Synthesis, characterization and structure of diiron organometallic derivatives of 2,9-dimethyl-1,10-dihydro-dicyclopenta[a,h]naphthalene

A new fused ring compound 2,9-dimethyl-1,10-dihydro-dicyclopenta[a,h]naphthalene (VI), (H₂L), has been synthesized from naphthalic anhydride. Two organometallic binuclear complexes, [Cp*Fe-L-FeCp*] (1) and the mixed valence compound, (2) have been characterized by spectroscopic and electrochemical techniques. The structure resolution of (1) by single crystal X-ray diffraction shows that the two organometallic fragments Cp*Fe are in an anti position. Cyclic voltammetry exhibits a potential difference of 348 mV between both redox peaks. The Mössbauer investigation at different temperatures shows a uniform environment for the neutral compound (1) and two sites, assigned to Fe²⁺ and Fe³⁺ for the compound (2). The information gathered by all the previously mentioned techniques indicates that the studied binuclear complex belongs to the mixed valence class II complexes according to the classification of Robin and Day.