Inter- versus Intraannular Ring-Closing Metathesis of Polyallylferrocenes: Five-Fold RCM within a Single Molecule

Treatment of decaallylferrocene (1) with the Grubbs-II catalyst in refluxing dichloromethane has promoted the 5-fold ring-closing metathesis in 1 to afford single-bridged bis­(1,4,5,8-tetrahydrofluorenyl)­iron­(II) species 3 in excellent yield. The preferential formation of 3 over quintuply bridged “superferrocenophane” 2 was explained as the intraannular RCM process being preferred over the interannular one in the reactions of polyallylferrocenes.