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Electronic Tuneable Dynamic and Electrochemical Behavior of N ‐(Diferrocenylmethylene)anilines
Author(s) -
Saloman Sebastian,
Hildebrandt Alexander,
Korb Marcus,
Schwind Manuel,
Lang Heinrich
Publication year - 2015
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201500557
Subject(s) - chemistry , aniline , electrochemistry , substituent , redox , ketone , metal , crystallography , schiff base , electronic effect , medicinal chemistry , stereochemistry , inorganic chemistry , electrode , organic chemistry , steric effects
Abstract N ‐(Diferrocenylmethylene)anilines Fc 2 C=N‐4‐C 6 H 4 – R [ 3a R = CF 3 ; 3b R = Cl; 3c R = H; 3d R = CH 3 ; 3e R = OCH 3 ; Fc = Fe(η 5 ‐C 5 H 4 )(η 5 ‐C 5 H 5 )] with different electron‐donating or ‐withdrawing functionalities were synthesized by a Schiff base reaction of substituted anilines H 2 N‐4‐C 6 H 4 ‐ R ( 2a – 2e ) with diferrocenyl ketone ( 1 ). Within variable temperature NMR experiments activation enthalpies between 68.1 and 72.3 kJ · mol –1 for an E / Z exchange reaction of the imines were determined. It could be shown that the inversion barrier depends on the nature of the substituent R . Furthermore, electrochemical measurements were performed, demonstrating that the ferrocenyl units are oxidized separately. The electron density at the nitrogen atom is influenced by the electronic nature of the aniline groups R thus giving rise to varying attractive electrostatic interactions to the ferrocenium units. This results in decreasing redox separations for the ferrocenyl oxidation with a decreasing electron‐withdrawing character of the anilines. Spectroelectrochemical measurements confirmed that the redox separations are mainly caused by electrostatic interactions as no electronic metal–metal coupling is observed. For 3a , b , d , e the molecular structure in solid state was determined by single‐crystal X‐ray diffractometry. In all compounds different forms of π–π interactions occur. Compound 3a shows a complex network of parallel‐ and T ‐shaped π–π interactions, whereas 3d is forming 5‐ and 6‐membered cycles.