Nitrosation and nitrosylation of haemoproteins and related compounds. Part 3. Attack at the vinyl groups of protoporphyrin dimethyl ester. X-Ray analysis of 81(E)-82-nitroprotoporphyrin dimethyl ester

Abstract

Treatment of heptaethyl(vinyl)porphyrin (1) with acidified nitrite solution gives a greenish porphyrin which is shown to be 2¹(E)-3,7,8,12,13,17,18-heptaethyl-2-(2-nitrovinyl)porphyrin, (2). Protoporphyrin dimethyl ester (3) similarly treated gives a mixture of compounds, including two greenish porphyries which are formulated as the analogous 3(8)-(2-nitrovinyl)-8(3)-vinyldeuteroporphyrin derivatives. The less-polar isomer was crystalline and shown to be 8¹(E)-8²-nitroprotoporphyrin dimethyl ester (4) by X-ray analysis. Crystals are triclinic, space group P, a= 10.591(4), b= 12.967(1), c= 14.203(2)Å, α= 105.79(1), β= 94.91(3), γ= 94.99(2)°. The structure was solved by direct methods and refined to R 0.082.