ELECTRONIC-STRUCTURE INVESTIGATION OF THE A(2)PTH(4) HYDRIDES (A=NA, K) CONTAINING [PTH4] COMPLEXES

Ternary platinum hydrides have been synthesized and structurally chara cterized in recent years. The defective hydride K2PtH4 crystallizes wi thin the K2PtCl6 structure above 197 K, while at low temperatures, the defective phase presents long range hydrogen ordering. Na2PtH4 has be en synthesized and shows also hydrogen ordering but of a different nat ure. We have investigated the electronic structure and bonding in the hydrogen ordered compounds by means of the augmented plane wave (APW) method. The band structure, the total density of states and their part ial wave analysis are discussed. We found that these hydrides are insu lators and behave essentially as quasi-molecular solids characterized by narrow d-bands and weak [PtH4]-[PtH4] interactions.