Lone Pairs as Chemical Scissors in New Antimony Oxychlorides, Sb₂ZnO₃Cl₂ and Sb₁₆Cd₈O₂₅Cl₁₄

Abstract

Two new metal antimony oxychlorides, Sb(2)ZnO(3)Cl(2) and Sb(16)Cd(8)O(25)Cl(14), have been synthesized by solid-state reactions using Sb(2)O(3) and ZnCl(2) (or CdCl(2)) as reagents. The structures of Sb(2)ZnO(3)Cl(2) and Sb(16)Cd(8)O(25)Cl(14) have been determined by single-crystal X-ray diffraction. Both of the reported materials contain Sb(3+) cations that are in an asymmetric coordination environment attributable to their stereoactive lone pair. Sb(2)ZnO(3)Cl(2) has a novel two-dimensional layered structure consisting of distorted ZnO(2)Cl(2) tetrahedra and SbO(3) polyhedra. Sb(16)Cd(8)O(25)Cl(14) exhibits a one-dimensional structure consisting of Sb(3+)-Cd(2+)-oxide rods, Cd(2+)-chloride double chains, and isolated Cl(-) ions. Complete separation of the halophile and chalcophile moieties is observed from the reported materials. Detailed structural analysis, IR spectra, thermogravimetric analysis, ion-exchange reactions, and dipole moment calculations are presented. Crystal data: Sb(2)ZnO(3)Cl(2), orthorhombic, space group Pnma (No. 62), a = 17.124(4) A, b = 5.5598(12) A, c = 6.4823(14) A, V = 617.2(2) A(3), and Z = 4; Sb(16)Cd(8)O(25)Cl(14), monoclinic, space group I2/m (No. 12), a = 14.251(3) A, b = 3.9895(8) A, c = 21.145(4) A, beta = 97.35(3) degrees, V = 1192.3(4) A(3), and Z = 8.

Polar Noncentrosymmetric ZnMoSb2O7 and Nonpolar Centrosymmetric CdMoSb4O10: d10 Transition Metal Size Effect Influencing the Stoichiometry and the Centricity

“…Especially with SbO 3 and SbO 4 polyhedra, a localized distance of 1.08 Å between Sb 3+ and the lone pair was adopted from the previously reported work, and the charge of the lone pair was assigned as −2 . By means of this method, the dipole moments of ZnO 4 , CdO 6 , MoO 4 , SbO 3 , and SbO 4 groups in the reported materials were approximately calculated to be 2.6, 0, 4.4–7.5, 9.7–11.4, and 10.0–10.3 D, respectively, which are quite similar to the values of formerly reported polyhedra . With NCS polar ZnMoSb 2 O 7 , the calculated net dipole moment along the [01̅0] direction for a unit cell is ca.…”

“…The lone pairs on the asymmetric Sb 3+ cations are directed toward the outside of the 1D rods (see Figure d). Similar tubules containing lone pairs pointing outward have been observed in Sb 16 Cd 8 O 25 Cl 14 . However, the morphologies are quite different: the infinite tubes found in Sb 16 Cd 8 O 25 Cl 14 consist of SbO 4 polyhedra and wrap around edge-sharing double chains of CdO 6 octahedra.…”

[NaCl][Cu(HSeO3)2], NaCl-intercalated Cu(HSeO3)2: synthesis, crystal structure and comparison with related compounds

“…The interest has also been stimulated by the attempts to understand purely fundamental reasons for structural diversity in selenites and its underlying crystal chemical mechanisms [10][11][12]. In this regard, copper selenite chlorides are of particular importance, due to their natural occurrences as minerals [13][14][15][16][17] and the structures featuring 'scissor'-type disruption of a bonding network induced by the well-localized stereochemically active but chemicall inactive lone electron pairs [18][19][20][21][22].…”

Copper–lead selenite bromides: a new large family of compounds partly having Cu2+ substructures derivable from kagome nets

“…There is a known tendency for transition metal oxyhalide compounds containing 'lone pair' cations to crystallize in lowdimensional structural architectures due to the 'chemical scissors' (Mayerová et al, 2006;Jo et al, 2010) role of the stereochemically active lone electron pairs. All the structures described herein demonstrate the association of 'lone pairs' on Pb 2+ and Se 4+ in so-called lone electron pair micelles (Makovicky, 1997), thus demonstrating the presence of attractive interactions.…”