Organoazides are intermediates in the synthesis of imidometal complexes. Metalimido complexes have an important role in catalysis. Thus, the organoazide interaction with metals is an important issue. However, the isolation of organoazidometal complexes is difficult due to the easy loss of N-2.The present study describes the complexation of nickel by nitrobenzyl azides by means of electrospray ionization mass spectrometry (ESI-MS), which was used also as a probe for the characterization of isomers. Organoazidometal complexes were observed and isolated from solutions of NiCl2 and NiBr2 in methanol/water. A different solvent, ethanol/water was also used. The complexes detected were singly and doubly positively charged, with various stoichiometries. The most abundant species were [Ni(II)Az(3)](2+) for ortho- and para-isomers, and [Ni(II)Az(3)(H2O)](2+) for meta isomer, where Az stands for nitrobenzyl azides. The ortho isomer showed several single positively charged complexes integrating chloride as a ligand. The mass spectra of the three isomers allowed their differentiation based on different behaviour in the mass range m/z 296 m/z 312. The MS2 spectra of [Ni(II)Az(3)](2+) were investigated aiming to characterize the three isomers but this analysis was not absolutely conclusive about the coordination site(s). Density functional theory calculations provided possible structures for the [Ni(II)Az(3)](2+) cation with the different isomers and their coordination modes could be responsible for their fragmentation pathways. (C) 2013 Elsevier B.V. All rights reserved.

The electronic structure, vibrational properties and pyrolysis behaviour of 3-azidopropionitrile (3APN, N3CH2CH2CN) are investigated using ultraviolet photoelectron spectroscopy (UVPES) and matrix-isolation infrared (IR) spectroscopy, supported by results from ab initio and DFT electronic structure calculations. 3APN is found to have an HOMO vertical ionisation energy (VIE) of 10.05±0.02eV and the strongest IR absorption bands located at 2173 and 1296cm−1. Pyrolysis of the title compound revealed the presence of N2, HCN, CH3CN and ketenimine, H2CCNH, among the decomposition products, the latter behaving as a reaction intermediate. From G3 computational results, 3-iminopropionitrile, CNCH2CHNH, was found to be formed in competition with H2CN−CH2CN, through 160–180kJmol−1 energy barriers. On the basis of experimental evidence and G3 results, ketenimine is proposed as the dominant intermediate arising from further decomposition of both imine (CNCH2CHNH) and H2CNCH2CN compounds.

Methyl 2-azidopropionate (N(3)CH(3)CHCOOCH(3), M2AP) has been synthesized and characterized by different spectroscopic methods, and the thermal decomposition of this molecule has been investigated by matrix isolation infrared (IR) spectroscopy and ultraviolet photoelectron spectroscopy (UVPES). Computational methods have been employed in the spectral simulation of both UVPES and matrix IR spectra and in the rationalization of the thermal decomposition results. M2AP presents a HOMO vertical ionization energy (VIE) of 9.60 ± 0.03 eV and contributions from all four lowest-energy conformations of this molecule are detected in the gas phase. Its thermal decomposition starts at ca. 400 °C and is complete at ca. 650 °C, yielding N(2), CO, CO(2), CH(3)CN, and CH(3)OH as the final decomposition products. Methyl formate (MF) and CH(4) are also found during the pyrolysis process. Analysis of the potential energy surface of the decomposition of M2AP indicates that M2AP decomposes preferentially into the corresponding imine (M2IP), through a 1,2-H shift synchronous with the N(2) elimination (Type 1 mechanism), requiring an activation energy of 160.8 kJ/mol. The imine further decomposes via two competitive routes: one accounting for CO, CH(3)OH, and CH(3)CN (ΔE(G3) = 260.2 kJ/mol) and another leading to CO(2), CH(4), and CH(3)CN (ΔE(G3) = 268.6 kJ/mol). A heterocyclic intermediate (Type 2 mechanism)-4-Me-5-oxazolidone-can also be formed from M2AP via H transfer from the remote O-CH(3) group, together with the N(2) elimination (ΔE(G3) = 260.2 kJ/mol). Finally, a third pathway which accounts for the formation of MF through an M2AP isomer is envisioned.

The relative populations of the 1H- and 2H-tautomer of gas-phase 5-methyltetrazole (5MTZ) have been assessed through core-level photoelectron spectroscopy, and compared with the results obtained from Gaussian-n (Gn, n=1, 2 and 3) and Complete Basis Set methods (CBS-4M and CBS-Q). The C 1s and N 1s core–electron binding energies (CEBEs) for each ionization site of both tautomers have been computed using the Δself-consistent-field (ΔSCF) approach. The C 1s and N 1s XPS spectra, obtained at 313K, yield a 1H/2H tautomer ratio of ca. 0.16/0.84 and 0.21/0.79, respectively.

Benzyl azide and the three methylbenzyl azides were synthesized and characterized by mass spectrometry (MS) and ultraviolet photoelectron spectroscopy (UVPES). The electron ionization fragmentation mechanisms for benzyl azide and their methyl derivatives were studied by accurate mass measurements and linked scans at constant B/E. For benzyl azide, in order to clarify the fragmentation mechanism, labelling experiments were performed. From the mass analysis of methylbenzyl azides isomers it was possible to differentiate the isomers ortho, meta and para. The abundance and nature of the ions resulting from the molecular ion fragmentation, for the three distinct isomers of substituted benzyl azides, were rationalized in terms of the electronic properties of the substituent. Concerning the para-isomer, IRC calculations were performed at UHF/6-31G(d) level. The photoionization study of benzyl azide, with He(I) radiation, revealed five bands in the 8–21eV ionization energies region. From every photoelectron spectrum of methylbenzyl azides isomers it has been identified seven bands, on the same range as the benzyl azide. Interpretation of the photoelectron spectra was accomplished applying Koopmans’ theorem to the SCF orbital energies obtained at HF/6-311++G(d,p) level.

Ionization energies of benzyl azide (BA), C6H5CH2N3, its methyl derivatives, 2-, 3- and 4-methyl benzyl azide and (1-azidoethyl)benzene (2-, 3- and 4-MBA and 1-AEB), (CH3)C6H4CH2 N3, have been calculated with several basis sets, with Møller–Plesset and Hartree–Fock methods. The data are compared to the ionizations energies obtained from HeI photoelectron spectroscopy (UVPES) experiments, in order to support the correct assignment of the bands. The nature and character of the molecular orbitals are also discussed.

An extensive conformational analysis was carried at ab initio and DFT levels of theory on two molecules – methyl 2–azidopropionate (N3CH3CHCOOCH3) and methyl 3–azidopropionate (N3CH2CH2COOCH3). In each case, the lowest energy conformers were characterized and the energy barriers between them were estimated. Ionization energies and vibrational frequencies were also computed, in order to support future spectroscopic studies with ultraviolet photoelectron spectroscopy (UVPES) and matrix isolation infrared spectroscopy (Matrix Isolation FTIR).

Angle resolved constant-ionic-state (CIS) and photoelectron (PE) spectra have been recorded for the NO radical from 13.2 to 30.0 eV. CIS spectra obtained for selected vibrational components of the first PE band in the photon energy range 13.5-15.7 eV are dominated by a sharp, intense structure arising from 5 sigma -> np Rydberg resonances, which are parts of series which converge to NO+(b(3)Pi). Spectra of the first PE band of NO were recorded at the observed resonance photon energies to study the effect on the PE vibrational envelopes and the asymmetry parameter beta. The evidence obtained, supported by results of Franck-Condon simulations, has allowed assignment of the bands in the CIS spectrum associated with NO(b(3)Pi, 3p) and NO(b(3)Pi, 4p) resonances. This has led to a correction of some of the published assignments of these bands, which have been observed by other methods. A 2 pi -> k sigma shape resonance has also been observed centred at 14eV and its effect on the vibrational envelope and asymmetry parameter of the first PE band has been investigated.

The CF radical has been studied with photoelectron (PE) and constant-ionic-state (CIS) spectroscopy using synchrotron radiation. By scanning the photon energy in the region between the first and second ionization onsets, while monitoring the intensity of selected vibrational components in the first photoelectron band, excitations to Rydberg states, which are part of a series which converge to the second ionization limit, were revealed. By comparing PE spectra recorded at selected resonance positions with calculated Franck-Condon PE vibrational envelopes to establish the excited state vibrational numbering, fitting the observed resonance positions to Rydberg series, and comparing the results obtained with results from a preceding paper on the isoelectronic molecule NO (1), the structure obtained could be assigned to excitation to np Rydberg states with a CF+(a(3)Pi) core. The Rydberg series fits led to an improved adiabatic ionization energy (AIE) from CF(X-2 Pi) to the CF+(a(3)Pi) state of (13.942 +/- 0.003) eV.

Ab initio and density functional calculations have been performed to study the benzyl azide, 2-, 3- and 4-methyl benzyl azides. Several molecular properties, such as conformational equilibrium, optimal geometry, and vibrational frequencies, have been computed for these molecules. Ionisation energies were also computed.

The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2-azido-N,N-dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N-2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four-membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five-membered-ring compound 2-oxazolidone. In contrast, the initial pyrolysis of 2-azido-N,N-dimethyl acetamide, yields the novel imine intermediate Me2NCOCH=NH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations.

In this paper angularly resolved photoelectron spectra (PES) and constant-ionic-state (CIS) spectra are presented for the atmospherically important species N and OH.The natural width Gamma, line shape parameters q and p(2) and discrete oscillator strengths f have been measured for the members of the N*[2s2p(3)(S-5). np] (P-4) <-- N(S-4) autoionizing resonances for n = 5-10. The n = 5 parameters calculated in this work are in good agreement with the values obtained previously whereas for the resonances with n = 6-10 the values of these parameters are reported for the first time. The asymmetry parameter (beta) for the first band of N atoms, the N+(P-3) <-- N(S-4) ionization, has also been measured in the photon energy range of the above autoionizing resonances.For OH, CIS spectra have been recorded for the first photoelectron band corresponding to the ionization OH+(X(3)Sigma(-), v(+) = 0) <-- OH(X(2)Pi. v" = 0). In these spectra, rotationally partially resolved bands associated with OH*(a(1)Delta3d, v' = 0) <-- OH(X(2)Pi, v" = 0) resonances have been observed. Suggestions for their assignment are made on the basis of their positions and band simulations which use rotational line strength calculations. (C) 2004 Elsevier B.V. All rights reserved.

The thermal decomposition of 2-azidoacetamide (N3CH2CONH2) has been studied by matrix-isolation infrared spectroscopy and real-time ultraviolet pbotoelectron spectroscopy. N-2, CH2NH, HNCO, CO, NH3, and HCN are observed as high-temperature decomposition products, while at lower temperatures, the novel imine intermediate H2NCOCH=NH is observed in the matrix-isolation IR experiments. The identity of this intermediate is confirmed both by ab initio molecular orbital calculations of its IR spectrum and by the temperature dependence and distribution of products in the photoelectron spectroscopy (PES) and IR studies. Mechanisms are proposed for the formation and decomposition of the intermediate consistent both with the observed results and with estimated activation energies based on pathway calculations.

Gas-phase reactions of anionic and cationic rhodium clusters with azidoacetonitrile are studied by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry under near-thermal conditions. All anionic and large cationic clusters react by adding [C-2,N-2] in consecutive steps, either by forming interstitial carbides and nitrides or by adding two CN groups to the cluster surface. Small cationic clusters behave differently, with the unimolecular decomposition of the azide determining the reactivity. Saturation is identified via the size-dependent efficiency of consecutive reaction steps. The present results are the first study of organic azides on transition metal clusters. The observed selectivity of the reaction is in contrast to the high exothermicity of any reaction with azide species. The cationic cluster reactivity shows a gradual transition from gas-phase to surface-like behavior with increasing cluster size.

Rapid Communications in Mass SpectrometryVolume 18, Issue 3 p. 363-366 Letter to the Editor Electron ionization mass spectrometry in the characterization of azidonitriles Filipa Martins, Filipa Martins CEFITEC, Departamento de Física da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this authorM. Filomena Duarte, Corresponding Author M. Filomena Duarte [email protected] Departamento de Química e Bioquímica da Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, PortugalDepartamento de Química e Bioquímica da Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.Search for more papers by this authorM. Tereza Fernandez, M. Tereza Fernandez Departamento de Química e Bioquímica da Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, PortugalSearch for more papers by this authorG. John Langley, G. John Langley Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UKSearch for more papers by this authorPaula Rodrigues, Paula Rodrigues CQFB, Departamento de Química da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this authorM. Teresa Barros, M. Teresa Barros CQFB, Departamento de Química da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this authorM. Lourdes Costa, M. Lourdes Costa CEFITEC, Departamento de Física da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this author Filipa Martins, Filipa Martins CEFITEC, Departamento de Física da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this authorM. Filomena Duarte, Corresponding Author M. Filomena Duarte [email protected] Departamento de Química e Bioquímica da Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, PortugalDepartamento de Química e Bioquímica da Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.Search for more papers by this authorM. Tereza Fernandez, M. Tereza Fernandez Departamento de Química e Bioquímica da Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, PortugalSearch for more papers by this authorG. John Langley, G. John Langley Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UKSearch for more papers by this authorPaula Rodrigues, Paula Rodrigues CQFB, Departamento de Química da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this authorM. Teresa Barros, M. Teresa Barros CQFB, Departamento de Química da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this authorM. Lourdes Costa, M. Lourdes Costa CEFITEC, Departamento de Física da Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2825-114 Monte da Caparica, PortugalSearch for more papers by this author First published: 06 January 2004 https://doi.org/10.1002/rcm.1331Citations: 7Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume18, Issue315 February 2004Pages 363-366 RelatedInformation

The reactions of Ar+ with 3-azidopropionitrile, 2-azidopropionitrile, and azidoacetonitrile have been studied in a Fourier transform ion cyclotron resonance mass spectrometer. The dominant and, in the case of 2-azidopropionitrile the only, primary reaction is charge transfer although the resultant molecular ion immediately fragments. In the cases of 3-azidopropionitrile and azidoacetonitrile a small amount of hydrogen abstraction to form ArH+ occurs. In addition to the unambiguous identification of the molecular formula of the product ions leading in most cases to suggested chemical structures with known proton affinities, the time profiles of the product ions were determined and kinetic analysis allowed the primary product ions to be differentiated from the secondary product ions. Many secondary reactions of the primary ions with the parent neutral molecule occur, the majority initiated by proton transfer. Some of them lead to fragmentation but others to the protonated azidonitrile. A comparison with a recently published account of the EI fragmentation of the same three azidonitriles leads to the suggestion that Ar+ chemical ionisation is potentially more appropriate for investigating the decomposition of fragile molecules such as the azidonitriles than is EI.

A series of derivatives of 2-azidoacetic acid and 2-azidoacetone were synthesized and their behaviour under electron ionization conditions was investigated. This paper reports the electron ionization fragmentation mechanisms for five aliphatic alpha-carbonyl azides, which were clarified bv accurate mass measurements and B/E linked scans. The substituent influences the abundance and the nature of the ions resulting from the molecular ion fragmentation. Copyright (C) 2003 John Wiley Sons, Ltd.

Ab initio calculations have been performed to study the methyl azidoformate (N3COOCH3) and the ethyl azidoformate (N3COOCH2CH3). Several molecular properties, such as conformational equilibrium, optimal geometry, and vibrational frequencies, have been computed for these molecules. Ionization energies based on Koopman's theorem were also computed.

Azidoacetonitrile (N3CH2CN) and azidoacetone (N3CH2COCH3) are studied by matrix-isolation FTIR spectroscopy in solid neon, argon, and nitrogen. The IR spectra calculated using the density-fuctional theoretical method are discussed in comparison with the experimental data. Significant broadening of the recorded azide bands indicate an awkward fit of these compounds into the solid environment. The strongest absorption is observed for both compounds in the regions of asymmetric and symmetric stretches of the N3 azide group. Strong band splittings in the N3 asymmetric stretch region can be most likely explained by very strong Fermi resonances with the CN stretch and combinations and overtones of the numerous lower-frequency vibrational modes.