György Tarczay, Terry A. Miller, Gábor Czakó and Attila G. Császár

Phys. Chem. Chem. Phys., 2005, 7, 2881, DOI: 10.1039/b506790a. Amendment published 15th May 2008

Since the publication of our paper, the following misprints, errors, and misrepresentations of the computed results came to our attention, listed in the order of their occurrence:

(1) In the caption to Table 1 the correct level of theory used for the geometry optimization is CCSD(T)/aug-cc-pCVTZ instead of CCSD(T)/aug-cc-pCVQZ.

(2) In the last line in Table 1 the correct structural parameter is r_HC instead of r_HCl.

(3) The extrapolated CBS values reported in Table 8 were obtained by the use of the two-parameter eqn (2) and the extrapolation was performed by fitting the three available energies. For CCl₂, in the case of the extrapolation of the MP2 correlation energy, in the formulas (X + 1) has been used incorrectly instead of X. Furthermore, it is slightly preferable to use only two energies obtained with the two largest basis sets. The corrected CBS {ΔMP2, ΔΔE_TS(CC)} values for CCl₂ are {−160, −192} cm⁻¹ instead of the originally reported {−143, −176} cm⁻¹. The CBS {ΔMP2, ΔΔETS(CC)} values determined for HCCl using the best two energies are {−147, −164} cm⁻¹ instead of the originally reported {−120, −146} cm⁻¹. The new core correlation corrections change the computed triplet-singlet energy gap for CCl₂ and HCCl to 7029 ± 60 cm⁻¹ (previously 7045 ± 60 cm⁻¹) and 2152 ± 40 cm⁻¹ (previously 2170 ± 40 cm⁻¹), respectively.

(4) In Tables 10 and 12 the labels of the v₂ and v₃ modes of the state of HCCl should be reversed throughout.

(5) In Section V.2, the first sentence of the second paragraph correctly reads as follows (the part printed in bold here was missing in the original text):

(6) In Table 17 some of the entries have been incorrectly reported. These are replaced with the correct, boldface entries in the table below.

Finally, since it has been possible to perform larger electronic structure computations than those reported in the original article, a new focal-point analysis (FPA) of the computed results could be executed for both species.

Most importantly, all previous electronic structure computations have been repeated at new reference structures optimized at the frozen-core aug-cc-pV(Q+d)Z CCSD(T) level. The new computations utilized the aug-cc-pV(6+d)Z basis sets (585 contracted Gaussian functions for CCl₂) up to the CCSD(T) level of theory, aug-cc-pV(T+d)Z CCSDT(Q) results have been added, and all FPA computations have also been performed for the ground electronic state of Cl₂.

Using the new electronic energies, the reactions ¹CH₂ + 2 HCl → ¹CCl₂ + 2 H₂ and ¹CH₂ + Cl₂ → ¹CCl₂ + H₂, the auxiliary data of the original article and, taking the average of the two new results, the enthalpy of formation of ¹CCl₂ is computed to be 54.11 kcal mol⁻¹ at 0 K. Using the new electronic energies, the reactions ¹CH₂ + HCl → ¹HCCl + H₂, ¹CH₂ + Cl₂ → ¹HCCl + HCl, and 2 ¹CH₂ + Cl₂ → 2 ¹HCCl + H₂, the auxiliary data of the original article and, taking the average of the three new results, the enthalpy of formation of ¹HCCl is computed to be 76.14 kcal mol⁻¹ at 0 K. (Please contact the authors for details concerning the new FPA analysis.)

Taking into consideration an improved estimate of the enthalpy of formation of C_gas (as reported in G. Tasi, R. Izsák, G. Matisz, A. G. Császár, M. Kállay, B. Ruscic, and J. F. Stanton, Chem. Phys. Chem., 2006, 7, 1664), the best ab initio estimate of the above table on the enthalpy of formation of ¹CH₂ is increased by 0.13 kcal mol⁻¹ to 102.45 kcal mol⁻¹. The best estimates from this study of the 0 K enthalpies of formation of ¹HCCl and ¹CCl₂ will be changed to 54.24 ± 0.20 and 76.27 ± 0.20 kcal mol⁻¹.

These values, slightly different from the ones reported in the original publication, are considered to be the best computational estimates for the enthalpies of formation of ¹CCl₂ and ¹HCCl available today.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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