| Abstract
| - The chemical fixation of nitric oxide (NO) reacting with alkynyllithium to produce 5-methyl-3-oxide-1,2,3-oxadiazole has been investigated by using ab initio (U)MP2 and DFT/(U)B3LYP methods.The solvent effect was assessed using the combination of microsolvation model with explicit THFligands on lithium and continuum solvent model based on the SCRF/CPCM method at the (U)B3LYP/6-31G* level. Our results reveal that the overall reaction is stepwise and considered toinclude two processes. In process 1, the nitrogen atom in nitric oxide at first attacks the C1 atomin alkynyllithium to afford the intermediate 5. In process 2, after another nitric oxide reacted withthe intermediate 5 to produce 8a, we found that two pathways are involved. For path 1, the O2atom at first attacks the C2 atom to form a five-membered ring geometry, and then lithium canrotate around the N1−O1 bond, leading to the product 5-methyl-3-oxide-1,2,3-oxadiazole followedaddition of water. However, for path 2, lithium atom rotates first around the N1−O1 bond, andthen the product 5-methyl-3-oxide-1,2,3-oxadiazole is also generated by addition of water. Ourcalculations indicate that path 1 is more favorable than path 2 in the gas phase, while both ofthem exist possibly in THF solvent. The overall reaction is exothermic.
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