Bipyrrole, 2,2 - spectra

The reaction of 2,2 -bipyrrole with orthoformic acid triethyl ester in the presence of phosphoryl chloride (POCI3) produced a compound which gave the H NMR spectrum 5. Which compound has been prepared ... 

Mass spectrum of one enantiomer of C9H4N2CI6 from Box 24-1. [From w. Vetter and W. Jun,"Elucidation of a Polychlorinated Bipyrrole Structure Using Enantioseiectlve GC,"Anal. Chem. 2002, 74,4287.]... 

Finally, a coupled and decoupled 13C NMR spectrum of 2,2 -bipyrrole (Fig. 4.14(a,b) and an inversion-recovery series of 2,2 -bi pyridine (Fig. 4.15 [73 i]) illustrate signal assignments of heteroaromatic compounds by means of carbon-proton couplings and spin-lattice relaxation times. These spectra also exemplify the characteristic shift differences between n-excessive (2,2 -bipyrrole) and n-deficient heteroaromatic compounds (2,2 -bipyridine). 

The smallest pentapyrrolic is [20]pentaphyrin(1.0.1.0.0) (orangarin) 152. Acid-catalyzed condensation between hexamethyl terpyrrole 146 (Scheme 62) and diformyl bipyrrole 124 (1995CEJ56) furnishes 152. Compared to Huckel (18jt, 22it) aromatic species, 152 is 20jt antiaromatic as attested by its extremely broad absorption spectrum. While the pentapyrrolic aromatic species displays appreciable fluorescence, no appreciable fluorescence is seen for the antiaromatic species. 

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