Synthesis and the molecular and crystal structure of 1, 4-dihydro-1-methyl-4-(2, 3, 3-tricyanoallylidene)quinoline

The reaction of 1, 4-dimethylquinolinium iodide with tetracyanoethylene in presence of triethylamine proceeds highly regioselectively with the formation of l, 4-dihydro-l-methyl-4-(2, 3, 3-tricyanoallylidene)quinoline. It was shown by an x-ray structural investigation that its crystal is built from two, not quite planar, symmetrically independent molecules (IIIa) and (IIIb): The dihedral angles in these between the dihydroquinoline nucleus and the tricyanoallylidene group are 8.6 and 10.8. An examination is made of the influence on the structure of the molecules of steric factors and effects of the conjugation of the donor and acceptor parts of the molecules, leading to considerable intramolecular transfer of charge. In the crystal the molecules form stacks of the type ...aabb... with the participation of both symmetrically independent molecules and with interplanar distances d of 3.341, 3.449, and 3.347 å, which may be conducive to intermolecular transfer of charge.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 690–696, March, 1991.