Solventothermal Synthesis of Solid‐State Chalcogenidometalates

Abstract

Development of solventothermal methods in the intermediate‐temperature (100–600°C) range has been motivated by current interest in the design of solid‐state compounds with open framework structures. The preparation of nanoporous chalcogenidometalates by this technique is particularly promising, as a combination of the typical ion‐exchanging and catalytic features of zeolite‐like phases with the unique optoelectronic properties of transition metal and group 13–16 chalcogenides could afford novel multifunctional materials. Superheated strongly polarizing solvents such as water, methanol, and amines at temperatures in the range 110–200°C provide reaction conditions adequate to greatly enhance solubility, diffusion, and crystallization but still mild enough to leave molecular building blocks such as chains and rings intact to participate in the formation of polymeric anions. Such intermediate temperatures often allow the isolation of metastable solid‐state compounds and thermodynamically stable phases that decompose at higher temperatures. The dimensionality and pore size of the anion network can be influenced by the choice of a suitable structure‐directing alkali metal or alkyl‐ammonium cation. Methanolothermal conditions have been found to be particularly suitable for the preparation of selenido‐ and telluridometalates, and have afforded a new class of very tellurium‐rich alkali metal tellurides such as RbTe 6 and Cs 3 Te 22. This article presents a comprehensive review of the application of mild solventothermal techniques to the preparation of heavier group 14–16 and transition metal chalcogenidometalates.