New Schiff base derivatives were prepared by the condensation of 5-chloro and 5-bromo salicylaldehyde with bis(o-aminophenol)ethers. Five bis(o-nitrophenol)ether compounds were synthesized using some ditosylate, 1,3-dibromopropane and 1,4-dibromobuthane with o-nitrophenol. These compounds were reduced to bis(o-aminophenol)ethers. The products have been characterized by elemental analysis, FTIR, H-1, C-13 NMR, HETCOR and HMBC spectroscopic techniques. The tautomerisms of all of the Schiff bases compounds were determined in DMSO, CHCl3, C2H5OH and C6H12 solvents and in both acidic and basic media using the UV-vis spectrophotometric method. The heat of formation (Delta H-f),enthalpy (Delta H), entropy (Delta S). Gibbs free energy (Delta G(f) and Delta G), stable isomers, conformations and tautomers of the synthesized compounds are calculated using the MOPAC2009 (PM6) program. (C) 2011 Elsevier B.V. All rights reserved.