7535-07-1Relevant academic research and scientific papers
Regioselective Hydrosilylation of Olefins Catalyzed by a Molecular Calcium Hydride Cation
Schuhknecht, Danny,Spaniol, Thomas P.,Maron, Laurent,Okuda, Jun
supporting information, p. 310 - 314 (2019/11/26)
Chemo- and regioselectivity are often difficult to control during olefin hydrosilylation catalyzed by d- and f-block metal complexes. The cationic hydride of calcium [CaH]+ stabilized by an NNNN macrocycle was found to catalyze the regioselective hydrosilylation of aliphatic olefins to give anti-Markovnikov products, while aryl-substituted olefins were hydrosilyated with Markovnikov regioselectivity. Ethylene was efficiently hydrosilylated by primary and secondary hydrosilanes to give di- and monoethylated silanes. Aliphatic hydrosilanes were preferred over other commonly employed hydrosilanes: Arylsilanes such as PhSiH3 underwent scrambling reactions promoted by the nucleophilic hydride, while alkoxy- and siloxy-substituted hydrosilanes gave isolable alkoxy and siloxy calcium derivatives.
Interconversion and reactivity of manganese silyl, silylene, and silene complexes
Price, Jeffrey S.,Emslie, David J. H.
, p. 10853 - 10869 (2019/12/23)
Manganese disilyl hydride complexes [(dmpe)2MnH(SiH2R)2] (4Ph: R = Ph, 4Bu: R = nBu) reacted with ethylene to form silene hydride complexes [(dmpe)2MnH(RHSiCHMe)] (6Ph,H: R = Ph, 6Bu,H: R = nBu). Compounds 6R,H reacted with a second equivalent of ethylene to generate [(dmpe)2MnH(REtSiCHMe)] (6Ph,Et: R = Ph, 6Bu,Et: R = nBu), resulting from apparent ethylene insertion into the silene Si-H bond. Furthermore, in the absence of ethylene, silene complex 6Bu,H slowly isomerized to the silylene hydride complex [(dmpe)2MnH(SiEtnBu)] (3Bu,Et). Reactions of 4R with ethylene likely proceed via low-coordinate silyl {[(dmpe)2Mn(SiH2R)] (2Ph: R = Ph, 2Bu: R = nBu)} or silylene hydride {[(dmpe)2MnH(SiHR)] (3Ph,H: R = Ph, 3Bu,H: R = nBu)} intermediates accessed from 4R by H3SiR elimination. DFT calculations and high temperature NMR spectra support the accessibility of these intermediates, and reactions of 4R with isonitriles or N-heterocyclic carbenes yielded the silyl isonitrile complexes [(dmpe)2Mn(SiH2R)(CNR′)] (7a-d: R = Ph or nBu; R′ = o-xylyl or tBu), and NHC-stabilized silylene hydride complexes [(dmpe)2MnH{SiHR(NHC)}] (8a-d: R = Ph or nBu; NHC = 1,3-diisopropylimidazolin-2-ylidene or 1,3,4,5-Tetramethyl-4-imidazolin-2-ylidene), respectively, all of which were crystallographically characterized. Silyl, silylene and silene complexes in this work were accessed via reactions of [(dmpe)2MnH(C2H4)] (1) with hydrosilanes, in some cases followed by ethylene. Therefore, ethylene (C2H4 and C2D4) hydrosilylation was investigated using [(dmpe)2MnH(C2H4)] (1) as a pre-catalyst, resulting in stepwise conversion of primary to secondary to tertiary hydrosilanes. Various catalytically active manganese-containing species were observed during catalysis, including silylene and silene complexes, and a catalytic cycle is proposed.
Syntheses, Characterization, and Reactivity of Diruthenium Hydrido Complexes
Wiltse, Heather R.,Johnson, Alyssa N.,Durand, Raphael J.,Brennessel, William,Chin, Robert M.
, p. 1079 - 1085 (2016/05/24)
The reaction of [cis-{(η5-C5H3)2(CMe2)2}Ru2(κ2-4,4′-di-tert-butyl-2,2′-bipyridine)2(MeCN)2][OTf]2, 1, with H2 yields a μ-dihydrido complex, [cis-{(η5-C5H3)2(CMe2)2}Ru2(κ2-4,4′-di-tert-butyl-2,2′-bipyridine)2(μ-H)2][OTf]2, 2, in 79% yield. The reaction of 2 with Et3SiH affords a mono-μ-hydrido complex, cis-{(η5-C5H3)2(CMe2)2}Ru2(κ2-4,4′-di-tert-butyl-2,2′-bipyridine)2(μ-H)][OTf], 3. The reaction of either 2 or 3 (1-2 mol %) with C6H6 and Et3SiH results in the catalytic cleavage of the C-H bond in benzene along with the cleavage of the Si-Et bond to form PhEt2SiH (23-27% conversion) and C2H6. The reaction of 2 or 3 (1 mol %) with THF and Et3SiH results in the cleavage of the C-H bond in THF followed by the insertion of the SiEt2 group into the C-O bond, forming 2,2-diethyl-1-oxa-2-silacyclohexane (14% conversion) as one of the products.
