Ring rotation of ferrocene in interlocked molecules in single crystals.

This work describes unique molecular motions of ferrocene-containing interlocked molecules observed by single-crystal X-ray crystallography. The rotational flexibility of ferrocene is achieved using combinations of ferrocene-tethered ammonium and 30-membered ring dibenzo-crown ether. By contrast, ferrocene was locked in the complex with an 18-membered ring dibenzo-crown ether and CH2Cl2. When the complex was heated at 358 K, CH2Cl2 was removed from the complex, which led to drastic structural changes, including a semieclipsed-to-disordered transition of ferrocene and flipping of the dibenzo-crown ether.