A complete map of the ion chemistry of the naphthalene radical cation? DFT and RRKM modeling of a complex potential energy surface.

摘要: The fragmentation mechanisms of the naphthalene molecular ion to [M–C4H2]+•, [M–C2H2]+•, [M–H2]+•, and [M–H•]+ were obtained at UB3LYP/6-311+G(3df,2p)//UB3LYP/6-31G(d) level theory subsequently used calculate microcanonical rate constants, k(E)’s, for all steps by Rice-Ramsperger-Kassel-Marcus formalism. pre-equilibrium steady state approximations applied on different regions potential energy profiles obtain k(E)’s relative abundances ions as a function energy. These results reproduce acceptably well imaging photoelectron-photoion coincidence spectra naphthalene, in photon-energy range 14.0–18.8 eV that was previously reported our group. Prior dissociation, rapidly equilibrates with set isomers includes Z- E-phenylvinylacetylene (PVA) radical cations. is predominant isomer below 10 internal energy, other remaining concentrations. Later on, new steady-state intermediates are formed, such azulene 1-phenyl-butatriene does not eject an H atom directly but eliminates H2 molecule two-step fragmentation. H• loss occurs instead from ion. PVA initiate ejection diacetylene (C4H2) yield benzene cation. Acetylene elimination yields pentalene cation low energies (where it can account 45.9%–100.0% constant this channel), three-step mechanism starting However, above 7.6 eV, major [M–C2H2]+• structure phenylacetylene