Two New Cubic Structures of Mercury Arsenidehalides

✍ Scribed by Andrei V. Shevelkov; Evgeny V. Dikarev; Boris A. Popovkin

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 376 KB
• Volume: 126
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1996.0344

✦ Synopsis

of a new mercury arsenidochloride, Hg 7.4 As 4 Cl 6 , which has Crystal structures of Hg 4 As 2 Br 3 (I) and Hg 7.4 As 4 Cl 6 (II), which an intermediate composition between 4 : 2 : 3 (ϭ8 : 4 : 6) and was prepared for the first time, have been refined based on the 7 : 4 : 6, and belongs to the 7 : 4 : 6 structure type. We also X-ray single crystal experiments. Both phases crystallize in the report the crystal structure of a known phase, Hg 4 As 2 Br 3 cubic space group Pa3. Crystal data: I, a ‫؍‬ 12.610(1), Z ‫؍‬ 8, (3, 4), which belongs to the 4 : 2 : 3 structure type. Compar-R 1 ‫؍‬ 0.0602; II, a ‫؍‬ 12.178(1), Z ‫؍‬ 4, R 1 ‫؍‬ 0.0584. Characteris-ing the 4 : 2 : 3 and 7 : 4 : 6 structure types, we suggest an tic of both structures are the As 2 Hg 6 octahedra having an As-As idealized path for the structure transformation. separation of ca. 2.38 A ˚. Such octahedra share vertices with AsHg 4 tetrahedra in I, while in II they compose a perovskite-EXPERIMENTAL like three-dimensional network by sharing all vertices. Part of the mercury atoms in II have no neighbors up to 3.53 A ˚and Synthesis. Hg 4 As 2 Br 3 was prepared by heating a stoiare considered to possess a zero oxidation state. An idealized chiometric mixture of liquid mercury, mercury dibromide, path for the I to II structure transformation, which is based and gray arsenic in a sealed silica tube at 350ЊC for 7 days.

on the difference of halogen radii, is suggested.