Synthesis, Crystal and Band Structures, and Properties of a New Mixed Three-Dimensional Framework Metal Pnictidehalide Semiconductor, (Hg 6 Sb 4 )(CdI 6 ) Jian-Ping Zou, ²,‡ Yan Li, ² Zhang-Jing Zhang, ² Guo-Cong Guo,* ,² Xi Liu, ² Ming-Sheng Wang, ² Li-Zhen Cai, ² Ying-Bing Lu, ² and Jin-Shun Huang ² State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China, and Graduate School, Chinese Academy of Sciences, Beijing 100039, P. R. China Received December 16, 2006 A new, quaternary mercury and cadmium pnictidehalide semiconductor (Hg 6 Sb 4 )(CdI 6 )(1) has been prepared by the solid-state reaction and structurally characterized by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the space group R-3c of the rhombohedral system with four formula units in a cell: a ) 13.3818(9) Å, R) 90.93°, and V ) 2395.3(3) Å 3 . The crystal structural novelty of 1 derives from the fact that a 3-D mercury antimonide cationic network interpenetrates with an unusual 3-D cadmium iodide octahedral anionic network through the weak covalent interactions between mercury and iodine atoms to form a mixed 3-D framework. Among them, the cationic moiety features a perovskite-like 3-D network while the anionic moiety is characterized by a 3-D I 6 octahedral anionic network with two-thirds I 6 octahedra being occupied by Cd atoms. The optical properties were investigated in terms of the diffuse reflectance and Fourier transform infrared spectra. The electronic band structure along with density of states calculated by the density functional theory method indicates that compound 1 is a semiconductor with a direct band gap and that the optical absorption of 1 is mainly ascribed to the charge transitions from I-5p and Sb-5p states to Cd-5s and Hg-6s states. Introduction Recently, design and syntheses of mixed-framework compounds have attracted much attention because they offer scientifically and technologically significant opportunities for combining attractive features of different framework moieties within a single compound. For instance, inorganic-organic hybrid materials are likely to exhibit diverse structures, improved properties, and unique functions that are not obtained from their purely inorganic or organic moieties. 1 The hybrid materials of mixed covalent and ionic lattices made of transition metal oxides and alkali and alkaline-earth metal halides, which exhibit salt-templated porous structures, noncentrosymmetric lattices, and frameworks containing magnetic nanostructures, 2 are another new class of mixed- framework materials. According to the concept of mixed- framework compounds, metal pnictidehalides are investigated to explore new mixed-framework materials due to the distinct size and electronegativity of pnicogen and halogen anions. Furthermore, metal pnictidehalides have been of much interest in advanced material research because of their diverse structure, unique electronic properties, and good physical properties, such as magnetic, electric, and optical properties. 3 Till now, there are more than twenty mercury pnictidehalides containing 3-D cationic network with two different cavities * To whom correspondence should be addressed. Tel.: +86-591- 83705882. Fax: +86-591-83714946. E-mail: gcguo@ms.fjirsm.ac.cn. ² Fujian Institute of Research on the Structure of Matter. ‡ Graduate School, Chinese Academy of Sciences. (1) (a) Fe ˘ rey, G. Chem. Mater. 2001, 13, 3084. (b) Mitzi, D. B.; Field, C. A.; Harrison, W. T. A.; Guloy, A. M. Nature 1994, 369, 467. (c) Mitzi, D. B. Chem. Mater. 1996, 8, 791. (d) Zheng, N.; Bu, X.; Wang, B.; Feng, P. Science 2002, 198, 2366. (e) Calabrese, J.; Jones, N. L.; Harlow, R. L.; Thorn, D.; Wang, Y. J. Am. Chem. Soc. 1991, 113, 2328. (2) (a) Wang, L.; Hung, Y.-C.; Hwu, S.-J.; Koo, H.-J.; Whangbo, M.-H. Chem. Mater. 2006, 18, 1219. (b) Huang, Q.; Hwu, S.-J.; Mo, X. Angew. Chem., Int. Ed. 2001, 40, 1690. (c) Huang, Q.; Ulutagay, M.; Michener, P. A.; Hwu, S.-J. J. Am. Chem. Soc. 1999, 121, 10323. (d) Mo, X.; Hwu, S.-J. Inorg. Chem. 2003, 42, 3978. (e) Huang, Q.; Hwu, S.-J. Inorg. Chem. 2003, 42, 655. (e) Hwu, S.-J.; Ulutagay-Kartin, M.; Clayhold, J. A.; Mackay, R.; Wardojo, T. A.; O’ Connor, C. J.; Krawiec, M. J. Am. Chem. Soc. 2002, 124, 12404. (f) Clayhold, J. A.; Ulutagay-Kartin, M.; Hwu, S.-J.; Koo, H.-J.; Whangbo, M.-H.; Voigt, A.; Eaiprasertsak, K. Phys. ReV.B 2002, 66, 052403. Inorg. Chem. 2007, 46, 7321-7325 10.1021/ic0624165 CCC: $37.00 © 2007 American Chemical Society Inorganic Chemistry, Vol. 46, No. 18, 2007 7321 Published on Web 08/01/2007