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Although silane diamine copolymers have captured the attention of the catalysis community, the optimization of their synthesis and end uses have yet to be explored. In this study, a well-defined Earth-abundant metal catalyst, [(2,6-iPr2PhBDI)Mn(µ-H)]2, has been found to couple organosilanes to diamines to prepare networks that feature varied silane substitution and diamine chain lengths. By performing dehydrocoupling in the absence of solvent with 0.01 mol% catalyst loading, substrate utilisation turnover frequencies of up to 300 s-1 have been achieved at early reaction times, the highest Si–N dehydrocoupling activity ever observed. These networks have been employed as absorbents for common organic solvents, a property that had not been studied for this class of materials. By incorporating a long-chain hydrophobic linker, one network has been found to absorb 7.7× its orginal mass in THF and recycling has been demonstrated upon solvent removal. Controlling the degree of dehydrocoupling also offered an opportunity to deposit coatings from freshly-prepared silane diamine polymer solutions and monitor their integrity upon curing in air. While uniform and persistent coatings have been obtained from 1,6-hexanediamine derived polymers, the need to prepare dilute solutions that have a short shelf-life and the tackiness associated with extended dry times have been identified as potential limitations. 

The phosphine-substituted aryl diimine cobalt catalyst, (Ph2PPrADI)Co, has been found to mediate the dehydrocoupling of diamines or polyamines to poly(methylhydrosiloxane) (PMHS) to generate hydrogen and crosslinked solids in an atom-efficient fashion. The resulting siloxane diamine and siloxane polyamine networks persist in the presence of air or water at room temperature and can tolerate temperatures of up to 1,600 °C. Upon lowering the catalyst loading to 0.01 mol%, (Ph2PPrADI)Co was found to catalyze the dehydrocoupling of 1,3-propanediamine and PMHS (m = 35) to generate a siloxane diamine foam with a turnover frequency of 157 s-1 relative to diamine consumption, the highest activity ever reported for Si‒N dehydrocoupling. Furthermore, upon systematically reducing the number of potential branch points, the (Ph2PPrADI)Co catalyzed dehydrocoupling of diamines with hydride-terminated poly(dimethylsiloxane) (PDMS) was found to yield linear siloxane diamine polymers with molecular weights of up to 47,300 g/mol. 

Through the application of a redox-innocent aryl diimine chelate, the discovery and utilization of a cobalt catalyst, ( Ph 2 PPr ADI)Co, that exhibits carbonyl hydrosilylation turnover frequencies of up to 330 s −1 is described. This activity is believed to be the highest ever reported for metal-catalyzed carbonyl hydrosilylation. 

This article highlights the utilization of phosphine-containing redox-active ligands for efficient hydrosilylation catalysis. Manganese, iron, cobalt, and nickel precatalysts featuring these chelates have been described and leading activities for carbonyl, carboxylate, and ester C–O bond hydrosilylation have been achieved. Mechanistic studies have provided insight into the importance of phosphine hemilability.