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

众所周知，氮孤对电子通过锥体倒置而发生倒置，导致立体氮中心的手性迅速丧失。但金属配位的氮原子已被证明是不对称的氮。类似地，当与金属离子配位时，不对称醚的氧原子可能成为手性中心。在这种情况下，由于剩余的氧孤对电子的快速反转，手性也非常不稳定。通过金属离子配位来防止孤对反转是获得具有手性氧原子的化合物的潜在途径。金属离子与醚氧原子的强配位可能导致两个氧孤对的必要区分。在分离具有金属键合的不对称氧原子的化合物的任何努力中，都需要仔细的配体设计。本项目主要讨论了在吡啶二甲胺-铜（II）配合物体系中，不对称氧原子组装的控制因素，包括配体结构、配位数、溶剂等因素的影响

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