W. R. Stevens, B. Ruscic, and T. Baer, J. Phys. Chem A 114, 13134�13145 (2010)

The Heats of Formation of C₆H₅, C₆H₅⁺, and C₆H₅NO by TPEPICO and Active Thermochemical Tables Analysis

William R. Stevens,^a Branko Ruscic,^b,c and Tomas Baer^a

^a Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27517, United States
^b Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
^c Computation Institute, University of Chicago, Chicago, Illinois 60637, United States

J. Phys. Chem. A 114(50), 13134�13145 (2010)

Threshold photoelectron photoion coincidence has been used to prepare selected internal energy distributions of nitrosobenzene ions [C₆H₅NO⁺]. Dissociation to C₆H₅⁺ + NO products was measured over a range of internal energies and rate constants from 10³ to 10⁷ s^-1 and fitted with the statistical theory of unimolecular decay. A 0 K dissociative photoionization onset energy of 10.607 � 0.020 eV was derived by using the simplified statistical adiabatic channel model. The thermochemical network of Active Thermochemical Tables (ATcT) was expanded to include phenyl and phenylium, as well as nitrosobenzene. The current ATcT heats of formation of these three species at 0 K (298.15 K) are 350.6 (337.3) � 0.6, 1148.7 (1136.8) � 1.0, and 215.6 (198.6) � 1.5 kJ mol^-1, respectively. The resulting adiabatic ionization energy of phenyl is 8.272 � 0.010 eV. The new ATcT thermochemistry for phenyl entails a 0 K (298.15 K) C-H bond dissociation enthalpy of benzene of 465.9 (472.1) � 0.6 kJ mol^-1. Several related thermochemical quantities from ATcT, including the current enthalpies of formation of benzene, monohalobenzenes, and their ions, as well as interim ATcT values for the constituent atoms, are also given.

comment:
The paper reports, inter alia, ATcT (version 1.110) enthalpies of formation (heats of formation) at 0 K (Δ_fH°₀, aka Hf0) and 298 K (Δ_fH°₂₉₈, aka Hf298), as well as total atomization energies at 0 K (TAE₀) for: phenyl (C₆H₅), phenylium (phenyl cation, C₆H₅⁺), phenide (phenyl anion, C₆H₅^-), benzene (C₆H₆), benzene cation (C₆H₆⁺), fluorobenzene (C₆H₅F), fluorobenzene cation (C₆H₅F⁺), chlorobenzene (C₆H₅Cl), chlorobenzene cation (C₆H₅Cl⁺), bromobenzene (C₆H₅Br), bromobenzene cation (C₆H₅Br⁺), iodobenzene (C₆H₅I), iodobenzene cation (C₆H₅I⁺), nitrosobenzene (C₆H₅NO), nitric oxide (NO), carbon atom (C), nitrogen atom (N), oxygen atom (O), hydrogen atom (H), fluorine atom (F), chlorine atom (Cl), bromine atom (Br), and iodine atom (I). ATcT enthalpies of formation for benzene and monohalo substituted benzenes are given both for gas phase and condensed (liquid) states. The paper also reports a number of other related ATcT thermochemical quantities, such as the bond dissociation energy of benzene and monohalo substituted benzenes, the gas phase acidity of benzene, the enthalpy of deprotonation of benzene, the ionization energy of phenyl, the electron affinity of phenyl, the ionization energies of benzene and monohalo substituted benzenes, the appearance energies (photodissociative ionization onsets) of phenylium fragment from benzene and monohalobenzenes, etc.