The crystal structures of compounds containing a transition metal-carbon sigma bond

Conformation-reactivity relationships for the organotransition metal complexes (.eta.5-C5H5)Fe(CO)(PPh3)R and (.eta.5-C5H5)Re(NO)(PPh3)R (R = alkyl and aryl)

“…The rather broad energy well corresponds to the two phenyl rings being approximately parallel, consistent with the X-ray crystallographic data reported for (7j5-C5H5)Fe(CO)(PPh3)Ph. 47 The PE maximum occurs when the planes of the two phenyl groups are perpendicular to each other.…”