Resonance capture of electrons and photoelectron spectroscopy of the molecules of substituted anisoles and thioanisoles

In the electron resonance capture mass spectra of phenol, anisole, thioanisole, and their fluorinated analogs the resonances above 3.8 eV are electronically excited Fischbach resonances due to the excitation of the electron from several occupied MOs to one unoccupied MO. The mechanisms of the formation of the negative ions for these compounds are identical and do not depend on the nature of the heteroatoms. The low-energy resonances in the second energy region for PhR compounds (R=OH, OMe, SMe) correlate with the positions of the second singlet transitions. With thermal electron energies fluorinated anisoles are characterized by the formation of long-lived rearrangement ions. The absence of the rearrangement ion in fluorinated thioanisole can be explained by the energetically less favorable removal of the neutral CHF=S fragment compared with the CHF=0 fragment for fluorinated anisole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1042–1048, May, 1990.     

Mass spectra of negative ions from thiophane and its alkyl derivatives

The mass spectra of the negative ions from the dissociative capture of electrons were obtained for thiophane and its alkyl derivatives. With a few exceptions, all of these negative ions of the spectrum contain sulfur atoms: electron capture is not observed in cyclic compounds — cyclopentane and methylcyclopentane. The principle routes of dissociation during electron capture were isolated for thiophane and alkylthiophanes and explain the greater portion of the observed lines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1631–1632, December, 1971.     

Negative ion mass spectroscopy of several cyclic sulfones

Conclusions The formation of negative ions by several cyclic sulfone molecules was studied. The introduction of electron-withdrawing substituents or unsaturated bonds markedly stabilizes the negative molecular ion. A difference is observed in the negative ion mass spectra of isomers, while the positive ion mass spectra obtained upon electron impact are identical.Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2477–2482, November, 1985.     

Mass spectrometry of π-complexes of the transition metals. Communication 29. Dissociative electron capture spectra of monosubstituted cymantrenes

Conclusions The dissociative electron capture mass spectra of eight monosubstituted cymantrenes have been studied. The lifetimes of the molecular negative ions of these compounds were measured and the main fragmentation paths under dissociative electron capture conditions established.For communication 28, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimiya, No. 6, pp. 1299–1301, June, 1982.     

Chemical-ionization mass spectra of diterpene alkaloids

The chemical-ionization spectra of diterpene alkaloids have been investigated for the first time with the recording of positive and negative ions [Cl(+) and (–)). A comparison has been made of the CI(+) spectra with the EI and SIMS spectra. It has been shown that the nature of the CI(+) and (–) spectra depends greatly on the type and position of substituents in the lycoctonine skeleton.Deceased.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 114–122, January-February, 1995. Original article submitted October 31, 1994.     

Mass-spectrometric study of the cyclization of diazo compounds. 10. 2-Diazomalonic acid amides. Mass spectra of the negative ions

The mass spectra of the negative ions of the dissociative resonance capture of electrons of diazo amides and the isomeric triazoles were studied. The molecular negative ions of these compounds are unstable and do not undergo interisomerization. The principal fragmentation process involves the elimination of a molecule of nitrogen and transformation of the resulting [M-N₂]^– ions to the heterocyclic form, which is the same for the two isomers.See [1] for communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 941–944, July, 1987.     

Mass spectrometry of crown ethers

The mass spectra of benzo-15-crown-5 and benzo-l8-crown-6 were investigated by mass spectrometry with different inlet systems, such as direct introduction, gas chromatography and liquid chromatography inlets. Different ionisation methods such as electron impact, chemical ionisation, electron capture or negative ion chemical ionisation were also studied. The results and the specific problems encountered for this group of substances are discussed based on the spectra obtained.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995.     

Semiempirical structure analysis for long-wave X-ray emission satellites. 2. Period II and III transition-element hydrides

Conclusions Comparison with OCM calculations shows that the Rydberg states and states in the continuum are very important in configuration interaction for the hydrides, which is due to the very small numbers of vacant MO included in the CI basis (only one each for HF and HCl). Therefore, the hydrides are the most inconvenient substances for LWS structure calculations for x-ray spectra by this method. Nevertheless, here again the role of the vacant MO in the CI is important. One naturally expects that the role of those MO will increase considerably as their number increases (see in particular [17]).The conclusions are that for lines corresponding to transitions from the upper filled MO, the long-wave satellites have little effect on the spectrum shape but alter the intensities by 3–7%. As one proceeds to the deeper MO, the role of the LWS increases rapidly, and leads in fact to the diagram lines vanishing. For the hydrides, that range begins with the MO for which the ionization potentials are 15–20 eV. Here one gets the L spectra of the corresponding elements with complicated LWS. One can say that at these ionization potentials, one gets a multielectron limit, beyond which the one-electron approach to interpreting the spectra becomes inadequate. The K_, spectra for these compounds are almost undistorted by long-wave satellites, and one can use the changes in intensity ratio in the K spectra for the interacting compounds to draw conclusions on the participation of the orbitals in the bonding.Inorganic Chemistry Institute, Siberian Branch, USSR Academy of Sciences. Translated from Zhurnal Strukturnol Khimii, Vol. 31, No. 1, pp. 74–83, January–February, 1990.     

ESR,spectroscopic, and quantum-chemical studies on the electronic structures of complexes formed by Cu(I) with radicals

The optical and ESR spectra have been examined for complexes of Cu(I) with various radicals, which contain various numbers of Cl ions in the central-atom coordination sphere. The spin-Kamiltonian parameters have been determined for all these radical complexes, and the observed ESR spectra have been compared with those calculated with allowance for second-order effects. The observed values for the isotropic and anisotropic components of the HFI constant from the central ion have been used to estimate the contributions from the 4s and 3d² _z orbitals of the copper ion to the unpaired-electron MO. Quantum-chemical calculations have been performed by the INDO method on the electronic structures and geometries of complexes formed by CH₂OH with Cu(I) for various Cl contents in the coordination sphere. The radical is coordinated by the orbital on the carbon atom, and the stabilities of the radical complexes decrease as the number of Cl ions in the coordination sphere increases. A geometry close to planar is proposed for the CuCl₄ ^–3 fragment in a complex containing four Cl ions.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 1, pp. 32–38, January–February, 1986.     

Photoionization mass spectrometry of aliphatic monoterpene alcohols

Summary 1. The dissociative processes observed in the photoionization of monoterpene alcohols have been investigated. It has been established that the relative intensities of the peaks of the heavy ions, including the molecular ions, are higher on photoionization than on electron impact.2. It has been found that the mass spectra of the isomeric alcohols obtained on photoionization differ from one another to a greater degree than the electronic mass spectra.Agrophysical Scientific-Research Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 723–726, November–December, 1974.     

Dissociative electron capture by 1,3-dithiolanes and 1,3-dioxalanes

A study was carried out on dissociative electron capture by 1,3-dithiolanes and 1,3-dioxalanes. The mechanisms for the fragmentation pathways of the negative ions differ significantly between the oxygen- and sulfur-containing compounds. The (M-H)^– ions are formed with excess internal excitation energy.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 208–210, January, 1990.     

Field desorption mass spectra of flavonoid acylglycosides. I. Natural acetyl derivatives

The field desorption mass spectra (FD spectra) of 17 natural flavonoid acetylglycosides have been studied. In the spectra of each of the 0-monoglycosides the molecular ion (M or M + H) appears as the main peak and it is accompanied by the ions of the aglycone (A or A + H) and of the acylated anhydrosugar (S). The intensity of the latter peak is largely connected with the structure of the substance. In the FD spectra of flavone 0-biosides, fragment S is absent but its mass can be calculated from the difference (M – A). Useful information for establishing the position of the acetyl group is given by the fragments S₁ and (M – S₁) corresponding to the detachment of the terminal sugar residue. The FD spectra of flavone C-glycosides differ greatly from the spectra of the 0-glycosides: In them the main peak is that of the ion (M), but peaks (A) and (S) are absent and the ions present resemble the fragmentation of the C-glycosides under the action of electron impact.All-Union Scientific-Institute of Medicinal Plants, Moscow. L. Ya. Karpov Scientific-Research Institute of Physical Chemistry, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 573–582, September–October, 1984.     

Negative ion formation in compounds relevant to SF6 decomposition in electrical discharges

Dissociative and nondissociative electron attachment in the electron impact energy range 0–14 eV are reported for SOF₂ SOF₄, SO₂F₂, SF₄, SO₂, and SiF₄ compounds which can be formed by electrical discharges in SF₆. The electron energy dependences of the mass-identified negative ions were determined in a time-of-flight mass spectrometer. The ions studied include F^– and SOF ₂ ^–* from SOF₂; SOF ₃ ^– and F^– from SOF₄; SO₂F ₂ ^–* , SO₂F^–, F ₂ ^– , and F^– from SO₂F₂; SF ₄ ^–* and F^– from SF₄; O^–, SO^–, and S^– from SO₂; and SiF ₃ ^– and F^– from SiF₄. Thermochemical data have been determined from the threshold energies of some of the fragment negative ions. Lifetimes of the anions SOF ₂ ^–* , SO₂F ₂ ^–* , and SF ₄ ^–* are also reported.     

Effect of perfluorophenyl groups on the nature of the electronic absorption spectra of 1, 3, 5-triaryl-Δ2-pyrazolines

The results of calculations by the self-consistent field (SCF) MO Pariser-Parr-Pople (PPP) method explain the nature of the electron transitions responsible for the electronic absorption spectra of 1, 3, 5-triphenylpyrazoline and its perfluorophenyl derivatives. The perfluorophenyl group behaves like a strong electron donor in the excited states. According to the results of the calculation, a perfluorophenyl group in the 1 position of the pyrazoline ring deviates markedly from the planar conformation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 669–672, May, 1978.The authors thank B. Ya. Simkin for his useful discussion.     

Quantum-chemical simulation of dicyanamide and tricyanomethanide ion solvation

SCF MO LCAO has been applied in the MNDO-WS approximation to calculate the spatial and electronic structures for solvates formed by dicyanamide and tricyanomethanide ions with alcohols, water, chloroform, and methylene chloride. The monosolvates formed by those anions are molecular complexes having medium-strength H bonds.Translated from Teoreticheskaya i Ékperimental'naya Khimiya, Vol. 25, No. 1, pp. 92–96, January–February, 1989.     

Mass spectroscopic study of compounds from the cyclopropane series 6. Behavior of alkyl and aryloxy gem-dichlorocyclopropanes under chemical ionization

Conclusions Chemical ionization mass spectra have many advantages over electron impact mass spectra in studying the alkyl and aryloxy gem-dichlorocyclopropanes. Most of these compounds gives highly stable quasimolecular ions and the products obtained from decomposition of the latter furnish more complete information concerning molecular structures.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2310–2316, October, 1978.     

Mass-spectrometric investigation of some new derivatives of the alkaloid lupinine

The mass spectra of some new derivatives of lupinine have been studied with the use of the spectra of metastable ions. On the basis of the results of an investigation of DADI spectra it has been shown that in the formation of low-mass quinolizidine ions the ions with m/z 152–150 are of considerable importance.A. S. Sadykov Institute of Biororganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 508–512, July–August, 1990.     

Dissociative electron capture by sulfide,sulfoxide, and sulfone molecules

Conclusions The low energy resonance in the negative ion mass spectra of alkyl vinyl, 2,3-epoxypropyl alkyl, and 2, 3-epithiopropyl alkyl sulfies and their sulfoxide and sulfone analogs is related to electron capture in the ^* orbital of the S-C bond. The oxidation state of the sulfur atom has no qualitative effect on the major processes involved in the formation of the negative ions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, 1653–1657, July, 1984.     

Mass spectra of benzylpyridines

The mass spectra of dimethylbenzyl- and dimethyldibenzylpyridines at different ionizing electron energies were investigated. The anomalously low intensities of the molecular ion peaks of 3,4-dibenzylpyridines, as compared with the 2,5-isomers, and the greater probability of the formation of primary (M-2)⁺ ions in the mass spectra are explained by the synchronous loss of a neutral H₂ particle and the formation of cyclic fragment ions from the weakly excited molecular ions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 70–73, January, 1973.