Revisiting the Intriguing Electronic Features of the BeOBeC Carbyne and Some Isomers: A Quantum‐Chemical Assessment

• Published in: Angewandte Chemie International Edition 2020-09, Vol.59 (39), p.17261-17265
• Main Authors: Li, Jilai, Geng, Caiyun, Weiske, Thomas, Zhou, Mingfei, Li, Jun, Schwarz, Helmut
• Format: Article
• Language: English
• Subjects: Beryllium; Carbyne; carbyne radicals; Communication; Communications; electronic configuration; Isomers; Photochemicals; quantum-chemical calculations; spin states
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202007990

Extensive high‐level quantum‐chemical calculations reveal that the rod‐shaped molecule BeOBeC, which was recently generated in matrix experiments, exists in two nearly isoenergetic states, the 5Σ quintet (56) and the 3Σ triplet (36). Their IR features are hardly distinguishable at finite temperature. The major difference concerns the mode of spin coupling between the terminal beryllium and carbon atoms. Further, the ground‐state potential‐energy surface of the [2Be,C,O] system at 4 K is presented and differences between the photochemical and thermal behaviors are highlighted. Finally, a previously not considered, so far unknown C2v‐symmetric rhombus‐like four‐membered ring 3[Be(O)(C)Be] (35) is predicted to represent the global minimum on the potential‐energy surface. One way or another: The coexistence of two isoenergetic electromers of the novel BeOBeC molecule, possessing practically indistinguishable IR features, has been revealed by quantum‐chemical calculations. Further, the triplet state of a so far unknown C2v‐symmetric rhombus‐like four‐membered ring 3[Be(O)(C)Be] is predicted to represent the global minimum on the potential‐energy surface in the thermal reaction of Be2 with CO.