N,N′-Bis(3,4-dimethoxybenzylidene)butane-1,4-diamine

The title Schiff base compound, C22H28N2O4, was synthesized by the reaction of 3,4-dimethoxybenzaldehyde and 1,4-diaminobutane in methanol. The molecule is located on a center of inversion with one half-molecule in the asymmetric unit. Both C=N double bonds are in a trans configuration. Intermolecular C—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

The title Schiff base compound, C 22 H 28 N 2 O 4 , was synthesized by the reaction of 3,4-dimethoxybenzaldehyde and 1,4diaminobutane in methanol. The molecule is located on a center of inversion with one half-molecule in the asymmetric unit. Both C N double bonds are in a trans configuration. Intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network.
The molecule of the title compound is shown in Fig.1. A l l bond lengths and angles are comparable with those observed in similar compounds (Khalaji & Ng, 2008;Khalaji et al., 2007). The C7-N1 and C8-N1 bond lengths of 1.2657 (19) and 1.4620 (17) Å, respectively, conform to the value for a double and single bond. The molecule displays an E configuration about the C=N double bond.
Oxygen O1 and methyl C11H 3 participate in two symmetry independent hydrogen bonds C-H···O which connect the molecules into a three-dimensional network (Fig. 2).

Refinement
All hydrogen atoms were discernible in difference Fourier maps and could be refined to reasonable geometry. According to common practice they were nevertheless kept in ideal positions during the refinement. The isotropic atomic displacement parameters of hydrogen atoms were set to 1.2U eq of the parent atom.

Special details
Refinement. The refinement was carried out against all reflections. The conventional R-factor is always based on F. The goodness of fit as well as the weighted R-factor are based on F and F 2 for refinement carried out on F and F 2 , respectively. The threshold expression is used only for calculating R-factors etc. and it is not relevant to the choice of reflections for refinement.