ChemInform Abstract: Polycationic Hg‐Pnictide Frameworks with a Novel Kind of Filling in the Structures of Hg₃As₂TlCl₃ and Hg₃Sb₂TlBr₃.

Abstract

title compounds are prepared in nearly quantitative yields from mixtures of Hg 2 X 2 , HgX 2 (X: Cl, Br), As or Sb, and Tl (evacuated glass tubes, temp. gradients 330→290 • C for the As compound and 290→260 • C for the Sb compound, 2 weeks). As revealed by single crystal XRD, both compounds crystallize in the orthorhombic space group Pbcm with Z = 4. The structures can be described either as a cubic closest packing of As 2 /Sb 2 dumbbells and halide anions with all octahedral interstices filled with Hg 2+ and Tl + , or as a polycationic framework (Hg 3 Z 2 ) 2+ (Z: As, Sb) consisting of pnictide-pnictide dumbbells each connected by six Hg atoms to a three-dimensional porous network. The bonding character of the Tl-halide and Hg-halide bonds is explained using extended Hueckel band structure calculations.

TlHgInS3: An Indirect-Band-Gap Semiconductor with X-ray Photoconductivity Response

“…20,38−41 Hg, on the other hand, adopts a flexible coordination geometry (from linear to trigonal planar, to tetrahedral, and even octahedral), resulting in diverse structure types. 5,42−48 Several halide and chalcogenide compounds containing both elemental thallium and mercury, such as TlHgAs 3 S 6 , 35 Hg 3 Y 2 TlX 3 (Y = As, Sb; X = Cl, Br), 49 and Tl 2 HgMQ 4 (M = Si, Ge, Sn; Q = Se, Te) 20,50−52 have been reported but not investigated in detail, except Tl 4 HgI 6 53 (with respect to the radiation detection). Previously, we have identified Tl 2 Hg 3 Q 4 (Q = S, Se, Te) as promising detector materials (using the "dimensional reduction" approach) 10 and TlHg 6 Q 4 Br 5 (Q = S, Se) (using the "lattice hybridization" approach).…”

“…In search for new materials, which may replace the current detector materials, compounds containing Tl and Hg are particularly attractive, because the two elements are strong X-ray and γ-ray absorbers, which enables the effective detection using smaller crystals of material, thus relaxing the μτ requirements . From a chemical point of view, Tl is often considered to be a pseudo-alkali metal, because of the preferred +1 oxidation state and similar ionic radius to K + /Rb + . ,− Hg, on the other hand, adopts a flexible coordination geometry (from linear to trigonal planar, to tetrahedral, and even octahedral), resulting in diverse structure types. ,− Several halide and chalcogenide compounds containing both elemental thallium and mercury, such as TlHgAs 3 S 6 , Hg 3 Y 2 TlX 3 (Y = As, Sb; X = Cl, Br), and Tl 2 HgMQ 4 (M = Si, Ge, Sn; Q = Se, Te) ,− have been reported but not investigated in detail, except Tl 4 HgI 6 (with respect to the radiation detection). Previously, we have identified Tl 2 Hg 3 Q 4 (Q = S, Se, Te) as promising detector materials (using the “dimensional reduction” approach) and TlHg 6 Q 4 Br 5 (Q = S, Se) (using the “lattice hybridization” approach) …”