Fast Atom Bombardment Mass Spectral Observations on Some β-Halogenated Tetraphenylporphyrins and Their Iron Derivatives

Abstract

The fast atom bombardment mass spectral observations on some β-halogenated tetraphenylporphyrins and their iron derivatives were compared in order to investigate the relative stability of these complexes. The investigated compounds are represented as O[FeBr₄TPP]₂, O(FeTPP)₂, O[FeTPP(4-Br)]₂, O[FeTPP(4-OCH₃)]₂, H₂(Br₄TPP), Fe(Br₄TPP)Cl, H₂(Cl₁₆TDCDMPP) and Fe(Cl₁₆TDCDMPP)Cl where Br₄TPP is the dianion of 7,8,17,18-tetrabromo-5,10,15,20-tetraphenylporphyrin, TPP is the dianion of 5,10,15,20-tetraphenylporphyrin, TPP(4-Br) is the dianion of 5,10,15,20-tetra(4-bromo)phenylporphyrin, TPP(4-OCH₃) is the dianion of 5,10,15,20-tetra-(4-methoxy)-phenylporphyrin and Cl₁₆TDCDMPP is the dianion of 2,3,7,8,12,13,17,18-octachloro,5,10,15,20-tetra-(2,6-dimethoxy,3,5-dichloro)phenylporphyrin. The stability of each molecular ion and the subsequent fragmentations were correlated to the substitution of the porphyrin rings and to the loss of steric hindrance.