Hydrolysis and condensation of (CH3COCHCOCH3)2SnF(Otert-Am) and (CF3COCHCOCH3)2Sn(Otert-Am)2 gave soluble stannic oxo-oligomers or -polymers including fluorine and β-diketonate groups. Under thermal treatment in air at 550 °C, they yielded nanocrystalline fluorine-doped tin dioxide powders. The amount of remaining ligands in the xerosols depends on the hydrolysis ratio and on the nature of the solvent used, dimethylformamide (DMF) favoring ligand removal. The thermolytic reactions have been investigated by thermogravimetry coupled to mass spectrometry: (1) the β-diketonate ligands pyrolyze in two stages, at 200 and 320 °C, involving two different processes; (2) elimination of polar solvents of high boiling point, such as DMF, occurs up to 300 °C; (3) fluorine is lost as fluorhydric acid from 230 °C. The best strategy to prepare F-doped SnO2 materials by the sol−gel route is thus to start from precursors including Sn−F bonds and to use a polar aprotic solvent of low boiling point such as acetonitrile. It led to nanocrystalline, highly conductive F-doped tin dioxide materials with resistivities 1 order of magnitude lower than that reported for Sb-doped tin dioxide powders.

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Dialkoxydi(beta-diketonate)tin(IV) compounds react either with difluorodi(beta-diketonate)tin(IV) or with butanoyl fluoride to yield novel tin complexes Sn(OR(1))F(R(2)COCHCOR(2))(2) 1 (R(1) = tert-amyl, isopropyl, ethyl; R(2) = methyl, tert-butyl). Multinuclear (1)H, (13)C, (19)F, and (119)Sn NMR spectroscopic characterization showed that complexes 1 are octahedral in solution with a cis configuration for the fluorine and the alkoxide group. Kinetics of configurational rearrangements were studied by variable-temperature (13)C NMR spectroscopy. The hydrolytic behavior of 1 was determined for different hydrolysis ratios h = [H(2)O]/[1]. For R(1) = tert-amyl, a dimeric fluorinated species was mainly obtained for h = 0.5, and addition of 2 mol equiv of water led to a fluorinated stannic oxopolymer soluble in CH(3)CN. In the latter case, the powder obtained after solvent elimination and treatment in air at 550 degrees C consisted of crystalline SnO(2) cassiterite particles containing the required amount (3 mol %) of doping fluorine and exhibiting electronic conductivity comparable to that of Sn-doped In(2)O(3). Complexes 1 are the first precursors of F-doped SnO(2) materials prepared by the sol-gel route.

Insoluble polystyrene grafted compounds of the type (P-H)(1-t){P-(CH2)n SnBu(p)Cl(3-p)}(t), (P-H)(1-t){P-(CH2)n SnBuO}(t) and (P-H)(1-t)[{P-(CH2)n SnBuCl}2O](t/2), in which (P-H) is a cross-linked polystyrene; n=4, 6, and 11; p=0 and 1; and t the degree of functionalisation, were synthesised from Amberlite XE-305, a polystyrene cross-linked with divinylbenzene. The compounds were characterised by using elemental analysis, and IR, Raman, solid-state 117Sn NMR, and 1H and 119Sn high-resolution MAS NMR spectroscopy. The influence of the spacer length and the tin functionality on the catalytic activity of these compounds, as well as their recycling ability, was assessed in the transesterification reaction of ethyl acetate with various alcohols. These studies showed significant differences in the activity of the catalysts interpreted in terms of changes in the mobility of the catalytic centres. Some of the supported catalysts could be recycled at least seven times without noticeable loss of activity. The residual tin content in the reaction products was found to be as low as 3 ppm.

The coordination behavior of three ester-functionalized monoorganotin trichlorides of the type ω-(trichlorostannyl)alkyl acetate, CH3COO(CH2) n SnCl3 (n = 3−5), has been investigated by multinuclear solid- and solution-state NMR, as well as AM1 quantum-chemical calculations. The data reveal basically the existence of a fast equilibrium between two species involved respectively in an intramolecular and intermolecular donor-acceptor interaction between the ester function and the tin atom. In the n = 3 case, the species involving the intramolecular interaction is by far the dominant one, with a coordination from the alkoxy oxygen atom to the tin atom, resulting in an interaction of the type −CH2O(Ac)→SnCl3 (Ac = CH3CO−). In contrast, for the n = 4 and 5 cases, the species involving the intermolecular interaction prevails, resulting in (cyclo)dimeric or oligomeric species displaying coordinations from the carbonyl oxygen atom to the tin atom of the type −CH2OC(CH3)O→SnCl3.

The preparation of alkylene-, arylene-, or benzylene-bridged ditin hexachlorides in high yields from the reaction of the corresponding hexacyclohexylated compounds with tin tetrachloride is described. The tetragonal geometry of the tin atom of 1,4-bis(trichlorostannyl)butane in the solid state indicates that no intramolecular or intermolecular interaction involving either end of the molecule exists in this compound. The ditin hexachlorides were successfully transformed in the corresponding hexaalkynides, precursors of hybrid materials.

Upon exposure to air, 1,2-bis(acyloxy)tetraalkyldistannanes incorporated in mixtures of either silicone oils and curing agent, or of isocyanates and alcohols, are oxidized to 1,3bis(acy1oxy)tetraalkyldistannoxanes which show excellent catalytic properties for curing silicones or for preparing polyurethanes. Under nitrogen, they induce longer pot-lives than the usua 1 bis (acy 1 oxy) d ia 1 ky Is tannane catalysts. Peru 1 ky 1 - polycyclostannanes, obtained either by the palladiumcatalyzed decomposition of dialkylstannanes or by reduction of dichlorodialkylstannanes with metals, are also very good latent catalysts for silicone curing. When incorporated into reactive mixtures under nitrogen, they do not catalyze the condensation. Upon exposure to air, they are oxidized to active catalysts which cure silicones. These di-or polystannanes can be considered airactivated latent organotin catalysts.In the plastics industry, the most important reactions catalyzed by bis(acy1oxy)dialkylstannanes' are the curing of silicones, which need to be cured to show their interesting elastomeric properties? the preparation of polyurethanes? which has to be accelerated when high production rates are needed, and esterification processes. Organotin catalysts are used in these reactions because of their high efficiency, their low cost, and their moderate toxicity. Such high efficiency may cause inconvenience, however, as condensation or addition reactions start as soon as reactants and catalyst are mixed t~g e t h e r .~ We recently designed and prepared new latent organotin catalysts, bis-[2-(acyloxy)dkyl] diorganostannanes,6 which provide long pot-lives for the mixtures into which they have been incorporated and which can be activated at will by heating. These tetraorganostannanes are inactive, but upon heating, they undergo an anti @-elimination reaction leading to 0 (5) Jousseaume, B.; Gouron, V.; Maillard, B.; Pereyre, M.; Franc&, J.-M. Organometallics 1990,9,1330. Jousseaume, B.; Gouron, V.; Pereyre, M.; FrancBs, J.-M. Appl. Organomet. Chem. 1991,5, 136. Gouron, V.; Jousseaume, B.; Pereyre, M.; Verlhac, J. B.; Franc&, J.-M. In Chemistry and Technology of Silicon and Tin; Oxford University Press, Oxford Science Publishers: Oxford, U.K., p 239. Franc&, J.-M.; Gouron, V.; Jousseaume, B.; Pereyre, M. Eur. Pat. 338947, 1989; 421891,1991. (6) Jousseaume, B.; Noiret, N.; Pereyre, M.; Franc& J.-M.; Petraud, M. Organometallics 1992,11,3910. Jousseaume, B.; Guillou, V.; Noiret, N.; Pereyre, M.; Franch, J.-M. J. Organomet. Chem. 1993, 450, 91. Jousseaume, B.; Noiret, N.; Pereyre, M.; FrancBs, J.-M. J. Chem. SOC., Chem. Commun. 1992, 739.