Mol­ecular structures of the penta­phenyl­cyclo­penta­dienyl iron com­plexes [(C(5)Ph(5))Fe(CO)(2) R] (R = Me, Ph, iPr and Bu)

The Pd(II)-catalysed reaction of [(C(5)Ph(5))Fe(CO)(2)Br] with Grignard com­pounds RMgX or butyl lithium gave the iron alk­yl/aryl com­plexes [(C(5)Ph(5))Fe(CO)(2) R] (R = Me, Ph, iPr and Bu) in 59–73% yield, namely, di­carbonyl­meth­yl(η(5)-penta­phenyl­cyclo­penta­dien­yl)iron, [Fe(CH(3))(C(35)H(25))(CO)(2)], dicarbon­yl(η(5)-penta­phenyl­cyclo­penta­dien­yl)phenyliron, [Fe(C(6)H(5))(C(35)H(25))(CO)(2)], dicarbon­yl(isoprop­yl)(η(5)-penta­phenyl­cyclo­penta­dien­yl)iron, [Fe(C(3)H(7))(C(35)H(25))(CO)(2)], and butyl­dicarbon­yl(η(5)-penta­phenyl­cyclo­penta­dien­yl)iron, [Fe(C(4)H(9))(C(35)H(25))(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.