SYNTHESIS AND STRUCTURE OF LI3RHH4, A TERNARY HYDRIDE WITH PLANAR [RHH4]3- GROUPS

The ternary rhodium hydride Li3RhH4 was synthesized by the reaction of lithium hydride with finely divided rhodium powder in a pure hydrogen atmosphere. The crystal structure was determined by X-ray investigations on powdered samples and an elastic neutron diffraction experiment on the deuterated compound. The orthorhombic structure (space group: Cmcm; a = 3,883(1) angstrom; b = 9,022(2) angstrom; c = 8,891(2) angstrom; Z = 4) is characterized by planar [RhH4]3--groups. The short distances between these groups are evidence of interactions between the rhodium atoms.