Iron-Promoted Nucleophilic Additions to Diimine-Type Ligands: A Synthetic and Structural Study

Vallina, Ana Tesouro; Stoeckli-Evans, Helen; Neels, Antonia; Ensling, Jürgen; Decurtins, Silvio (2003). Iron-Promoted Nucleophilic Additions to Diimine-Type Ligands: A Synthetic and Structural Study. Inorganic chemistry, 42(10), pp. 3374-3382. American Chemical Society 10.1021/ic026079l

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We report here three examples of the reactivity of protic nucleophiles with diimine-type ligands in the presence of FeII salts. In the first case, the iron-promoted alcoholysis reaction of one nitrile group of the ligand 2,3-dicyano-5,6-bis(2-pyridyl)-pyrazine (L1) permitted the isolation of an stable E-imido−ester, [Fe(L1‘)2](CF3SO3)2 (1), which has been characterized by spectroscopic studies (IR, ES-MS, Mössbauer), elemental analysis, and crystallographically. Compound 1 consists of mononuclear octahedrally coordinated FeII complexes where the FeII ion is in its low-spin state. The iron-mediated nucleophilic attack of water to the asymmetric ligand 2,3-bis(2-pyridyl)pyrido[3,4-b]pyrazine (L2) has also been studied. In this context, the crystal structures of two hydration−oxidation FeIII products, [Fe(L2‘)2](ClO4)3·3CH3CN (2) and trans-[FeL2‘‘Cl2] (3), are described. Compounds 2 and 3 are both mononuclear FeIII complexes where the metals occupy octahedral positions. In principle, L2 is expected to coordinate to metal ions through its bipyridine-type units to form a five-membered ring; however, this is not the case in compounds 2 and 3. In 2, the ligand coordinates through its pyridines and through the hydroxyl group attached to the pyrazine imino carbon after hydration, that is, in an N,O,N tridentate manner. In compound 3, the ligand has suffered further transformations leading to a very stable diamido complex. In this case, the metal ion achieves its octahedral geometry by means of two pyridines, two amido N atoms, and two axial chlorine atoms. Magnetic susceptibility measurements confirmed the spin state of these two FeIII species:  compounds 2 and 3 are low-spin and high-spin, respectively.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Neels, Antonia and Decurtins, Silvio

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

0020-1669

Publisher:

American Chemical Society

Language:

English

Submitter:

Silvio Decurtins

Date Deposited:

20 May 2015 10:16

Last Modified:

21 May 2015 20:56

Publisher DOI:

10.1021/ic026079l

BORIS DOI:

10.7892/boris.68532

URI:

https://boris.unibe.ch/id/eprint/68532

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