Mercury Phosphates with the Triangular Hg4+3 Cluster: (Hg3)3(PO4)4 and (Hg3)2(HgO2)(PO4)2

✍ Scribed by Matthias Weil; Robert Glaum

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 339 KB
• Volume: 157
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.9040

✦ Synopsis

Hydrothermal treatment of microcrystalline (Hg 2 ) 2 P 2 O 7 in diluted phosphoric acid or demineralized water at 4003C yields colorless crystals of (Hg 3 ) 3 (PO 4 ) 4 and yellow crystals of (Hg 3 ) 2 (HgO 2 )(PO 4 ) 2 , respectively. The crystal structures have been solved and re5ned from single crystal di4ractometer data to residuals R [F 2 > 2 (F 2 )] ‫؍‬ 0.021 and wR2 [F 2 ] ‫؍‬ 0.047 for (Hg 3 ) 3 (PO 4 ) 4 and R [F 2 > 2 (F 2 )] ‫؍‬ 0.028 and wR2 [F 2 ] ‫؍‬ 0.072 for (Hg 3 ) 2 (HgO 2 )(PO 4 ) 2 . The crystal structure of (Hg 3 ) 3 (PO 4 ) 4 (R3c (No. 161), Z ‫؍‬ 6, a ‫؍‬ 16.3957(10) A > , c ‫؍‬ 10.6606(9) A > , V ‫؍‬ 2481.9(3) A > 3 ) is isotypic with the corresponding arsenate (Hg 3 ) 3 (AsO 4 ) 4 . (Hg 3 ) 2 (HgO 2 )(PO 4 ) 2 crystallizes with two formula units in the monoclinic space group P2 1 /c (No. 14), with lattice parameters a ‫؍‬ 6.2506(7) A > , b ‫؍‬ 9.9366(10) A > , c ‫؍‬ 9.6663(12) A > , ‫؍‬ 95.783(10)3, and V ‫؍‬ 597.3(1) A > 3 , and shows a topological relationship to the mineral terlinguaite (Hg 4 O 2 Cl 2 ). Both phosphates contain tetrahedral PO 3؊ 4 groups and the triangular mercury cluster Hg 4؉ 3 with d (Hg+Hg) ‫؍‬ 2.666 A > for (Hg 3 ) 3 (PO 4 ) 4 and 2.682 A > for (Hg 3 ) 2 (HgO 2 )(PO 4 ) 2 , respectively. In the latter compound a linear mercurate group, HgO 2؊ 2 with d (Hg+O) ‫؍‬ 2.031(7) A > , is also present. For both structures the threedimensional connection between the building units is achieved via common oxygen atoms. Both compounds disproportionate upon heating (T > 3003C) to Hg 3 (PO 4 ) 2 and elemental mercury. 2001 Academic Press