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Half a century since the photocatalytic disproportionation of Lappert's dialkyl stannylene SnR 2 , R = CH(SiMe 3 ) 2 (1) gave the persistent trivalent radical [·SnR 3 ], the characterization of the corresponding Sn(I) product, ·SnR is now described. It was isolated as the hexastannaprismane Sn 6 R 6 (2), from the reduction of 1 by the Mg(I)-reagent, Mg(BDI Dip ) 2 , (BDI = (DipNCMe) 2 CH, Dip + 2,6-diisopropylphenyl).more » « lessFree, publicly-accessible full text available May 2, 2024
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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 SnCl2afforded 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) whereas3 is preferred near 298 K. Van't Hoff analysis revealed the3 to2 conversion has a ΔH =33.36 kcal mol−1and ΔS =0.102 kcal mol−1 K−1, which gives a ΔG 300 K=+2.86 kcal mol−1, showing that the conversion of3 to2 is an endergonic process. Computational studies show that DED stabilization in3 is −28.5 kcal mol−1per {Sn(C6H2−2,4,6‐Cyp3)2unit, which exceeds the DED energy in2 of −16.3 kcal mol−1per unit. The data clearly show that dispersion interactions are the main arbiter of the3 to2 equilibrium. Both2 and3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results). -
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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 SnCl2afforded 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) whereas3 is preferred near 298 K. Van't Hoff analysis revealed the3 to2 conversion has a ΔH =33.36 kcal mol−1and ΔS =0.102 kcal mol−1 K−1, which gives a ΔG 300 K=+2.86 kcal mol−1, showing that the conversion of3 to2 is an endergonic process. Computational studies show that DED stabilization in3 is −28.5 kcal mol−1per {Sn(C6H2−2,4,6‐Cyp3)2unit, which exceeds the DED energy in2 of −16.3 kcal mol−1per unit. The data clearly show that dispersion interactions are the main arbiter of the3 to2 equilibrium. Both2 and3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results).
