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          Institute: MPI für bioanorganische Chemie     Collection: MPI für bioanorganische Chemie     Display Documents

ID: 712829.0, MPI für bioanorganische Chemie / MPI für bioanorganische Chemie
Calcium and heterometallic manganese-calcium complexes supported by tripodal pyridine-carboxylate ligands: structural, EPR and theoretical investigations
Authors:Gerey, Bertrand; Gennari, Marcello; Goure, Eric; Pecaut, Jacques; Blackman, Allan; Pantazis, Dimitrios A.; Neese, Frank; Molton, Florian; Fortage, Jerome; Duboc, Carole; Collomb, Marie-Noelle
Date of Publication (YYYY-MM-DD):2015
Title of Journal:Dalton Transactions
Journal Abbrev.:Dalton Trans.
Issue / Number:28
Start Page:12757
End Page:12770
Review Status:Internal review
Audience:Experts Only
Abstract / Description:Carboxylate-bridged Mn(II)-Ca(II) complexes are potentially relevant for mimicking the first stages of the Oxygen-Evolving Complex (OEC) assembly process. Here, we report on new homonuclear Ca(II) and heteronuclear Mn(II)-Ca(II) complexes with carboxylate-functionalized tripodal tris(2-pyridylmethyl) amine ligands, the heptadentate H(3)tpaa, previously reported, and the new hexadentate H(2)tpada, containing respectively three and two carboxylate units. The mononuclear [Ca(Htpaa)(OH2)] (Ca-1) and dinuclear [Ca(tpada)(OH2)(2)](2) (Ca-2) calcium complexes, as well as the tetranuclear [{Mn(tpaa)}(2){Ca(OH2)(5)(mu-OH2)}(2)]-[ Mn(tpaa)](2) (Mn2Ca2 center dot 2Mn) and dinuclear [Mn(tpada) ClCa(OH2)(2.67)(MeOH)(2.33)] Cl (MnCa) heterometallic species have been structurally characterized; the syntheses of Ca1 and Mn2Ca2 center dot 2Mn being previously reported by us (Inorg. Chem., 2015, 54, 1283). The Mn(II) and Ca(II) are linked by two mu(1,1)-bridging carboxylates in MnCa, while only one mu(1,3)-carboxylate bridge connects each Ca2+ ion to each Mn(II) in Mn2Ca2. A variable number of water molecules (n = 1 to 7) are coordinated to Ca in all complexes, most of them being involved in hydrogen-bond networks, in analogy to what occurs in the photosystem II. All donor atoms of the tpaa(3-) and tpada(2-) ligands are coordinated to the Mn2+ ions, despite the unusually long distance between the Mn2+ ion and the tertiary amine imposed by the constraining nature of the ligands, as supported by theoretical calculations. Solid state EPR spectroscopy, in combination with DFT calculations, has also shown that the Ca2+ ion has an effect on the electronic parameters (zero field splitting) of the linked Mn(II) in the case of MnCa (mu(1,1)-carboxylate bridges). In Mn2Ca2 (mu(1,3)-carboxylate bridge) the Ca2+ ion induces only slight structural changes in the Mn coordination sphere.
Comment of the Author/Creator:Date: 2015, 2015
External Publication Status:published
Document Type:Article
Version Comment:Automatic journal name synchronization
Communicated by:N. N.
Affiliations:MPI für bioanorganische Chemie
External Affiliations:[Gerey,B.; Gennari,M.; Goure,E.; Molton,F.; Fortage,J.; Duboc,C.] Univ Grenoble Alpes, DCM UMR 5250, F-38000 Grenoble, France.
[Pecaut,J. ] Univ Grenoble Alpes, INAC SCIB, F-38000 Grenoble, France.
[Blackman,A.] Auckland Univ Technol, Sch Appl Sci, Auckland 1142, New Zealand.
Identifiers:ISI:000357899600038 [ID No:1]
ISSN:1477-9226 [ID No:2]
DOI:10.1039/c5dt01776a [ID No:3]
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