Synthetic, structural and magnetic implications of introducing 2,2’-dipyridylamide to sodium-ferrate complexes

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Maddock, Lewis Caradoc Huw and Borliovic, Ivana and McIntyre, Jamie and Kennedy, Alan R. and Aromi, Guilem and Hevia, Eva (2017) Synthetic, structural and magnetic implications of introducing 2,2’-dipyridylamide to sodium-ferrate complexes. Dalton Transactions. ISSN 1477-9226 (https://doi.org/10.1039/C7DT01319A)

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Abstract

Using a transamination approach to access novel Fe(II) complexes, this study presents the synthesis, X-ray crystallographic and magnetic characterisation of a series of new iron complexes containing the multifunctional 2,2-dipyridylamide (DPA) ligand using iron bis(amide) [{Fe(HMDS)2}2] and sodium ferrate [{NaFe(HMDS)3}∞] (1) as precursors (HMDS = 1,1,1,3,3,3-hexamethyldisilazide). Reactions of DPA(H) with 1 show exceptionally good stoichiometric control, allowing access to heteroleptic [(THF)2·NaFe(DPA)(HMDS)2] (3) and homoleptic [{THF·NaFe(DPA)3}∞] (4) by using 1 and 3 equivalents of DPA(H) respectively. Linking this methodology and co-complexation, which is a more widely used approach to prepare heterobimetallic complexes, 3 can also be prepared by combining NaHMDS with heteroleptic [{Fe(DPA)(HMDS)}2] (2). In turn, 2 has been also synthesised and structurally defined by reacting [{Fe(HMDS)2}2] with two equivalents of DPA(H). Structural studies demonstrate the coordination flexibility of the N-bridged bis(heterocycle) ligand DPA, with 2 and 3 exhibiting discrete monomeric motifs, whereas 4 displays a much more intricate supramolecular structure, with one of its DPA ligands coordinating in an anti/anti fashion (as opposed to 2 and 3 where DPA shows a syn/syn conformation), which facilitates propagation of the structure via its central amido N. Magnetic studies confirmed the high-spin electron configuration of the iron(II) centres in all three compounds and revealed the existence of weak ferromagnetic interactions in dinuclear compound 2 (J = 1.01 cm-1).

ORCID iDs

Maddock, Lewis Caradoc Huw ORCID logoORCID: https://orcid.org/0000-0001-7446-6565, Borliovic, Ivana, McIntyre, Jamie ORCID logoORCID: https://orcid.org/0000-0002-4425-9917, Kennedy, Alan R. ORCID logoORCID: https://orcid.org/0000-0003-3652-6015, Aromi, Guilem and Hevia, Eva ORCID logoORCID: https://orcid.org/0000-0002-3998-7506;
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