Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
Inorg Chem. 2010 Mar 1;49(5):2141-52. doi: 10.1021/ic9019926.
A new multimetal complexation system that can change its complexation behavior by C-C bond formation has been developed. The acyclic tetraoxime ligand H(4)L(1) having two terminal allyl groups was synthesized. The olefin metathesis of H(4)L(1) selectively produced trans-H(4)L(2) while the reaction of [L(1)Zn(2)Ca] exclusively afforded cis-H(4)L(2). The saturated analogue H(4)L(3) was synthesized by hydrogenation. The complexation of the ligands H(4)L (L = L(1), trans-L(2), cis-L(2), L(3)) with zinc(II) acetate (3 equiv) yielded the trinuclear complexes [LZn(3)] with a similar trinuclear core bridged by acetato ligands. Whereas the formation process of [L(1)Zn(3)] having an acyclic ligand was highly cooperative, the macrocyclic analogues [LZn(3)] (L = trans-L(2), cis-L(2), L(3)) were formed in a stepwise fashion via the intermediate 2:3 complex [(HL)(2)Zn(3)]. The trinuclear complexes [LZn(3)] (L = L(1), trans-L(2), cis-L(2), L(3)) can recognize alkaline earth metal ions via site-selective metal exchange. The acyclic [L(1)Zn(3)] selectively recognizes Ca(2+), while the cyclic [trans-L(2)Zn(3)] showed a Ba(2+) selectivity. The metal exchange of [LZn(3)] (L = L(1), trans-L(2), cis-L(2), L(3)) with La(3+) efficiently occurred to give [LZn(2)La], but the trans-olefin linker of the [trans-L(2)Zn(2)La] significantly deforms the structure in such a way that one of the salicylaldoxime moieties does not participate in the coordination. Consequently, the chemical transformation of the olefinic moiety significantly affects the multimetal complexation behavior of the tetraoxime ligands.
一种新的多金属络合体系已经被开发出来，它可以通过 C-C 键的形成改变其络合行为。合成了具有两个末端烯丙基基团的非环四肟配体 H(4)L(1)。H(4)L(1)的烯烃复分解反应选择性地生成反式-H(4)L(2)，而[L(1)Zn(2)Ca]的反应则专一地得到顺式-H(4)L(2)。通过氢化合成了饱和类似物 H(4)L(3)。配体 H(4)L(L = L(1)、trans-L(2)、cis-L(2)、L(3))与醋酸锌(3 当量)的络合生成了具有类似三核核桥接的三核配合物[LZn(3)]通过乙酰氧配体。虽然具有非环配体的[L(1)Zn(3)]的形成过程是高度协同的，但大环类似物[LZn(3)](L = trans-L(2)、cis-L(2)、L(3))则是通过中间体 2:3 配合物[(HL)(2)Zn(3)]以逐步的方式形成的。三核配合物[LZn(3)](L = L(1)、trans-L(2)、cis-L(2)、L(3))可以通过位点选择性的金属交换来识别碱土金属离子。非环[L(1)Zn(3)]选择性地识别 Ca(2+)，而环状[trans-L(2)Zn(3)]则表现出 Ba(2+)选择性。[LZn(3)](L = L(1)、trans-L(2)、cis-L(2)、L(3))与 La(3+)的金属交换有效地发生，得到[LZn(2)La]，但[trans-L(2)Zn(2)La]的顺式烯烃键显著变形，使一个水杨醛肟基团不参与配位。因此，烯烃部分的化学转化显著影响了四肟配体的多金属络合行为。
