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

Several five coordinate complexes of [(TPP)FeIII(L)] in which TPP is the dianion of tetraphenylporphyrin and L is the monoanion of phenylcyanamide (pcyd) (1), 2,5-dichlorophenylcyanamide (2,5-Cl2pcyd) (2), 2,6-dichlorophenylcyanamide (2,6-Cl2pcyd) (3), and 2,3,4,6-tetrachlorophenylcyanamide (2,3,4,6-Cl4pcyd) (4) have been prepared by the reaction of [(TPP)FeIIICl] with appropriate thallium salt of phenylcyanamide. Each of the complexes has been characterized by IR, UV–Vis and 1H NMR spectroscopic data. Dark red-brown needles of [(TPP)FeIII(2,6-Cl2pcyd)] (C51H31Cl2FeN6 · CHCl3) 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) Å out of plane of the porphyrin toward phenylcyanamide ligand. In non-coordinating solvents, such as benzene or chloroform, these complexes exhibit 1H 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 TPPFeIIICl.