A Second Modification of Mercury(I) Orthoarsenate(V): Preparation and Crystal Structure of β-(Hg2)3(AsO4)2

Abstract

Abstract Light-yellow crystals of a second modification of mercury(I) orthoarsenate(V), β-(Hg2)3(AsO4)2, were obtained during a diffusion-controlled precipitation reaction starting from diluted solutions of Hg2(NO3)2, Hg(NO3)2, and H3AsO4. The crystal structure was determined from a single crystal X-ray diffraction data set. The previously reported crystal structure of synthetic chursinite, α-(Hg2)3(AsO4)2, has also been re-investigated and refined with better accuracy and precision. Both phases crystallize in space group type P21/c (no. 14) [α- (β -): Z = 2 (4), a = 8.7915(6) (10.2034(18)), b = 5.0699(4) (8.5875(14)), c = 15.6839(10) (13.5172(19)) Å , β = 128.761(1) (101.016(3))°, 1661 (3528) structure factors, 74 (146) parameters, RF2 > 2σ (F2)] = 0.0195 (0.0492)] and are made up from Hg2 2+ dumbbells and AsO4 3− tetrahedra as the main building units, but the topologies of the structures are quite different.