Distorted Sandwich Compounds: [1]Ferrocenophanes and [2]Ruthenocenophanes

The current world record for the largest tilt angle in a [1]ferrocenophane is held by complex 1; no [1]metallocenophanes have been prepared with a bridge smaller than the sulfur atom here (I. Manners et al. Angew. Chem. Int. Ed. Engl. 1995, 34, 1506). The greater the ring strain in metallocene derivatives, the more readily they polymerize giving compounds like 3, which is formed from 2 by desulfurization with phosphane. Since the metal atoms in these polymers are arranged in a regular sequence, interesting material properties are anticipated.