Cesium Platinide Hydride 4Cs2 Pt⋅CsH: An Intermetallic Double Salt Featuring Metal Anions.

With Cs9 Pt4 H a new representative of ionic compounds featuring metal anions can be added to this rare-membered family. Cs9 Pt4 H exhibits a complex crystal structure containing Cs+ cations, Pt2- and H- anions. Being a red, transparent compound its band gap is in the visible range of the electromagnetic spectrum and the ionic type of bonding is confirmed by quantum chemical calculations. This cesium platinide hydride can formally be considered as a double salt of the "alloy" cesium-platinum, or better cesium platinide, Cs2 Pt, and the salt cesium hydride CsH according to Cs9 Pt4 H≡4 Cs2 Pt⋅CsH.