Molecular structures of the pentaphenylcyclopentadienyl iron complexes [(C5Ph5)Fe(CO)2R] (R= Me, Ph, iPr and Bu).

Karlheinz Sünkel,Christian Klein-Hessling

doi:10.1107/s2053229621006057

Karlheinz Sünkel, Christian Klein-Hessling

Open Access

https://doi.org/10.1107/s2053229621006057

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Abstract

The PdII-catalysed reaction of [(C5Ph5)Fe(CO)2Br] with Grignard compounds RMgX or butyl lithium gave the iron alkyl/aryl complexes [(C5Ph5)Fe(CO)2R] (R= Me, Ph, iPr and Bu) in 59-73% yield, namely, dicarbonylmethyl(η5-pentaphenylcyclopentadienyl)iron, [Fe(CH3)(C35H25)(CO)2], dicarbonyl(η5-pentaphenylcyclopentadienyl)phenyliron, [Fe(C6H5)(C35H25)(CO)2], dicarbonyl(isopropyl)(η5-pentaphenylcyclopentadienyl)iron, [Fe(C3H7)(C35H25)(CO)2], and butyldicarbonyl(η5-pentaphenylcyclopentadienyl)iron, [Fe(C4H9)(C35H25)(CO)2]. The crystal structure determinations showed the usual `paddle-wheel' orientation of the phenyl rings, with an average canting angle of ca 50°. The bond parameters are mainly dictated by the steric requirements of the alkyl/aryl groups and only the phenyl complex shows electronic effects.

Highlights

Pentaarylcyclopentadienyl complexes have been known for nearly 60 years
During the course of our studies on the coordination chemistry of perhalogenated cyclopentadienyl complexes (Klein-Heßling et al, 2021; Sunkel et al, 2015) we studied the [(C5X5)Fe(CO)2R] system
The synthesis is based on a procedure that was described for the preparation of aryl iron complexes [(C5H5)Fe(CO)2Ar]

Summary

Introduction

Pentaarylcyclopentadienyl complexes have been known for nearly 60 years They were studied mainly because the bulky nature of these cyclopentadienyl derivatives gives their complexes high kinetic stability, including the formation of stable radicals (Field et al, 2011) or unusual structures in main group or lanthanoid metallocenes (Schulte et al, 2020). A very important subgroup of compounds containing the [CpFe(CO)] moiety contains the derived alkyl and aryl complexes [CpFe(CO)2R] (Pannell & Sharma, 2010). These compounds were shown to have catalytic properties, for example, in dehydrogenative couplings (Fukumoto et al, 2015; Argouarch et al, 2012) or, perhaps more importantly, as reagents in photoinduced DNA cleavage (Mohler et al, 2002; Mohler & Shell, 2005). It seemed worthwhile to study compounds of the type [(C5Ph5)Fe(CO)2R], which might combine the unique properties of the pentaphenylcyclo-

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