REACTIVITY TREND LICENSE

REACTIVITY TREND LICENSE

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Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. Burns in aspects of the experiment.Ĭomputational chemistry, distonic, gas-phase, ion-trap mass spectrometry, kinetics, laser photolysis, PAH formation, radical cationĬurrent > Research Centres > Centre for Materials ScienceĬurrent > QUT Faculties and Divisions > Faculty of ScienceĬurrent > Schools > School of Chemistry & PhysicsĢ021 American Society for Mass Spectrometry We are also grateful for the assistance of A. acknowledge receipt of an Australian Government Research Training Program Scholarship. The authors also acknowledge the generous allocation of computing resources by the National Computational Infrastructure National Facility (Canberra, ACT, Australia) under the Merit Allocation Scheme. Furthermore, a review of the overall reaction patterns presented in this table discloses only a broad and rather non-specific set of reactivity trends. This work was supported by computational resources provided by the Australian Government through the National Computation Infrastructure under the National Computational Merit Allocation Scheme. The least reactive species 1a mes and 1a PhF show a marked stabilization as reflected in isoenergetic or endergonic, relative protonation free-energies ( G prot 0.2 and +19.7 kcal mol 1, respectively). acknowledge project funding from the Australian Research Council Discovery Program (DP170101596). The reactivity trend is inversely correlated to the stability of the -monoboryl carbanions. The rate coefficient trend can be rationalized by a simple model based on the prereactive complex forward barrier height.įunding Information: A.J.T., S.J.B., and G.d.S. The G3X-K method guides the assignment of product ions following adduct formation. Quantum chemical calculations, using M06-2X-D3(0)/6-31++G(2df,p) geometries and DSD-PBEP86-NL/aug-cc-pVQZ energies, are deployed to rationalize reactivity trends based on the stability of prereactive complexes. The second-order rate coefficients can be sorted into three groups: low, between 1 and 3 × 10-12 cm3 molecule-1 s-1 (3Anl and 4Anl) intermediate, between 5 and 15 × 10-12 cm3 molecule-1 s-1 (2Bzn, 3Bzn, and 4Bzn) and high, between 8 and 31 × 10-11 cm3 molecule-1 s-1 (2Anl, 2Pyr, 3Pyr, and 4Pyr) and 2Anl is the only radical cation with a rate coefficient distinctly different from its isomers. The rate coefficients increase from para to ortho positions. Using a room temperature ion trap, second-order rate coefficients, product branching ratios, and reaction efficiencies are measured. Three isomers are studied in each case (radical sites at the ortho, meta, and para positions). This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl), and benzonitrilium (Bzn) ions. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. A similar process can happen for N-containing aromatics.

The reason, once more, is that the polarising power of the M 2+ decreases as ionic radius increases.A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. The thermal stability of the nitrates follows the same trend as that of the carbonates, with thermal stability increasing with proton number. This means that beryllium carbonate decomposes at a lower temperature to the rest of the group. The greater the distortion caused by the polarising ion the less stable the compound is to heat. Hence polarising ability of the M 2+ ion decreases down the group. The larger the anion the easier the distortion, as seen with the carbonate ion. Small highly charged positive ions distort the electron cloud of the anion. This trend is explained in terms of the Group II metal ions ability to polarise the anion, the carbonate ion. Beryllium carbonate decomposing most easily. The thermal stability of Group II carbonates increases as we descend the group. Thermal stability of carbonates and nitrates Carbonates

Reactivity trend