Reversible Single Crystal to Single Crystal Transformation through Fe-O(H)Me/Fe-OH_2 Bond Formation/Bond Breaking in a Gas-Solid Reaction at an Ambient Condition

摘要

We have characterized all three states/stages of the reversible gas-solid reaction, namely, compound 1 (water coordinated), compound 2 (MeOH coordinated), and regenerated 1 by single-crystal X-ray crystallography. This is not only a reversible single-crystal-to-single-crystal transformation through Fe-O(H)Me bond formation and Fe-OH_2 bond breaking (and vice versa) in a gas—solid reaction, it is selective toward methanol the molecule as well, which is evidenced from the following facts. When the single crystals of compound 1 were exposed to a mixture of different alcohols, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, etc. (in the case of a high-boiling alcohol, the setup was warmed up in order to initialize the vaporization), the exposed crystals of 1 remained unreacted with all alcohols except methanol vapor (see section 2D in Supporting Information for details). It is important to note that, both H_2O and MeOH molecules are the competitors for the iron center, and the system needs water vapor to regenerate compound 1 in maintaining the cycle (e.g., Scheme 2). Thus, the forward reaction (compound 1 → compound 2) is inhibited/retarded by the presence of water molecules in MeOH solvent. However, it has been observed that the present system (compound 1) can recognize MeOH vapor from a 95 MeOH solvent (95 MeOH and 5 H_2O).