Jump to main content
Jump to site search

Issue 19, 2014
Previous Article Next Article

Halogen-bonding in a new family of tris(haloanilato)metallate(III) magnetic molecular building blocks

Author affiliations


Here we report on new tris(haloanilato)metallate(III) complexes with general formula [A]3[M(X2An)3] (A = (n-Bu)4N+, (Ph)4P+; M = Cr(III), Fe(III); X2An = 3,6-dihalo derivatives of 2,5-dihydroxybenzoquinone (H4C6O4), chloranilate (Cl2An2−), bromanilate (Br2An2−) and iodanilate (I2An2−)), obtained by a general synthetic strategy, and their full characterization. The crystal structures of these Fe(III) and Cr(III) haloanilate complexes consist of anions formed by homoleptic complexes formulated as [M(X2An)3]3− and (Et)3NH+, (n-Bu)4N+, or (Ph4)P+ cations. All complexes exhibit octahedral coordination geometry with metal ions surrounded by six oxygen atoms from three chelate ligands. These complexes are chiral according to the metal coordination of three bidentate ligands, and both Λ and Δ enantiomers are present in their crystal lattice. The packing of [(n-Bu)4N]3[Cr(I2An)3] (5a) shows that the complexes form supramolecular dimers that are held together by two symmetry related I⋯O interactions (3.092(8) Å), considerably shorter than the sum of iodine and oxygen van der Waals radii (3.50 Å). The I⋯O interaction can be regarded as a halogen bond (XB), where the iodine behaves as the XB donor and the oxygen atom as the XB acceptor. This is in agreement with the properties of the electrostatic potential for [Cr(I2An)3]3− that predicts a negative charge accumulation on the peripheral oxygen atoms and a positive charge accumulation on the iodine. The magnetic behaviour of all complexes, except 5a, may be explained by considering a set of paramagnetic non-interacting Fe(III) or Cr(III) ions, taking into account the zero-field splitting effect. The presence of strong XB interactions in 5a are able, instead, to promote antiferromagnetic interactions among paramagnetic centers at low temperature, as shown by the fit with the Curie–Weiss law, in agreement with the formation of halogen-bonded supramolecular dimers.

Graphical abstract: Halogen-bonding in a new family of tris(haloanilato)metallate(iii) magnetic molecular building blocks

Back to tab navigation

Supplementary files

Publication details

The article was received on 14 Jan 2014, accepted on 05 Feb 2014 and first published on 06 Feb 2014

Article type: Paper
DOI: 10.1039/C4DT00127C
Author version available: Download Author version (PDF)
Citation: Dalton Trans., 2014,43, 7006-7019
  •   Request permissions

    Halogen-bonding in a new family of tris(haloanilato)metallate(III) magnetic molecular building blocks

    M. Atzori, F. Artizzu, E. Sessini, L. Marchiò, D. Loche, A. Serpe, P. Deplano, G. Concas, F. Pop, N. Avarvari and M. Laura Mercuri, Dalton Trans., 2014, 43, 7006
    DOI: 10.1039/C4DT00127C

Search articles by author