Novel ferrocene imide derivatives: synthesis, conformational analysis and X-ray structure.

The synthesis and structural characterization of the ferrocene imide derivatives Fc-CO-NH-CO-Me (), Fc-CO-NH-CO-Fc () and Fc-CO-NH-CO-Fn-CO-NH-CO-Fc () have been reported. The mononuclear, dinuclear and trinuclear ferrocene imides were prepared by the reaction of ferrocenecarboxamide (), with acetyl chloride, ferrocenecarbonyl chloride () and ferrocene-1,1'-(dicarbonyl chloride) (), respectively. IR spectroscopic analysis revealed the absence of intramolecular hydrogen bonds in solutions of imides , and . The crystal packing of -acetylferrocenecarboxamide () is characterized by N-H⋯O hydrogen bonds forming centrosymmetric dimers, while the molecules of its homologue -methylferrocenecarboxamide () are self-assembled by intermolecular N-H⋯O bonds into infinite chains. A detailed conformational analysis (DFT study) suggests the - configuration of ferrocene imide derivative in solution. The effect of different substituents attached to bridged imide nitrogen on conformational properties of bis-ferrocenyl imides was further investigated and results compared to the existing experimental data.