Some reactions of phthalocyanines of silicon, germanium and tin under alkaline conditions

Abstract

Phthalocyaninatosilicon(IV), germanium(IV) and tin(IV) dihydroxides react with potassium hydroxide in o-xylene in the presence of crown ether 15-cr-5 initially forming paramagnetic compounds of dark-blue color with absorption bands at 580–590 nm and 620–625 nm and then diamagnetic compounds of red color with an absorption band at 518–523 nm. The red compounds are very reactive towards proton donors, restoring the initial phthalocyanines, and oxidation agents under decomposition of the phthalocyanines. The color changes are due to the formation of the mono- and dianions, ( PcMO 2)2- and ( PcMO 2)-, accompanied with transfer of electrons from oxygen atoms to the tetrapyrrol macrocycle.