Synthesis and structure of bis(3,3-dimethyl-3,4-dihydroisoquinolyl-1) ketoxime

The reaction of bis(3,3-dimethyl-3,4-dihydroisoquinolyl-1)methane with NaNO2 resulted in the formation of bis(3,3-dimethyl-3,4-dihydroisoquinolyl-1) ketoxime (I). The crystal and molecular structure of I was determined (X-ray structure analysis, Enraf-Nonius CAD-4, MoKα-radiation, graphite monochromator, θ/2θ scan, 2θmax = 58°, 4800 unique reflections; a = 10.327(4), b = 9.070(5), and c = 21.62(1) Å; β = 94.02(3)°; V = 2020(1) Å3; Z = 4; and sp. gr. Pn). In the crystal, I exists in the oxime tautomeric form. Two symmetry-independent molecules are bound into a dimer through the intermolecular N = OH⋯N3 cycl hydrogen bond. Both molecules are nonplanar; the dihedral angles between the mean planes of their 3,4-dihydroisoquinoline moieties are 72° and 74°. According to IR and electron absorption spectra, the tautomeric form of compound I is also retained in solutions, and the π-conjugation between the 3,4-dihydroisoquinoline fragments of I is actually absent.