Borate Hydrides as a New Material Class: Structure, Computational Studies, and Spectroscopic Investigations on Sr 5 (BO 3 ) 3 H and Sr 5 ( 11 BO 3 ) 3 D

The unprecedented borate hydride Sr 5 (BO 3 ) 3 H and deuteride Sr 5 ( 11 BO 3 ) 3 D crystallizing in an apatite‐related structure are reported. Despite the presence of hydride anions, the compound decomposes only slowly in air. Doped with Eu 2+ , it shows broad‐band orange‐red emission under violet excitation owing to the 4f 6 5d–4f 7 transition of Eu 2+ . The observed 1 H NMR chemical shift is in good agreement with previously reported 1 H chemical shifts of ionic metal hydrides as well as with quantum chemical calculations and very different from 1 H chemical shifts usually found for hydroxide ions in similar materials. FTIR and Raman spectroscopy of different samples containing 1 H, 2 H, nat B, and 11 B combined with calculations unambiguously prove the absence of hydroxide ions and the sole incorporation of hydride ions into the borate. The orange‐red emission obtained by doping with Eu 2+ shows that the new compound class might be a promising host material for optical applications.