Structural characaterization of some symmetric bis-imines

The symmetric bis-imines [1,1’-{4,4’-[(2-BrC6H4)CH=N]2C6H4}]2 (1), [1,1’-{3,3’-(CH3)2-4,4’-[(2-BrC6H4)CH=N]2C6H4}]2 (2) and 1,4-[(2-BrC6H4)CH=N]2C6H4 (3) were prepared by condensation of 2-bromobenzaldehyde with the appropriate diamines. The compounds were characterized in solution by 1H, 13C and two-dimensional NMR spectroscopy and mass spectrometry. For all derivatives, the presence of C=N double bonds was confirmed in solid-state by IR spectroscopy. Single-crystal X-ray diffraction analyses revealed the polymorphs for compound 1 and E configuration of substituents for all imine bonds.