Electron flow in reaction mechanisms--revealed from first principles.
The "curly arrow" of Robinson and Ingold is the primary tool for describing and rationalizing reaction mechanisms. Despite this approach's ubiquity and stellar success, its physical basis has never been clarified and a direct connection to quantum chemistry has never been found. Here we report that the bond rearrangements expressed by curly arrows can be directly observed in ab initio computations, as transformations of intrinsic bond orbitals (IBOs) along the reaction coordinate. Our results clarify that curly arrows are rooted in physical reality-a notion which has been challenged before-and show how quantum chemistry can directly establish reaction mechanisms in intuitive terms and unprecedented detail.
Institut für Theoretische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany); Present address: Department of Chemistry, Pennsylvania State University, 401A Chemistry Bldg; University Park, PA 16802 (USA). knizia@psu.edu.
Gerald
G
Knizia
Johannes E M N
JE
Klein
ab initio calculations; bond theory; quantum chemistry; reaction mechanisms