Figure 91.
(a) Catalytic reaction cycle for the Kemp elimination catalyzed by cage 37.353 (b) Autocatalysis of this reaction occurs in cage 35 in the presence of chloride.354 (c) X-ray structure of 325⊂37.302 (d) Structure of phosphoester guests bound by the chloride salt of cage 35 and X-ray structure of the BF4– salt crystallized with dichlorvos 327, showing both the internally and externally interacting guests.355 In both structural representations the guests are shown in space-filling mode, and the tetrafluoroborate anions that occupy the cage windows are shown with the frontmost anion omitted for clarity in both cases.