Synthesis and characterization of novel charge transfer complexes formed by N,N '-bis(ferrocenylmethylidene)-p-phenyl and N-(ferrocenylmethylidene)aniline

N,N'-Bis(ferrocenylmethylidene)-p-phenylenediamine 1 and N-(ferrocenylmethy lidene) aniline 2 are readily synthesized by Schiff base condensation of ap propriate units. Iodine (I-2), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (D DQ), tetrachloro-1,4-benzoquinone (CA), tetracyanoethylene (TCNE) and 7,7,8 ,8-tetracyanoquinodimethane (TCNQ) form charge transfer complexes with 1 an d 2. IR spectroscopy suggests an increase in the amount of charge transferr ed from the ferrocenyl ring to the oxidant in the order, I-2 < CA < TCNQ < TCNE approximate to DDQ. EPR spectra of the oxidized binuclear complexes ar e indicative of localized species containing iron- and carbon-centered radi cals. The Mossbauer spectrum of the iodine oxidized complex of 1 reveals th e presence of both Fe(III) and Fe(II) centers. Variable temperature magneti c and Mossbauer studies show that the ratio of Fe(III)/Fe(II) centers varie s as a function of temperature. The larger Fe(II)/Fe(III) ratio at lower te mperatures is best explained by a retro charge transfer from the iodide to the iron(III) metal center. There is negligible solvent effect on the forma tion of the iodine oxidized charge transfer complex of 1. (C) 1999 Elsevier Science S.A. All rights reserved.