X-ray structure and H-1 NMR assignment of 1-methyl-1,4-dihydro-4-oxo-4 '-methylthio-3,3 '-diquinolinyl sulfide

The title compound (C20H16N2OS2) is orthorhombic, with a = 9.290(2), b = 11 .874(3), c = 15.971(4) Angstrom and space group P2(1)2(1)2(1). Two quinolin e moieties are nearly perpendicular to each other (103.5(2)degrees). Two pa irs of heteroatoms in ortho-positions are in very close contact. The 4-oxo and 4'-methylthio groups are trans-orientated to the central sulfur bridge. The sulfide preserves a skew conformation. The unusual H-2' proton upfield shift is induced by the ring current effect.