Electron donor-acceptor properties of porphyrins, phthalocyanines, and related ring chelates

A molecular orbital approach

C. Fierro, Alfred B. Anderson, Daniel Alberto Scherson

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

Tetraazaporphyrin is used as a primitive fragment to examine theoretically the electron donor-acceptor properties of a variety of highly conjugated planar ligands of the porphyrin and phthalocyanine type. Calculations employing the atom superposition electron delocalization MO theory indicate that for iron macrocycles the energy gap between the occupied dxz, dyz orbitals and the empty eg(π*) ring orbitals plays a key role in controlling the extent of metal to ring back-bonding. This provides a framework for a rational search of structural modifications of chelating ligands that may afford an optimized activation of axially coordinated π electron acceptor molecules such as dioxygen, nitric oxide, and carbon monoxide. The higher reactivity of iron(II) porphyrins toward such π acceptor species, compared to iron(II) phthalocyanine, is attributed to the longer Me-N bond length in the porphyrins, which leads to less metal to ligand back-bonding and thus to more electron charge at the metal center.

Original languageEnglish
Pages (from-to)6902-6907
Number of pages6
JournalJournal of physical chemistry
Volume92
Issue number24
DOIs
Publication statusPublished - 1988 Jan 1
Externally publishedYes

Fingerprint

Porphyrins
Molecular orbitals
chelates
porphyrins
molecular orbitals
Iron
Electrons
Metals
rings
Ligands
iron
ligands
electrons
metals
orbitals
Nitric oxide
Bond length
Carbon Monoxide
nitric oxide
Chelation

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

Cite this

Electron donor-acceptor properties of porphyrins, phthalocyanines, and related ring chelates : A molecular orbital approach. / Fierro, C.; Anderson, Alfred B.; Scherson, Daniel Alberto.

In: Journal of physical chemistry, Vol. 92, No. 24, 01.01.1988, p. 6902-6907.

Research output: Contribution to journalArticle

@article{f650932bed684e1a8bbb0024cdfabcae,
title = "Electron donor-acceptor properties of porphyrins, phthalocyanines, and related ring chelates: A molecular orbital approach",
abstract = "Tetraazaporphyrin is used as a primitive fragment to examine theoretically the electron donor-acceptor properties of a variety of highly conjugated planar ligands of the porphyrin and phthalocyanine type. Calculations employing the atom superposition electron delocalization MO theory indicate that for iron macrocycles the energy gap between the occupied dxz, dyz orbitals and the empty eg(π*) ring orbitals plays a key role in controlling the extent of metal to ring back-bonding. This provides a framework for a rational search of structural modifications of chelating ligands that may afford an optimized activation of axially coordinated π electron acceptor molecules such as dioxygen, nitric oxide, and carbon monoxide. The higher reactivity of iron(II) porphyrins toward such π acceptor species, compared to iron(II) phthalocyanine, is attributed to the longer Me-N bond length in the porphyrins, which leads to less metal to ligand back-bonding and thus to more electron charge at the metal center.",
author = "C. Fierro and Anderson, {Alfred B.} and Scherson, {Daniel Alberto}",
year = "1988",
month = "1",
day = "1",
doi = "10.1021/j100335a013",
language = "English",
volume = "92",
pages = "6902--6907",
journal = "Journal of Physical Chemistry",
issn = "0022-3654",
publisher = "American Chemical Society",
number = "24",

}

TY - JOUR

T1 - Electron donor-acceptor properties of porphyrins, phthalocyanines, and related ring chelates

T2 - A molecular orbital approach

AU - Fierro, C.

AU - Anderson, Alfred B.

AU - Scherson, Daniel Alberto

PY - 1988/1/1

Y1 - 1988/1/1

N2 - Tetraazaporphyrin is used as a primitive fragment to examine theoretically the electron donor-acceptor properties of a variety of highly conjugated planar ligands of the porphyrin and phthalocyanine type. Calculations employing the atom superposition electron delocalization MO theory indicate that for iron macrocycles the energy gap between the occupied dxz, dyz orbitals and the empty eg(π*) ring orbitals plays a key role in controlling the extent of metal to ring back-bonding. This provides a framework for a rational search of structural modifications of chelating ligands that may afford an optimized activation of axially coordinated π electron acceptor molecules such as dioxygen, nitric oxide, and carbon monoxide. The higher reactivity of iron(II) porphyrins toward such π acceptor species, compared to iron(II) phthalocyanine, is attributed to the longer Me-N bond length in the porphyrins, which leads to less metal to ligand back-bonding and thus to more electron charge at the metal center.

AB - Tetraazaporphyrin is used as a primitive fragment to examine theoretically the electron donor-acceptor properties of a variety of highly conjugated planar ligands of the porphyrin and phthalocyanine type. Calculations employing the atom superposition electron delocalization MO theory indicate that for iron macrocycles the energy gap between the occupied dxz, dyz orbitals and the empty eg(π*) ring orbitals plays a key role in controlling the extent of metal to ring back-bonding. This provides a framework for a rational search of structural modifications of chelating ligands that may afford an optimized activation of axially coordinated π electron acceptor molecules such as dioxygen, nitric oxide, and carbon monoxide. The higher reactivity of iron(II) porphyrins toward such π acceptor species, compared to iron(II) phthalocyanine, is attributed to the longer Me-N bond length in the porphyrins, which leads to less metal to ligand back-bonding and thus to more electron charge at the metal center.

UR - http://www.scopus.com/inward/record.url?scp=0001240950&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001240950&partnerID=8YFLogxK

U2 - 10.1021/j100335a013

DO - 10.1021/j100335a013

M3 - Article

VL - 92

SP - 6902

EP - 6907

JO - Journal of Physical Chemistry

JF - Journal of Physical Chemistry

SN - 0022-3654

IS - 24

ER -