Ground-State Copper(III) Stabilized by N‑Confused/N-Linked Corroles: Synthesis, Characterization, and Redox Reactivity

Stable square planar organocopper­(III) complexes (CuNCC2, CuNCC4, and CuBN) supported by carbacorrole-based tetradentate macrocyclic ligands with NNNC coordination cores were synthesized, and their structures were elucidated by spectroscopic means including X-ray crystallographic analysis. On the basis of their distinct planar structures, X-ray absorption/photoelectron spectroscopic features, and temperature-independent diamagnetic nature, these organocopper complexes can be preferably considered as novel organocopper­(III) species. The remarkable stability of the high-valent Cu­(III) states of the complexes stems from the closed-shell electronic structure derived from the peculiar NNNC coordination of the corrole-modified frameworks, which contrasts with the redox-noninnocent radical nature of regular corrole copper­(II) complexes with an NNNN core. The proposed structure was supported by DFT (B3LYP) calculations. Furthermore, a π-laminated dimer architecture linked through the inner carbons was obtained from the one-electron oxidation of CuNCC4. We envisage that the precise manipulation of the molecular orbital energies and redox profiles of these organometallic corrole complexes could eventually lead to the isolation of yet unexplored high-valent metal species and the development of their organometallic reactions.本研究合成了以带有NNNC配位核的碳卟啉基四齿大环配体稳定的方形平面有机铜(III)配合物（CuNCC2、CuNCC4及CuBN），并通过包括X射线晶体衍射分析在内的光谱手段解析了其结构。基于其独特的平面结构、X射线吸收/光电子能谱特征以及与温度无关的抗磁性质，这类有机铜配合物可被认定为新型有机铜(III)物种。该配合物高价铜(III)价态的优异稳定性，源于卟啉修饰骨架特殊的NNNC配位模式所衍生的闭壳层电子结构，这与具有NNNN配位核的普通卟啉铜(II)配合物的氧化还原非无辜自由基特性形成鲜明对比。所提出的配合物结构得到了密度泛函理论(DFT, B3LYP)计算的支持。此外，通过对CuNCC4进行单电子氧化，得到了由内部碳原子连接的π堆叠二聚体结构。我们设想，精准调控这类有机金属卟啉配合物的分子轨道能级与氧化还原特性，有望最终分离出尚未被探索的高价金属物种，并推动其有机金属反应的发展。