Carbon-13 chemical shift assignment of some organophosphorus compounds: 1—Dialkyl and diaryl (alkylamido)phosphates with general formula Y2P(X)NHR

Carbon-13 chemical shifts and the POC, POCC, PNC and PNCC coupling constants of 18 compounds containing the amine moiety, and with the general formula Y₂P(X)NHR [Y=C₂H₅O, C₆H₅O, CH₂O, Y₂=1,2-dioxybenzene; X = O or S; R = H, CH₃, C₂H₅, PhCH₂CH₂, (CH₃)₂CH, C(CH₃)₃, C₆H₁₁, C₆H₅, C₆H₅NH] have been determined. The Y₂P(X) group shows a sterically induced effect on the amine moiety; the ¹³C chemical shift of the Y group is, however, almost unaffected on replacing P(O) by a P(S) group.     

Geometry optimization in ab initio SCF calculations. VII. Proton affinities and ion structures calculated with floating orbital geometry optimization (FOGO)

The FOGO method is used to calculate absolute proton affinities of the molecules H₂, HF, NH₃, H₂O, CH₃OH, C₂H₅OH, H₂O₂, CH₂O, CO, and CH₂CO. Comparison with experimental values demonstrates that the geometrical and energetical data resulting from this type of ab initio calculation are of chemical accuracy. Predictive data for higher energy isomers, such as hydroxymethylene and ethynol are given as possible aid for the identification of these species.     

Evaluated and estimated kinetic data for phase reactions of the hydroperoxyl radical

Methods are discussed for the production and detection of the hydroperoxyl radical for use in gas phase kinetic studies. Rate constants for gas phase reactions of the hydroperoxyl radical with itself, H₂, H₂O, CO, NO, SO₂, O₃, C₂H₆, C₃H₈, i-and n-C₄H₁₀, C₂H₄, i-C₄H₈, HCHO, C₂H₅CHO, n-C₃H₇CHO, Br, O, OH, and H are critically evaluated. Recommended or estimated rate constant expressions with associated error limits are given applicable over specified temperature ranges (normally 300–1000°K). The reactivity of HO₂ compared with OH, O, H, F, Cl, Br, CH₃, and CH₃O is presented in tabular form and the implications for atmospheric chemistry are discussed.     

Diiod(methylthio)gallan. Darstellung und reaktivität

Different synthetic routes for the preparation of diiodo(methylthio)gallane are given. Some reactions of this compound with Lewis bases, such as O(CH₃)₂, S(CH₃)₂, S₂(CH₃)₂, N(CH₃)₃, P(CH₃)₃, and other compounds, such as CH₃I, CH₃OH, C₂H₅OH, C₂H₅SH, i-C₃H₇SH, and C₂H₅SeH are investigated. Spectra and some physical and chemical properties of the new compounds are reported. The structure of diiodo(methylthio)gallane is discussed in view of some interesting differences of this molecule in solution and in crystal form.     

The use of transition-state theory to extrapolate rate coefficients for reactions of O atoms with alkanes

Conventional transition-state theory is used for extrapolating rate coefficients for reactions of O atoms with alkanes to temperatures above the range of experimental data. Expressions are developed for estimating structural properties of the activated complex necessary for calculating enthalpies and entropies of activation. Particular attention is given to the problem of the effect of the O atom adduct on the internal rotations in the activated complex. Differences between primary, secondary, and tertiary attack are discussed, and the validity of representing the activated complexes of all O + alkane reactions by a fixed set of vibrational frequencies and other internal modes is evaluated. Experimental data for reactions of O atoms with 15 different alkanes (CH₄, C₂H₆, C₃H₈, C₄H₁₀, C₅H₁₂, C₆H₁₄, C₇H₁₆, C₈H₁₈, i–C₄H₁₀, (CH₃)₄C, (CH₃)₂CHCH(CH₃)₂, (CH₃)₃CC(CH₃)₃, c–C₅H₁₀, c–C₆H₁₂, c–C₇H₁₄) are reviewed. The following approximate expressions for ΔS^?(298) and E(298), the entropy and energy of activation, respectively, are consistent with the experimental data and with the calculations: where n_C = number of carbon atoms in the alkane and n_H = the number of “equivalent” H atoms. Using the conventional transition state theory expression, k(298) = 10^15.06 exp(ΔS^?/R) exp(–E(298)/298R) L mol^?1s^?1, one then obtains: These expressions agree with experimental values within a factor approximately 2 for alkanes larger than C₃H₈.     

On the use of localized orbitals and restricted alternant orbitals in chemical systems

An analysis of the transformation of localized orbitals into restricted alternant orbitals is proposed. This approach has the advantage of expressing the wave-function in an orbital product while some electron correlation is introduced permitting the study of dissociation reactions. All applications of the orbital technique may be made as easily as with RHF, but with the additional possibility of studying chemical radicals. Some illustrations of this fact are shown for the molecules HF, H₂O, NH₃, CH₄, C₂H₆ and for the dissociation reactions of CH₄ and C₂H₆ generating CH₃ radicals.     

Chlor(methyl)(organylthio)gallane,die ersten vertreter dieser gallium(III)-verbindungen

The reactions between dichloromethylgallane and the silyl sulfides (CH₃)₃SiSR (R = CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, Ph and CH₂Ph) in benzene result in the formation of the hitherto unknown, extremely moisture-sensitive chloro(methyl)(organylthio)gallanes. Reactions of these thiogallanes with the donor compounds N(CH₃)₃ and O(CH₃)₂ are reported. Spectra as well as some physical and chemical properties of the new compounds are given.     

Synthesis of formamidines from 2-amino-3-methylquinazolin-4-one and its 6-nitro derivative

The condensation of 2-amino-3-methylquinazolin-4-one and its 6-nitro derivative with dialkyl-, arylalkyl-, and heterylformamides has given the corresponding formamidines of the quinazolinone series. The details of the compounds synthesized are as follows X, R, R′, yield (%), mp (°C, ethanol), R_f (chloroform-methanol (20:1) Al₂O₃): empirical formula: H, CH₃, CH₃, 77, 238–240, 0.49, C₁₂H₁₄ON₄; H, C₂H₅, C₂H₅, 65, 208–210, 0.96, C₁₄H₁₈ON₄; H, CH₃, C₆H₅, 84, 162–164, 0.54, C₁₇H₁₆ON₄; H, (CH₂)₂O(CH₂)₂, 60, 196–197, 0.43, C₁₄H₁₆O₂N₄; H, (CH₂)₅, 6.6, 196–198, 0.4, C₁₅H₁₈·ON₄; NO₂, CH₃, CH₃, 64. 194–196, 0.83, C₁₂H₁₃O₃N₅; NO₂, C₂H₅, C₂H₅, 37, 142–144, 0.8, C₁₄H₁₇O₃N₅; NO₂; CH₃, C₆H₅, 38, 298, 0.88, C₁₇H₁₅O₃N₅; NO₂, (CH₂)₂O(CH₂)₂, 60, 148–150, 0.7, C₁₄H₁₅O₄N₅. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 680–684, September–October, 1980.     

Study of the ethane oxidation reaction by the kinetic tracer method

The kinetics of ethane oxidation was studied at 320, 340, 353 and 380°C, mixture composition 2 C₂H₆ + 1 O₂, and total pressure 609 torr. It was found that at 320°C CH₂O and CH₃CHO were branching agents. A series of experiments was conducted on 2C₂H₆ + O₂ oxidation in the presence of 0.7% ¹⁴C-labeled ethylene. The ethylene oxide was found to form only from C₂H₄, formaldehyde formed from C₂H₄ and C₂H₆; and CH₃CHO, C₂H₅OH, and CH₃OH formed only from ethane. The formation rates of C₂H₄, C₂H₄O, and CH₂O were calculated by the kinetic tracer method. At 320°C the fraction of oxygen-containing products formed from C₂H₄ was 16–18%, and at 353 and 380°C it was 30–40%.     

Vapour—liquid equilibrium at elevated pressures from the perturbation theory. II. Binary systems

Vapour—liquid equilibria in binary systems of non-polar non-spherical molecule compounds were studied theoretically by combining the perturbation theory of convex molecule fluids with a new variant of the conformal solution theory. The recently proposed equation of state of hard convex body mixtures and the corresponding expressions for the contact values of distribution functions were employed to determine the reference thermodynamic functions and the perturbation terms. Ten binary systems, i.e. ArCH₄, N₂CH₄, N₂C₂H₄, N₂C₂H₆, CH₄C₂H₄, CH₄C₂H₆, C₂H₄C₂H₆, CO₂C₂H₄, CO₂C₂H₆, and ArCO₂ were studied at constant temperatures. Comparison of theoretical predictions with experimental data is given.     

Calculation of harmonic force constants,vibrational frequencies and integrated intensities of some organic molecules using the MINDO—Forces method

The harmonic force constants, vibrational frequencies and integrated intensity ratios of CH₂, H₂O, CH₂O, C₂H₂, CO₂, HCN, CH₃, CH₄, and C₂H₄ have been calculated using the MINDO—FORCES program and the Pulay method for the calculation of the molecular force constants. The results obtained are in general quite satisfactory when compared with available literature values. The results are, however, not as satisfactory in case of molecules containing heteroatoms, due to the neglect of some dipolar repulsion integrals for the heteroatoms by the MINDO/3 method. Calculated integrated intensities for CH₃ and C₂H₄ agree well with experimental results. The calculated integrated intensities for other molecules are obtained for the first time and no comparison with published data is therefore possible.Part of the M.Sc. Thesis of K. H. A. 1978.     

Vapor—solid equilibrium for the CHONi system

The equilibrium states of the CHONi system are defined in relation to H₂CO compositions for temperatures ranging from 300 to 700 K and at atmospheric pressure.The gaseous species, H₂, H₂O, CO, CH₄…C₈H₁₈, C₂H₄… C₄H₈ are taken into account to determine the gas phase compositions imposed by the different equilibria between condensed phases (〈C〉, 〈Ni〉, 〈NiO〉, 〈Ni₃C〉, 〈Ni,C〉 solution).We have particularly investigated the values of chemical potential of carbon in the gas phases, fixed by equilibria between solid phases involving carbon, at which hydrocarbons higher than CH₄ appear. The method for determining the standard free enthalpy of formation of Ni₃C is discussed.     

Study on the method of chemical trapping for formyl intermediates

The method of chemical trapping for formyl intermediates has been studied, with syngas conversion to ethanol over rhodium-based catalysts as the diagnostic reaction concerned, and CH₃I as the trapping reagent. Two species of acetaldehyde, i.e., CH₃CHO and CH₃CDO, were produced in the trapping reaction following CO + 2D₂ reaction. It was shown that the formation of CH₃CHO in the trapping reaction resulted from dehydrogenation of CH₃ from CH₃I to give H, which induced the formation of CH₃CHO in the presence of CO and CH₃ So there may be two pathways for the formation of CH₃CDO in the trapping reaction: one, methylation of DCO adspecies; the other, deuteration of CH₃ CO formed by CO insertion into CH₃ The catalyst surface was purged with Ar following CO + 2D₂ reaction before the trapping reaction was performed. By means of this modified method of chemical trapping for formyl intermediates, CH₃CDO was found to be mainly derived from the methylation of DCO adspecies. Accordingly, it could be concluded that formyl is a C₁ intermediate in the syngas conversion to ethanol over rhodium-based catalysts.     

Onium salts of sulfur-containing oxyanions resulting from reaction of sulfur(IV) oxide with aqueous solutions of 1,2-diamines and morpholine

Reaction products have been isolated from SO₂–L–H₂O–О2 systems (L = ethylenediamine, N,N,N′,N′-tetramethylethylenediamine, piperazine, and morpholine) as onium salts [H₃NCH₂CH₂NH₃]SO₄, [(CH₃)₂NHCH₂CH₂NH(CH₃)₂]SO₄, [(CH₃)₂NHCH₂CH₂NH(CH₃)₂]S₂O₆ ? H₂O, [C₄H₈N₂H₄]SO₃ ? H₂O, [C₄H₈N₂H₄]S₂O₆, [C₄H₈N₂H₄]SO₄ ? H₂O, [O(C₂H₄)₂NH₂]₂SO₄ ? H₂O. The prepared compounds have been characterized by X-ray diffraction analysis, X-ray powder diffraction, IR and mass spectroscopy.     

The behaviour of beryllium μ4-oxo-μ-carboxylates under electron impact

The electron impact mass spectra of eight polynuclear beryllium complexes Be₄O(RCO₂)₆ (R?H, CH₃, C₂H₅) and Be₄O(RCO₂)₅OR′ (R?CH₃, R′?H, CH₃, C₂H₅, C₃H₇; R?C₂H₅, R′?C₂H₅) are reported. The major fragmentations involve the elimination of (RCO)₂O (RCOOR′) or Be(RCO₂)₂ (Be(RCO₂)OR′) from the ions [M? L]⁺ and of {(R? H)CO}, (R′? H), H₂O and BeO from the lighter ions. The fragmentation patterns are practically independent of the organic groups present and can be rationalized by stereochemical considerations.     

A Theoretical Investigation of the Decomposition Reactions of Ethyl Formate in the S0 State

This study revisits the stability of the possible conformations and the decomposition reactions of ethyl formate in the S₀ state using the (U)MP2, MP4SDTQ, CCSD(T), and (U)B3LYP methods with various basis sets. The transition states of the decomposition channels to HCOOH + C₂H₄, CO + CH₃CH₂OH, CH₂O + CH₃CHO, HCOH + CH₃CHO, C₂H₆ + CO₂, and H₂ + CH₂CHOCHO are determined. The microcanonical rate constants derived from the RRKM theory are calculated for each of the decomposition reactions. The high‐pressure limit rate constants are calculated for the decomposition channels to HCOOH + C₂H₄, CO + CH₃CH₂OH, and CH₂O + CH₃CHO.     

Theoretical study of the structure and unimolecular decomposition pathways of ethyloxonium, [CH3CH2OH2]+

Ab initio molecular orbital calculations with split-valence plus polarization basis sets and incorporating valence-electron correlation have been performed to determine the equilibrium structure of ethyloxonium ([CH₃CH₂OH₂]⁺) and examine its modes of unimolecular dissociation. An asymmetric structure (1) is predicted to be the most stable form of ethyloxonium, but a second conformational isomer of C_s symmetry lies only 1.4 kJ mol^?1 higher in energy than 1. Four unimolecular decomposition pathways for 1 have been examined involving loss of H₂, CH₄, H₂O or C₂H₄. The most stable fragmentation products, lying 65 kJ mol^?1 above 1, are associated with the H₂ elimination reaction. However, large barriers of 257 and 223 kJ mol^?1 have to be surmounted for H₂ and CH₄ loss, respectively. On the other hand, elimination of either C₂H₄ or H₂O from ethyloxonium can proceed without a barrier to the reverse associations and, with total endothermicities of 130 and 160 kJ mol^?1, respectively, these reactions are expected to dominate at lower energies. A second important equilibrium structure on the surface is a hydrogen-bridged complex, lying 53 kJ mol^?1 above 1. This complex is involved in the C₂H₄ elimination reaction, acts as an intermediate in the proton-transfer reaction connecting [C₂H₅]⁺ +H₂O and C₂H₄ + [H₃O]⁺ and plays an important role in the isotopic scrambling that has been observed experimentally in the elimination of either H₂O or C₂H₄ from ethyloxonium. The proton affinity of ethanol was calculated as 799 kJ mol^?1, in close agreement with the experimental value of 794 kJ mol^?1.     

Komplexchemie polyfunktioneller Liganden. XXXI. Komplexe des Tetrakis(diphenylphosphorylmethyl)-methan mit FeCl3, SnCl4 und SbCl5

Complex Chemistry of Polyfunctional Ligands. XXXI. Complexes of Tetrakis(diphenylphosphorylmethyl) methane with FeCl₃, SnCl₄, and SbCl₅ C[CH₂P(O)(C₆H₅)₂]₄ forms with FeCl₃ the compounds C[CH₂P(O)(C₆H₅)₂]₄ · 2FeCl₃ and C[CH₂P(O)(C₆H₅)₂]₄ · 4 FeCl₃. From their IR spectra ionic, spirocyclic structures have been derived. C[CH₂P(O)(C₆H₅)₂]₄ yields with SnCl₄ and SbCl₅ also spirocyclic compounds of the composition C[CH₂P(O)(C₆H₅)₂]₄ · 2 SnCl₄ and C[CH₂P(O)(C₆H₅)₂]₄ · 4 SbCl₅, but the SnCl₄ derivative has a nonionic structure.     

Dipole moment derivatives from MINDO/3 semi-empirical MO calculations

Dipole moment derivatives for CO, NO, CO₂, H₂O, HCN, BF₃, CH₄, C₂H₄, C₂H₆, CH₃F, F₂CO and H₂CO molecules have been evaluated using MINDO/3 MO calculations. The values are compared with those obtained by other semi-empirical MO methods.     

K-shell ionization energies in molecules by SCF GF calculations

Energies of CH₄, NH₃, H₂O and C₂H₄ K-ionized molecules are calculated by means of a Group Function method using minimal or near minimal basis sets of STO's. Further results from very large basis sets are reported for CH₄, NH₃, and H₂O. Results seemingly do not suffer the shortcomings of a previous SCF MO treatment.