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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 47, Number 6
JKCSEZ 47(6)
December 20, 2003 

 
Title
Synthesis of New N2O Tridentate Ligands and Their Stability Constants of Transition Metal Complexes

새로운 N2O계 세 자리 리간드의 합성과 전이금속 착물 안정도상수
Author
Sun Deuk Kim*, Young Sik Park

김선덕*, 박영식
Keywords
세 자리 리간드, 총괄 양성자 해리상수, 착물 안정도상수 , Tridentate Ligand, Overall Proton Dissociation Constant, Stability Constant
Abstract
피리딘과 페놀을 포함하는 N2O계 세 자리 리간드 2-[(2-pyridine-2- ethylamino)-methyl]-phenol(H-PEMP)를 합성하였다. 또한 H-PEMP 페놀의 5-위치에 치환기로 브롬, 염소 및 메톡시를 가지는 Br-PEMP, Cl-PEMP 및 CH3O-PEMP를, 그리고 2-hydroxy-1-naphthalene기를 가진 Naph-PEMP을 합성하였다. 합성된 각 리간드들을 수용액에서 전위차 적정 결과 양성자 해리는 3 단계로 일어났으며, 계산된 각 리간드의 총괄 양성자 해리상수(logβ) 값은 CH3O-PEMP〉Naph-PEMP〉H-PEMP〉Br-PEMP〉Cl-PEMP의 순서로 Hammett식의 치환기 상수(σp) 값 크기 순서와 일치하였다. 전이금속 이온들의 착물 안정도상수(logML 및 logML2) 값의 크기는 금속이온에 따라 Co(II)< Ni(II)< Cu(II)>Zn(II)의 순서이었고, 치환기에 따른 각 리간드의 착물 안정도상수 값은 리간드의 총괄 양성자 해리상수 값의 크기순서와 일치하였다.

Ligands, Br-PEMP, Cl-PEMP and CH3O-PEMP having Br, Cl and CH3O substituents at 5-position of the N2O tridentate ligand, 2-[(2-pyridine-2-ethylamio)-methyl]-phenol (H-PEMP) containing pyridine and phenol were synthesized. Another ligand, Naph-PEMP having pyridine and 2-hydroxy-1-naphthalene was also synthesized. The ligands were characterized using elemental analysis, UV-visible, IR, 1H NMR and 13C NMR spectroscopy and mass analysis. The potentiometric titration study in aqueous solution revealed that the proton dissociation of the ligands occurred in three steps and the order of overall proton dissociation constants (logβ) was CH3O-PEMP > Naph-PEMP > H-PEMP > Cl-PEMP > Br-PEMP. The order of stability constants (logML and logML2) of their transition metal complexes was Co(II) < Ni(II) < Cu(II) > Zn(II). The order in their stability constants values of each transition metal complex agreed well with that in overall proton dissociation constant value of the ligands.

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