Influence of electronic conjugation and steric effects on the crystal structures of imino- and hydrazido-derivatives of ferrocenecarbaldehyde

Abstract

The crystal and molecular structures of [Fe(C₅H₅)(C₅H₄CHNC₆H₄X-p)](X = Br or F) have been determined. The two compounds have markedly different molecular conformations. These are compared with the structures of two series of related ferrocenyl compounds and it is found that the major driving force for the molecular conformation is intra- rather than inter-molecular interaction. The compounds all have electron-withdrawing CN groups which have previously been shown to act as electron sinks. All the structures have bond lengths in keeping with this finding, though a major steric interaction disguises some bond-length information which would have shed more light on the overall electronic structure of the molecule. The value of Mössbauer spectroscopic data as a complement to the X-ray structural findings is demonstrated.