Chelate effect - Chelate effect

Japanese: キレート効果 - キレートコウカ

The stability of chelate complexes formed by polydentate ligands coordinated to a central metal is greater than that of the corresponding complexes formed by monodentate ligands. This stabilization by chelate ring formation is called the chelate effect. For example, the stability constants of monoethylenediamine complexes of metals M = Co, Ni, Cu, Zn, and Cd in the following equilibrium (en = ethylenediamine) M ²⁺ +en⇄M(en) ²⁺ are 5.89, 7.66, 10.55, 5.71, and 5.47, respectively, which are greater than the stability constants of diamine complexes of the above metals in the corresponding equilibrium M ²⁺ +2NH ₃ ⇄M(NH ₃ ) ₂ ²⁺ , which are 3.62, 4.95, 7.61, 4.61, and 4.65.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

多座配位子が中心金属に配位してできるキレート錯体の安定度は，対応する単座配位子のつくる錯体の安定度よりも大きい。このキレート環形成による安定化をキレート効果という。たとえば，つぎの平衡(en＝エチレンジアミン)　M^2＋＋en⇄M(en)^2＋における金属M＝Co,Ni,Cu,Zn,Cdのモノエチレンジアミン錯体の安定度定数は，それぞれ5.89,7.66,10.55,5.71,5.47であって，対応するつぎの平衡　M^2＋＋2NH₃⇄M(NH₃)₂^2＋における上記金属のジアンミン錯体の安定度定数3.62,4.95,7.61,4.61,4.65よりも大きい。

出典　株式会社平凡社世界大百科事典第２版について　情報

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