The Interaction of Hydrogen with Iron Benzene-1,3,5-Tricarboxylate (Fe-BTC)

Abstract

Inelastic neutron scattering (INS) spectroscopy is used to explore the 0–12,000 cm−1 range to characterise the interaction of H2 with iron benzene-1,3,5-tricarboxylate (Fe-BTC). Two peaks are observed in the low energy (<350 cm−1) region after exposure to H2. Measurements with hydrogen deuteride (HD) confirm that the peaks originate from H2. The most likely explanation is that there are two populations of H2 (HD) present. For both the H2- and the HD-loaded samples, the higher energy peak is close in energy to that of the pure isotopomer, so it is assigned to bulk-like H2/HD held in pores of the Fe-BTC. The lower energy peak is assigned to H2/HD interacting directly with the Fe ion exposed on dehydration. It was also possible to detect the H–H stretch in the same experiment; however, unfortunately, the instrumental resolution is insufficient to separate the stretch modes of the bound H2 (HD) and that in the pores.