Document Type

Article

Publication Date

2018

Publication Title

Acta Crystallographica Section C: Structural Chemistry

Volume

C

Issue

74

Pages

1641-1649

Abstract

Treatment of the ortho-tri­aza­cyclo­phane 1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-triene [(C6H5)3(NH)(NCH3)2, L1] with Fe[N(SiMe3)2]2 yields the dimeric iron(II) complex bis­(μ-1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-trien-7-ido)bis­[(μ-1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-trien-7-ido)iron(II)], [Fe(C20H18N3)4] or Fe2(L1)4 (9). Dissolution of 9 in tetra­hydro­furan (THF) results in solvation by two THF ligands and the formation of a simpler monoiron complex, namely bis­(μ-1,4-di­methyl­tribenzo[b,e,h][1,4,7]tri­aza­cyclo­nona-2,5,8-trien-7-ido-κN7)bis­(tetra­hydro­furan-κO)iron(II), [Fe(C20H18N3)2(C4H8O)2] or (L1)2Fe(THF)2 (10). The reaction is reversible and 10 reverts in vacuo to diiron complex 9. In the structures of both 9 and 10, the monoanionic tri­aza­cyclo­phane ligand L1 is observed in only the less-symmetric saddle conformation. No bowl-shaped crown conformers are observed in the solid state, thus preventing chelating κ3-coordination to the metal as had been proposed earlier based on density functional theory (DFT) calculations. Instead, the L1 ligands are bound in either a η2-chelating fashion through the amide and one amine donor (for one of the four ligands of 9), or solely through their amide N atoms in an even simpler monodentate η1-coordination mode. Density functional calculations on dimer 9 revealed nearly full cationic charges on each Fe atom and no bonding inter­action between the two metal centers, consistent with the relatively long FeFe distance of 2.912 (1) Å observed in the solid state.

Comments

Author Posting. © International Union of Crystallography 2018. This article is posted here by permission of the International Union of Crystallography for personal use, not for redistribution. The article was published in Acta Crystallographica Section C, 2018, https://doi.org/10.1107/S2053229618015255.

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