Alemayehu Abraham B, Gonzalez Emmanuel, Hansen Lars Kristian, Ghosh Abhik
Department of Chemistry and Center for Theoretical and Computational Chemistry, University of Tromsø, 9037 Tromsø, Norway.
Inorg Chem. 2009 Aug 17;48(16):7794-9. doi: 10.1021/ic900744v.
X-ray crystallographic analyses of two sterically unhindered copper meso-triarylcorroles, Cu[5,15-P(2)-10-(4-MeOP)C] and Cu[5,15-(4-CF(3)P)(2)-10-(4-MeOP)C] (P = phenyl and C = corrole), revealed substantially saddled corrole rings. These results are in marked contrast to those on highly sterically hindered cobalt(III) and iridium(III) corroles, which exhibit planar corrole macrocycles. The solution to this conundrum is that copper corroles are inherently saddled, as a result of a specific copper(d)-corrole(pi) orbital interaction. This orbital interaction results in a noninnocent corrole ligand, and the overall electronic structure may thus be described as Cu(II)-corrole(*2-). While many specific metal(d)-macrocycle(pi) orbital interactions are known for nonplanar metalloporphyrins, this work provides a rare example of such an orbital interaction providing the actual driving force for a significant nonplanar distortion. Our findings on copper corroles, along with those of others on cobalt and iridium corroles, thus constitute an intriguing and somewhat counterintuitive chapter in the structural chemistry of metallocorroles.
对两种空间位阻较小的铜中-三芳基卟吩Cu[5,15-P(2)-10-(4-MeOP)C]和Cu[5,15-(4-CF(3)P)(2)-10-(4-MeOP)C]（P = 苯基，C = 卟吩）进行的X射线晶体学分析显示，卟吩环存在明显的鞍形结构。这些结果与高度空间位阻的钴(III)和铱(III)卟吩的结果形成显著对比，后者呈现平面卟吩大环结构。这个难题的答案是，由于特定的铜(d)-卟吩(π)轨道相互作用，铜卟吩本质上就是鞍形的。这种轨道相互作用导致卟吩配体具有非单纯性，因此整体电子结构可描述为Cu(II)-卟吩(*2-)。虽然对于非平面金属卟啉，许多特定的金属(d)-大环(π)轨道相互作用是已知的，但这项工作提供了一个罕见的例子，即这种轨道相互作用为显著的非平面畸变提供了实际驱动力。我们关于铜卟吩的发现，以及其他人关于钴和铱卟吩的发现，因此在金属卟啉的结构化学中构成了引人入胜且有点违反直觉的一章。
