biphenyl. The width of a resulting ‘metastable peak’ has been measured by setting the magnetic field to accept [C₁₁H₇]⁺² ions and scanning the high voltage at fixed electric sector voltage. The kinetic energy released in the decomposition, calculated from the peak width, amounted to 4.5 eV. With the assumption that this energy release is due entirely to charge separation, the charge distribution in [C₁₂H₁₀]⁺³ is discussed. The derivation of the equations used to calculate the energy released is given in the Appendix.     

Analysis of initial energies of fragments produced by 65-keV proton-molecule collisions using a time-of-flight mass spectrometer

A method is described to evaluate initial-energy distributions of fragments produced by proton-molecule collisions. The fragments are analysed by means of a time-of-flight mass spectrometer and their initial energies are evaluated from their time-of-flight spectrum. These energies are presented for various fragments of H₂, N₂, O₂, CO₂, CH₃Cl, CH₃Br, CH₃I, C₂H₆ and C₃H₈ produced with 65-keV protons. The results indicate the generation of several energetic fragments of the halomethanes, ethane and propane via dissociation of a doubly charged molecule followed by evaporation of one or more hydrogen atoms.     

Photoionization and Dissociation Study of 2-Methyl-2-propen-1-ol: Experimental and Theoretical Insights

The photoionization and dissociation of 2-methyl-2-propen-1-ol (MPO) have been investigated by using molecular beam experimental apparatus with tunable vacuum ultravioletsynchrotron radiation in the photon energy region of 8.0-15.5 eV. The photoionization efficiency (PIE) curves for molecule ion and fragment ions: C₄H₈O⁺、C₄H₇O⁺、C₃H₅O⁺、C₄H₇⁺、C₄H₆⁺、C₄H₅⁺、C₂H₄O⁺、C₂H₃O⁺、C₃H₆⁺、C₃H₅⁺、C₃H₃⁺、CH₃O⁺、CHO⁺ have been measured, and the ionization energy (IE) and the appearance energies (AEs) of the fragment ions have been obtained. The stable species and the first order saddle points have been calculated on the CCSD(T)/cc-pvTZ//B3LYP/6-31+G(d,p) level. With combination of theoretical and experimental results, the dissociative photoionization pathways of 2-methyl-2-propen-1-ol are proposed. Hydrogen migrations within the molecule are the dominant processes in most of the fragmentation pathways of MPO.     

Über Chalkogenolate. 85. Untersuchungen über Halbester der Trithiokohlensäure 3. Schwingungsspektren von Alkylthioxanthogensäuren und Wasserstoffbrücken in den freien Säuren

On Chalcogenolates. 85. Studies on Hemiesters of Trithiocarbonic Acid 3. Vibrational Spectra of Alkyl Thioxanthic Acids and Hydrogen Bondings in the Free Acids The IR spectra of alkyl thioxanthic acids RS? CS(SH) with R = CH₃, C₂H₅, ⁿC₃H₇, ⁱC₃H₇, ⁿC₄H₉, ^sC₄H₉, ^tC₄H₉, and CH₃S? CS(SD) as well as the Raman spectrum of the Compound with R = CH₃ have been assigned. The formation of hydrogen bondings in the free acids has been studied by means of i.r. spectra, ¹H-n.m.r. spectra, and electron absorption spectra. The energies of the hydrogen bondings have been calculated.     

Directed Gas‐Phase Synthesis of Triafulvene under Single‐Collision Conditions

The triafulvene molecule (c‐C₄H₄)—the simplest representative of the fulvene family—has been synthesized for the first time in the gas phase through the reaction of the methylidyne radical (CH) with methylacetylene (CH₃CCH) and allene (H₂CCCH₂) under single‐collision conditions. The experimental and computational data suggest triafulvene is formed by the barrierless cycloaddition of the methylidyne radical to the π‐electron density of either C₃H₄ isomer followed by unimolecular decomposition through elimination of atomic hydrogen from the CH₃ or CH₂ groups of the reactants. The dipole moment of triafulvene of 1.90 D suggests that this molecule could represent a critical tracer of microwave‐inactive allene in cold molecular clouds, thus defining constraints on the largely elusive hydrocarbon chemistry in low‐temperature interstellar environments, such as that of the Taurus Molecular Cloud 1 (TMC‐1).     

Silicon transitions, 3p 2→→3p n f (n=4, 5) and 3p 2→→3p 6p,detected in the multiphoton dissociation of phenylsilane

Fragmentation to neutral atoms has been observed in the laser photolysis of phenylsilane, C₆H₅SiH₃. A tunable dye laser (UV region) was used both to photolyze the molecule and to probe the resulting fragments. Atomic silicon and carbon lines (two photon resonances) are prominent in the multiphoton dissociation/ionization spectrum of phenylsilane.     

Evidence for the distortion of C2H4 and C2H2 chemisorbed on W(100)

The adsorption of C₂H₄ on W(100) has been studied by ultraviolet photoelectron spectroscopy with hν = 21.22 eV. The spectrum measured after in initial saturation exposure at 80 K exhibits structure which correlates well with energy levels recently calculated by Demuth and Eastman (DE) for sp³ rehybridized C₂H₄. Dehydrogenation of the adsorbate, either by subsequent heating to 295 K or direct adsorption at 295 K, yields a spectrum which correlates with DE's calculation for sp² rehybridized C₂H₂. These results suggest that C₂H₄ and C₂H₂ may be distorted from their planar and linear structures respectively and that the CC bonds on these molecules are stretched by adsorption on W(100). Qualitative arguments suggest that the bonding site for both melecules is directly over a W atom and that the Dewar—Chatt model for πd bonding in organometallic compounds is applicable.     

Minimal basis study of inner-shell ionization potentials for molecules containing sulfur: S,S-Diphenyl-N-p-Tolylsulfonyl-Sulfilimine

Ab initio calculations with a minimal (STO -3G) basis set on a number of sulfur-containing molecules are used to show that Koopmans' theorem and minimal basis calculations may be a simple but adequate way of obtaining inner-shell ionization potentials and chemical shifts of large molecules. The x-ray photoelectron spectrum of (C₆H₅)₂SNSO₂C₆H₄CH₃ is discussed with reference to an ab initio SCF minimal basis calculation on the model molecule H₂SNSO₂H.     

Hartree—Fock—Slater-LCAO studies of the acetylene—transition metal interaction. III. Binding to mono- and dinuclear Ni complexes with carbonyl and isocyanide ligands

The bonding of C₂H₂ in the nickel complexes [π-(C₂H₂)Ni(CO)₂], [π-(C₂H₂)Ni(CNH)₂] and [μ₂-(C₂H₂) {NI(CNH)₂}₂] has been studied by the non-empirical self-consistent Hartree—Fock—Slater-LCAO method. Calculations have been performed, not only for these complexes, but also for free C₂H₂ and its substituted analogues, propyne, but-2-yne and hexafluorobut-2-yne, and for the mono- and dinuclear complex fragments, [Ni(CNH)₂] and [{NI(CNH)₂}₂], which interact with the C₂H₂ molecule. The main difference with nickel surfaces, which have analogous π and μ₂ adsorption sites for C₂H₂ that we have studied by the same method, is the much stronger 3d, 4s, 4p hybridization induced by the CNH and CO ligands. In the bis(diisocyanide—nickel) complex these hybrids form a rather broad dsp “band”. The low lying occupied levels in this “band” cause a strong interaction with the filled acetylene π_u orbitals which dominates the π to metal donation effect. In the mononickel—acetylene complex this donation does occur, however, just as for acetylene adsorbed on nickel surfaces (in combination with the more prominent metal to π^* back donation which we find in all cases). A linear relation has been derived between the CC stretch frequencies in coordinated C₂H₂ molecules and the calculated CC overlap populations. Substitutio of the H atoms in (free) C₂H₂ by CH₃ or CF₃ groups has almost no effect on the CC overlap population and force constant.     

Multicomponent crystals of erlotinib

Erlotinib [systematic name: N‐(3‐ethynylphenyl)‐6,7‐bis(2‐methoxyethoxy)quinazolin‐4‐amine], a small‐molecule epidermal growth factor receptor inhibitor, useful for the treatment of non‐small‐cell lung cancer, has been crystallized as erlotinib monohydrate, C₂₂H₂₃N₃O₄·H₂O, (I), the erlotinib hemioxalate salt [systematic name: 4‐amino‐N‐(3‐ethynylphenyl)‐6,7‐bis(2‐methoxyethoxy)quinazolin‐1‐ium hemioxalate], C₂₂H₂₄N₃O₄⁺·0.5C₂O₄²⁻, (II), and the cocrystal erlotinib fumaric acid hemisolvate dihydrate, C₂₂H₂₃N₃O₄·0.5C₄H₄O₄·2H₂O, (III). In (II) and (III), the oxalate anion and the fumaric acid molecule are located across inversion centres. The water molecules in (I) and (III) play an active role in hydrogen‐bonding interactions which lead to the formation of tetrameric and hexameric hydrogen‐bonded networks, while in (II) the cations and anions form a tetrameric hydrogen‐bonded network in the crystal packing. The title multicomponent crystals of erlotinib have been elucidated to study the assembly of molecules through intermolecular interactions, such as hydrogen bonds and aromatic π–π stacking.     

Über die Reaktion von 2,2-Dimethylpropylidinphosphan mit Wolframhexachlorid; die Kristallstrukturen von [(Cl3PO)WCl4(H9C4?CC?C4H9)] und [(H5C6)4As][WCl6]

Reaction of 2,2-Dimethylpropylidynephosphane with Tungsten Hexachloride as well as the Crystal Structures of [(Cl₃PO)WCl₄(H₉C₄? C?C—C₄H₉)] and [(H₅C₆)₄As][WCl₆] The reaction of 2,2-dimethylpropylidynephosphane, (CH₃)₃C? C?P|, with tungsten hexachloride suspended in POCl₃ results, with oxidation of the phosphorus atom, in 2,2,5,5-tetramethylhex-3-yne. This compound reacts with tungsten tetrachloride simultaneously formed to give the alkyne complex [(Cl₃PO)WCl₄(H₉C₄? C?C—C₄H₉)], which is dark green in colour. A small amount of tungsten hexachloride is reduced merely to tungsten pentachloride; after the addition of tetraphenyl arsonium chloride it can be isolated as [(H₅C₆)₄As][WCl₆]. For this compound, a new and very simple synthesis from WCl₆, [(H₅C₆)₄As]Cl and C₂Cl₄ as reducing agent is described. The structure of [(Cl₃PO)WCl₄(H₉C₄? C?C? C₄H₉)] has been determined from X-ray diffraction data (R = 5.8%). The complex crystallizes in the monoclinic space group P2₁/n with: {a = 1510; b = 1517; c = 849 pm; β = 93.1°; Z = 4}. The tungsten atom is sevenfold coordinated by four equatorial chlorine atoms, by the C°C group of the acetylene ligand and by the oxygen atom of the POCl₃ molecule in trans position. The bulky acetylene ligand which is nearly symmetrically bound shifts the chlorine atoms towards the solvated POCl₃ molecule so that no common plane with the tungsten atom is possible. With 130 pm the C°C bond length of the 2,2,5,5-tetramethyl-3-yne ligand corresponds to a C°C double bond. The i.r. spectrum of [(H₅C₆)As][WCl₆] shows two WCl₆ strectching vibrations and therefore proves a reduction of octahedral symmetry. In agreement with the results of a crystal structure determination (space group P4/n; a = 1301; c = 780 pm; Z = 2.7%) the [WCl₆]^?-anion has nearly exact C_4V symmetry with somewhat shorter W? Cl bond lengths parallel to the fourfold axis of rotation.     

Synthesis,molecular, crystal and electronic structure of [(C6H6)Ru(1,2,4-triazole)3](CF3SO3)2

[(C₆H₆)Ru(1,2,4-triazole)₃](CF₃SO₃)₂ has been prepared and studied by IR, electronic and ¹H?NMR spectroscopy and X-ray crystallography. The complex was prepared by reaction of [(C₆H₆)RuCl₂]₂ with 1,2,4-triazole in the presence of AgCF₃SO₃ in methanol. The electronic spectrum of the compound has been calculated using the TDDFT method.     

Rehybridization of C2H2 chemisorbed on W(110)

Chemisorption of C₂H₂ on W(110) has been studied by high resolution electron energy low spectroscopy. At low coverages the molecule dissociates, while at thigh coverage C₂H₂ is di-σ adsorbed with a CC bond order of 0.25 and a CH bond angle of. ≈ 103°.     

Oxygen in a box: an oxygen atom surrounded by a cube of 8 lithium atoms

Although molecular structures in which there is an oxygen atom surrounded by a tetrahedral or an octahedral array of cations are familiar (though not common), no molecule has previously been reported in which an oxygen atom is surrounded by a cubic array of metal atoms. We describe here such a molecule, (C₁₁H₁₃N₃)₆Li₈O, where C₁₁H₁₃N₃ is a bidentate, uninegative ligand.