The nucleophilic addition of Nu 1 to [(η 5 -Cp)Fe(η 6 -cot)]PF 6 (1PF 6 ) (cot ) cyclooctatetraene) exclusively yields the neutral complex [(η 5 -Cp)Fe (1,2,3,4,5-η-C 8 with the nucleophiles linked to the cyclo-C 8 ligand solely and stereoselectively in exo position with respect to the metal center. The protonation of the neutral complexes 2a-c by addition of HBF 4 reveals the new ionic product [(η 5 -Cp)Fe(η 6 -C 8 H 9 -Nu 1 )]BF 4 (3BF 4 ) with a 1,2,3,4,5,6-η coordination mode of the cyclo-C 8 ligand. The cationic complexes 3a-c are suitable for a second nucleophilic addition affording the exo-6,8The cyclo-C 8 ligand can be cleaved as cis-5,7-disubstituted cycloocta-1,3-diene ( 5) by protonation of the complexes 4a-f with CF 3 CO 2 H in acetonitrile:In an attempt to construct fused bicyclic ring systems with annelated 9-to 13-membered cycles employing the ring-closing metathesis (RCM), a novel ring opening-ring closing metathesis reaction was encountered to yield new methylene-bridged, bicyclic systems (7).