Synthesis and molecular structure of [n-Bu2(F)SnOSn(F)t-Bu2]2 - an unsymmetrically substituted tetraorganodistannoxane

The dimeric tetraorganodistannoxane [n-Bu₂(F)SnOSn(F)t-Bu₂]₂ (1) was prepared by the reaction of (t-Bu₂SnO)₃ with n-Bu₂SnF₂ and characterized in solution by multinuclear NMR spectroscopy and ESI MS spectrometry and in the solid state by ¹¹⁹Sn MAS NMR spectroscopy and single crystal X-ray diffraction.

Hydrolysis of (Me3SiCH2)PhSnCl2. Isomerisation of the dimeric tetraorganodistannoxane [(Me3SiCH2)Ph(Cl)SnOSn(Cl)-Ph(CH2SiMe3)]2

The hydrolysis of (Me₃SiCH₂)PhSnCl₂( 1) was studied under two different reaction conditions (i) by using an excess of aqueous NaOH in toluene at reflux temperature and (ii) by using small amounts of NEt₃ and water in CH₂Cl₂ at room temperature. For (i) the products  (Me₃SiCH₂)Ph₂SnOSnPh₂(CH₂SiMe₃)( 2) and [(Me₃SiCH₂Sn)₁₂O₁₄(OH)₆](OH)₂( 3) were isolated indicating that a phenyl group migration took place. For (ii) the dimeric tetraorganodistannoxane [(Me₃SiCH₂)Ph(Cl)SnOSn(Cl)Ph(CH₂SiMe₃)]₂( 4) was obtained. In solution, 4 exists as an equilibrium mixture of all five possible isomers 4a–4e; in the solid state two of these isomers 4d and 4e co-crystallized in the same crystal modification. The observation of interconvertible isomers of 4 was attributed to the kinetic lability of the ladder-like Sn4O2Cl4 structural motif. Compounds 1 and 4 were investigated by X-ray crystallography.

New insights in asymmetric tetraorganodistannoxane ladder formation. A NMR-spectroscopic and crystallographic study

The syntheses of the asymmetrically substituted tetraorganodistannoxanes [t-Bu₂(X)SnOSn(Y)(CH₂SiMe₃)₂1₂ (1, X = Y = OH; 2, X = Cl, Y = OH; 3, X = Y = Cl) are reported and their structures in solution and in the solid state are characterized by multinuclear NMR spectroscopy and single crystal X-ray analyses. In toluene, the tetrahydroxy-substituted derivative 1 is in equilibrium with the organotin oxides cyclo-[t-Bu₂Sn{OSn(CH₂SiMe₃)₂}₂O] (4), cyclo[(Me₃SiCH₂)₂Sn(OSnt-Bu₂)₂O] (5), and cyclo-(t-Bu₂SnO)₃, and some additional, undefined species containing pentacoordinated tin atoms. In contrast, the dihydroxydichloro-substituted derivative 2 is inert in solution.

A novel route for the preparation of dimeric tetraorganodistannoxanes

The reaction of polymeric diorganotin oxides, (R₂SnO)_n (R=Me, Et, n-Bu, n-Oct, c-Hex, i-Pr, Ph), with saturated aqueous NH₄X (X=F, Cl, Br, I, OAc) in refluxing 1,4-dioxane afforded in high yields dimeric tetraorganodistannoxanes, [R₂(X)SnOSn(X)R₂]₂, and in a few cases diorganotin dihalides or diacetates, R₂SnX₂. The reported method appears suitable for the synthesis of fluorinated tetraorganodistannoxanes. Identification of [R₂(OH)SnOSn(X)R₂]₂ (R=n-Bu; X=Cl, Br) and [R₂(OH)SnOSn(X)R₂] [R₂(X)SnOSn(X)R₂] suggest a serial substitution mechanism starting from [R₂(OH)SnOSn(OH)R₂]₂. X-ray crystal structure determinations are reported for [Me₂(AcO)SnOSn(OAc)Me₂]₂ (29a), [i-Pr₂(Br)SnOSn(Br)i-Pr₂]₂ (20a), [c-Hex2(F)SnOSn(F)c-Hex₂]₂ (5a) and [c-Hex₂(F)SnOSn(Cl)c-Hex₂]₂ (36), respectively. These show the presence of a central (R₂Sn)₂O₂ core that is connected, via the oxygen atoms, to R₂Sn entities. Acetate (29a) or halides (5a, 20a, 36) complete the coordination about the tin centres.

Hydrolysis of bis((trimethylsilyl)methyl)tin dihalides. Crystallographic and spectroscopic study of the hydrolysis pathway

The synthesis and characterization by multinuclear NMR spectroscopy of the diorganotin dihalides (Me₃SiCH₂)₂SnX₂ (1, X = Cl; 2, X = Br), the diorganotin dichloride water adduct (Me₃SiCH₂)₂SnCl₂·H₂O (1a), the dimeric tetraorganodistannoxanes [(Me₃SiCH₂)₂(X)SnOSn(Y)(CH₂SiMe₃)₂]₂ (3, X = Y = Cl; 4, X = Br, Y = OH; 5, X = Br, Y = F; 6, X = Y = OH; 8, X = Cl, Y = OH), and the molecular diorganotin oxide cyclo-[(Me₃SiCH₂)₂SnO]₃ (7) are reported. The structures in the solid state of compounds 1a, 3, 6, and 7 were determined by single-crystal X-ray analysis. In toluene solution, the hydroxy-substituted tetraorganodistannoxane 6 is in equilibrium with the diorganotin oxide 7 and water. The eight-membered diorganotin oxide cyclo-[(Me₃SiCH₂)₂SnO]₄ (7a) is proposed to be involved in this equilibrium. On the basis of the results of this and previous works, a general hydrolysis pathway is developed for diorganotin dichlorides containing reasonably bulky substituents.

Solvent-controlled assembling by hydrogen bridges and halogen-halogen interactions of novel organotin oxo clusters

The crystal structure of the novel methylene-bridged tetraorganodistannoxane {[Ph(HO)SnCH₂Sn(I)Ph]O}₄ (1) depends on the solvent it is crystallised from and is controlled by hydrogen bridges and interhalogen interactions.