Synthesis and Properties of Polydentate Schiff Base Ligands having $N_nO_2$ (n=3~5) Donor Atoms and Bromine Substituent and their Transition Metal Complexes

여러자리 질소-산소계 시프염기 리간드와 전이금속착물의 합성 및 전기화학적 특성

  • 김선덕 (대구대학교 자연과학대학 화학과) ;
  • 신윤열 (대구대학교 자연과학대학 화학과) ;
  • 박성우 (국립과학수사연구소)
  • Received : 1998.06.20
  • Published : 1998.12.25

Abstract

Polydentate Schiff base ligands 5-Br-BSDT(bis(5-bromosalicylaldehyde)diethylenetriamine) having $N_3O_2$ atoms, 5-Br-BSTT(bis(5-bromosalicylaldehyde)triethylenetetramine) having $N_3O_2$ atoms, 5-Br-BSTP(bis(5-bromosalicylaldehyde)tetraethylenepentamine) having $N_3O_2$ atoms were synthesized. Stability constants of the complexes between these ligands and the metal ions such as Cu(II), Ni(II) and Zn(II) were measured in DMSO by a polarographic method. It was observed that all metal(II) ions employed in this study formed 1 : 1 complexes with Schiff base ligands. Stability constants for the ligands were in the order of Cu(II)>Ni(II)>Zn(II), and for complex formation were in the order of 5-Br-BSTP>5-Br-BSTT>5-Br-BSDT according to the increasing in the number of donor atoms. Both enthalpy and entropy changes are obtained in negative valves. Exothermicity for the complex formation indicated tight binding between the ligands and metal ions. The negative entropy change would be related to the fact that solvent molecules are strongly interacting with the metal complexes.

Keywords

Schiff base ligand;donor atoms;protonation constant

Acknowledgement

Supported by : 대구대학교