Synthesis and Crystal Structure of Tris[1-(2-azoyl)-2-azabuten-4-yl]amineiron(III), [Fe((pyrol)₃tren)]


The low-spin iron(III) complex with the Schiff base formed from 2,2′,2″-tris(ethylamino)amine (tren) and pyrrole has been synthesized and its crystal and molecular structures have been determined. Although the ligand is potentially a heptadentate, the complex contains six strong iron-nitrogen bonds, while the distance between the metal atom and the apical nitrogen N(10), the potential seventh donor, is 3.304 (1) Å, which approximates the van der Waals contact distance. The crystallographic symmetry imposes a precise threefold axis (C3) on the molecule through the iron atom and the apical nitrogen N(10). The ligand environment about the metal is a trigonally distorted octahedron, with three upper (pointing toward N(10)) Fe-N bonds of 1.989 (1) Å and three lower Fe-N bonds of 1.936 (1) Å. From comparison with literature data on other ligands, ring substitution at the pyrrole of (pyrol)3tren should lead to neutral high-spin and spin-state crossover complexes; the [Fe((pyrol)3tren)] complex is a good model for the low-spin extreme of such a series. Crystal data: space group I43d, a = 20.058 (4) Å, V = 8069 Å3, R = 2.5% for 526 reflections. Full-matrix least-squares refinement converged with a conventional R factor of 2.5%. © 1978 American Chemical Society.



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© 1978 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Jan 1978