Tieftemperaturuntersuchungen von Wasserstoffbrückenbindungen in den Hydroxiden β‐Be(OH) 2 und ε‐Zn(OH) 2 mit Raman‐Spektroskopie sowie Röntgen‐ und Neutronenbeugung

Low Temperature Investigations of Hydrogen Bridge Bonds in the Hydroxides β‐Be(OH) 2 and ε‐Zn(OH) 2 by Raman‐Spectroscopy as well as X‐Ray and Neutron Diffraction Fully and partially deuterated samples of β‐Be(OH) 2 and ε‐Zn(OH) 2 were investigated by Raman‐spectroscopy in the temperature range from ∼ 10 K to ∼ 300 K. X‐ray and neutron diffraction data from 5 K to 245 K were evaluated for β‐Be(OD) 2 on powder samples. Neutron diffraction on ε‐Zn(OD) 2 was carried out between 5 K and 298 K. Within these temperature regions the two hydroxides crystallize isotypic with orthorhombic symmetry, space group P2 1 2 1 2 1 with Z = 4. The Raman‐spectra of β‐Be(OH) 2 show an unexpected and until now not understood effect: with decreasing temperatures beginning at ∼ 40 K the stretching modes of the two crystallograpically inequivalent hydroxide ions connected by hydrogen bridgebonds shift to higher wave numbers. For ε‐Zn(OH) 2 this inversion occurs already at 50 K and the effect is markedly stronger.