Linear polystannanes

Relatively few linear polystannanes have been the subject of crystallographic analysis Table IV and Fig. 4 provide some selected structural... 

Selected Bond Lengths and Bond Angles for Linear Polystannanes... 

The series of linear polystannanes represented by compounds 31, 33, 35, 48, and 49 have also been the subject of spectroscopic analysis. In this case, a similar trend is observed, although the magnitude of the red-shift per tin atom is less than that observed for the previous series (Fig. 6). This discrepency between the two series of linear polystannanes is likely to be a result of the strong nonbonded interactions in the former (i.e., 39, 40, 50, and 51), which severely restrict conformational mobility... 

Fig. 6. Electronic spectra for the linear polystannanes represented by compound 31 (n = 0), compound 33 ( = 1), compound 35 n = 2), compound 48 (n = 3), and compound 49 (n = 4). Reprinted with permission from Sita (52).

Much less has been documented concerning the chemical reactivity of linear polystannane oligomers, but, at the outset, it can be expected to closely parallel that reported for distannanes. It is known that these compounds are air-sensitive when the substituents posses small steric bulk. But so far, no attempts have been conveyed concerning the controlled... 

Sita, L. R. (1992) A new strategy for the synthesis of homologously pure linear polystannane oligomers, Organometallics 11,1442-1444. 

The Sn-NMR chemical shifts of the poly(alkyl-) and poly(arylstannanes), surprisingly, are quite similar the cyclic products have up field chemical shifts (Table 8.1). In contrast to the fairly linear polystannanes prepared by the catalytic action of zirconocene catalysts, branched polymers are obtained in the reaction of Bu2SnH2 with the rho-... 

Emax = 13 690) of compound 2 was similar to that previously observed fbr short-chain linear polystannanes [5], an oligomeric polystatmane structure with Sn-Sn a-delocalization was assumed. Indeed, as shown in Figure 2, crystallographic analysis revealed that the molecular structure of 2 possesses six tin atoms arranged in a bicyclo[2.2.0]hexane framework comprised of a cis fusion... 

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