Synthesis and characterization of tetraphenylporphyrin iron(III) complexes with substituted phenylcyanamide ligands

Several five coordinate complexes of [(TPP)Fe(III)(L)] in which TPP is the dianion of tetraphenylporphyrin and L is the monoanion of phenylcyanamide (pcyd) (1), 2,5-dichlorophenylcyanamide (2,5-Cl(2)pcyd) (2), 2,6-dichlorophenylcyanamide (2,6-Cl(2)pcyd) (3), and 2,3,4,6-tetrachlorophenylcyanamide (2,3,4,6-Cl(4)pcyd) (4) have been prepared by the reaction of [(TPP)Fe(III)Cl] with appropriate thallium salt of phenylcyanamide. Each of the complexes has been characterized by IR, UV-Vis and (1)H NMR spectroscopic data. Dark red-brown needles of [(TPP)Fe(III)(2,6-Cl(2)pcyd)] (C(51)H(31)Cl(2)FeN(6)(.)CHCl(3)) Crystallize in the triclinic system. The crystal structure of Fe(III) compound shows a slight distortion from square pyramidal coordination with the 2,6-dichlorophenylcyanamide anion in the axial position through nitrile nitrogen atom. Iron atom is 0.47(1) angstrom out of plane of the porphyrin toward phenylcyanamide ligand. In non-coordinating solvents, such as benzene or chloroform, these complexes exhibit (1)H NMR spectra that are characteristic of high-spin (S = 5/2) species. The X-ray crystal structure parameters are also consistent with high-spin iron(III) complexes. The iron(III) phenylcyanamide complexes are not reactive toward molecular oxygen; however, these complexes react with HCl and produce TPPFe(III)Cl. (c) 2006 Elsevier B.V. All rights reserved.