Synthesis of ferrocenyldiimine metal carbonyl complexes and an investigation of the Mo adduct encapsulated in cyclodextrin

Abstract

Cr and Mo tetracarbonyl complexes bearing the diimine ligand N,N′-bis(ferrocenylmethylene)ethylenediamine (FcNN) have been prepared from the ligand and M(CO)6. Two isomeric forms of (FcNN)Mo(CO)4, corresponding to the cis,cis and cis,trans geometries with respect to the CN bonds of the free ligand, were shown to exist in a 1∶12.5 ratio by 1H NMR (NOE experiments). By contrast, only the trans,trans isomer is observed for the Cr complex (FcNN)Cr(CO)4. The compounds (FcNN)M(CO)4 show ferrocene-based irreversible oxidation processes that lead to the deposition of a film at the electrode surface. (FcNN)Mo(CO)4 was immobilised in permethylated β-CD (TRIMEB) by addition of the guest to a solution of TRIMEB in dichloromethane. Removal of the solvent led to the isolation of an inclusion compound with a 2∶1 host∶guest stoichiometry, as evidenced by powder X-ray diffraction, thermogravimetric analysis, FTIR and 13C CP MAS NMR spectroscopy. The electrochemical properties of (FcNN)Mo(CO)4 upon encapsulation are discussed.