Oxatriaza macrocyclic ligands: studies of protonation and metal complexation
作者:Maria Teresa S. Amorim、S�lvia Chaves、Rita Delgado、Jo�o J. R. Fra�sto da Silva
DOI:10.1039/dt9910003065
日期:——
might be expected if the metals were inserted in the ring. Curiously, the behaviour of the copper(II) and especially nickel(II) complexes is opposite in the two series. Stability constants of complexes of the methylated amines are lower than those of the complexes with the parent amines and the same metalions, but the differences are smaller for the oxatriaza than for the tetraaza series. This suggests
已经合成了一些12至14元的草酸氧杂环大环配体及其甲基化衍生物,并通过电势和1 H NMR技术研究了它们的质子化。这些配体与几种第一系列过渡金属离子Zn II,Cd II和Pb II形成的配合物的稳定性常数在反应缓慢平衡的情况下,可以通过自动电位法或通过“细胞外”技术确定。所有的配体都有两个非常碱性的氮原子。第三个氮原子在较低的pH下被质子化,该值越低,两个质子化的氮原子之间的距离越短。oxatriaza配体的配合物的稳定性常数低于相同大小的四氮杂配体的稳定性常数,其中14元配体的差异更为明显。较大的离子(例如Cd II和Pb II)似乎更喜欢较小的环,这与将金属插入环中所期望的相反。奇怪的是,铜(II),尤其是镍(II)的行为)复合体在两个系列中是相反的。甲基化胺的配合物的稳定常数低于与母体胺和相同金属离子的配合物的稳定常数,但是草酸氮杂的差异小于四氮杂系列的差异。这表明在前一个系列中,
A Highly Reactive Oxoiron(IV) Complex Supported by a Bioinspired N<sub>3</sub>
O Macrocyclic Ligand
作者:Inés Monte Pérez、Xenia Engelmann、Yong-Min Lee、Mi Yoo、Elumalai Kumaran、Erik R. Farquhar、Eckhard Bill、Jason England、Wonwoo Nam、Marcel Swart、Kallol Ray
DOI:10.1002/anie.201707872
日期:2017.11.13
12-trimethyl-1-oxa-4,8,12-triazacyclotetradecane; see picture) in an N3O environment exhibits drastically enhanced reactivity relative to the [FeIV(O)(TMC)(CH3CN)]2+ (TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) complex in an N4 environment. This explains nature's preference for using oxygen-rich ligand environments for the hydroxylation of strong C−H bonds.