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.