Tin, alkyl derivatives

In contrast to the scarcity of stable poly(pyrazolyl)borato alkyl complexes of Si, Ge, and Pb, such derivatives are common for tin. The first poly(pyrazolyl)borato tin alkyl derivatives to be prepared were the parent derivatives, namely five-coordinate [Bp]SnMe Cl3 and six-coordinate [Tp]SnMe Cl3 (n = 0-3), obtained by the reactions of MenSnCl4 with K[Bp] and K[Tp], respectively [Eqs. (25) and (26)] (116). 

In addition to tin alkyl derivatives with one poly(pyrazolyl)borato ligand, bis[(poIy)pyrazolylborato] complexes of the types [Tp]2SnR2 and [R2Bp]2SnR2 have also been prepared (123,124). 

Question Is it definitely inorganic tin, and not some tin-alkyl derivative such as a methyl tin compound ... 

Mengoli, G., Recent Developments in the Electrochemical Synthesis of Lead and Tin Alkyl Derivatives, Rev. Silicon Germanium Tin Lead Compounds 4 [1979] 59/89. 

The alkyl derivatives of thiazoles can be catalytically oxidized in the vapor phase at 250 to 400°C to afford the corresponding formyl derivatives (21). Molybdenum oxide, V2O5, and tin vanadate are used as catalysts either alone or with a support. The resulting carbonyl compounds can be selectively oxidized to the acids. 

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. 

Of the group 14 elements (Si, Ge, Sn and Pb), only tin is known to form a variety of poly(pyrazoIyl)borato alkyl derivatives. For example, the reactions between K[pzTp] and the silicon derivatives Me SiCl4 (n = 1-3) have not given tractable products (115). Similarly, the reaction between K[pzTp] and Me2GeCl2 gives a complex that has been spectroscopically characterized as [pzTp]2GeMe2, but which readily decomposes. 

The above requirements limit the number of species that can be fractionated by this technique. However, hydride forming elements and those that can be converted into volatile alkyl derivatives can be used. Lead tin arsenic mer-... 

The reaction of diols with alkylating agents can also be performed such that approximately the theoretical amount of monoalkylated product is obtained. Some substrates can even be monoalkylated [36, 41, 42] or monoarylated [43] with substantially higher yields than statistics would predict what must be due to the slowness of the second alkylation. This behavior, however, is not usually observed, and other strategies must usually be used to achieve clean monoalkylations. Use of excess diol will often furnish pure monoalkylated diol, but a suitable means of removal of excess diol will be required. In the examples sketched in Scheme 10.10 the products were purified by column chromatography, recrystallization, or distillation. As with acylations, the formation of monoalkylated diols can also be promoted by Ag20 [44] or by transient protection with boron [45] or tin [46] derivatives. 

Of greater practical interest for the production of tin alkylhalogenides is organomagnesium synthesis, which is based on the interaction of alkyl-magnesiumhalogenides with tin tetrachloride. This technique can also yield tin tetraalkyl derivatives. Since these substances are semiproducts in the production of organic salts of dialkyl tin, their organomagnesium synthesis is described along with the production of diethyl tin dicaprylate. 

More reactive anions, such as the very well studied enolate anions from ketones and esters, do not imdergo allylic alkylation except in special cases. Tin enolate derivatives are generally effective (equation 52). 

Other ways to obtain 3-OH acceptors are the use of mannose precursors with a temporary 3-0-allyl protecting group in the Grignard reaction [16,18,20], or phase transfer benzylation [42] of a heptopyranosyl 2,3-diol, or benzylation of a tin-activated [43] heptofuranosyl 2,3-diol, both last methods giving preferentially the 2-0-benzyl derivative [27,15]. However, if the tin-assisted alkylation is performed on a heptopyranosyl 2,3-diol, the 3-0-alkyl derivative is the main product [5,28]. 

Yamamoto and coworkers protonated silyl enol ethers with a stoichiometric amount of a complex derived from BINOL and SnCLj giving optically active a-alkyl ketones. A catalytic reaction was developed employing another tin complex derived from BINOL monomethyl ether (LBA), in which 2,6-dimethylphenol was used as the proton source (equation 65). ... 

Hill and co-workers studied the thermal decomposition of a large number of metal complexes of various alkyl derivatives of xanthic and dithiocarbamic acids. The complexes were studied by using TG. DSC. and other TA techniques. Compounds investigated included Nil IB alkyl xanthates (79), Cu(II) dithiocarbamate complexes (80), dihalotin (IV) bisdiethyldithio-carbamates (81), bisldiethyldithiocarbamatoi diphenyl tin (IV) (82), tetrakis-(diethyldithiocarbamatoi tin(lV) (83, 84), and bisidieihyldithiocarbamato) tin(IV) (85). 

Alkyl-4-oxopentanals. In the presence of LiBr, the tin enolate derived from diketene and bis(tributyltin) oxide reacts with a-bromoaldehydes in a chemoselective manner. It involves displacement of the bromine and decarboxylation. 

The applications of organometallic agents in technology show every promise of increasing. The traditional use of tetraethyllead in motor fuels may eventurlly be replaced by some other type. Tin alkyls have gained some recent prominence both for the biocidal properties of certain trialkyl-tin derivatives and for the ultraviolet-discoloration protection offered vinyl plastics by dibutyltin dilaurate. Also attention should be drawn to the possi-... 

Thus, it can be concluded that reactions, in which there is a possibility of the formation of platinum(IV) derivatives with alkyl fragments containing a hydrogen bond in the p-position, lead to olefin ff-cotnp exes of platinum(II). These reactions are the interactions of platinum chlorides with alkyl iodides and alkyl derivatives of tin as well as the thermal and photochemical dehydrogenation of n-hexane by PtCU (Scheme VI.5). One possible mechanism for the dehydrogenation of n-hexane is the formation of a cr-hcxyl complex of plati-num(IV) and its subsequent transformation into a n-olefin complex of plati-num(II) via p-elimination of hydrogen [16] ... 

Dialkylamino derivatives of elements located in the periodic table to the left or below those listed above cannot be prepared by the above method due to either the ionic character of some of the inorganic halides or the formation of stable metal halide-amine addition products. Therefore, other methods must be applied. Dialkylamino derivatives of tin and antimony are conveniently obtained by reaction of the corresponding halides with lithium dialkylamides. Others, such as the dialkylamino derivatives of aluminum, are made by the interaction of the hydride with dialkylamines. Dialkylamino derivatives of beryl-lium or lithium result from the reaction of the respective alkyl derivative with a dialkylamine. 

---