Dimethyltin di

In dimethyltin diformate, however, the two carbonyl groups bridge intermolecularly, to form infinite sheets similar to those in dimethyltin difluoride or dimethyltin di(fluorosulfonate).29 If the linearly polymeric diorganotin carboxylates are dissolved in chloroform, the 119Sn NMR chemical shift moves downfield by 50 to 100 ppm, and is then almost independent of concentration, showing that the compounds are monomeric in solution.23-30 Dibutyltin glutarate is a linear polymer as shown in 13-9.31... 

At least one exception in the organotin mercaptides has been noted. In the dimethyltin di( benzyl mercaptide )/dimethyltin dichloride system, regardless of the relative concentrations used, the NMR spectra consisted of broad lines and did not contain any resonances characteristic of the excess component. At 25°C, the reaction appears to be one involving a rapid equilibrium exchange of groups (14). However, at about — 10°C, the resonances of the individual components can be observed owing to a slow rate of exchange (15). 

The crystal structure of the terpyridyl complex of dimethyltin di-isothiocyanate shows that the tin is in pentagonal-bipyramidal co-ordination (Figure 25). The two methyl groups occupy rm/w-axial positions [r(Sn—C) = 2.105 A]. The five equatorial positions are occupied by the three terpyridyl and two NCS nitrogen atoms at distances of 2.515 A and 2.283 A, respectively. The equatorial plane is slightly distorted from planarity. ... 

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