London Dispersion Effects in a Distannene/Tristannane Equilibrium: Energies of their Interconversion and the Suppression of the Monomeric Stannylene Intermediate |
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| Authors: | Wenxing Zou Markus Bursch Kristian L Mears Cary R Stennett Ping Yu James C Fettinger Stefan Grimme Philip P Power |
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| Institution: | 1. Department of Chemistry, University of California, Davis, 1 Shields Ave, Davis, CA 95616 USA;2. Max-Planck-Institut für Kohlenforschung, 45470 Mülheim an der Ruhr, Germany;3. Department of Chemistry, NMR Facility, University of California, Davis, 1 Shields Ave, Davis, CA 95616 USA;4. Mulliken Center for Theoretical Chemistry, Universität Bonn, 53115 Bonn, Germany |
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| Abstract: | Reaction of {LiC6H2?2,4,6-Cyp3?Et2O}2 (Cyp=cyclopentyl) ( 1 ) of the new dispersion energy donor (DED) ligand, 2,4,6-triscyclopentylphenyl with SnCl2 afforded a mixture of the distannene {Sn(C6H2?2,4,6-Cyp3)2}2 ( 2 ), and the cyclotristannane {Sn(C6H2?2,4,6-Cyp3)2}3 ( 3 ). 2 is favored in solution at higher temperature (345 K or above) whereas 3 is preferred near 298 K. Van't Hoff analysis revealed the 3 to 2 conversion has a ΔH=33.36 kcal mol?1 and ΔS=0.102 kcal mol?1 K?1, which gives a ΔG300 K=+2.86 kcal mol?1, showing that the conversion of 3 to 2 is an endergonic process. Computational studies show that DED stabilization in 3 is ?28.5 kcal mol?1 per {Sn(C6H2?2,4,6-Cyp3)2 unit, which exceeds the DED energy in 2 of ?16.3 kcal mol?1 per unit. The data clearly show that dispersion interactions are the main arbiter of the 3 to 2 equilibrium. Both 2 and 3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results). |
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| Keywords: | Cyclotristannane Energy Decomposition Analysis Equilibrium London Dispersion Organotin |
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