N-methyltetraphenylporphyrin with an inverted N-methylpyrrole ring: the first isomer of N-methyltetraphenylporphyrin

Abstract

In the course of the mild methylation of 5,10,15,20-tetraphenyl-21-carbaporphyrin (CTPPH₂) a novel isomer of N-methyl-5,10,15,20-tetraphenylporphyrin with an inverted N-methylated pyrrole ring, i.e. 2-N-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrin (2-NCH₃TPPH) has been synthesised. The protonation of 2-NCH₃CTPPH proceeds stepwise including mono- and two di-cationic species. 2-NCH₃CTPPH can be considered as a new anion-specific binding agent. The lability of the 21-CH proton afforded the easy insertion of nickel(II) to form a stable organometallic macrocyclic complex.