Polystannanes: Synthesis, Properties, and Outlook

Abstract

Polystannanes are characterized by a main chain which consists of covalently bound tin atoms. Characteristic absorption maxima in UV‐vis spectra of poly(dialkylstannane)s are due to σ‐delocalization and of poly(diarylstannane)s to σ–π delocalization. Poly(diorganostannane)s are thermally stable with decomposition commencing above 200 °C. Poly(dialkylstannane)s can show liquid‐crystalline behavior around room temperature. They can be oriented by various procedures, whereby orientation of the polystannane main chain depends on the orientation procedure and the length of the alkyl side groups. Some of the oriented systems showed a pronounced dichroism. Polystannanes degrade under the action of light, in particular when in solution.

Synthesis and Characterization of Readily Modified Poly(aryl)(alkoxy)stannanes by use of Hypercoordinated Sn Monomers

“…Lower molecular weight (10 3 Da) polystannanes were more recently obtained by Caseria nd co-workers from the Wurtz coupling of dialkyltin dichlorides in liquid ammonia. [8,12] Electrochemical coupling of dialkyltin dichlorides to low molecular weightp olymers (10 3 Da) has also been demonstrated by Okano et al. [13,14] In 2015, Harrypersada nd Foucher described the preparation of moderate molecular weight (10 4 -10 5 Da) alternating polystannanes from the condensation polymerization of diaryl or dialkyl tin dihydridesw ith appropriately chosen dialkyltind iamides.…”

“…The first well‐characterized examples were reported by Tilley and co‐workers in 1993 and were prepared by dehydrogenative coupling of diorganostannanes in the presence of an early transition‐metal catalyst . More recently, Caseri and co‐workers have demonstrated the successful dehydrocoupling of dialkylstannanes to yield cyclic‐free high molecular weight (10 5 Da) polystannanes, such as 1 , in the presence of a late transition‐metal complex (i.e., Wilkinson's Catalyst) . This Rh compound was identified by the authors as the most efficient dehydropolymerization catalyst for dialkyltin dihydrides from the testing of over thirty transition‐metal complexes .…”

“…Earlier work by Molloy and co‐workers had also shown that high molecular weight (10 5 Da) polystannanes can be prepared through a low‐temperature (60 °C) Na‐mediated Wurtz coupling of dialkyltin dichlorides or alkylaryltin dibromides in toluene in the presence of 15‐crown‐5. Lower molecular weight (10 3 Da) polystannanes were more recently obtained by Caseri and co‐workers from the Wurtz coupling of dialkyltin dichlorides in liquid ammonia . Electrochemical coupling of dialkyltin dichlorides to low molecular weight polymers (10 3 Da) has also been demonstrated by Okano et al.…”

“…[4][5][6] More recently,C aseri and co-workers have demonstrated the successful dehydrocouplingof dialkylstannanes to yield cyclic-free high molecular weight (10 5 Da) polystannanes, such as 1,i nt he presence of al ate transition-metal complex (i.e., Wilkinson's Catalyst). [7,8] This Rh compound was identified by the authors as the most efficient dehydropolymerization catalyst for dialkyltin dihydrides from the testing of overt hirty transition-metal complexes. [7,9] Earlier work by Molloy and co-workers had also shown that high molecular weight ( 10 5 Da) polystannanes can be prepared through al ow-temperature (60 8C) Na-mediated Wurtz coupling of dialkyltin dichlorides [10] or alkylaryltin dibromides [11] in toluene in the presence of 15-crown-5.…”

Group 2 Mediated Dehydrocoupling

“…Most commonly tin-tin bond synthesis is carried out via Wurtz-type couplings yielding significant waste and little functional group tolerance, 24 or via the dehydrogenative coupling of tin hydrides mediated by a variety of transition metal 25 and f-block catalysts. 26 Ditin compounds have come to recent prominence as electrophilic tin sources in palladium-catalysed stannylation of arenes, 19,27 and poly(stannanes), 28 It is thus possible to speculate upon a manifold wherein suggests tin-nitrogen coupling occurs, however the incipient stannylamine formed is subsequently consumed (Scheme 3.7).…”