Cobalt-catalyzed dehydrogenative cross-coupling reaction: Selective access to dihydrosiloxanes, hydrosiloxanes and functionalized silsesquioxanes

Co‐catalyzed Selective syn‐Hydrosilylation of Internal Alkynes

“…of catalyst A at room temperature, and instantly observed liberation of dihydrogen, chlorophenylsilane, as well as a mixture of [Co−H] species at −8.74 ppm (t, J =41.6 Hz) and −9.79 ppm (t, J =43.2 Hz), indicating (PN 5 P)Co I H and (PN 5 P)Co III H 2 (SiH 2 Ph) respectively [40,59,60] . Remarkably, such Co I /Co III mechanism is compatible with our recent investigations and suggested in other Co‐catalyzed processes [40,51–54,61,62] . Interestingly, a triplet at −22.87 (t, J =63.8 Hz) was also initially detected, which appears to be a short‐lasting dimeric form of our activated catalyst [63] .…”

“…[40,59,60] Remarkably, such Co I /Co III mechanism is compatible with our recent investigations and suggested in other Co-catalyzed processes. [40,[51][52][53][54]61,62] Interestingly, a triplet at À 22.87 (t, J = 63.8 Hz) was also initially detected, which appears to be a short-lasting dimeric form of our activated catalyst. [63] Subsequently, increasing the amount of phenylsilane (2 a) up to 10 equiv.…”

“…Since our previous works confirmed the potential for pre-catalyst activation through hydrosilanes, no external additives were evaluated during this stage. [51][52][53][54][55] A summary of the results can be found in Table 1.…”

“…This model reaction was performed in the presence of five previously synthesized PNP‐Co complexes with different substituents attached to the triazine ring ( A – E ). Since our previous works confirmed the potential for pre‐catalyst activation through hydrosilanes, no external additives were evaluated during this stage [51–55] . A summary of the results can be found in Table 1.…”

Cobalt pincer-type complexes demonstrating unique selectivity for the hydroboration reaction of olefins under mild conditions

“…Based on this and our previous studies on pincer cobalt complexes, as well as literature reports, 44–46,57,63–67 we postulate that in the reaction mixture, as a result of activation with pinacolborane or sodium triethylboron hydride, the two forms of the cobalt complex (Co( i ) and Co( iii )) coexist in equilibrium. Either of them can catalyze the process; however, based on recent reports, 66 we assume that the main catalytically active form is Co( i ) (LCo-H).…”