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

The reaction of ferric(III) acetylacetonate (donor), Fe(acac) 3, with iodine as a σ-acceptor and with other different π-acceptors have been studied spectrophotometrically at room temperature in chloroform. The π-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] 2I +I 3 −, 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.