Synthesis, Characterization, Crystal and Molecular Structure of 1,5-Dihydro-2H-cyclopenta[1,2-b:5,4-b′]dipyridin-2-imine

The reaction of 1,5-diliydro-2H-cyclopenta[1,2-b:5,4-b'ldipyridin-2-one (3) with an alkylamine (butvlamine, hexylamine or ethylenediamine) yields, quite unexpectedly and in the absence of catalyst, the novel compound 1,5-dihydro-2H-cyclopentafl,2-b:5.4-b']dipyridin-2-imine (4) as the sole, analytically pure, solid product, which was fully characterized. The structure of 4 was unequivocally solved by single-crystal X-ray-diffraction analysis. The compound crystallizes in a monoclinic cell (space group P 2(1/c)). with two molecules in the asymmetric unit. held together by intermolecular H-bonds. Compound 4 could be interesting as a bi- or even tridentate ligand, and exhibits a strong fluorescence upon excitation at 310 nm. A mechanism, based on the observed C-N bond cleavage, is proposed.