Mass spectra of some (Z)-α-Phenyl-β-(2-thienyl)acrylonitriles

The mass spectra of some (Z)α-(4-R′-phenyl)-β-(2-thienyl-5-R)acrylonitriles (R = H, CH₃, Br; R′ = H, CH₃O, CH₃, Cl, NO₂) at 70 eV are reported. Mass spectra exhibit pronounced molecular ions. The compound's where R = H, and CH₃ are characterized by the occurrence of a strong [M - H]⁺ peak. Moreover, in all the compounds a m/z 177 peak occurs. In the compounds where R = H, [M - HS]* and [M - CHS]* ions are present except the nitroderivatives. Where R = CH₃, [M - HS]⁺ ion occurs.     

EPR,ENDOR and DFT study of l-lysine·HCl·2H2O single crystals X-irradiated at 66 K

Electron Paramagnetic Resonance (EPR), Electron-Nuclear DOuble Resonance (ENDOR) and ENDOR-Induced EPR (EIE) results indicated at least three radicals produced in l-lysine·HCl·2H₂O crystals irradiated at 66 K. EPR from radical R1 dominated the spectra and it was identified as the carboxyl anion, (H₂OO?) CH (NH₃)⁺ (CH₂)₄ (NH₃)⁺. Density-Functional Theory (DFT) calculations supported the assignment and indicated that the carboxyl group transformed from planar to a pyramidal configuration following electron trapping. Two small couplings detected from R1 were ascribed to protons transferred to the carboxyl group from neighboring molecules through intermolecular hydrogen bonds. Radical R2 was identified as the product of decarboxylation, ?H (NH₃)⁺(CH₂)₄ (NH₃)⁺. Although it was not possible to obtain R2's α-coupling tensor from the experiment, EPR simulations and DFT calculations provided strong support for the identification. Radical R3 exhibited several β-couplings but could be detected only in one plane and could not be identified.     

Electron-impact fragmentation of aliphatic polynitro compounds

The mass spectra of two series of aliphatic polynitro compounds are reported and discussed. The fragmentation patterns of aliphatic nitro and polynitro compounds are similar in that no appreciable molecular ion current is observed; however, there are several other features in the fragmentation of aliphatic polynitro compounds which differ from that of nitroalkane spectra. Both series of compounds studied-C(NO₂)_x(CH₃)_4?x, where x = 4 to 0 and C₂(NO₂)_x(CH₃)_6?x, where x = 6,4,2-show a decrease in the number and intensity of alkylions with an increase in the NO⁺ and NO₂⁺ ion current as x increases. The main ions resulting from the more nitrated compounds are [NO]⁺, [NO₂]⁺, [CO₂]^+. and [CH₃CO]⁺, whose noncharged counterparts are the principal species produced in the detonation of these compounds. This similarity of the products of the two processes suggests the use of mass spectroscopy for the investigation of the initial explosive processes. The principal fragmentation pathways of the polynitroalkanes have been elucidated by exact mass measurements and the observation of metastable ion transitions.     

Electron impact ionization of ethylene–methanol heteroclusters: Stable configurations and mechanisms in intracluster ion–molecule reactions

Reactions that proceed within mixed ethylene–methanol cluster ions were studied using an electron impact time-of-flight mass spectrometer. The ion abundance ratio, [(C₂H₄)_n(CH₃OH)_mH⁺]/[(C₂H₄)_n(CH₃OH)_m⁺], shows a propensity to increase as the ethylene/methanol mixing ratio increases, indicating that the proton is preferentially bound to a methanol molecule in the heterocluster ions. The results from isotope-labelling experiments indicate that the effective formation of a protonated heterocluster is responsible for ethylene molecules in the clusters. The observed (C₂H₄)_n(CH₃OH)_m⁺ and (C₂H₄)_n(CH₃OH)_m–1CH₃O⁺ ions are interpreted as a consequence of the ion–neutral complex and intracluster ion–molecule reaction, respectively. Experimental evidence for the stable configurations of heterocluster species is found from the distinct abundance distributions of these ions and also from the observation of fragment peaks in the mass spectra. Investigations on the relative cluster ion distribution under various conditions suggest that (C₂H₄)_n(CH₃OH)_mH⁺ ions with n + m ≤ 3 have particularly stable structures. The result is understood on the basis of ion–molecule condensation reactions, leading to the formation of fragment ions, $ {\rm CH}_2=\!=\mathop {\rm O}\limits^ + {\rm CH}_3 $ and (CH₃OH)H₃O⁺, and the effective stabilization by a polar molecule. The reaction energies of proposed mechanisms are presented for (C₂H₄)_n(CH₃OH)_mH⁺(n + m ≤ 3) using semi-empirical molecular orbital calculations.     

Syntheses,Structures and Spectroscopic Studies of Quadruply Bonded Complexes Containing Bridging Acetate and η3-etp Ligands (etp = Ph2PCH2CH2P(Ph)CH2CH2PPh2)

The quadruply bonded complexes containing bridging acetate and polydentate phosphine ligands of the type Mo₂(O₂CCR₃)X_J(η³-etp) (R = H, X = Br, 1; R = F, X = CI, 2; R = F, X = Br, 3; etp = Ph₂PCH₂CH₂P(Ph)CH₂CH₂PPh₂) were prepared by reactions of Mo₂(O₂CCR₃)X₂(PPh₃)₂ with etp in CH₂X₂. Their UV-vis and ³¹P{¹H}-NMR spectra have been recorded, and the structure of 1 has been determined by X-ray crystallography. Crystal data for 1·2CH₂Br₂: space group P2₁/c, a = 13.924(7) Å, b = 21.157(4) Å, c = 14.427(5) Å, β = 101.82(3)°, V = 4159(2) ų, Z = 4, with final residuals R = 0.0797 and Rw = 0.0793. The absorption wavelengths of the δ → δ* transitions and the chemical shifts and the coupling constants of the ³¹P{¹H}-NMR spectra of these complexes are dependent on the natures of the halogen atoms and the acetate ligands.     

Interaction of rhodium trichloride with N-functionalized calix[4]resorcinol in acetone

A supramolecular neutral complex was isolated in the solid state in the reaction of calix[4]-resorcinol having nitrogen-containing substituents [CH₂N(CH₃)₂] on the upper rim of the molecule with RhCl₃·3H₂O in acetone. The complex, in addition to the calixarene structure and the rhodium-containing fragment, includes the dioxygen molecules bound to the rhodium ion [Rh⁺³(O₂⁻)]. The compound was characterized by IR, Raman, ¹H NMR, ESR and electron spectroscopy, and by conductivity. The composition was confirmed by elemental analysis, XRD study and derivatography. The electronic structure of the complex was revealed by analysis of electron spin resonance spectrum and electron absorption spectrum.     

Investigation of the volatile carboxylates of some platinum metals in the gaseous phase by electron-impact mass spectrometry

The mass spectra of the compounds Rh₂ (RCOO)₄[R=C(CH₃)₃ (I), CH(CH₃)₂ (II), CF₃ (III)], Pd₃(RCOO)₆ [R=C(CH₃)₃ (IV), CH(CH₃)₂ (V), CF₃ (VI)], Os₂(RCOO)₄Cl₂ [R=C(CH₃)₃ (VII)], and Ru₂(RCOO)₄ [R=C(CH₃)₃ (VIII)] have been investigated. It has been shown that in the gaseous state compounds I–III, VII, and VIII have a dimeric structure, while compounds IV–VI have a trimeric structure. The mass spectra of compounds I–VIII show peaks of the molecular ions [M]⁺; and the fragmentation of the molecular ions takes place mainly with the elimination of the RCOO groups. Rearrangements with the elimination of F₂O have been discovered for compounds III and VI, and rearrangements with the elimination of O=C--OH have been discovered for IV and V. The migration of a fluorine atom to the metal in compound III and its absence in compound V have been explained in the framework of the principle of hard and soft acids and bases. A scheme for the fragmentation of [M]⁺. under the action of electron impact has been proposed.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 22, No. 3, pp. 322–330, May–June, 1986.     

Theoretical and Experimental Study of Complex Ions from Reactions of Al+ (Cu+) with Amine Molecules

The gas phase reactions of metal ions (Al⁺, Cu⁺) with amine molecules [CH₃NH₂=MA, (CH₃)₂NH=DMA] were investigated using a laser ablation‐molecular beam method. The directly associated product complex ions,Al⁺‐MA and Al⁺‐DMA, and the dehydrogenation product ions, Cu⁺(CH₂NH) and Cu⁺(C₂H₅N), as well as hydrated ion Cu⁺(NC₂H₅·H₂O), have been obtained and recorded from the reactions of the metal ions and organic amine molecules, and density functional theory (B3LYP) calculations have been performed to reveal the optimized geometry, energetics, and reaction mechanism of the title reactions with basis set 6‐311+G(d,p) adopted.     

Effect of method of ion preparation on low-energy collision-induced dissociation mass spectra

The collision-induced dissociation (CID) mass spectra of protonated cocaine and protonated heroin have been measured using a triple quadrupole mass spectrometer at 50 eV ion/neutral collision energy for protonated molecules prepared by different protonating agents. The CID mass spectra of protonated cocaine using H⁺(H₂O)_n, H⁺(NH₃)_n and H⁺((CH₃)₂NH)_n as protonating agents are essentially identical and it is concluded that, regardless of the initial site of protonation, the fragmentation reactions occurring on collisional activation are identical. By contrast, protonated heorin prepared with H⁺(H₂O)_n and H⁺(NH₃)_n as protonating agents show substantial differences. That formed by reaction of H⁺(H₂O)_n shows a much more abundant peak corresponding to loss of CH₃CO₂H. From a comparison with model compounds, and from a consideration of the three-dimensional structure of heroin, it is concluded that with H⁺(H₂O)_n as protonating agent significant protonation occurs at the acetate group attached to the alicyclic ring, leading to acetic acid loss on collisional activation, but that reaction of H⁺(NH₃)_n leads to protonation at the nitrogen function. The proton attached to nitrogen cannot interact with the acetate group and, consequently, the probability of loss of acetic acid on collislional activation is greatly reduced.     

N-Heteroaralkyl substituted α-amidinium thiolsulfates

The syntheses of a number of N-substituted α-amidinium thiolsulfates, CH₂(S₂O₃^?)-C(=NH₂⁺)NH(CH₂)nR are described, where n was varied from 1 to 3 and R represents such heteroaryl groups as 2-furyl, 2-thienyl, 3-indolyl and 2-, 3- and 4-pyridyl. The preparation of S-(2-imidazolinemethyl)thiolsulfuric acid, as an example of an N, N'-disubstituted α-amidinium thiolsulfate, is also reported.     

Micellar alkylation: a methylating surfactant

Micellar $\text{n}$-C₁₆H₃₃$\text{N}\text{+}$(CH₃)₂CH₂$\text{S}\text{+}$(CH₃)₂, 2CF₃SO₃^? rapidly methylates bound thiophenoxide ions.     

Reaction of Carbon Anions With Iron α,β-Unsaturated Ketimine Complexes

Complexes (η⁴-PhCH=CHCR=NPh)Fe(CO)₃, where R=H(1a) and CH₃ were synthesized in excellent yield from the reaction of the corresponding α,β-unsaturated ketimines with excess Fe₂(CO)₉. Reaction of la with (Ph)₂CHLi and (CH₃)₂(NC)CLi at ?78°C or ambient temperature followed by acid quenching gave trans-PhCH=CHCHRNHPh, where R=CHPH₂ and C(CH₃)₂CN, respectively, in good yield. In the presence of 1 atm. of CO the reaction of 1a with (CH₃)₂(NC)CLi, followed by CuCl₂ oxidation resulted in the formation of a carbamyl choride, trans-PhCH=CHCH[C(CH₃)₂CN]N(Ph)COCl. This species was converted to a carbamate compound trans-PhCH=CHCH[C(CH₃)₂ - CN]N(Ph)COOCH₃ in MeOH in the presence of Ag⁺.     

The site of ionization in the acetylation of aliphatic esters by [(CH3CO)3]+

A series of esters RCOOR′ (where R, R′ = CH₃, CH₃CH₂, (CH₃)₂CH, (CH₃)₃C) were reacted with the [(CH₃CO)₃]⁺ ion from biacetyl in an ion cyclotron resonance spectrometer. A steric effect influences the rate of formation of stable products [RCOOR′·CH₃CO]⁺ and is used to determine that either oxygen of the ester may be initially acylated by [(CH₃CO)₃]⁺.     

Vibrational spectroscopy of Cs+ solvated by methylamine

We report the vibrational spectra of the cluster ions Cs⁺(CH₃NH₂)_N, N=3–22. Bands in the 1015–1050 cm^?1 region of the infrared are due to the v8 mode (CN stretch) of methylamine molecules displaying different degrees of interaction with the central ion. Monte Carlo simulations of the solvated Cs⁺ ion indicate that nine methylamine molecules fill the first solvation shell of Cs⁺ and that possible rearrangements in cluster structure occur at N=14?15. No absorptions due to bulklike methylamine molecules are observed through N=22.     

Formation and hydrolysis of gas‐phase [UO2(R)]+: R═CH3, CH2CH3, CH═CH2, and C6H5

The goals of the present study were (a) to create positively charged organo‐uranyl complexes with general formula [UO₂(R)]⁺ (eg, R═CH₃ and CH₂CH₃) by decarboxylation of [UO₂(O₂C─R)]⁺ precursors and (b) to identify the pathways by which the complexes, if formed, dissociate by collisional activation or otherwise react when exposed to gas‐phase H₂O. Collision‐induced dissociation (CID) of both [UO₂(O₂C─CH₃)]⁺ and [UO₂(O₂C─CH₂CH₃)]⁺ causes H⁺ transfer and elimination of a ketene to leave [UO₂(OH)]⁺. However, CID of the alkoxides [UO₂(OCH₂CH₃)]⁺ and [UO₂(OCH₂CH₂CH₃)]⁺ produced [UO₂(CH₃)]⁺ and [UO₂(CH₂CH₃)]⁺, respectively. Isolation of [UO₂(CH₃)]⁺ and [UO₂(CH₂CH₃)]⁺ for reaction with H₂O caused formation of [UO₂(H₂O)]⁺ by elimination of ·CH₃ and ·CH₂CH₃: Hydrolysis was not observed. CID of the acrylate and benzoate versions of the complexes, [UO₂(O₂C─CH═CH₂)]⁺ and [UO₂(O₂C─C₆H₅)]⁺, caused decarboxylation to leave [UO₂(CH═CH₂)]⁺ and [UO₂(C₆H₅)]⁺, respectively. These organometallic species do react with H₂O to produce [UO₂(OH)]⁺, and loss of the respective radicals to leave [UO₂(H₂O)]⁺ was not detected. Density functional theory calculations suggest that formation of [UO₂(OH)]⁺, rather than the hydrated U^VO₂⁺, cation is energetically favored regardless of the precursor ion. However, for the [UO₂(CH₃)]⁺ and [UO₂(CH₂CH₃)]⁺ precursors, the transition state energy for proton transfer to generate [UO₂(OH)]⁺ and the associated neutral alkanes is higher than the path involving direct elimination of the organic neutral to form [UO₂(H₂O)]⁺. The situation is reversed for the [UO₂(CH═CH₂)]⁺ and [UO₂(C₆H₅)]⁺ precursors: The transition state for proton transfer is lower than the energy required for creation of [UO₂(H₂O)]⁺ by elimination of CH═CH₂ or C₆H₅ radical.     

Fast atom bombardment mass spectrometry of some alkoxv- and chloro-silanes

The positive and negative FAB mass spectra of a series of alkoxy- and chloro-silanes X_m(CH₃)₃-_mSi(CH₂)_nR [m = 1 or 3, n = 3, 10 or 17, X = Cl or OMe or OEt, R = Me, NH₂, glycidoxy, COOMe, NHCO(CH₂)₇COOMe or NHCO(CH₂)₁₀CH₂OAc] were recorded in NBA and NPOE matrices. The chlorosilanes underwent rapid hydrolysis into silanols which condense to form siloxanes, the process being complete in NBA and partial in NPOE, yielding siloxane-based fragment ions in the positive spectra and silyloxyanions in the negative spectra. The alkoxysilanes were more resistant to hydrolysis, affording abundant [MH – HX]⁺ ions (X = OMe or OEt) in their positive FAB spectra and moderate to high intensity [M – H]^? ions in the negative mode, the latter undergoing characteristic sequential loss of C₂H₄, EtOH and C₂H₄. Significant variations were observed in the positive spectra of all the silanes with change of matrix.     

Relationship between the Physicochemical Properties of Electrolytes and the Electronic Structure of Solvated Alkali Metal Cations

Group theoretical analysis and linear combinations of molecular orbitals of the cation and solvent are used to establish the nature and stability of bonds and hence the electric mobility of the cation and the viscosity of the electrolyte depending on the type of cation (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) and molecules (H₂O, NH₃, H₂CO, (CH₃)₂CO, CH₃CN). Solvation effects on the UV photoelectron and intramolecular vibrational IR and NMR spectra are revealed.     

Metastable ion study of organosilicon compounds part II—hexamethyldisiloxane

Unimolecular reactions of the metastable silicenium ion (CH₃)₃SiOSi(CH₃)₂ ⁺ generated by dissociative ionization of bexamethyldisiloxane were investigated by mass-analysed ion kinetic energy (PUKE) Spectrometry. The characteristic fragmentations observed were losses of CH₄ and (CH₃)₂Si?O molecules. Complete scrambling of all methyl groups prior to these reactions was found by investigating the MIKE spectra of deuterium labelled analogues (CD₃)₃SiOSi(CH₃)₂⁺ and (CH₃)₃SiOSi(CD₃)₃⁺. The loss of methane was accompanied by a large kinetic energy release (T_0.5 = 482 meV). The MIKE spectra of silicenium ions were compared with those of their carbon analogues. The most predominant reaction of metastable (CH₃)₃COC(CH₃)₃⁺ ion was the loss of CH₂?C(C H₃)₂ leading to protonated acetone. Significant differences between the ion fragmention characteristics of silicon and carbon compounds were found.