Tin halides. 74

The structural chemistry of Sn halides is particularly complex, partly because of the 

Structure of SnFj showing (a) interconnected rings of (SnjEi(Fj)). and (b) the unsymmetiicai 3 + 3 coordination around Sn. 

High-temperature neutron diffraction studies have shown that this latter phase has the cubic ordered Re03-type structure (p, 1047) with octahedral coordination of both types of Sn atoms by F (Sn -F 229 pm, Sn -F 186 pm). The fi-phase also features octahedral coordination in a structure closely related to that of rhombohedral LiSbF6. 

Tin(II) chlorides are similarly complex (Fig. 10.5). In the gas phase, SnCh forms bent molecules, but the crystalline material (mp 246°, bp 623°) has a layer structure with chains of comer-shared trigonal pyramidal SnClsl groups. The dihydrate also has a 3-coordinated structure with only I of the H2O molecules directly bonded to the Sn (Fig. I0.5c) the neutral aquo complexes are arranged in double layers with the second H2O molecules interleaved between them to form a two-dimensional H-bonded network 

Ruchaud, C. Mirambet, L. Folrnes, J. Grannec and J. L. SOUBEYROUX, Z anor. allfi. Chem. 590, 173-80 (1990). 

Apart from its structural interest, SnCl2 is important as a widely used mild reducing agent in acid solution. The dihydrate is commercially available for use in electrolytic tin-plating baths, as a sensitizer in silvering mirrors and in the plating of plastics, and as a perfume stabilizer in toilet soaps. The anhydrous material can be obtained either by dehydration using acetic 

Kiriyama, K. Kitahama, O. Nakamura and R. Kiriyama, Bull. Chem. Soc. Japan 46, 1389-95 (1973). 

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The ligand exchange reaction of tin halides with bis(trifliioroinethyl)iner-cury has been used to prepare trifluoromethyltin halides [6 7] (equation 5)... 

Perfluoroalkylacecylenic tin compounds have been synthesized via the reaction of perfluoroalkylacetylenic Grignard reagents with tin halide derivatives [21] (equation 14) The stability of several of these perfluoroalkylacetylenic tin derivatives has been studied [22],... 

Two approaches for the synthesis of allyl(alkyl)- and allyl(aryl)tin halides are thermolysis of halo(alkyl)tin ethers derived from tertiary homoallylic alcohols, and transmetalation of other allylstannanes. For example, dibutyl(-2-propenyl)tin chloride has been prepared by healing dibutyl(di-2-propenyl)stannane with dibutyltin dichloride42, and by thermolysis of mixtures of 2,3-dimethyl-5-hexen-3-ol or 2-methyl-4-penten-2-ol and tetrabutyl-l,3-dichlorodistannox-ane39. Alternatively dibutyltin dichloride and (dibutyl)(dimethoxy)tin were mixed to provide (dibutyl)(methoxy)tin chloride which was heated with 2,2,3-trimethyl-5-hexen-3-ol40. 

The classic route to halogenomethyltin compounds is the methylena-tion of tin halides with diazomethane, and this reaction has been used as the basis for the preparation of a series of thiomethyltin compounds (286). 

Potassium reacts explosively with all antimony trihalides except trifluoride, as with tin halides (p.223). 

The transmetalation of trimethylsilylphosphanes with germanium and tin halides is a useful way to prepare compounds with P—Ge and P—Sn bonds by simple chlorosilane elimination. The reverse reaction, i. e. formation of P—Si bonds by chlorosilane cleavage of germyl- and stannylphosphanes has not yet been reported. Recently, we observed that hexachlorodisilane "transsilylates di-r-butyl(trimethyl-silyl)phosphane 1 much faster than tetrachlorosilane to give trichlorosilylphosphane 2 ... 

TABLE 4. Equilibration of diastereomeric pentacoordinated triorga-no tin halides... 

A method for the preparation of dendritic Sn by the electrolysis of alkyltin complexes has been described. Bu2SnBr2 and BusSnBr form as intermediates143. The method is aimed at recovery of elemental tin from residues of tin compounds and for reuse in the preparation of tin halides. 

The most versatile synthesis involves the transmetallation of a zirconiacyclopentadiene231,232 with a tin halide under catalysis with CuCl233 (and an equivalent reaction occurs with other halides of other elements of Groups 13, 14, 15, and 16) (Equation (77)). Stannacyclopentenes can be prepared by analogous reactions of zirconacyclopentenes.233... 

Hydrolysis of the tin halides gives a family of important organotin oxides and hydroxides that have attracted a lot of attention in recent years. These compounds are considered in Section 3.14.16. 

The tin hydrides are usually prepared by reduction of a tin halide, oxide, or alkoxide with a metal hydride such as NaBH4, LiAlH4, or poly(methylhydrosiloxane) [(MeHSiO) (PMHS)]. 

Tetrahydropyran can be prepared by heating 1,5-dihydroxypentane at 190-210 C in the presence of butyltin trichloride (Scheme 4.12a). When the reaction is carried out using a cobalt catalyst [prepared by heating cobalt(II) oxalate (ethanedioate) under hydrogen at 600 °C] instead of the tin halide, the product is 3,4-dihydro-2 -pyran (Scheme 4.12b). 

Ammino-derivatives op Subgroup B—Derivatives of Tin Halides, Lead Halides. Chapter VIII. Metal - Ammines of Elements of Group V. 

Bis(phosphino) and bis(arsino) derivatives of germanium, tin or lead are unknown. However, monophosphino- and monoarsino-germanium and tin halides, BU2EMX (M = Ge, Sn E = P, As, X = Cl, Br), have been characterized as thermally stable, though easily oxidized solids, which are thought to be highly associated.658-663... 

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