Received 28 July 2008
In the title compound, C21H26N2O4, there is half a molecule in the asymmetric unit with a crystallographic twofold rotation axis passing through the central C atom of the -CH=N-O-(CH2)5-O-N=CH- bridge. The dihedral angle formed by the two benzene rings is 80.85 (2)°. Strong intramolecular O-HN and C-HO hydrogen bonds help to establish the molecular conformation. There are also weak intermolecular - stacking interactions between neighbouring benzene rings [centroid-centroid separation = 3.502 (3) Å].
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GW2048 ).
This work was supported by the Foundation of the Education Department of Gansu Province (No. 0604-01) and the `Qing Lan' Talent Engineering Fund of Lanzhou Jiaotong University (No. QL-03-01A), which are gratefully acknowledged.
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