Stabilization of "Asymmetric Oxygen" derived from Metal-Coordinated Oxygen Atom

众所周知，一对氮孤对通过金字塔倒置而倒置，导致立体起源氮中心的手性迅速丧失。但金属配位的氮原子已经被证明是不对称的氮。同样，当不对称的乙醚的氧原子与金属离子配位时，也有可能成为手性中心。在这种情况下，由于剩余氧孤子对的快速反转，手性也是非常不稳定的。通过金属离子配位防止孤对反转是合成具有手性氧原子的化合物的一条潜在途径。金属离子与乙醚氧原子的强烈配位可能导致两个氧孤子对的必要分化。为了分离具有金属结合的不对称氧原子的化合物，需要仔细的配体设计。在这个项目中，讨论了不对称氧原子组装的控制因素，包括配体结构、反离子和溶剂对一系列二吡啶甲胺-铜(II)络合物的影响

It is well known that a nitrogen lone pair inverts via pyramidal inversion, causing expeditious loss of chirality at a stereogenic nitrogen center. But metal-coordinated nitrogen atoms have been demonstrated as an asymmetric nitrogen. Similarly, it is possible that the oxygen atom of a unsymmetrical ether can become a chiral center when coordinated to a metal ion. In this case also, the chirality is extremely unstable due to the rapid inversion of the remaining oxygen lone pair. Preventing lone pair inversion by metal ion coordination is a potential route to compounds exhibiting a chiral oxygen atom. Strong coordination of the metal ion to the ether oxygen atom may lead to the necessary differentiation of the two oxygen lone pairs. Careful ligand design is needed in any effort to isolate a compound with a metal-bound asymmetric oxygen atom. In this project, controlling factors for the assembly of asymmetric oxygen atoms are discussed, including the effect of ligand structure, counterion, and solvent in a series of dipicolylamine-copper (II) complexes