Synthesis and Crystal Structure of a Phenazine N-oxide

Abstract

The preparation and crystal structure of 8-chloro-1H-pyrrolo[2,3-b]phenazine 5-oxide (1) are described. Compound 1 formed dark purple crystals from deeply colored solution in methanol. Crystal plates were in the triclinic system, P-1 space group with unit cell parameters a = 6.9514(8), b = 9.1568(10), c = 10.2067(11), α = 84.509(2), β = 82.936(2), γ = 72.357(2) and a cell volume of 613.25(12) A−3. The title compound which contains the first example of the extensively conjugated pyrrolo-phenazine N-oxide system exhibits strong light absorption in the green to cyan wavelength range which disappears upon protonation.