Synthesis and characterisation of pentaphenylcyclo-pentadienyliron arene sandwich complex cations [Fe(η5-C5Ph5)(arene)]+ and the X-ray crystal structure of the [Fe(η5-C5Ph5)(η6-C6H5Me)]+ cation

Abstract

A series of [Fe(η⁵-C₅Ph₅)(η⁶-arene)]⁺ complex cations [arene = benzene, toluene, o-, m- and p-xylene, mesitylene, durene (1,2,4,5-tetramethylbenzene) or hexamethylbenzene] is reported. The structure of the cation of the toluene derivative was determined by single-crystal X-ray diffraction [refined to R 0.034, R′ 0.038 with 4328 data having I 2.5σ(I)]. It crystallises from acetone as discrete molecules in the monoclinic space group P2₁/n, with a= 10.016(2), b= 21.568(6), c= 16.920(4)Å, β= 92.17(2)° and Z= 4. The cyclopentadienyl ring binds in an η⁵ fashion and the Fe–C (C₆ ring) bond distances average 2.093(3)Å; the Fe–C (C₅ ring) bond distances average 2.113(4)Å. The Fe–C (C₅ ring plane) and Fe–C (C₆ ring plane) distances are 1.702(5) and 1.588(5)Å, respectively. All complexes exhibit two reversible reductions.