From Aryltin Trihydrides to Nanosized Polymers- Mechanistic Insights and Material Characterization

Organotin dihydrides (R₂SnH₂) have been extensively studied as precursors in the formation of polymeric materials (polystannanes) exhibiting a linear backbone of covalently bonded tin atoms. Linear polystannanes can be seen as a molecular metal wire (Sn-Sn) embedded in an organic jacket, featuring an increased degree of electron delocalization by catenation leading to promising materials in charge-transfer devices.1
Similarly to organotin dihydrides (R₂SnH₂), organotin trihydrides (RSnH₃) undergo Sn-Sn bond formation upon loss of hydrogen via a dehydrogenative coupling reaction in the presence of the cheap and easy to handle amine base TMEDA (N,N,N’,N’- tetramethylethylenediamine) as polymerization catalyst.2 Therefore, a range of aryl substituted tin trihydrides (arylSnH₃) was successfully converted to novel aryl decorated tin nanoparticles (aryl@Sn) (Figure 1).3,4 By means of DFT calculations, EXAFS/XANES and NMR measurements a reductive dehydrocoupling mechanism is proposed allowing for H2 abstraction Sn-Sn bond formation.
In situ synchrotron SAXS measurements, HR-SEM, as well as TEM imaging were applied to elucidate the resulting morphology as well as the size of the nano-Sn/C composites formed.