3-Methoxy-5-(4-methylphenyldiazenyl)salicylaldehyde and 3-methoxy-5-(2-methylphenyldiazenyl)salicylaldehyde

Abstract

The two title molecules, both C(15)H(14)N(2)O(3), are roughly planar and display a trans conformation with respect to the -N=N- double bond, as found for other diazene derivatives. In both compounds, there are intramolecular O-H.O hydrogen bonds and the crystal packing is governed by weak intermolecular C-H.O hydrogen bonds and pi-pi stacking.

(E)-5-(4-Chlorophenyldiazenyl)salicylaldehyde

“…In the azo group, the N1-C5 and N2-C8 bond lengths indicate significant single-bond character, whereas the N1 N2 bond length is indicative of significant double-bond character. The C7 O1 and C2-O2 bond lengths agree with the corresponding distances in 3methoxy-5-(4-methylphenyldiazenyl)salicylaldehyde and 3methoxy-5-(2-methylphenyldiazenyl)salicylaldehyde [1.224 (2) and 1.350 (2) Å , respectively; Ersanli et al, 2004].…”

(Z)-6-{[1,3-Dihydroxy-2-(hydroxymethyl)propan-2-ylamino]methylene}-2-methoxy-4-[(E)-o-tolyldiazenyl]cyclohexa-2,4-dienone

“…The aromatic rings are in a trans con®guration with respect to the azo double bond. The N1ÐC1 and N2ÐC8 bond lengths indicate single-bond character, and the N N bond length is indicative of signi®cant double-bond character, as has been observed in other trans-azo compounds (Ersanlõ, Odabas Ëog AE lu et al, 2004a;Ersanlõ, Albayrak, Odabas Ëog AE lu, Kazak & Erdo È nmez, 2004).…”

(Z)-4-[(E)-(4-Butylphenyl)diazenyl]-6-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylamino]methylene}-2-methoxycyclohexa-2,4-dienone

“…The structural data clearly show that (I) adopts the keto-amine form, stabilized by the formation of an N-HÁ Á ÁO hydrogen bond. Similar o-hydroxy Schiff bases have been found to adopt the keto (Ersanlı et al, 2003;Ersanlı, Albayrak, Odabaşoǧ lu, Thö ne & Erdö nmez, 2004;Ersanlı et al, 2005), enol (Ersanlı, Albayrak, Odabaşoǧ lu & Erdö nmez, 2004; Ersanlı, Odabaşoǧ lu et al, 2004) or enol/keto forms (Nazır et al, 2000). The C14-O2 and C18-N3 bond distances (Table 1) are reasonably similar, a characteristic of systems in the keto-amine form, and comparable to those found in 4-[(2-chlorophenyl)diazenyl]-6-methoxy-2-{[tris-(hydroxymethyl)methyl]aminomethylene}cyclohexa-3,5-dien-1(2H)-one [1.287 (2) and 1.294 (2) Å ; Ersanlı, Albayrak, Odabaşoǧ lu, Thö ne & .…”