Hg<sub>16</sub>O<sub>12</sub>(NO<sub>3</sub>)<sub>6</sub>F<sub>2</sub>(H<sub>2</sub>O): A Mercury-Rich Nitrate Oxyfluoride with Diverse Triple-Coordinated Mercury-Based Units That Exhibits an Unparalleled [(Hg<sub>16</sub>O<sub>12</sub>F<sub>2</sub>(H<sub>2</sub>O))<sup>6+</sup>]<sub>∞</sub> Cationic Framework and a Large Birefringence
Yi‐Lei Lv, Wei Xu, Wen‐Dong Yao, Miao‐Bin Xu, Wenlong Liu, Sheng‐Ping Guo, Ru‐Ling Tang
Abstract
Designing new compounds based on anion regulation has been widely favored due to the production of diverse crystal structures and excellent optical properties. Here, a new nitrate oxyfluoride, Hg 16 O 12 (NO 3 ) 6 F 2 (H 2 O), has been obtained through a hydrothermal reaction. It crystallizes in the centric Ibca space group and shows a novel three-dimensional [(Hg 16 O 12 F 2 (H 2 O)) 6+ ] ∞ cationic framework composed of interconnected HgO 2 F, HgO 3, and HgO 2 (H 2 O) units, with isolated NO 3 – groups as balanced anions to build the whole structure. Notably, the HgO 2 F and HgO 2 (H 2 O) units are first presented here among mercury (Hg)-based compounds. Additionally, Hg 16 O 12 (NO 3 ) 6 F 2 (H 2 O) exhibits a large birefringence of 0.17 at 546 nm. This work enriches the multiformity of Hg-based compounds and provides a route for developing promising birefringent materials.