Three new tellurite halides with unusual Te 4+ coordinations and iron honeycomb lattice variants

Abstract

The crystal structure of three new iron and copper-iron tellurite halides are presented; ( I) Cu 3Fe 8Te 12O 32Cl 10 that crystallizes in the orthorhombic space group Pmmn, ( II) Fe 8Te 12O 32Cl 3Br 3 that crystallizes in the monoclinic space group P2 1/ c, and ( III) Fe 5(TeO 3) 6Cl 2 that crystallizes in the triclinic space group P-1. The crystal structures were solved from single crystal X-ray diffraction data. All three compounds have layered crystal structures where the Fe atoms form variants of the honeycomb lattice. Highly unusual Te 4+ coordination polyhedra are exemplified: [TeO 3+1 E], [TeO 3 XE], [TeO 3+1 XE], and [TeO 3 X 2 E] ( X=halide ion, E=the lone–pair valence electrons). The crystal structures contain large non-bonding volumes occupied by the stereochemically active lone–pair electrons on Te 4+.