Intramolecular hydrogen bonding and tautomerism in 1-[N-(4-bromophenyl)]aminomethylidene-2(1H) naphthalenone

1-[N-(4-bromophenyl)]aminomethylidene-2(1H)naphthalenone (C17H12NOBr) (1) was synthesized and its crystal structure was determined. Compound (1) is monoclinic, space group P21/n with a = 4.808(1) Å, b = 20.617(1) Å, c = 13.750(1) Å, β = 93.004(1)°, V = 1361.11(3) Å3, Z = 4, Dc = 1.592 g·cm−3, μ(Mo Kα) = 3.014 mm−1, R = 0.051 for 1013 reflections [I > 2σ(I)]. There is a strong intramolecular hydrogen bond of distance 2.544(2) Å between the hydroxyl oxygen atom and imine nitrogen atom, the hydrogen atom essentially being bonded to the nitrogen atom. The title molecule is not planar. X-ray crystal structure determination reveals the existence of the keto (or predominantly keto) tautomer in (1). Spectra of compound (1) were observed by IR and NMR, and UV–visible spectra of (1) were studied in different solvents and acidic media.