In the past decades hydrides and hydrido-metalates became of increasing scientific interest concerning their technical applications. Thus, they were used e.g. in chemical processes as catalysts or for selective hydrogenation. In the course of the development of sustainable technologies metal hydrides serve as hydrogen storage systems and apply for e.g. accumulators or heat storage systems.

After the development of a device for the reactive gas pressure synthesis we demonstrated in the course of our former investigations that cumulative oxidation of transition metals becomes possible with increasing hydrogen pressure, e.g. the oxidation of elemental platinum up to the oxidation state +4 in Rb₂PtH₆ and up to the oxidation state +7 in the case of rhenium in Rb₃ReH₁₀.

Figure 1. Schematical representation of the rubidiumhydride/hydridoplatinate pressure series. Phase formations are controlled by the adjusted gas pressures.

Furthermore, the high-pressure phases YbH_2.67 and (Sr₂N)H were synthesized and their crystal structures were solved.

Figure 2. Crystal structures of YbH_2.67 (left) and (Sr₂N)H (right).

The crystal structures of hydrogen containing compounds are usually determined by a combination of X-ray and neutron powder diffraction. Complementary investigations with neutron spectroscopy shed light on the strength of the metal-hydrogen-bond and on the dynamic of the hydrogen atoms.

References:

[1] W. Bronger, G. Auffermann, Chem. Mater., 10 (1998) 2723
[2] W. Bronger, G. Auffermann, Z. Anorg. Allg. Chem., 625 (1999) 1147
[3] G. Auffermann, Z. Anorg. Allg. Chem., 628 (2002) 1615
[4] G. Auffermann, W. Bronger, Z. Anorg. Allg. Chem., 628 (2002) 2159
[5] S. F. Parker, S. M. Bennington, A. J. Ramirez-Cuesta, G. Auffermann, W. Bronger, H. Herman, K. P. J. Williams, T. Smith, J. Am. Chem. Soc., 125 (2003) 11656
[6] G. Auffermann, P. Müller, and W. Bronger, Z. Anorg. Allg. Chem., 630 (2004) 2113
[7] G. Auffermann, G.D. Barrera, D. Colognesi, G. Corradi, A.J. Ramirez-Cuesta, M. Zoppi, J. Phys.: Condens. Matter, 16 (2004) 5731
[8] G. Auffermann, W. Bronger, P. Müller, G. Roth, H. Schilder, T. Sommer, Z. Anorg. Allg. Chem., 631 (2005) 1060
[9] R. Chemnitzer, G. Auffermann, D.M. Többens, R. Kniep, Z. Anorg. Allg. Chem., 631 (2005) 1813
[10] G. Auffermann, R. Kniep, W. Bronger, Z. Anorg. Allg. Chem., 632 (2006) 565