SN compounds

Aldehydes take part in the cycloaddition to give the methylenetetrahydrofuran 178 by the co-catalysis of Pd and Sn compounds[115]. A similar product 180 is obtained by the reaction of the allyl acetate 179, which has a tributyltin group instead of a TMS group, with aldehydesfl 16]. The pyrrolidine derivative 182 is formed by the addition of the tosylimine 181 to 154[117]. 

Indeed, the reaction chemistry of these substances (i.e., SN compounds) deserves to rank with that of boranes for novelty and interest . 

It will be convenient to describe first the binary. sulfur nitrides SjN,. and then the related cationic and anionic species, S,Nv. The sulfur imides and other cyclic S-N compounds will then be discus.sed and this will be followed by sections on S-N-halogen and S-N-O compounds. Several compounds which feature i.solated S<—N, S-N, S = N and S=N bonds have already been mentioned in the. section on SF4 e.g. F4S NC,H, F5S-NF2. F2S = NCF3, and FiS=N (p. 687). Flowever. many SN compounds do not lend themselves to simple bond diagrams, - and formal oxidation states are often unhelpful or even misleading. 

Figure 15,34 Siruciures of some SN compounds meniioned in Table 15.22 and the text.

The inhibition doses, ID50, for the compounds and the parent [Bu2Sn(IV)] derivatives are presented in Table 9. These data do not support the hypothesis of Atassi that water-soluble Sn compounds might exhibit higher antitumor activity, at least for the cell lines studied. It should be outlined that the... 

Minganti V, Capelli R, Depellegrini R (1995) Evaluation of different derivatization methods for the multielement detection of Hg, Pb and Sn compounds by gas chromatography-microwave induced plasma-atomic emission spectrometry in environmental samples. Fresenius Journal of Analytical Chemistry, 351 (4-5) 471 77. 

The increased strength of the C—H and C=0 bonds in PbH3C(0)H relative to the X = Si — Sn compounds could be related to the nature of the X—C bond in these compounds. Examining Tables 4-8 for both the XH3CCH and XH3C(0)H shows that, relative to... 

The two Ge atoms and the four C atoms attached to them form a centrosymmetric group, however, these atoms are not coplanar. The fold angle of the R—Ge—R plane with the Ge—Ge line is 32°. The analogous Sn compound was also investigated. 

TABLE 6. Calculated stmctural parameters for R2E=ER2 trans-bent (E = Ge, Sn) compounds... 

A superb comprehensive and up-to-date survey concerning the organic chemistry of tin is given in the multi-volume Gmelin series on Sn compounds. 

Oxidation, on the other hand, is irreversible and results in cleavage of the metal-metal bond. Sn compounds are oxidized at higher potentials than the corresponding Ge complexes. The products are [(P)M(IV)]2+ (M = Ge, Sn). 

Herrmann and coworkers183 reported a series of Cp-manganese carbonyl complexes which bind Ge, Sn and Pb as central atoms linearly coordinated in clusters, to two Mn atoms in one series and trigonal-planar coordinated to three Mn atoms in another series 8 and 9. The group 14 atoms are double-bonded to two Mn atoms in these compounds, or carry one double bond and two single bonds to three Mn atoms. Potentiometric measurements of these compounds show irreversible reductions and oxidation by CV. No products could be isolated from either reduction or oxidation. The exceptionally high oxidation potential of (/i-Pb) r/ -CsHs )Mn(CO)2]2 as compared to the apparently similar Sn compound is noteworthy (Table 15). 

The intermediate Sn-Pd-Sn compound in distannation (Equation (34)) has recently been isolated in the reaction of an r -distannane.126... 

A summary of Zintl phases found in alkali-tin alloys has been reported by Fassler and Hoffmann (2003) together with the description of a new Na-Sn compound. It is Na7Sn12 which was synthesized by quenching stoichiometric amounts of the elements (700°C) in a sealed Nb ampoule and further thermal treatment at 270°C for 40 days. It was described as a Zintl phase suggesting that, on the basis of its structure, its formula can be rewritten as (Na )7[(2b)Sn2 ]1[(3b)Sn ]s [(4b)Sn°]6 (where 2b, 3b, etc. denote two-three-fold bonded atoms) resulting in a polyanion i(Sn]2). 

The situation for tin-119 is more confused because of the uncertainty in AR/R. The first attempts to systematize isomer shifts for tin-119 were made by Cordey-Hayes and his co-workers (8). He assumed that ionic stannous compounds have a configuration 5s, Sn compounds or tetrahedral tin compounds have the configuration in which there are 4 p ... 

The unique contribution of MOssbauer spectroscopy to chemistry is the direct determination of changes in the s electron density at the Mossbauer nucleus for various compounds by measuring their chemical shift. Interpreting the chemical shift for Sn compounds, in contrast to Fe, has resulted in a great controversy. 

With the sign of AR/R established, the structure and bonding of tin compounds can be investigated. From the scatter plot in Figure 1, the Sn compounds fall to the left of white tin, while the Sn compounds fall to the right. The organotin compounds are clustered in the cross-... 

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