Synthesis and characterization of tetraphenylporphyrin manganese(III) complexes of phenylcyanamide ligands

Abstract

Several complexes of TPPMn–L, where TPP is the dianion of tetraphenylporphyrin and L is monoanion of 4-methylphenylcyanamide (4-Mepcyd) ( 1), 2,4-dimethylphenylcyanamide (2,4-Me 2pcyd) ( 2), 3,5-dimethylphenylcyanamide (3,5-Me 2pcyd) ( 3), 4-methoxyphenylcyanamide (4-MeOpcyd) ( 4), phenylcyanamide (pcyd) ( 5), 2-chlorophenylcyanamide (2-Clpcyd) ( 6), 2,5-dichlorophenylcyanamide (2,5-Cl 2pcyd) ( 7), 2,6-dichlorophenylcyanamide (2,6-Cl 2pcyd) ( 8), 4-bromophenylcyanamide (4-Brpcyd) ( 9), and 2,3,4,5-tetrachlorophenylcyanamide (2,3,4,5-Cl 4pcyd) ( 10), have been prepared from the reaction of TPPMnCl and thallium salt of related phenylcyanamide. Each of the complexes has been characterized by IR, UV–Vis and 1H NMR spectroscopies. 4-Methylphenylcyanamidotetraphenylporphyrin manganese(III) crystallized with one molecule of solvent CHCl 3 in the triclinic crystal system and space group P 1 ¯ with the following unit cell parameters of: a = 11.596(6) Å; b = 11.768(9) Å; c = 17.81(2) Å; and α, β, γ are 88.91(9)°, 88.16(7)°, 67.90(5)°, respectively; V = 2251(3) Å 3; Z = 2. A total of 4234 reflections with I > 2 σ( I) were used to refine the structure to R = 0.0680 and R w = 0.2297. The Mn(III) shows slightly distorted square pyramidal coordination with the 4-methylphenylcyanamide in the axial position, coordinated from nitrile nitrogen. The reduction of each of the TPPMn–L complexes was also examined in dichloromethane and spectroelectrochemical behavior of ( 1) was investigated and compared to TPPMnCl.