Frontispiece: Proton Order–Disorder Phenomena in a Hydrogen‐Bonded Rhodium–η 5 ‐Semiquinone Complex: A Possible Dielectric Response Mechanism

Proton Dynamics In their Full Paper on page 9682 ff. , M. Mitsumi et al. report a hydrogen‐bonded rhodium(II)–η 5 ‐semiquinone complex that exhibits a paraelectric–antiferroelectric second‐order phase transition at 237.1 K. Dielectric and 13 C CP/MAS NMR measurements revealed for the first time the relationship between the very first dielectric response of the hydrogen‐bonded proton and proton exchange rates. The dielectric response can be attributed to the rapid migration of the protonic solitons composed of η 6 ‐hydroquinone and η 4 ‐benzoquinone complexes, which would be generated in the hydrogen‐bonded chain.