Redox Site Confinement in Highly Unsymmetric Dimanganese Complexes

Sheng, Tianlu; Dechert, Sebastian; Hyla-Kryspin, Isabella; Winter, Rainer F.; Meyer, Franc

Redox Site Confinement in Highly Unsymmetric Dimanganese Complexes

Dateien

Winter.pdfGröße: 439.36 KBDownloads: 387

Datum

2005

Autor:innen

Sheng, Tianlu

Dechert, Sebastian

Hyla-Kryspin, Isabella

Winter, Rainer F.

Meyer, Franc

Open Access-Veröffentlichung

Open Access Green

Sammlungen

Chemie

Publikationstyp

Zeitschriftenartikel

Publikationsstatus

Published

Erschienen in

Inorganic Chemistry. 2005, 44(11), pp. 3863-3874. ISSN 0020-1669. Available under: doi: 10.1021/ic0503683

Zusammenfassung

A set of highly preorganized pyrazolate-bridged dimanganese complexes L(Mn)MnX have been prepared and structurally characterized. They can be described as hybrid organometallic/Werner-type systems that consist of a low-spin CpMn(I)(CO)2 subunit (Mn1) and a proximate tripodal tetradentate {N4} binding pocket accommodating a high-spin Mn(II) ion (Mn2), with Mn...Mn distances of approximately 4.3 A and different coligands bound to Mn2. Density functional theory (DFT) calculations (both the hybrid B3LYP and the pure BP86 functionals and the all-electron basis sets 6-311G and 6-311G*) confirm that the valence alpha and beta Kohn-Sham molecular orbitals (MOs) of these mixed-valent Mn(I)Mn(II) compounds have predominant Mn(3d) character and an almost perfectly localized nature: all five unpaired electrons are essentially localized at the Werner-type Mn2, whereas Mn1 possesses an effective closed-shell structure with the MOs of highest energy centered there. One-electron oxidation occurs in a clean process at approximately E(1/2) = -0.6 V (versus ferrocene/ferrocinium), giving the low-spin/high-spin Mn(II)Mn(II) species. UV/vis and IR spectroelectrochemistry as well as a detailed theoretical analysis reveal that the redox process takes place with strict site control at the organometallic subunit, while it does not significantly influence the spin and charge distribution on the Werner-type site. Positions and shifts of the nu(C[triple bond]O) absorptions are largely reproduced by the DFT calculations. These systems thus represent an exceptional example of the effect the unsymmetry of a dinucleating ligand scaffold has on the spin and charge distribution in homobimetallic complexes and might offer interesting prospects for the study of the cooperative effects of bimetallic arrays.

Zusammenfassung in einer weiteren Sprache

A set of highly preorganized pyrazolate-bridged dimanganese complexes LMnMnX have been prepared and structurally characterized. They can be described as hybrid organometallic/Werner-type systems that consist of a low-spin CpMnI(CO)2 subunit (Mn1) and a proximate tripodal tetradentate {N4} binding pocket accommodating a high-spin MnII ion (Mn2), with Mn···Mn distances of 4.3 Å and different coligands bound to Mn2. Density functional theory (DFT) calculations (both the hybrid B3LYP and the pure BP86 functionals and the all-electron basis sets 6-311G and 6-311G*) confirm that the valence α and β Kohn−Sham molecular orbitals (MOs) of these mixed-valent MnIMnII compounds have predominant Mn(3d) character and an almost perfectly localized nature: all five unpaired electrons are essentially localized at the Werner-type Mn2, whereas Mn1 possesses an effective closed-shell structure with the MOs of highest energy centered there. One-electron oxidation occurs in a clean process at approximately E1/2 = −0.6 V (versus ferrocene/ferrocinium), giving the low-spin/high-spin MnIIMnII species. UV/vis and IR spectroelectrochemistry as well as a detailed theoretical analysis reveal that the redox process takes place with strict site control at the organometallic subunit, while it does not significantly influence the spin and charge distribution on the Werner-type site. Positions and shifts of the ν(CO) absorptions are largely reproduced by the DFT calculations. These systems thus represent an exceptional example of the effect the unsymmetry of a dinucleating ligand scaffold has on the spin and charge distribution in homobimetallic complexes and might offer interesting prospects for the study of the cooperative effects of bimetallic arrays.

Fachgebiet (DDC)

540 Chemie

Zitieren

ISO 690

SHENG, Tianlu, Sebastian DECHERT, Isabella HYLA-KRYSPIN, Rainer F. WINTER, Franc MEYER, 2005. Redox Site Confinement in Highly Unsymmetric Dimanganese Complexes. In: Inorganic Chemistry. 2005, 44(11), pp. 3863-3874. ISSN 0020-1669. Available under: doi: 10.1021/ic0503683

BibTex

@article{Sheng2005-05-30Redox-13805,
  year={2005},
  doi={10.1021/ic0503683},
  title={Redox Site Confinement in Highly Unsymmetric Dimanganese Complexes},
  number={11},
  volume={44},
  issn={0020-1669},
  journal={Inorganic Chemistry},
  pages={3863--3874},
  author={Sheng, Tianlu and Dechert, Sebastian and Hyla-Kryspin, Isabella and Winter, Rainer F. and Meyer, Franc}
}

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