Tin-Based Hybrid Materials as Precursors of Mesoporous Tin Oxide
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Tin-Based Hybrid Materials as Precursors of Mesoporous Tin Oxide Bernard Jousseaume,1 Hocine Riague,1 Thierry Toupance,1 Mohamed Lahcini2 1 Laboratoire de Chimie Organique et Organométallique, UMR 5802, Université Bordeaux I, Talence, France; 2 Département de Chimie, Université Cadi Ayyad, Marrakech, Morocco. ABSTRACT Alkylene-, arylene- or benzylene-bridged ditin hexachlorides were obtained in high yields from the reaction of the corresponding hexacyclohexylated compounds with tin tetrachloride. These intermediates were successfully transformed into the corresponding alkynides, which gave gels of hybrid materials on hydrolysis. This is the first example of a gel formation from a organometal with the metal fully substituted with covalently-linked organic groups. Subsequent thermal treatment led to mesoporous tin oxide with high surface area and narrow pore size distribution. INTRODUCTION We have been interested [1] recently in the preparation of organotin precursors of hybrid materials [2] which allowed us to present a new route to functional monoorganotins [3]. In order to broaden the scope of the available precursors, as the corresponding disilylated compounds revealed excellent precursors of various types of microporous or mesoporous silica [4], monoorganodistannylated compounds were needed. The classical method of preparation involving the electrophilic cleavage of phenyl groups in α,ωbis(triphenyltin)alkanes cannot be applied to an aryl- or a benzyl-type linker where the electrophilic cleavage would not be selective enough and would also cleave tin-bridge bonds, which would greatly reduce the yields. Here we present a general access to alkylene-, aryleneor benzylene-bridged ditin compounds, based on the use of auxiliary cyclohexyl groups, their transformation into hybrid materials upon hydrolysis and into mesoporous tin oxide upon thermolysis. EXPERIMENTAL DETAILS. Preparation of bis(tricyclohexylstannyl)alkyl and -aryl derivatives. A solution of alkyl or aryl dibromide (59 mmol) in THF (80 ml) was slowly added to magnesium (3.0 g, 125 mmol) in THF (10 ml). The mixture was refluxed for 30 min, cooled at room temperature and a solution of tricyclohexyltin chloride (39.43 g, 97.8 mmol) in THF (150 ml) was added. After refluxing for 1 h the mixture was hydrolyzed with a saturated solution of NH4Cl, extracted with petroleum ether (100 ml), dried over MgSO4, and the solvents evaporated. Recrystallization from petroleum ether gave the pure products.Yields : 61-78 %. Preparation of bis(trichlorostannyl)alkyl and -aryl derivatives. SnCl4 (8.8 ml, 75 mmol) was slowly added to a solution of bis(tricyclohexylstannylated) compound (29 mmol) in toluene (60 ml). After stirring at 70 °C for 15 hours, the solvant was evaporated under reduced pressure. Acetonitrile (50 ml) was added. The solution was extracted with petroleum ether (5x20 ml) to remove tricyclohexyltin chloride. Acetonitrile was evaporated to give the pure hexachlorides. Yields : 89-98 %. Q6.6.1 Downloaded from https:/www.cambridge.org/core. Columbia University L
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