Peculiarities of interaction of H+, Me3C+, and Me3Si+ ions with multifunctional molecules in the gas phase

Peculiarities of interaction of H⁺, Me₃C⁺, and Me₃Si⁺ ions with functional groups of molecules in the gas phase have been studied. Proton tends to form chelates with virtually all of the functional groups studied, whereas Me₃Si⁺ ions exhibit no capacity for chelation. Using isomeric xylenes as examples it was shown that Me₃Si⁺ ions (unlike Me₃C⁺ ions) experience virtually no steric hindrance when they react with nucleophilic centers. Effects of functional groups present in molecules of nitriles on the generation of [M+Me₃C]⁺ adducts in the gas phase and the Ritter reaction in solution were estimated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1767–1773, September, 1995.This work was carried out with financial support from the International Science Foundation (Grant MA7 000) and the Russian Foundation for Basic Research (Project No. 93-03-18033).     

Cationic Complexes of Hydrogen with Helium

High‐resolution mass spectra of helium nanodroplets doped with hydrogen or deuterium reveal that copious amounts of helium can be bound to H⁺, H₂⁺, H₃⁺, and larger hydrogen‐cluster ions. All conceivable He_nH_x⁺ stoichiometries are identified if their mass is below the limit of ≈120 u set by the resolution of the spectrometer. Anomalies in the ion yields of He_nH_x⁺ for x=1, 2, or 3, and n≤30 reveal particularly stable cluster ions. Our results for He_nH₁⁺ are consistent with conclusions drawn from previous experimental and theoretical studies which were limited to smaller cluster ions. The He_nH₃⁺ series exhibits a pronounced anomaly at n=12 which was outside the reliable range of earlier experiments. Contrary to findings reported for other diatomic dopant molecules, the monomer ion (i.e. H₂⁺) retains helium with much greater efficiency than hydrogen‐cluster ions.     

Ion-molecular interactions in the HCl—isopropanol system

Multiple Attenuated Total Reflectance (MATR) IR spectra of solutions of HCl in isopropanol, containing 0 to 43 mol. % HCl, were studied in the 900–4000 cm^–1 range. The addition of HCl to PrⁱOH yields proton disolvates with strong symmetrical H-bonds. At high concentrations of HCl (C _HCl ⁰ > 5.7 mol L^–1, /C⁰ _HCl < 2), when the number of alcohol molecules is not enough to form disolvates with all of the protons present in the solution, (Cl...H...Cl)^– ions are formed, in addition to (C₃H₇OH)₂H⁺. The spectra of these ions have been assigned.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1753–1756, September, 1995.This work was carried out with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18356).     

Pyridine catalyzed decomposition of triphenylphosphite ozonide

Pyridine accelerates the decomposition of triphenylphosphite ozonide in CH₂Cl₂. The addition of ethanol to the (PhO)₃PO₃-C₅H₅N-CH₂Cl₂ system increases the rate of the process. The kinetic regularities of the decomposition of (PhO)₃PO₃ in the presence of pyridine, ethanol-pyridine, and propan-2-ol-pyridine mixtures in CH₂Cl₂ are studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 871–873, May, 1995.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-5231).     

Selenoketene (H2CCSe)+• and selenoketyl cumulene (HCCSe)+ ions and their neutral counterparts: a tandem mass spectrometric and computational study

Dissociative electron ionization (70eV) of selenophene (C₄H₄Se) generates m/z 106 ions of composition [H₂, C₂, ⁸⁰Se]^+? and m/z 105 ions of [H, C₂, ⁸⁰Se]⁺. From tandem mass spectrometric experiments, Density Functional Theory (DFT) and ab initio calculations, it is concluded that these ions have the structure of selenoketene H₂C?C?Se^+? (1a^+? )and selenoketyl HC?C?Se⁺ (2a⁺) ions respectively. The calculations predict that selenoketene ion 1a^+? is separated by high energy barriers from its isomers selenirene (H e)^+? 1b^+?, ethyne selenol (HCCSeH)^+? 1c^+?, (CCHSeH)^+? 1d^+? and (CCSeH₂)^+? 1e^+?. The selenoketyl ion 2a⁺ is separated by high barriers from its isomers (CCHSe)⁺ 2b⁺, and (CCSeH)⁺ 2c⁺. Neutralization‐reionization mass spectra (NRMS) of these structurally characterized ions confirmed that the corresponding neutral analogues, selenoketene H₂CCSe 1a and selenoketyl radical HCCSe 2a^? are stable in the rarefied gas phase. The relative, dissociation, and isomerization energies for selenoketene and selenoketyl ions and neutrals studied at B3LYP/6–31G(d,p) and G2/G2(MP2) levels are used to support and interpret the experimental results. Copyright © 2005 John Wiley & Sons, Ltd.     

ESR study of spin-adducts of boron-centered carboranyl radicals with fullerene-60 and fullerene-70

Spin-adducts of boron-centered radicals, derivatives ofm-carboran-12, with fullerenes C₆₀ and C₇₀ have been studied by ESR spectroscopy. Constants of hyperfine splitting (HFS) of an unpaired electron with¹⁰B and¹¹B nuclei have been determined from the ESR spectra of C₆₀-B₁₀H₉C₂H₂ radicals. Three isomeric spin-adducts were detected with different HFS constants with¹¹B, andg-factors were detected in the reaction of B₁₀H₉C₂H₂ with C₇₀.Dedicated to Academician of the RAS N. S. Zefirov (on his 60th birthday).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1840–1842, September, 1995.This study was performed in the framework of the International Research Program of Russia Fullerenes and Atomic Clusters and was financially supported by the Russian Foundation for Basic Research (Project Nos. 93-03-18725 and 93-03-4101).     

Theoretical analysis of competitive directions of electrocyclization of 3,4,6-triazaocta-1,3,5,7-tetraene. Investigation of the structure and electrocyclization of 1,2,4-triazahexa-1,3,5-triene

Theoretical analysis of competing directions of electrocyclization of triazatetraene H₂C=CH-N=N-CH=N-CH=CH₂, triazatrienes H₂C=CH-N=N-CH=NH and HN=N-CH=N-CH=CH₂, and 1,4-diphenyl-1,2,4-triazabuta-1,3-diene Ph-N=N-C(R)=N-Ph was carried out. Specific features of cyclization of these compounds were explained by differences in the energies of -orbitals of C=C, C=N, and N=N bonds and in bond orders of atoms forming a new bond in the reaction. The activation barrier and the structure of the transition state of the electrocyclization of 1,2,4-triazahexa-1,3,5-triene were studied by AMI, MNDO, and MINDO/3 methods. The electrocyclization of triazatriene is an asymmetric disrotatory process. The rotation angle of the terminal CH₂ group around the C=C bonds is twice as large as that of the NH group around the N=N bond. The 1,3-prototropic shift in dihydro-1,2,4-triazines is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1459–1465, August, 1995.The work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-5069).     

One-step synthesis of the chelate oxides of bis(trialkylantimony) by an oxidative method

The chelate oxides of bis(trimethylantimony) (Me₃SbL¹)₂O (i = 1 or 2, L¹-acetylacetonate, L² - trifluoroacetylacetonate) and bis(triethylantimony) (Et₃SbL¹)₂O have been obtained in 79–85% yields by a one-step oxidation of trialkylantimony withtertbutylhydroperoxide in the presence of -diketones in benzene at 20 °C.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 154–155, January, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No. 94-03-08846).     

Synthesis and structural studies of (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}pyridin-2-yl)imino]butan-2-one oxime, ligand and its mono-, di- and trinuclear copper(II) complexes

A new dioxime ligand, (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}-pyridin-2-yl)imino]butan-2-one oxime, (H₂Pymdo) (3) has been synthesized in H₂O by reacting 2,3-butenedione monoxime (2) with 2,6-diaminopyridine. Mono-, di- and tri-nuclear copper(II) complexes of the dioxime ligand (H₂Pymdo) and/or 1,10-phenanthroline have been prepared. The dioxime ligand (H₂Pymdo) and its copper(II) complexes were characterized by ¹H-n.m.r., ¹³C-n.m.r. and elemental analyses, magnetic moments, i.r. and mass spectral studies. The mononuclear copper(II) complex of H₂Pymdo was found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). In the dinuclear complexes, in which the first Cu(II) ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu(II) ion is ligated with dianionic oxygen atoms of the oxime groups and are linked to the 1,10-phenanthroline nitrogen atoms. The trinuclear copper(II) complex (6) was formed by coordination of the third Cu(II) ion with dianionic oxygen atoms of each of two molecules of the mononuclear copper(II) complexes. The data support the proposed structure of H₂Pymdo and its Cu(II) complexes.     

Polyol—Metall-Komplexe. III. Lithium-bis(oxolandiolato)cuprat-Tetrahydrat und Lithium-μ-propantriolato-cuprat-Hexahydrat — zwei homoleptische Kupfer(II)-Komplexe mit Polyolat-Liganden aus den mehrfach deprotonierten Polyolen Anhydro-erythrit und Glycerol

Polyol Metal Complexes. III. Lithium Bis(oxolanediolato)cuprate Tetrahydrate and Lithium μ-Propanetriolatocuprate Hexahydrate — Two Homoleptic Copper(II) Complexes with Polyolate Ligands Derived from the Multiply Deprotonated Polyols Anhydro-erythritol and Glycerol . In the blue-violet crystals of lithium bis{meso-oxolane-3, 4-diolato(2 - )}cuprate tetrahydrate, Li₂[Cu(C₄H₆O₃)₂] · 4H₂O ( 1 ) (P2₁/c, a = 706.2(4), b = 1114.0(6), c = 958.3(5) pm, β = 107.67(3)°, Z = 2, R_w = 0.022), square-planar coordinated copper(II) ions are bound to twofold deprotonated anhydro-erythrol ligands (Cu? O 194.36(17) and 191.83(17) pm). The oxygen ligator atoms of the mononuclear cuprate ions are bound to lithium ions or they are acceptors in asymmetrical hydrogen bonds. Trinuclear tris-{μ-propanetriolato(3 - )}tricuprate ions with triply deprotonated glycerol as ligands are present in the deep blue columns of LiCuC₃H₅O₃ · 6H₂O ( 2 ) (P3 c1, a = 1 278.8(6), c = 2 420.5(12) pm, Z = 12, R_w = 0.059), which has been prepared for the first time by Bullnheimer [2]. The copper(II) ions in 2 are also bound to alkoxide oxygen atoms in square-planar coordination (Cu? O 190.7(7) and 192.4(8), Cu? μ-O 196.6(6) and 195.0(7) pm). The hydrogen bond system and the content of channels parallel [001] are described in terms of a disorder model.     

Characterization of N‐methylated amino acids by GC‐MS after ethyl chloroformate derivatization

Methylation is an essential metabolic process in the biological systems, and it is significant for several biological reactions in living organisms. Methylated compounds are known to be involved in most of the bodily functions, and some of them serve as biomarkers. Theoretically, all α‐amino acids can be methylated, and it is possible to encounter them in most animal/plant samples. But the analytical data, especially the mass spectral data, are available only for a few of the methylated amino acids. Thus, it is essential to generate mass spectral data and to develop mass spectrometry methods for the identification of all possible methylated amino acids for future metabolomic studies. In this study, all N‐methyl and N,N‐dimethyl amino acids were synthesized by the methylation of α‐amino acids and characterized by a GC‐MS method. The methylated amino acids were derivatized with ethyl chloroformate and analyzed by GC‐MS under EI and methane/CI conditions. The EI mass spectra of ethyl chloroformate derivatives of N‐methyl ( 1–18 ) and N,N‐dimethyl amino acids ( 19–35 ) showed abundant [M‐COOC₂H₅]⁺ ions. The fragment ions due to loss of C₂H₄, CO₂, (CO₂ + C₂H₄) from [M‐COOC₂H₅]⁺ were of structure indicative for 1–18 . The EI spectra of 19–35 showed less number of fragment ions when compared with those of 1–18 . The side chain group (R) caused specific fragment ions characteristic to its structure. The methane/CI spectra of the studied compounds showed [M + H]⁺ ions to substantiate their molecular weights. The detected EI fragment ions were characteristic of the structure that made easy identification of the studied compounds, including isomeric/isobaric compounds. Fragmentation patterns of the studied compounds ( 1–35 ) were confirmed by high‐resolution mass spectra data and further substantiated by the data obtained from ¹³C₂‐labeled glycines and N‐ethoxycarbonyl methoxy esters. The method was applied to human plasma samples for the identification of amino acids and methylated amino acids. Copyright © 2016 John Wiley & Sons, Ltd.     

Processes of dissociative electron capture by 20-hydroxyecdysone molecules

The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by the elimination of H₂O and H₂ molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH₂O]^.− (n=1–3) and [M−H₂−nH₂O]^.− (n=0−3) ions that are generated exclusively by the rearrangement. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000.     

The doubly-charged ion mass spectra of hydrocarbons

The doubly-charged ion mass spectra of some hydrocarbons, including a variety of structural types, have been obtained by a new technique in which doubly-charged ions are charge exchanged with neutral molecules and so separated from singly-charged ions. The spectra show strong similarities, independent of hydrocarbon structure; characteristic ions include [C_mH₂]⁺⁺ (m = 2 to 5), [C_nH₆]⁺⁺(n > 6), [C₁₀H₈]⁺⁺, [C₁₂H₈]⁺⁺, [C₁₁H₁₀]⁺⁺, [C₇H₇]⁺⁺·, [C₉H₇]⁺⁺· and [C₁₃H₁₁]⁺⁺·. The fragmentation pattern of 2-phenylnaphthalene has been reconstructed, based on observed reactions of metastable doubly-charged ions to give fragment doubly-charged ions. In addition, we examined metastable ion fragmentations leading to two singly-charged ions for some of the characteristic ions, using several compounds. The value of doubly-charged ion mass spectra of hydrocarbons appears to lie in the information they provide on ion structures; this information was sufficient to permit the proposal of structures for the major ions encountered in this study.     

The elimination of metal(I) hydride in the mass spectra of some metal(II) compounds

Metal(I) hydrides are eliminated as neutral species in the electron impact ionization mass spectra of copper(II) and palladium(II) complexes of ethylene-N,N′-3-benzoylprop-2-en-2-amine. Deuterium labelling shows that the hydrogen atom of the metal(I) hydride is derived predominantly from the ethylene bridge both for ion source reactions and for metastable ion transitions. Evidence supporting the proposed rationalization for elimination of metal(I) hydride is provided by the observation of an analogous reaction in the mass spectrum of (ethylene-N,N′-salicylaldiminato)copper(II). The mass spectrum of ethylene-d₄-N,N′-3-benzoylprop-2-en-2-amine shows an unusual rearrangement to give [C₇H₅D₂]⁺ ions involving a formal phenyl-to-methylene transfer.     

Synthesis and structural studies of (2 E ,3 E ,6 R ,9 E ,11 E )-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime, ligand and its Mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes

This article describes the synthesis of a new (2E,3E,6R,9E,11E)-6-isopropenyl-3,6,10-trimethyl-5,8-dioxa-4,9-diazadodeca-3,9-diene-2,11-dione dioxime (H₂hmdm), and its mono-, homo, and heterodinuclear copper(II)/nickel(II) complexes. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). The Cu(H₂hmdm), molecule coordinates to the second copper(II) ion through the oximate oxygens to afford a binuclear structure doubly bridged by the oximate groups in the cis arrangement. In the dinuclear complexes, in which the first Cu^II ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu^II ion is ligated with the 1,10-phenanthroline nitrogen atoms. Ligand and its mononuclear copper(II), homo and heterodinuclear copper(II)–nickel(II) complexes of (H₂hmdm) were characterized by elemental analyses, magnetic moments, ¹H-n.m.r. and ¹³C-n.m.r., i.r., and mass spectral studies. The data support the proposed structure of H₂hmdm and its complexes.     

Synthesis and Structural Studies of 2-(hydroxyimino)-1-methylpropylideneamino-phenyliminobutan-2-one Oxime, Ligand and its Complexes with Cu(II) and Ni(II)

A new ligand incorporating a dioxime moiety, (2E,3E)-3-[(2-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}phenyl)imino]butan-2-one oxime, (H₂Phmdo) (3) has been prepared by reacting 2,3-butanedionemono-{O-[4-(1-methyl-2-oxo-propylideneaminooxy)-2,3-bis-(1-methyl-2-oxo-propylideneaminooxy-methyl)-but-2-enyl]-oxime} (2) with 1,2-phenylenediamine. Mono-, di- and trinuclear copper(II) and/or nickel(II) complexes of H₂Phmdo were characterized by elemental analyses, magnetic moments, ¹H-n.m.r. and ¹³C-n.m.r., i.r. and mass spectral studies. The mononuclear copper(II) and nickel(II) complexes of H₂Phmdo were found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). In the dinuclear complexes, in which the first Cu^(II) or Ni^(II) ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu^(II) ion is ligated with dianionic oxygen atoms of the oxime groups and are linked to the 1,10-phenanthroline nitrogen atoms. The data support the proposed structure of H₂Phmdo and its complexes.     

Mercuration ofB(9)-substitutedmeta- andortho-carboranes

The mercuration of substituted R₂C₂B₁₀H₉X-9 type carboranes (where R=m-H, X= Cl, Br, I, Me; R=o-H, X=Me) was studied. It was found that mercury atoms add to the boron atoms in position 10 ofmeta-carboranes and in position 12 ofortho-carboranes,i.e., to the boron atoms adjacent to the boron atom bonded to the X substituent. Symmetrical (R₂C₂B₁₀H₈X)₂Hg type derivatives were obtained. It was shown that they can be used as starting materials in transmetallation reactions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 743–747, April, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No 93-03-18654) and the International Science Foundation (Grant NDM 000).     

Doubly charged ion mass spectra: III—N-alkanes

Doubly charged ion mass spectra have been obtained for 15 n-alkane hydrocarbons. Spectra were measured using a Nier-Johnson geometry Hitachi RMU-7L mass spectrometer operated at 1.6kV accelerating voltage. Fragment ions, which resulted from C? C bond rupture and extensive H loss, dominated the spectra. Molecular ions have not been observed. The most intense ions in the doubly charged ion mass spectra of n-alkanes were [C₂H₄]²⁺, [C₃H₂]²⁺, [C₄H₃]²⁺, [C₅H₂]²⁺, [C₆H₆]²⁺, [C₆H₈]²⁺, [C₇H₆]²⁺, [C₇H₈]²⁺, [C₈H₆]²⁺ and [C₈H₈]²⁺. Appearance energies for forming the prominent doubly charged fragment ions have been measured and range from 27.5 eV to energies greater than 60eV. A geometry optimized SCF approach has been used to compute the energies and structures of prominent ions in the doubly charged mass spectra.     

Preparation and reactivity of metal-containing monomers

The kinetics and mechanism of thermal decay of an unsaturated copper carboxylate, Cu(OCOCH=CH₂)₂ (CuAcr₂), have been studied. At 190–240°C the rate of thermal decay can be adequately described by a set of zero and first order rate equations. The initial rate of decay,W ₀, is equal to 1.7·10¹⁷exp[-48500/(RT)] s^–1. The decay products of CuAcr₂ were analyzed by IR and mass spectroscopy as well as by optical microscopy. It has been established that the thermal decay of the monomer under study is accompanied by polymerization, fragmentation, and recombination processes in the solid phase which produce polymeric agglomerates.For part 25, seeIzv.Akad.Nauk, Ser.Khim., 1993, 76 [Russ. Chem. Bull., 1993,42, 66].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 303–307, February, 1993.     

Synthesis and liquid crystalline behavior of a series of ferrocene 1,1′-bis-azino-derivatives

A series of liquid-crystalline ferrocene derivatives, Fe{C₅H₄-C(CH₃)=N-N=CH-C₆H₃(X)-OOC-C₆H₄-OC _n H_2n+1}₂ (X = H, OH;n = 3 to 12), were obtained by the condensation of 1,1 -bishydrazondiacetylferrocene withp-alkoxybenzoyloxybenzaldehides. According to DSC and polythermic microscopy, all of the compounds exhibit an enantiotropic nematic mesophase in the 150–230 °C temperature range. A polycrystalline transition precedes the nematic transition. The liquid crystalline properties of the obtained compounds were investigated with respect to the number of carbon atoms in the terminal alkyl chain and the terminal hydroxyl group. The composition and structure of the obtained compounds were determined by elemental analysis and IR and NMR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 358–361, February, 1995.This work was carried out with financial support from the Russian Fundation for Basic Research (Project No. 94-03-08978).