(Indenyl)Iron Complex [(η5‐indenyl)Fe(η‐C6H6)]+: Synthesis, Arene Exchange Reactions and Bonding

• Published in: ChemistrySelect (Weinheim) Vol. 2; no. 12; pp. 3549 - 3556
• Main Authors: Loginov, Dmitry A., Chamkin, Alexander A., Kharitonov, Vladimir B., Sovdagarova, Elizaveta R., Nelyubina, Yulia V., Kudinov, Alexander R.
• Format: Journal Article
• Language: English
• Published: 24-04-2017
• Subjects: Arene complexes; DFT calculations; Indenyl complexes; Iron; Sandwich compounds
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201700747

The indenyl‐benzene complex [(η5‐indenyl)Fe(η‐C6H6)]+ (2) was synthesized by photochemical reaction of the cyclohexadienyl derivative [(η5‐C6H7)Fe(η‐C6H6)]+ and indenyl anion with the subsequent treatment of complex (η5‐C6H7)Fe(η5‐indenyl) formed by acetic acid. Visible light irradiation of cations [(η5‐indenyl)Fe(η6‐indene)]+ (1) or 2 in the presence of substituted benzenes in CH2Cl2 results in arene exchange giving [(η5‐indenyl)Fe(η6‐arene)]+ (arene=o‐xylene (3 a), mesitylene (3 b), hexamethylbenzene (3 c) and [2.2]paracyclophane (3 d)). The rate of this reaction is lower than for the related cyclopentadienyl complex [CpFe(η‐C6H6)]+. μ‐Pentaphospholyl triple‐decker complex [(η5‐indenyl)Fe(μ‐η:η‐cyclo‐P5)FeCp*]+ (4) was synthesized by photochemical reaction of 1 with Cp*Fe(η‐cyclo‐P5). The structures of 2PF6, 3 cPF6 and 4PF6 were determined by X‐ray diffraction. According to energy decomposition analysis, the metal‐benzene bonding in 2 is weaker than in [CpFe(η‐C6H6)]+ but stronger than in [Cp*Fe(η‐C6H6)]+. The mechanism of thermal benzene replacement in 2 and [CpFe(η‐C6H6)]+ as well as structure of excited state were analyzed by DFT calculations.
The indenyl‐benzene complex [(η5‐indenyl)Fe(η‐C6H6)]+ which was synthesized from the cyclohexadienyl derivative [(η5‐C6H7)Fe(η‐C6H6)]+ and indenyl anion proved to be useful synthon of the cationic species [Fe(η5‐indenyl)]+, as illustrated by the preparation of its arene and triple‐decker derivatives.