THE STRUCTURE OF A SODIUM-SUBSTITUTED PALLADIUM HYDRIDE, NAPD3H2

Stoichiometric NaPd3H2 has been synthesized, and the crystal structure has been determined with a metal atom structure related to the binary palladium hydride. The structure was refined from powder X-ray and neutron diffraction data in the orthorhombic space group Cmmm (65) with unit cell dimensions a = 5.6532(7) angstrom, b = 8.590(3) angstrom and c = 2.8197(4) angstrom, Z = 2. The metal atoms form an almost close-packed framework with hydrogen located in the octahedral sites. Two types of metal atom octahedra constitute the structure, one of them comprising one, and the other two sodium atoms. Hydrogen completely fills the octahedra of the first type and is absent from the second type, due to space limitations. A short Pd - H distance of 1.832(3) angstrom is found in the structure where two hydrogen atoms in adjacent octahedra form a linear arrangement with the interjacent palladium atom.