[Hg7As4I3](SnI3): Trapping the SnI31– Anion in the Cavities of the Unprecedented Mercury-Arsenic-Iodine Network

Abstract

A novel host–guest compound [Hg7As4I3](SnI3) has been prepared by a standard ampoule technique and its crystal structure was determined. It crystallizes in a cubic system [space group P213, a = 13.110(1) Å, Z = 4] with a unique structure type. The crystal structure comprises two parts: the three‐dimensional [Hg7As4I3]1+ host network, and the SnI31– guest anions encapsulated in the cavities of the network. The network is built from the As2Hg7 bitetrahedra and As2Hg6 octahedra, which share corners, and contains an additional iodine atom connected to one of the mercury vertices. The SnI31– anion has the shape of a pyramid with the tin atom in a vertex. According to the quantum‐chemistry calculations, the geometry of the anion deviates substantially from the equilibrium one, and is influenced by the distant mercury atoms of the host network.

Three‐Dimensional Mercury Pnictide [Hg4Z2]2+ Cationic Frameworks Stabilized by Tetravalent Metal Halide Anions in Supramolecular Complexes: [Hg4Z2][MCl6] (Z = P, As; M = Zr, Hf)

“…The Hg–P and Hg–As bond lengths in the cationic frameworks of 1 – 4 range widely from 2.362(6) to 2.417(6) Å and from 2.442(3) to 2.476(3) Å (Table S1), respectively, and they are all in agreement with those reported for mercury pnictide halides 3c,8. The Zr–Cl and Hf–Cl bond lengths in 1 – 4 fall in the ranges 2.437(4)–2.483(3), 2.435(2)–2.478(2), 2.436(6)–2.467(6), and 2.420(8)–2.467(6) Å, respectively, and are comparable to those found in zirconium or hafnium halides 9…”

“…Tetravalent Zr 4+ and Hf 4+ cations serve as the central ions of the guests and are octahedrally coordinated by chlorine atoms to form distorted octahedral polyanions (M = Zr, Hf; Figure 2), which are embedded in infinite channels of the host framework (Figure 1b). In contrast to other reported tetrahedral guests such as [HgBr 4 ] – ,5a [CdI 4 ] – ,5c and [ZnI 4 ] – ,5d octahedral guest substitution brings about the larger cell volumes and higher symmetry of 1 – 4 .…”

“…The shortest distance between the chlorine atoms of the guest anions and the mercury atoms in the host frameworks of 1 – 4 are 3.031, 2.991, 3.033, and 2.967 Å, respectively, and are much longer than the Hg–Cl covalent bond length but shorter than the sum of the van der Waals radii of Hg and Cl atoms; this indicates that there are typical weak supramolecular interactions between the cationic and anionic moieties, namely, between the [Hg 4 Z 2 ] 2+ (Z = P, As) hosts and the [MCl 6 ] 2– (M = Zr, Hf) guests, as reported in the literature 8,10…”

The Hg 3 2+ Group as a Framework Unit in a Host–Guest Compound: [Hg 11 As 4 ](GaBr 4 ) 4

“…The crystal structures of two compounds reported earlier,3a namely, [Hg 23 As 12 ](ZnBr 4 ) 6 and [Hg 13 As 8 ](ZnCl 4 ) 4 , provide examples for the adaptation of the three‐dimensional mercury–pnicogen frameworks to the size of the guest anions by “stitching” the tunnels with As−As bonds. Compound 1 represents another way of modifying the framework: the Hg−Hg groups expand the tunnels.…”

“…Various inorganic supramolecular compounds with three‐dimensional host structures are known 1. Among them is a separate group of phases in which the three‐dimensional network is formed by tetrahedrally coordinated pnicogen and linearly coordinated mercury atoms 2. In some structures, some or all of the pnicogen atoms are joined into dumbbells while keeping their tetrahedral arrangement 3.…”