Stoichiometry of Diorganotin Dihalide Adducts in Solution

Claude H. Yoder, Dian Mokrvnka, Suzanne M. Coley, Julie C. Otter, Ronald E. Haines, Michele A. Shermak, Joseph Mikus, J. N. Spencer, James W. Hovick, Lori J. Ansel, Alex Grushow

Research output: Contribution to journalArticlepeer-review

Abstract

The formation of Lewis acid-base adducts of diorganotin dihalides of the type R2SnX2, where R = CH3, C2H5, C3H7, n-C4H9, £-C4H9, or C6H5and X = Cl or Br, with a variety of bases (triphenylphosphine oxide [TPPO], Me2SO, DMA, diphenyl sulfoxide, dibenzyl sulfoxide, pyridine AT-oxide, and acetonitrile) was studied by both NMR spectroscopy and calorimetry. The31P chemical shift of TPPO and theU9Sn shift of the acid were monitored as a function of concentration. The effects of different equilibria including formation of the 1:1 adduct, the 1:2 adduct, simultaneous formation of the 1:1 and 1:2 adducts, and simultaneous formation of the 1:1 adduct and either associated acid, associated base, or associated adduct on the NMR shifts as a function of concentration were determined by computer simulation. The experimentally observed plots, can be attributed to predominant formation of the 1:1 adduct along with the associated adduct. The formation of the 1:2 adduct also occurs in solution as demonstrated by isolation of 1:2 adducts and the curvature obtained in the chemical shift plots for weak acids and bases. Calorimetric data were analyzed by schematic mapping and show that the only model that successfully reproduces the data is predominant formaton of the 1:1 adduct. The size of the substituents on the acid was found to have a significant effect on the equilibrium constants; the constants for di-tert-butyltin dichloride were a factor of 100 lower than those of dimethyltin dichloride. Base strengths toward dimethyltin dichloride vary in the order TPPO > pyridine iV-oxide > Me2SO > DMA > dibenzyl sulfoxide > diphenyl sulfoxide > acetonitrile. Previous reports that the 1:2 adducts are favored for the dihalotins are most likely a result of the use of excess base to precipitate the 1:2 adduct and the generally greater insolubility of the 1:2 adduct.

Original languageEnglish (US)
Pages (from-to)1679-1684
Number of pages6
JournalOrganometallics
Volume6
Issue number8
DOIs
StatePublished - Aug 1 1987
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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