Mechanism of interconversion of the silica-supported tin alkyl complexes (ΞSiO)3-nSn (n-C4H9)n+1, n = 0, 1, 2. Synthesis and characterization of the tin-containing polyhedral oligo-silsesquioxanes [(c-C5H9)7 Si8O12(CH3)2Sn(n-C4H9)3], [(c-C5H9)7Si7O11(OH)Sn(n-C4H9)2] and [(c-C5H9)7Si7 O12Sn(n-C4H9)] as possible models for the expected surface structures

Christophe Nédez, Véronique Dufaud, Frédéric Lefebvre*, Jean-Marie Maurice Basset, Bernard Fenêt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Thermolysis of the organometallic complex ΞSiOSn(n-C4H9)3 1 grafted on silica dehydroxylated either at 200 (silica(200)) or 500 °C (silica(500)) can be interpreted by assuming two decomposition pathways: (i) hydrolysis of the butyl groups by silanols, leading to n-butane and their stepwise substitution by surface siloxy ligands, and (ii) β-H elimination, followed by a reductive elimination of butane and formation of tin(II) surface species. In order to have further evidences of these two decomposition pathways on the two types of silica, both the thermolysis of (ΞSiO)2Sn(n-C4H9)2 2 supported on silica(200) and silica(500) (which is assumed to be formed during the thermolysis of 1) and the synthesis of molecular models with a silsesquioxane ligand were undertaken. It has been shown that on silica(200) the major decomposition pathway of 2 is the hydrolysis by remaining hydroxyl groups, leading to (ΞSiO)3Sn(n-C4H9) 3 and finally to dealkylated species, while on silica(500) the major decomposition pathway is the β-H elimination, leading to (ΞSiO)2SnII. Molecular models of 1, 2 and 3 were synthesized by reaction of oligo-silsesquioxanes with butyltin chlorides in presence of triethylamine. We chose this way instead to the direct reaction with tin hydrides simply for commodity and because butyltin trihydride is not known. [(c-C5H9)7Si7O11 (OH)Sn(n-C4H9)2] 2′ and [(c-C5H9)7Si7O12 Sn(n-C4H9)] 3′, which can be considered as molecular models of 2 and 3, were synthesized by reaction of (c-C5H9)7Si7O9 (OH)3 with Cl2Sn(n-C4 H9)2 and Cl3Sn(n-C4 H9) respectively. [(c-C5 H9)7Si8O12 Sn(n-C4H9)3 (CH3)2] 1′, which can be considered as a molecular model of 1, was synthesized by reaction of (c-C5H9)7Si8O9 (CH3)2(OH) with ClSn(n-C4H9)3. The 13C and 119Sn NMR chemical shifts of these compounds, both in solution and in the solid state, compared well with those of the surface organometallic species.

Original languageEnglish (US)
Pages (from-to)785-796
Number of pages12
JournalComptes Rendus Chimie
Volume7
Issue number8-9
DOIs
StatePublished - Aug 1 2004

Keywords

  • Alkyltin
  • Silica
  • Silsesquioxanes
  • Solid-state NMR
  • Thermolysis

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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