1-(4-Cyanophenyldiazen-2-ium-1-yl)-2-naphtholate

Abstract

In the mol­ecule of the zwitterionic title compound, C17H11N3O, the naphthalene ring system is planar [maximum deviation = 0.029 (3) Å] and is oriented at a dihedral angle of 3.55 (3)° with respect to the benzene ring. An intra­molecular N—H⋯O hydrogen bond results in the formation of a planar six-membered ring. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into centrosymmetric dimers.

Torsionally Responsive C3-Symmetric Azo Dyes: Azo−Hydrazone Tautomerism, Conformational Switching, and Application for Chemical Sensing

“…During our comparative structural analysis, we noted that a series of 1-arylazo-2-hydroxynaphthols containing nitro groups ( 10a − d ; Figure ) have unusually long N−N bond distances of 1.333(6)−1.385(4) Å, while their C−O and C−N bond distances are comparable to those of others, except in the case of 10d (Figure b). − Such elongated N−N bonds have occasionally been described as evidence for the hydrazone tautomer. ,,, According to previous reports, ,, both 10b and 10e exist mainly as the hydrazone tautomers in solution, but the N−N bond distance in 10b [1.345(7) Å] is significantly longer than that [1.307(2) Å] in 10e . Increasing the number of nitro substituents, as in 10d , results in a further lengthening of N−N bond to 1.385(4) Å.…”

“…[56][57][58][59] Such elongated N-N bonds have occasionally been described as evidence for the hydrazone tautomer. 42,57,60,61 According to previous reports, 43,62,63 both 10b and 10e exist mainly as the hydrazone tautomers in solution, but the N-N bond distance in 10b [1.345(7) Å] is significantly longer than that [1.307( 2) Å] 64 in 10e. Increasing the number of nitro substituents, as in 10d, results in a further lengthening of N-N bond to 1.385(4) Å.…”