Synthesis, spectral, and electrochemical characterization of the first arsenic(V)-phthalocyanines

The first arsenic(V)-phthalocyanines, [As(tbpc)X(2)](+), where tbpc denotes tetra(tert-butyl)phthalocyaninate, C(48)H(48)N(8)(2-) and X = F, Cl, and Br) have been prepared through an appropriate oxidative addition process to a highly soluble arsenic(III) derivative, [As(tbpc)](+). Among them, [As(tbpc)F(2)](+) has been isolated as PF(6)(-) salt. Unlike conventional metal derivatives of phthalocyanines, they show a significantly red-shifted (by >1000 cm(-1)) Q-band and facile reduction of the macrocyclic ligand (redox potentials for [As(tbpc)F(2)](+) have been determined by cyclic voltammetry; 1.13 V vs ferricinium(+)/ferrocene (tbpc(-/2-)), -0.45 V (tbpc(2-/3-)), and -0.90 V (tbpc(3-/4-)), of which the values are anodically shifted by about 1 V) as compared to those of conventional phthalocyanines. Although the anomaly in their spectral and electrochemical properties is similar to that of the known antimony analogues, the arsenic-phthalocyanines have been found less stable.