KEu2In3B12S13: a novel type of thioborate featuring B12S12 cluster and unique In6S6 12-membered ring

Abstract

Both borates and sulfides are important inorganic multifunctional materials. Encouraged by this background, thioborates attract considerable interest. However, their investigations are highly hindered by the scarcity of the available ones and the synthetic difficulty of the new ones. Here, we report a new thioborate KEu₂In₃B₁₂S₁₃ (1), which was obtained via a facile solid-state reaction in KI flux. It crystallizes in the trigonal Rm structure, and the three-dimensional structure features a six InS₆ octahedron consolidated B₁₂ icosahedron built {[In₃B₁₂S₁₂]⁵⁻}_∞ polyanionic framework and a unique In₆S₆ 12-membered ring, representing a new type of compound. The B₁₂S₁₂ cluster is also different from the other known thioborates. The structural chemistry, optical and magnetic properties, as well as theoretical calculations of 1 were systematically studied. This study not only provides a new type of thioborate but also makes a breakthrough in the synthesis of thioborates.