Ring-expanded iridium and rhodium N-heterocyclic carbene complexes: a comparative DFT study of heterocycle ring size and metal center diversity |
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Authors: | E. Ö. Karaca M. Akkoç E. Öz S. Altin V. Dorcet T. Roisnel |
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Affiliation: | 1. Department of Chemistry, ?n?nü University, Malatya, Turkey;2. Department of Physics, ?n?nü University, Malatya, Turkey;3. Université de Rennes, UMR 6226: CNRS Sciences Chimiques de Rennes, Rennes, France |
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Abstract: | A new series of ring-expanded six- and seven-membered N-heterocyclic carbene precursors (re-NHCs) and their transition metal complexes were synthesized. The basic properties of the synthesized materials were investigated by density functional theory (DFT). The six- and seven-membered re-NHCs were synthesized in good yield via reaction of the corresponding alkyldibromides or alkyldiiodides with N,N′-bis-(2-phenylbenzene)formamidine in the presence of K2CO3 under aerobic conditions. Complexes, represented by the formula [ML1,2(COD)Cl] (where M = Ir or Rh and L is a ring-expanded N-heterocyclic carbene ligand), were synthesized in the presence of the corresponding free carbene and iridium or rhodium metal precursors in tetrahydrofuran. All new re-NHC complexes were characterized by different analytical techniques, including NMR spectroscopy, X-ray diffraction, UV spectroscopy and elemental analysis. According to molecular electrostatic potential calculations, the electrophilic properties of the complexes were aligned, from highest to lowest, as Ir-6-DiPh, Rh-6-DiPh and Ir-7-DiPh. The HOMO, LUMO and energy gaps of the complexes were calculated by DFT. On the basis of the DFT analysis, it can be predicted that Rh-6-DiPh is the most stable complex and Ir-7-DiPh is more reactive than Ir-6-DiPh. |
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Keywords: | Iridium rhodium N-Heterocyclic carbene DFT calculation X-ray |
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