An Old Dog with New Tricks - Additions to the Cesium Lithium Chloride System: Cs₃Li₂Cl₅ and the Hydrated Cs₃LiCl₄ ·...

The CsCl/LiCl system has been studied for over a century now. Numerous phases have been predicted - only three have hitherto been found. We present the synthesis and single-crystal structure of the cesium lithium pentachloride Cs₃Li₂Cl₅, predicted earlier but with a different structure. The anhydrous new phase readily reacts to Cs₃LiCl₄ · 4H₂O in air. The tetrahydrate can also be obtained through the simplest, most inexpensive and green synthesis possible: an immediate, room-temperature mechanosynthesis from only CsCl and LiCl (3 : 1) in air. Differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA), as well as in situ temperature-dependent powder X-ray diffraction studies on this second ever reported ternary alkali chloride hydrate allowed for a revision of the CsCl/LiCl phase diagram. Density of states and total energy calculations further elucidate the new alkali chlorides and update the relative stability of previous structure predictions.