Tieftemperaturuntersuchung von Wasserstoffbrückenbindungen in Lithiumtetrahydroxoborat mit Raman‐Spektroskopie,Röntgen‐ und Neutronenbeugung (Li11B(OD)4)

Low Temperature Investigation of Hydrogen Bridge Bonds in Lithium Tetrahydroxoborate by Raman Spectroscopy, X‐Ray and Neutron Diffraction (Li¹¹B(OD)₄) Low temperature Raman spectroscopic measurements on isotopically diluted Li¹¹B(OH)₄ with 8 % D and Li¹¹B(OD)₄ with 8 % H reveal four crystallographically different hydrogen bridge bonds. With decreasing temperatures beginning at ～50 K measured down to ～10 K the stretching modes of the hydroxide ions shift to higher wave numbers. For the strongest bond O–D···O the frequency shift is 16 cm^?1and for the weakest 7 cm^?1. For O–H···O the maximum in the frequency shift is 22 cm^?1. X‐ray single crystal (LiB(OH)₄) and neutron powder diffraction (Li¹¹B(OD)₄) data result in bond lengths for the four hydroxide ions in the range of 0.943 (3) Å ≤ d(O–D) ≤ 0.974 (3) Å. The value of the effect of inversion of the stretching mode frequencies seems to correlate with the strength of the hydrogen bridge bonds and is found to be different for the two isotopes H and D in this compound.