Unexpected fragmentation of bis(triarylstannanethiocarbonyl)disulfides, formation and X-ray structure of triarylstannyl triarylstannanecarbodithioates

Abstract

Keywords: stannanecarbodithioate, intramolecular nucleophilic substitution, X-ray analysis, intramolecular interaction.The synthesis of bis(triarylstannanethiocarbonyl)disulfides was attempted by oxidation of lithium triarylstannanecarbodithioates with molecular iodine. Unexpectedly, the desired compounds are highly unstable and undergo subsequent fragmentation giving triarylstannyl triarylstannanecarbodithioates. The proposed mechanism for this transformation assumes intramolecular nucleophilic substitution with formation of six-membered ring transition complex, stabilized by interaction between tin and thiocarbonyl sulfur atom. Obtained compounds were identified by mass-spectrometry and NMR spectroscopies, and their structures were analyzed by X-ray diffraction. These molecules show the existence of intramolecular non-bonding interactions between the sulfur atoms of the thiocarbonyl moieties and tin atoms. These interactions reflect the tin -sulfur affinity and are the main driving force in the fragmentation of bis(triphenylstannanethiocarbonyl)disulfides. ________________________________________________________________________________

RAFT Polymerization with Triphenylstannylcarbodithioates (Sn-RAFT)

“…Such lability can be explained by the influence of triphenylstannyl group on the reactivity of the thiocarbo-nylthio group. 42 These problems may be overcome by running Sn-RAFT polymerizations at lower temperature and for limited reaction times.…”

“…These results demonstrate that some degradation of the Sn-RAFT reactive end-group takes place over prolonged reaction times at 60 °C. Such lability can be explained by the influence of triphenylstannyl group on the reactivity of the thiocarbonylthio group . These problems may be overcome by running Sn-RAFT polymerizations at lower temperature and for limited reaction times.…”