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

여러자리 질소-산소계 시프염기 리간드와 전이금속착물의 합성 및 특성

  • 김선덕 (대구대학교 자연과학대학 화학과) ;
  • 신윤열 (국립과학수사연구소) ;
  • 박성우 (국립과학수사연구소)
  • Received : 1998.05.20
  • Published : 1998.10.25

Abstract

Polydentate Schiff base ligands, BSDT(1,9-bis(2-hydroxyphenyl)-2,5,8-triaza-1,8-nonadiene) having $N_3O_2$ atoms, BSTT(1,12-bis(2-hydroxyphenyl)-2,5,8,11-tetraaza-1,11-dodecadiene) having $N_4O_2$ atoms, BSTP(1,15-bis(2-hydroxyphenyl)-2,5,8,11,14-pentaaza-1,14-pentadodecadiene) having $N_5O_2$ atoms were synthesized. Protonation constants of these polydentate ligands were measured by potentiometry. 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 complex formation were in the order of Cu(II)>Ni(II)>Zn(II), and for the ligands were in the order of BSTP>BSTT>BSDT. There are due to the increase in the number of donor atoms. Both enthalpy and entropy changes were obtained in negative values. 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;protonation constant;stability constant