The Pi‐Nature of Methyl Obtained by the Natural Bond Orbital Method: Orbital‐Based Rationalizations of Site‐Dependent Substitution Effects on Fine Color‐Tuning of Luminescence |
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| Authors: | Wei‐Lin Su Cheng‐Chi Wang Shao‐Pin Wang |
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| Institution: | Department of Chemistry, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan (R.O.C.) |
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| Abstract: | Both C‐H bonding and antibonding (σCH and σ*CH) of a methyl group would contribute to the highest occupied or lowest unoccupied molecular orbitals (HOMO or LUMO) in methylated derivatives of Ir(ppz)2 3 iq (ppz = 1‐phenylpyrazole and 3iq = isoquinoline‐3‐carboxylate). This is found by analysis of HOMO (or LUMO) formed by linear combination of bond orbitals using the natural bond orbital (NBO) method. The elevated level of HOMO (or LUMO) uniformly found for each methylated derivative, indicating the σCH‐destabilization outweighs the σ*CH‐stabilization. To broaden the HOMO‐LUMO gap, methylation at a carbon having smaller contribution to HOMO and/or larger contribution to LUMO is suggested. |
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| Keywords: | Natural bond orbital method Fine color‐tuning Luminescent cyclometalated heteroleptic complexes |
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