Fast atom bombardment mass spectral observations on some

b-halogenated tetraphenylporphyrins and their iron derivatives

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Eur. J. Mass Spectrom. 3, 355 - 360 (1997)

Fast atom bombardment mass spectral observations on some b-halogenated tetraphenylporphyrins and their iron derivatives

Tristano Boschi, Giuseppe D'Arcangelo and Pietro Tagliatesta^*
Dipartimento di Scienze e Tecnologie Chimiche, Universit degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica, I-00173 Rome, Italy.

ABSTRACT:

The fast atom bombardment mass spectral observations on some b-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.

Keywords: porphyrins, iron porphyrins, b-halogenated metalloporphyrins, FAB mass spectrometry, dehalogenation processes, iron .mu.-oxo porphyrin dimers.