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Title: Hidden Superlattice in Tl2(SC6H4S) and Tl2(SeC6H4Se) Solved from Powder X-ray Diffraction

The crystal structures of the isostructural title compounds poly[({mu}-benzene-1,4-dithiolato)dithallium], Tl{sub 2}(SC{sub 6}H{sub 4}S), and poly[({mu}-benzene-1,4-diselenolato)dithallium], Tl{sub 2}(SeC{sub 6}H{sub 4}Se), were solved by simulated annealing from high-resolution synchrotron X-ray powder diffraction. Rietveld refinements of an initial structure with one formula unit per triclinic cell gave satisfactory agreement with the data, but led to a structure with impossibly close non-bonded contacts. A disordered model was proposed to alleviate this problem, but an alternative supercell structure leads to slightly improved agreement with the data. The isostructural superlattice structures were confirmed for both compounds through additional data collection, with substantially better counting statistics, which revealed the presence of very weak superlattice peaks not previously seen. Overall, each structure contains Tl-S or Tl-Se two-dimensional networks, connected by phenylene bridges. The sulfur (or selenium) coordination sphere around each thallium is a highly distorted square pyramid or a 'see-saw' shape, depending upon how many Tl-S or Tl-Se interactions are considered to be bonds. In addition, the two compounds contain pairs of Tl{sup I} ions that interact through a closed-shell 'thallophilic' interaction: in the sulfur compound there are two inequivalent pairs of Tl atoms with Tl-Tl distances of 3.49 and 3.58 {angstrom}, while in the selenium compound thosemore » Tl-Tl interactions are at 3.54 and 3.63 {angstrom}.« less
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
1041718
Report Number(s):
BNL--97396-2012-JA
Journal ID: ISSN 0108-7681; ASBSDK; TRN: US201212%%130
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallographica. Section B, Structural Science; Journal Volume: 67; Journal Issue: 5
Research Org:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Org:
USDOE SC OFFICE OF SCIENCE (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; ATOMS; CRYSTAL STRUCTURE; DIFFRACTION; SELENIUM; SELENIUM COMPOUNDS; SHAPE; STATISTICS; SULFUR; SULFUR COMPOUNDS; SUPERLATTICES; SYNCHROTRONS; THALLIUM; X-RAY DIFFRACTION