Co₂(CO)₈ as an efficient catalyst for the synthesis of functionalized polymethylhydrosiloxane oils and unconventional cross-linked materials

Abstract

We report here the use of Co2(CO)8 as a cheap and structurally simple alternative to precious metals for the functionalization of polymethylhydrosiloxane (PMHS) with terminal alkenes. This catalytic system at...

A Cobalt-Containing Polysilane as an Effective Solid-State Catalyst for the Hydrosilylation of Alkenes

“…30), began to form the silicone gel within 1 h at 80 °C and afforded a cross-linked polymer after 24 h (Scheme ). It should be noted here that the obtained cross-linked polymer is nearly colorless, which is an important feature for commercial applications; this result also stands in stark contrast to some previously reported homogeneous Co 2 (CO) 8 -based catalyst systems that furnish darkly colored products …”

MnBr(CO)5: a commercially available highly active catalyst for olefin hydrosilylation under ambient air and green conditions

“…The crosslinking reaction occurred via the hydrosilylation of both double bonds as already observed by our group when Co 2 (CO) 8 was used as a catalyst. 25 We further focused our attention on the use of other unsaturated CvO containing compounds for the cross-linking of PMHS. Working with unsaturated acetates led to the formation of gels after 10 hours for allyl acetate and 4 hours for the vinylic homologue (Table 3 entries 3 and 4).…”

Ni(ii) and Co(ii) bis(acetylacetonato) complexes for alkene/vinylsilane silylation and silicone crosslinking

“…43,44 It could also be the result of Cobased nanoparticles/colloids (Co(0)/Co(I) reduced species) formed in the case of Co(acac) 2 that would induce a different catalytic pathway. 11,12,38,40,41 On the contrary, Ni precatalysts still promote the DS pathway, with identifiable characteristic olefinic protons (Fig. 5a) and carbons (Fig.…”

“…Co catalysis seems more difficult to rationalize, all systems are paramagnetic no matter the geometry and the darkening of the solution (see ESI, † section 9miscellaneous) could suggest reduction to Co(0) or Co(I) species, as previously proposed. [10][11][12]40,41 In the second part of our study, we monitored the activity of these catalysts for the crosslinking of Si-H and Si-vinyl functionalized silicone oils. Harnessing alkene (hydro)silylation to cure silicone formulations is the cornerstone of silicone materials' manufacturing: multiple applications heavily rely on this reaction.…”

“…Nickel, cobalt and iron catalysts have already been reported and reviewed as relatively active and selective for alkene hydrosilylation (HS) and dehydrogenative silylation (DS). [6][7][8][9][10][11][12][13] Two types of systems have been reported in the literature: low-oxidation state and high-oxidation state complexes. Among low oxidation state catalysts, Chirik's bis(imino) pyridine iron(0) 14 and cobalt(I) 15 are seminal examples, which are very active under strict inert conditions.…”