Sahariah Biswajit, Sarma Bani Kanta
Department of Chemistry , School of Natural Sciences , Shiv Nadar University , Dadri , Uttar Pradesh-201314 , India . Email:
Chem Sci. 2018 Oct 29;10(3):909-917. doi: 10.1039/c8sc04221g. eCollection 2019 Jan 21.
Carbonyl-carbonyl (CO···CO) interactions are emerging noncovalent interactions found in many small molecules, polyesters, peptides and proteins. However, little is known about the effect of the relative orientation of the two carbonyl groups on the nature of these interactions. Herein, we first show that simple homodimers of acetone and formaldehyde can serve as models to understand the effect of relative orientations of the two carbonyl groups on the nature of CO···CO interactions. Further, from a comprehensive statistical analysis of molecules having inter- or intramolecular CO···CO interactions, we show that the molecules can be broadly categorized into six different structural motifs (I-VI). The analysis of pyramidality of the acceptor carbon atoms in these motifs and natural bond orbital (NBO) analysis suggest that the relative orientation of the two interacting carbonyl groups determines whether the orbital interaction between the two carbonyl groups would be n → π* or π → π* or a combination of both.
羰基-羰基（CO···CO）相互作用是在许多小分子、聚酯、肽和蛋白质中发现的新兴非共价相互作用。然而，关于两个羰基的相对取向对这些相互作用性质的影响，人们所知甚少。在此，我们首先表明丙酮和甲醛的简单同二聚体可作为模型，以理解两个羰基的相对取向对CO···CO相互作用性质的影响。此外，通过对具有分子间或分子内CO···CO相互作用的分子进行全面的统计分析，我们表明这些分子可大致分为六种不同的结构基序（I-VI）。对这些基序中受体碳原子的金字塔形分析以及自然键轨道（NBO）分析表明，两个相互作用羰基的相对取向决定了两个羰基之间的轨道相互作用是n→π还是π→π，或者是两者的组合。
