(Mn1-xPbx)Pb10+ySb12-yS26-yCl4+yO, a new oxy-chloro-sulfide with similar to 2nm-spaced (Mn,Pb)Cl-4 single chains within a waffle-type crystal structure

摘要

The new oxy-chloro-sulfide (Mn1-xPbx)Pb10+ySb12-yS26-yCl4+yO (x is an element of [0.2-0.3]; y is an element of [0.3-1.6]) was synthesized by dry way at 500-600 degrees C. A single crystal similar to Mn0.7Pb11.0Sb11.3S25.3Cl4.7O indicates a rnonoclinic symmetry, space group C2/m, with a = 37.480(8), b = 4.1178(8), c = 18.167(4) angstrom, beta = 106.37(3)degrees, V = 2690.2(9) angstrom(3), Z = 2. Its crystal structure was determined by X-ray single crystal diffraction, with a final R = 5.11%. Modular analysis of the crystal structure reveals a "waffle" architecture, where complex rods with lozenge section delimitate an internal channel filled by a single chain of (Mn0.7Pb0.3)Cl-6 octahedra connected by opposite edges. Minimal inter-chain distances are close to 18 A. The rod wall, two-atom thick, presents, in alternation with S atoms, Pb or (Pb,Sb) cations with prismatic coordination in the internal atom layer, while the external atom layer is constituted exclusively by Sb cations with dissymmetric square pyramidal coordination. A (Pb,Sb)(2)S-2 fragment connects two successive rods along (201) to form a waffle-type palissadic layer. The unique O position, half filled, presents the same environment than the isolated O positions in the oxy-sulfide Pb14Sb30S54O5, or oxy-chloro-sulfides Pb18Sb20S46Cl2O and (Cu,Ag)(2)Pb21Sb23S55ClO. This compound belongs to a pseudo-homologous series of chalcogenides with waffle structure, ordered according to the size of their lozenge shape channel. Such a complex senary compound of the oxy-chloro-sulfide type illustrates the structural competition between three cations, on one hand, and, on the other hand, three anions. This compound is of special interest regarding the ID distribution of magnetic Mn2+ atoms at the similar to 2 nm scale. (C) 2007 Elsevier Inc. All rights reserved.