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Theoretical prediction of the co-c bond strength in cobalamins.

Jensen, Kasper LU and Ryde, Ulf LU (2003) In The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory 107(38). p.7539-7545
Abstract
The homolytic Co-C bond dissociation energy (BDE) is central to the understanding of the function of vitamin B12, an important coenzyme of many proteins. We investigate why earlier density functional (B3LYP) estimations of the BDE in methylcobalamin have given so poor results (91-117 kJ/mol) compared to the experimental estimate (155 ± 13 kJ/mol). Improving the basis set increases the discrepancy, as does a proper treatment of basis set superposition error (~3 kJ/mol) and inclusion of zero-point energy corrections (-21 kJ/mol). On the other hand, relativistic (+6 kJ/mol), solvation (+7 kJ/mol in water), and thermal corrections (+6 kJ/mol) increase the BDE. However, neither of these corrections can explain the discrepancy. Instead, the... (More)
The homolytic Co-C bond dissociation energy (BDE) is central to the understanding of the function of vitamin B12, an important coenzyme of many proteins. We investigate why earlier density functional (B3LYP) estimations of the BDE in methylcobalamin have given so poor results (91-117 kJ/mol) compared to the experimental estimate (155 ± 13 kJ/mol). Improving the basis set increases the discrepancy, as does a proper treatment of basis set superposition error (~3 kJ/mol) and inclusion of zero-point energy corrections (-21 kJ/mol). On the other hand, relativistic (+6 kJ/mol), solvation (+7 kJ/mol in water), and thermal corrections (+6 kJ/mol) increase the BDE. However, neither of these corrections can explain the discrepancy. Instead, the problem seems to be the B3LYP density functional, which gives a corrected BDE of 78 kJ/mol, whereas the density functional Becke-Perdew-86 method and second-order perturbation theory (MP2) give BDEs of 134-139 kJ/mol. A comparison with other methods indicates that the error comes from the Hartree-Fock exchange (~40 kJ/mol) and the LYP functional (~15 kJ/mol). The problem is not restricted to methylcobalamin but seems to be general for homolytic metal-carbon BDEs of transition metals in tetra-pyrrole-like systems. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
volume
107
issue
38
pages
7539 - 7545
publisher
The American Chemical Society
external identifiers
  • wos:000185401700026
  • scopus:0141959727
ISSN
1520-5215
DOI
language
English
LU publication?
yes
id
32019212-f726-46a6-88f0-d9e8aeaf807a (old id 128729)
date added to LUP
2007-07-17 10:47:54
date last changed
2018-05-29 10:03:52
@article{32019212-f726-46a6-88f0-d9e8aeaf807a,
  abstract     = {The homolytic Co-C bond dissociation energy (BDE) is central to the understanding of the function of vitamin B12, an important coenzyme of many proteins. We investigate why earlier density functional (B3LYP) estimations of the BDE in methylcobalamin have given so poor results (91-117 kJ/mol) compared to the experimental estimate (155 ± 13 kJ/mol). Improving the basis set increases the discrepancy, as does a proper treatment of basis set superposition error (~3 kJ/mol) and inclusion of zero-point energy corrections (-21 kJ/mol). On the other hand, relativistic (+6 kJ/mol), solvation (+7 kJ/mol in water), and thermal corrections (+6 kJ/mol) increase the BDE. However, neither of these corrections can explain the discrepancy. Instead, the problem seems to be the B3LYP density functional, which gives a corrected BDE of 78 kJ/mol, whereas the density functional Becke-Perdew-86 method and second-order perturbation theory (MP2) give BDEs of 134-139 kJ/mol. A comparison with other methods indicates that the error comes from the Hartree-Fock exchange (~40 kJ/mol) and the LYP functional (~15 kJ/mol). The problem is not restricted to methylcobalamin but seems to be general for homolytic metal-carbon BDEs of transition metals in tetra-pyrrole-like systems.},
  author       = {Jensen, Kasper and Ryde, Ulf},
  issn         = {1520-5215},
  language     = {eng},
  number       = {38},
  pages        = {7539--7545},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory},
  title        = {Theoretical prediction of the co-c bond strength in cobalamins.},
  url          = {http://dx.doi.org/},
  volume       = {107},
  year         = {2003},
}