Ylide stabilized carbenes: a computational study |
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Authors: | Bibi Narjes Haerizade Mohammad Zaman Kassaee Hassan Zandi Maryam Koohi Ali A Ahmadi |
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Institution: | 1. Department of Chemistry, Tarbiat Modares University, , Tehran, Iran;2. Department of Chemistry, Shahre‐ray Branch, Islamic Azad University, , 18155‐144 Tehran, Iran |
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Abstract: | High‐level Density Functional Theory calculations, coupled with appropriate isodesmic reaction, are employed to investigate the effects of α‐carbon, ammonium, phosphorus, and sulfur ylides, cyclization, and unsaturation on the stability, multiplicity, and reactivity of novel singlet (S) and triplet (T) carbenes. Among them the highly π‐donating α‐ammonium ylide is found to exert the highest stabilizing effect on the carbenic center. α‐Ammonium ylides resist dimerization and hydrogenation. They show wider singlet–triplet energy gap (ΔΕS–T), broader band gap (ΔΕHOMO–LUMO), and higher nucleophilicity compared to the reported stable N‐heterocyclic carbenes. Aromatic cyclic unsaturated ammonium, phosphorus, and sulfur ylide carbenes appear more stable than their saturated cyclic analogs which are in turn more viable than their acyclic counterparts. Copyright © 2014 John Wiley & Sons, Ltd. |
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Keywords: | DFT N‐ylide heterocyclic carbenes N‐heterocyclic carbenes ylide carbene nucleophilicity stability |
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