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The synthesis and structural studies of tin(IV) and organotin(V) sulfonates Yeats, Philip Allen

Abstract

The systematic investigation of the solvolysis of methyltin(IV) chlorides of the type (CH₃)[sub n] SnCl[sub 4-n], 1 < n < 4, in strong monobasic protonic acids, in particular HSO₃F and HSO₃CF₃, has resulted in the preparation of new trimethyltin(IV), dimethyltin(IV) and methyl-chlorotin(IV) sulfonates. Preferential cleavage of Sn-Cl over Sn-C bonds was noted resulting in mono- or bisubstitution on tin depending on the mole ratio of the reactants. Additional methylchlorotin(IV) fluorosulfates could be obtained by non-statistical ligand redistribution reactions with chloride and fluorosulfate exchange between suitable substrates, e.g. (CH₃)₂Sn(SO₃F)₂ + (CH₃)₂SnCl₂ → 2(CH₃)₂ClSnSO₃F Inorganic fluorosulfates Cl₂Sn(SO₃F)₂ and Br₂Sn(SO₃F)₂ were obtained by similar ligand scrambling of either SnCl₄ or SnBr₄ in Sn(SO₃F)₄. Sn(SO₃F)₄ was found to undergo complete SO₃F-Cl exchange with TiCl₄ resulting in the formation of Ti₃Cl₁₀(SO₃F)₂ which appears to have rather unique tetradentate SO₃F groups. Complexation reactions of the Lewis acid Sn(SO₃F)₄ with ClO₂SO₃F , I(SO₃F)₃ and Br(SO₃F)₃ result in the formation of Sn(SO₃F)₆²⁻ salts with ClO₂⁺, I(SO₃F)₂ and Br(SO₃F)₂ ⁺ cations. Nitrosonium and alkali metal hexakisfluorosulfato- stannates are obtained by the reaction M[sup I / sub 2]SnCl₆ + 3S₂O₆F₂ → M[sup I / sub 2]Sn(SO₃F)₆ The reactions of the Lewis acids AsF₅ and SbF₅ with some of the halogen fluorosulfates mentioned above is also discussed. Structural studies are based on vibrational and ¹¹⁹Sn Mossbauer spectra with the latter providing proof of the identity of the methyl- chlorotin(IV) fluorosulfates and the Sn(SO₃F)₆²⁻ ion. Except for the Sn(SO₃F)₆²⁻ compounds, the tin is either hexa- coordinated or occasionally pentacoordinated with the sulfonate groups acting as bidentate bridging links between the tin moieties. Two structural types emerge: the octahedral bisfluorosulfates XYSn(SO₃F)₂ with X, Y = CH₃, Br, CI, and SO₃F in trans octahedral positions and the trigonal bipyramidal X₂YSnSO₃F. Successful correlations of isomer shifts vs. the sum of the Pauling electronegativities of X and Y or quadrupole splitting vs. the Taft σ* for X and Y indicate isostructural compounds for the bisfluorosulfates. The monofluorosulfates allow no such correlations. In Sn(SO₃F)₆²⁻ monodentate SO₃F groups give rise to an octahedral environment for tin and hence a zero quadrupole splitting.

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