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Interpretation of EXAFS spectra for sitting-atop complexes with the help of computational methods

Hsiao, Ya-Wen LU and Ryde, Ulf LU orcid (2006) In Inorganica Chimica Acta 359(4). p.1081-1092
Abstract
The metallation of tetrapyrroles is believed to proceed via a sitting-atop (SAT) complex, in which some of the pyrrole nitrogen atoms are protonated and the metal ion resides above the ring plane. No crystal structure of such a complex has been presented, but NMR and EXAFS (extended X-ray absorption fine structure) data has been reported for Cu2+ in acetonitrile, which have been interpreted as the observation of a SAT complex. However, this interpretation has been challenged and other investigations have shown that there are many possible SAT structures. We have recently developed a method to combine quantum mechanical (QM) calculations and EXAFS fits (EXAFS/QM), which in principle is a standard EXAFS fit that employs all... (More)
The metallation of tetrapyrroles is believed to proceed via a sitting-atop (SAT) complex, in which some of the pyrrole nitrogen atoms are protonated and the metal ion resides above the ring plane. No crystal structure of such a complex has been presented, but NMR and EXAFS (extended X-ray absorption fine structure) data has been reported for Cu2+ in acetonitrile, which have been interpreted as the observation of a SAT complex. However, this interpretation has been challenged and other investigations have shown that there are many possible SAT structures. We have recently developed a method to combine quantum mechanical (QM) calculations and EXAFS fits (EXAFS/QM), which in principle is a standard EXAFS fit that employs all multiple-scattering information in an optimum and self-consistent way and uses the QM calculations to ensure that the obtained structures are chemically reasonable. By this approach, we show that out of the 15 putative SAT complexes, structures with the copper ion coordinating to two cis pyrrolenine nitrogen atoms and two or three acetonitrile molecules fit the experimental EXAFS spectrum best. However, an equally good fit can be obtained also by a mixture of the reactant and product complexes. (c) 2005 Elsevier B.V. All rights reserved. (Less)
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author
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organization
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type
Contribution to journal
publication status
published
subject
keywords
theory, Debye-Waller factors, density functional, ligand exchange, haem, sitting-atop complex, EXAFS
in
Inorganica Chimica Acta
volume
359
issue
4
pages
1081 - 1092
publisher
Elsevier
external identifiers
  • wos:000235753800008
  • scopus:32544451640
ISSN
0020-1693
DOI
10.1016/j.ica.2005.11.036
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)
id
1eb29dae-ae9d-427c-bc61-c9864a30e772 (old id 416757)
date added to LUP
2016-04-01 15:49:15
date last changed
2021-10-06 05:53:40
@article{1eb29dae-ae9d-427c-bc61-c9864a30e772,
  abstract     = {The metallation of tetrapyrroles is believed to proceed via a sitting-atop (SAT) complex, in which some of the pyrrole nitrogen atoms are protonated and the metal ion resides above the ring plane. No crystal structure of such a complex has been presented, but NMR and EXAFS (extended X-ray absorption fine structure) data has been reported for Cu2+ in acetonitrile, which have been interpreted as the observation of a SAT complex. However, this interpretation has been challenged and other investigations have shown that there are many possible SAT structures. We have recently developed a method to combine quantum mechanical (QM) calculations and EXAFS fits (EXAFS/QM), which in principle is a standard EXAFS fit that employs all multiple-scattering information in an optimum and self-consistent way and uses the QM calculations to ensure that the obtained structures are chemically reasonable. By this approach, we show that out of the 15 putative SAT complexes, structures with the copper ion coordinating to two cis pyrrolenine nitrogen atoms and two or three acetonitrile molecules fit the experimental EXAFS spectrum best. However, an equally good fit can be obtained also by a mixture of the reactant and product complexes. (c) 2005 Elsevier B.V. All rights reserved.},
  author       = {Hsiao, Ya-Wen and Ryde, Ulf},
  issn         = {0020-1693},
  language     = {eng},
  number       = {4},
  pages        = {1081--1092},
  publisher    = {Elsevier},
  series       = {Inorganica Chimica Acta},
  title        = {Interpretation of EXAFS spectra for sitting-atop complexes with the help of computational methods},
  url          = {http://dx.doi.org/10.1016/j.ica.2005.11.036},
  doi          = {10.1016/j.ica.2005.11.036},
  volume       = {359},
  year         = {2006},
}