Redetermination of the crystal structure of bis-(tri-2-pyridyl-amine)-iron(II) bis-(perchlorate), and a new refinement of the isotypic nickel(II) analogue: treatment of the perchlorate anion disorder.

Zouaoui Setifi,Necmi Dege,Christopher Glidewell,Rafika El Ati,Fatima Setifi

doi:10.1107/s2056989018005601

Abstract

The redetermination of the structure of the title compound, [Fe(C15H12N4)2](ClO4)2, (I), confirms the structure previously reported [Kucharski et al. (1978a ▸). Aust. J. Chem. 31, 53-56], but models the perchlorate over four sets of atomic sites, rather than using just one set of sites as in the original report. The supra-molecular assembly, not reported previously, takes the form of a complex three-dimensional framework built from C-H⋯O hydrogen bonds. The isotypic nickel(II) analogue, [Ni(C15H12N4)2](ClO4)2, (III), has been refined using the original data set [Wang et al. (2011 ▸). Acta Cryst. E67, m78], again using a four-component disorder model for the anion, rather than a two-component model as in the original report, leading to more satisfactory Cl-O distances and O-Cl-O angles.

Highlights

The redetermination of the structure of the title compound, [Fe(C15H12N4)2](ClO4)2, (I), confirms the structure previously reported [Kucharski et al (1978a)
The crystal structure of bis(tri-2-pyridylamine)iron(II) bis(perchlorate) was reported a number of years ago (Kucharski et al, 1978a), as was that of the isotypic CoII analogue (Kucharski et al, 1978b). In each of these structures, the metal centre lies at a centre of inversion, with a single perchlorate anion occupying a general position: the metal–N distances are consistent with a low-spin configuration in the FeII complex, but a high-spin configuration in the CoII complex (Kucharski et al, 1978a,b)
In each structure the unique perchlorate anion was modelled using a single set of atomic sites, but the anisotropic displacement parameters give a clear indication of unmodelled disorder in this species

Summary

Chemical context

The crystal structure of bis(tri-2-pyridylamine)iron(II) bis(perchlorate) was reported a number of years ago (Kucharski et al, 1978a), as was that of the isotypic CoII analogue (Kucharski et al, 1978b). The NiII analogue (III) is isotypic with compounds (I) and (II), in this case the refinement was conducted (Wang et al, 2011) in space group P21/n rather than in the alternative P21/a setting used for (I) and (II) (Kucharski et al, 1978a,b) In their refinement of the Ni complex, the perchlorate anion was modelled using two sets of atomic sites, having occupancies 0.528 (19) and 0.472 (19). When the refinement used only a single set of atomic sites for the perchlorate anion, this resulted in very large, prolate displacement ellipsoids for the O atoms, indicative of positional disorder This anion was modelled using, in succession, two, three or four sets of atomic sites and only for the last could the anisotropic displacement parameters be regarded as satisfactory: the final refined values of the occupancies are 0.415 (3), 0.267 (3), 0.256 (3) and 0.061 (3) (Fig. 1). It is interesting to note that no C—HÁ Á ÁO hydrogen bonds were mentioned in the original report on (I) (Kucharski et al, 1978a), possibly because only a decade or so earlier, the very idea of such interactions had been authoritatively dismissed (Donohue, 1968): perhaps more surprising is the absence of any mention of these interactions in the original report on compound (III) (Wang et al, 2011)

Supramolecular features

Synthesis and crystallization

Refinement