Synthesis and characterization of some biphenyl bridged complexes of a new class of binucleating ligands containing amide groups

Abstract

A series of biphenyl bridged polynuclear complexes, (M₂L₂·xH₂O)_n, has been synthesized from a new class of binucleating ligands (H₂L) containing amide group, where M = Fe(II), Co(II), Ni(II), Cu(II)and Zn(II), and H₂L are ligands obtained by reacting succinic (succi), phthalic (phthal) or maleic (male) anhydride with biphenyl bridged primary diamines such as 4,4'-diarninodiphenylmethane (dadpm), benzidine (benzi), <em>o</em>-tolidine (<em>o</em>-toli) and <em>o</em>-dianisidine (<em>o</em>-dianisi). The complexes (M₂L₂.xH₂O)_n have been characterized by elemental, spectral, magnetic and thermal studies. For M= Co²⁺, Ni²⁺ and Zn²⁺, x = 4 with two water molecules coordinated at each metal centre giving MO₆ weak field octahedral chromophores. For M = Cu²⁺ and Fe²⁺, x = O giving only MO₄ chromophores. Only normal magnetic moment values are observed at room and liquid nitrogen temperatures suggesting the absence of any strong antiferromagnetic interaction. Based on the elemental analysis, solubility and spectral data, a polymeric structure is tentatively suggested for the complexes.