The Synthesis, Crystal and Band Structures, and Properties of the Quaternary Supramolecular Complexes [Hg₆Z₄](MX₆)Hg<i>_y</i> (Z = As, Sb; M = Hg, Cd; X = Cl, Br, I; <i>y</i> = 0, 0.5, 0.6)

Abstract

Abstract The series of supramolecular complexes (Hg 6 As 4 )(CdCl 6 )Hg 0.5 ( 1 ), (Hg 6 As 4 )(HgCl 6 )Hg 0.5 ( 2 ), (Hg 6 As 4 )(CdBr 6 ) ( 3 ), and (Hg 6 Sb 4 )(CdI 6 )Hg 0.6 ( 4 ) has been prepared by a solid‐state reaction and their crystal structures determined by single‐crystal X‐ray diffraction. All these compounds crystallize in the space group Pa $\bar {3}$ with four formula units in a cell: a = 12.172(2) ( 1 ), 12.189(1) ( 2 ), 12.3738(5) ( 3 ), and 13.234(2) Å ( 4 ). Their structures feature a 3D cationic host framework that is built up of linearly coordinated mercury and tetrahedrally coordinated pnicogen atoms to form distorted As 2 Hg 6 or Sb 2 Hg 6 octahedra, and discrete guest anions. The distorted octahedra corner‐share with each other to form a perovskite‐like, 3D cationic framework that possess two types of closed cavities with different sizes. The octahedral guest anions (MX 6 ) 4– are embedded in the larger cavities, whereas the smaller cavities trap the excess mercury atoms or remain empty. The optical properties were investigated by diffuse reflectance and FT IR spectroscopy. The electronic band structures and density of states (DOS) calculated by DFT methods indicate that the present compounds are semiconductors and that the optical absorption mainly originates from the charge transitions from the p orbital of the pnicogen (As or Sb) and halogen (Cl, Br or I) atoms states to the Hg1 6s states for 1 , 3 , and 4 , and to Hg1 6s and Hg3 6sstates for 2 .(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)