Mononuclear high-spin iron(III) phthalocyanines

Abstract

2,9(or 10),16(or 17), 23(or 24)-Tetradecyloxycarbonylphthalocyaninatoiron, FeTDPc, and 2,3,9,10,16,17,23,24-octadecyloxycarbonylphthalocyaninatoiron, FeODPc, were synthesized and characterized. These compounds seem to be in trivalent iron high-spin state in solvents such as chloroform, dichloromethane, benzene, and chlorobenzene, although their counter anion could not be detected by elemental analyses. They react with strong bases such as pyridine and imidazoles to form their mono- and subsequently their di-base complexes with formation constant of >10⁶ and < 200 dm³ mol⁻¹, respectively, in dichloromethane at 20 °C. The resultant mono-adducts appear to be trivalent iron low-spin while the di-base adducts are bivalent iron low-spin state complexes. The addition of ca. 10–30 equivalent of tetrabutylammonium-chloride or -bromide (electrolyte) to the solution containing FeTDPc or FeODPc, causes their spin-state change from iron(III) high to low-spin state. In a solid power state, however, both FeTDPc and FeODPc exist as a mixture of high-spin iron(III)- and intermediate-spin iron(II) species. Strangely, when these compounds are dissolved in polystyrene, i.e. each molecules are isolated from each other, the signals originated from the iron(II) component disappear.