Compounds with tin-metal bonds

This chapter comprises organotin compounds with tin-metal bonds. All transition metal derivatives containing an organotin moiety are listed here unless the author specifically states that no metal-tin bond exists. In these cases the compounds are to be found in Chapters 2.7 2 through 2.7 8. Polymetallic derivatives with tellurium are listed in Chapter with... 

M. J. Newlands, Chap. 11 in Organotin Compounds with Tin—Other Metal Bonds in Organ-otin Compounds (Ed. A. K. Sawyer), Marcel Dekker Inc., New York, 1972, p. 881. 

Triorganotin salts of general formula [R3Sn] A+, A = alkali metal, are readily obtained from the reaction of the corresponding chlorotin compounds with the alkali metal. Reaction of these compounds with transition-metal halides is thus another useful salt-elimination reaction for the formation of tin-metal bonds. A representative selection of such reactions is illustrated in equation 72 -7448,49,232. 

P-Hydroxyalkyltin compounds can be prepared by the reaction of a tin-metal bonded compound I-FSn0 M0+ (M = Li,79 Na,80 or MgBr,81) with an epoxide, for example equation 6-33 79... 

Numerous compounds with Sn—M bonds, where M is a transition metal, have become available by various routes (e.g. insertion of SnCl2 into M—Cl bonds, oxidative addition, or simply by metathesis accompanied by alkali metal halide formation). Examples are given in Table 2.1.9. For the tin coordination number 4, one observes an increase in Sn nuclear shielding by a bond between tin and more heavy metals a similar trend is well known for and nuclear shielding in C—M and P—M bonds, respectively. 

Compounds bearing tin atoms bonded to metalloids of Group 14 are much more common than those with metals of Group 13, particularly in the cases of Sn—Si and Sn—Sn bonds, and to a lesser extent Sn—Ge bonds while for Sn—Pb, there are only two compounds structurally characterized bearing such a bond. 

A method for generating a perfluoroarylmagnesium compound is the cleavage of a pentafluorophenyl-metal bond by a nucleophile such as ethyltnagnesium bromide As an example, tetrakis(pentafluorophenyl)tin on reaction with ethyl-magnesium bromide gives a series of products, one of which may result from pentafluorophenylmagnesium bromide [27] (equation 7)... 

The chemistry of indium metal is the subject of current investigation, especially since the reactions induced by it can be performed in aqueous solution.15 The selective reductions of ethyl 4-nitrobenzoate (entry 1), 2-nitrobenzyl alcohol (entry 2), l-bromo-4-nitrobenzene (entry 3), 4-nitrocinnamyl alcohol (entry 4), 4-nitrobenzonitrile (entry 5), 4-nitrobenzamide (entry 6), 4-nitroanisole (entry 7), and 2-nitrofluorenone (entry 8) with indium metal in the presence of ammonium chloride using aqueous ethanol were performed and the corresponding amines were produced in good yield. These results indicate a useful selectivity in the reduction procedure. For example, ester, nitrile, bromo, amide, benzylic ketone, benzylic alcohol, aromatic ether, and unsaturated bonds remained unaffected during this transformation. Many of the previous methods produce a mixture of compounds. Other metals like zinc, tin, and iron usually require acid-catalysts for the activation process, with resultant problems of waste disposal. 

Other studies are under way, with other metal-metal bonded compounds, such as the tin and silicon alkyls. 

Several tri(cyclopentadienyl)tin(ll) and lead(ll) complexes have been prepared with alkali metal cations. The arrangement of Cp rings around the metal is in a paddle wheel configuration the alkali cation is bound to Cp and not Sn or Pb, further supporting the view of a weak alkali metal group 14 bond. Representative examples of these compounds include (77S-Cp)2E(/r-Cp)-Na(PMDTA) (E = Sn 230, Pb 231).239 240... 

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