P.G: Department of Chemistry, G. M. College, Sambalpur-768 004, Orissa, India E-mail: sarojbadmal@yahoo.com Silicon Institute of Technology, Sason, Sambalpur-768 200, Orissa, India Manuscript received 15 September 2009, revised 31 March 2010, accepted 13 April 2010 Six tetrameric and six dimerlc complexes of CoII , NiII , CuII , ZnII , Cdll and Hgll with one hexadentate (bistndentate) \(\stackrel\frown{OO}\stackrel\frown{N}-\stackrel\frown{NO}\stackrel\frown{O}\) donor and one tetradentate (bJS-bJdentate) \(\stackrel\frown{NO}-\stackrel\frown{NO}\) donor azo dye ligands, 4,4' -bis(2' -hydroxy-3' -carboxy-5' -chlorophenylazo)-3,3' -dimethoxydiphenyl [LH4) and 4,4' -bis(2' -hydroxynaphthylazo)-3,3' -dimethoxydiphenyl [L'H2] have been synthesized and characterized by analytical, conductance, magnetic susceptibility, IR, electronic spectra, ESR, NMR and X-ray diffraction (powder pattern) data. The cobalt(ll) and nickel(ll) complexes are octahedral, copper(II) complexes are distorted-octahedral and a tetrahedral stereochemistry has been suggested to zinc(ll), cadmium(II) and . mercury(II) complexes.