The importance of the length of the –(CH2)n– chain on the cycloplatination of the [(η5-C5H5)Fe{(η5-C5H4)–CHdouble bond; length as m-dashN–(CH2)n–NMe2}] (n = 2 or 3) ligands and the properties of the platinacycles

The study of reaction of [(η5-C5H5)Fe{(η5-C5H4)–CHdouble bond; length as m-dashN–(CH2)2–NMe2}] (1b) with cis-[PtCl2(dmso)2] under different experimental conditions is reported. When the reaction was carried out in the presence of NaOAc in a OAc−/1b molar ratio = 2 in a mixture of toluene/methanol (20:5) under reflux for 3 days, the cycloplatinated complex: [Pt{[(η5-C5H3)–CHdouble bond; length as m-dashN–(CH2)2–NMe2]Fe(η5-C5H5)}Cl(dmso)] (2b) together with small amounts of ferrocenecarboxaldehyde and cis-[Pt{(η5-C5H5)Fe[(η5-C5H4)–CHdouble bond; length as m-dashN–(CH2)2–NMe2])}Cl2(dmso)] (3b) was isolated. The X-ray crystal structure of 2b confirmed that the ligand acts as a terdentate image group. Complex 2b reacted with the stoichiometric amount of PPh3 giving [Pt{[(η5-C5H3)–CHdouble bond; length as m-dashN–(CH2)2–NMe2]Fe(η5-C5H5)}Cl(PPh3)] (4b). Electrochemical studies of 2b–4b reveal that the proclivity of the ferrocenyl moiety to oxidise is dependent on the mode of binding of the ligand to the platinum(II).