Neutron powder diffraction and solid-state deuterium NMR studies of Ca 2RuD 6 and the stability of transition metal hexahydride salts

Abstract

The crystal structure of Ca 2RuD 6 has been determined by neutron powder diffraction: space group Fm3 m, K 2PtCl 6 structure, as found for other hexahydride salts of group 8 metals with alkaline earth or lanthanide counter ions. No structural phase transition was observed between 340 K and 50 K. The deuterium nuclear quadrupole coupling constant, 54.7 kHz, leads to an ionic character of the Ru–D bond of 76%. The known trends in the behaviour of A 2MH 6 salts are interpreted in terms of the ionization energies of the cation and the central metal atom.