The anti-perovskite type hydride InPd 3H 0.89

Abstract

Hydrogenation of tetragonal InPd 3 in the ZrAl 3 type structure (four-fold ccp superstructure) yields a hydride with a cubic AuCu 3 type structure (one-fold ccp superstructure). Deuterium can be located by neutron powder diffraction in octahedral voids surrounded exclusively by palladium, [Pd 6], which are 88.5(6)% occupied in a statistical manner. The resulting deuteride InPd 3D 0.89 thus crystallizes in a cubic anti-perovskite type structure (space group Pm3¯ m (no. 221), a=402.25(1) pm at 299(2) K). The Pd–D distance of 201.13(1) pm is typical for interstitial hydrides with palladium. Inelastic neutron scattering on the hydride InPd 3H 0.89, which shows a spectrum similar to that of binary palladium hydride, confirms the cubic site symmetry of hydrogen in [Pd 6] interstices. This is also confirmed by the absence of any quadrupole splitting in the 2D-NMR signal of the deuteride. 1H NMR spectra of InPd 3H 0.89 do not show any motional narrowing. Values found for the H jump rate τ −1 in InPd 3H 0.89 remain below 10 6 s −1 in the studied temperature range 28–360 K, indicating a small hydrogen mobility in InPd 3H 0.8 as compared with binary palladium hydride, PdH ≤1. This can be attributed to the large spatial separation of the [Pd 6] sites.