Spectroscopic studies on charge-transfer complexes formed in the reaction of ferric(III) acetylacetonate with sigma- and pi-acceptors

The reaction of ferric(III) acetylacetonate (donor), Fe(acac)3, with iodine as a sigma-acceptor and with other different pi-acceptors have been studied spectrophotometrically at room temperature in chloroform. The pi-acceptors used in this investigation are 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil and 7,7',8,8'-tetracyanoquinodimethane (TCNQ). The results indicate the formation of 1: 1 charge-transfer complexes with a general formula, {[}Fe(acac)(3) (acceptors)]. The iodine complex was shown to contain the triiodide species, {[}Fe(acac)(3)](2)I+I3-, based on the electronic absorptions as well as on the Far-infrared absorption bands characteristic for the non-linear triiodide species, I-3(-), with C-2v symmetry. The proposed structure of this complex is further supported by thermal and middle infrared measurements. (C) 2003 Elsevier B.V. All rights reserved.