Frustrated Lewis acid-base Pairs (FLPs) can heterolytically split H2 gas to produce a hydride/proton ion pair. We have measured the enthalpy of hydrogenation of several linked FLP systems where the Lewis acidity and basicity can be altered to provide a ΔG approaching zero and therefore allow reversibility and thermal release of H2 gas. Most of the studies have been in solution, but solid FLP systems offer potential advantages in separation and gas purity. In this work we show how crystalline 1-{2-[bis(pentafluorophenyl)boryl]phenyl}-2,2,6,6-tetramethylpiperidine reacts with gaseous H2 under ambient conditions to form the corresponding ion pair. The reaction was studied using optical microscopy, x-ray diffraction, inelastic neutron spectroscopy, and molecular dynamics calculations to gain insight into the mechanism. The reaction appears to be a single crystal – single crystal transformation in which a small concentration of H2 gas diffuses into the crystal before reacting to the ion pair without an “encounter complex” intermediate.

Hydrogen chemi-sorption in condensed-phase frustrated Lewis acid-base pairs

2019 Spring National Meeting

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