skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Search for: All records

Creators/Authors contains: "Mears, Kristian"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Thermal Sn–C cleavage in the diarylstannylene Sn(AriPr4)2(AriPr4= C6H3-2,6-(C6H3-2,6-iPr2)2) was used to generate ˙Sn(AriPr4) and ˙AriPr4radicals for alkyne arylstannylation. 
    more » « less
  2. 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 » « less
  3. Structural characterization of the complex [B(β-pinane) 3 ] (1) reveals non-covalent H⋯H contacts that are consistent with the generation of London dispersion energies involving the β-pinane ligand frameworks. The homolytic fragmentations of 1 , and camphane and sabinane analogues ([B(camphane) 3 ] (2) and [B(sabinane) 3 ] (3)) were studied computationally. Isodesmic exchange results showed that London dispersion interactions are highly dependent on the terpene's stereochemistry, with the β-pinane framework providing the greatest dispersion free energy (Δ G = −7.9 kcal mol −1 ) with Grimme's dispersion correction (D3BJ) employed. PMe 3 was used to coordinate to [B(β-pinane) 3 ], giving the complex [Me 3 P–B(β-pinane) 3 ] ( 4 ), which displayed a dynamic coordination equilibrium in solution. The association process was found to be slightly endergonic at 302 K (Δ G = +0.29 kcal mol −1 ). 
    more » « less
  4. 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).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 ΔG300 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). 
    more » « less