Substituent Effects on the Stability of Thallium and Phosphorus Triple Bonds: A Density Functional Study
1
Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan
2
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
*
Author to whom correspondence should be addressed.
Molecules 2017, 22(7), 1111; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules22071111
Received: 12 June 2017
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Revised: 29 June 2017
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Accepted: 29 June 2017
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Published: 5 July 2017
(This article belongs to the Section Computational and Theoretical Chemistry)
Three computational methods (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B3LYP/LANL2DZ+dp) were used to study the effect of substitution on the potential energy surfaces of RTl≡PR (R = F, OH, H, CH3, SiH3, SiMe(SitBu3)2, SiiPrDis2, Tbt (=C6H2-2,4,6-(CH(SiMe3)2)3), and Ar* (=C6H3-2,6-(C6H2-2, 4,6-i-Pr3)2)). The theoretical results show that these triply bonded RTl≡PR compounds have a preference for a bent geometry (i.e., ∠R⎼Tl⎼P ≈ 180° and ∠Tl⎼P⎼R ≈ 120°). Two valence bond models are used to interpret the bonding character of the Tl≡P triple bond. One is model [I], which is best described as TlP. This interprets the bonding conditions for RTl≡PR molecules that feature small ligands. The other is model [II], which is best represented as TlP. This explains the bonding character of RTl≡PR molecules that feature large substituents. Irrespective of the types of substituents used for the RTl≡PR species, the theoretical investigations (based on the natural bond orbital, the natural resonance theory, and the charge decomposition analysis) demonstrate that their Tl≡P triple bonds are very weak. However, the theoretical results predict that only bulkier substituents greatly stabilize the triply bonded RTl≡PR species, from the kinetic viewpoint.
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Keywords:
triply bonded molecules; triple bond; acetylene; substituent effects
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MDPI and ACS Style
Lu, J.-S.; Yang, M.-C.; Su, M.-D. Substituent Effects on the Stability of Thallium and Phosphorus Triple Bonds: A Density Functional Study. Molecules 2017, 22, 1111. https://0-doi-org.brum.beds.ac.uk/10.3390/molecules22071111
AMA Style
Lu J-S, Yang M-C, Su M-D. Substituent Effects on the Stability of Thallium and Phosphorus Triple Bonds: A Density Functional Study. Molecules. 2017; 22(7):1111. https://0-doi-org.brum.beds.ac.uk/10.3390/molecules22071111
Chicago/Turabian StyleLu, Jia-Syun, Ming-Chung Yang, and Ming-Der Su. 2017. "Substituent Effects on the Stability of Thallium and Phosphorus Triple Bonds: A Density Functional Study" Molecules 22, no. 7: 1111. https://0-doi-org.brum.beds.ac.uk/10.3390/molecules22071111
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