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

Abstract

The Pd^II-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.

Keywords: Pd-catalysed; carbonyl; crystal structure; iron; pentaphenylcyclopentadienyl.