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London dispersion (LD) interactions, which stem from long‐range electron correlations arising from instantaneously induced dipoles can occur between neighboring atoms or molecules, for example, between H atoms within ligand C−H groups. These interactions are currently of interest as a new method of stabilizing long bonds and species with unusual oxidation states. They can also limit reactivity by installing LD enhanced groups into organic frameworks or ligand substituents. Here, we address the most recent advances in the design of LD enhanced ligands, the sterically counterintuitive structures that can be generated and the consequences that these interactions can have on the structures and reactivity of sterically crowded heavy group 14 species.

 

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).2is favored in solution at higher temperature (345 K or above) whereas3is preferred near 298 K. Van't Hoff analysis revealed the3to2conversion 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 of3to2is an endergonic process. Computational studies show that DED stabilization in3is −28.5 kcal mol⁻¹per {Sn(C₆H₂−2,4,6‐Cyp₃)₂unit, which exceeds the DED energy in2of −16.3 kcal mol⁻¹per unit. The data clearly show that dispersion interactions are the main arbiter of the3to2equilibrium. Both2and3possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results).

 

Thermal Sn–C cleavage in the diarylstannylene Sn(Ar^iPr4)₂(Ar^iPr4= C₆H₃-2,6-(C₆H₃-2,6-iPr₂)₂) was used to generate ˙Sn(Ar^iPr4) and ˙Ar^iPr4radicals for alkyne arylstannylation.

 

Spontaneous Ge₆O₈cluster formation under ambient conditions using dispersion enhanced aryloxo ligands.

 

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).