Crystal structures of novel bis-NO-acyclic Schiff base compounds

Characterization of Schiff bases derived from 3,4-dimethoxybenzaldehyde: The crystal structure of N,N′-bis(3,4-dimethoxy-benzylidene)-2,2-dimethylpropane-1,3-diamine hydrate

“…The molecule adopts an E configuration about the N1=C7 and N2=C13 bonds with the azomethine nitrogen atoms [18]. The bond lengths and angles of 1 are very close to the corresponding ones found in Cambridge Structural Database [11][12][13][14]19]. Bond lengths and angles within the aromatic rings are consistent with those expected for sp 2 aromatic carbon atoms.…”

“…Bond lengths and angles within the aromatic rings are consistent with those expected for sp 2 aromatic carbon atoms. The lengths of C4-C7 and C13-C14 (1.4645(16) Å and 1.4660(17) Å respectively) are consistent with the length of single bonds between sp 2 -hybridized carbon atoms while the lengths in azomethine groups (N1=C7 1.2703(15) Å and N2=C13 1.6677(13) Å) are close to the value for a double bond [11][12][13][14]. The C7-N1-C8, C12-N2-C13, N1-C7-C4, and N2-C13-C14 bond angles are 118.61(10)°, 118.27(11)°, 122.80(10)°, and 122.89 (14)° respectively, which is consistent with the sp 2 -hybridized nitrogen (N1 and N2) and carbon (C7 and C13) atoms.…”

“…The expected chemical structures of these compounds are supported from their FT-IR spectra by the absence of the carbonyl and primary amine groups of the reagents, and the presence of a Schiff base band at 1639 cm -1 in 1 and 1638 cm -1 in 2 [11,12]. The FT-IR spectra of 1 and 2 also show several bands corresponding to aromatic and aliphatic C-H stretching (2837 cm -1 , 2922 cm -1 , 2960 cm -1 , and 3009 cm -1 for 1 and 2865 cm -1 , 2912 cm -1 , 2937 cm -1 , 2972 cm -1 , 3001 cm -1 , and 3019 cm -1 for 2) and aromatic C-C stretching (1512 cm -1 , 1584 cm -1 ,and 1600 cm -1 for 1 and 1514 cm -1 , 1585 cm -1 , and 1600 cm -1 for 2).…”

“…The stability of dissolved compounds is much shorter than that in the solid state and depends on the nature of the solvent. The title compounds are stable at room temperature in methanol, ethanol, and acetonitrile for 5 days, and also remain unchanged in chloroform and dichloromethane for about 2 days [11].…”

“…The most common examples of these compounds are prepared from salicylaldehyde derivatives to form a Schiff base ligand [9,10]. Our group is interested in the synthesis, characterization and crystal structure of new Schiff base compounds and their transition metal complexes [11][12][13][14]. As a part of our ongoing studies, we report the synthesis and spectral characterization of Schiff bases prepared by the condensation of 3,4-dimethoxybenzaldehyde and two diamine derivatives (Scheme 1).…”