Silane alcoholysis by a nickel(II) complex in a N, O, S ligand environment

Barber, Daniel E.; Lü, Zheng Rong; Richardson, Thomas; Crabtree, Robert H.

doi:10.1021/ic00048a049

Cited by 68 publications

(35 citation statements)

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“…1) is thought to be catalyzed most efficiently by formation of an intermediate σ-complex. The metal is believed to polarize the Si H bond and so favors nucleophilic attack by ROH (Scheme 1) [16]. SCHEME 1 Proposed mechanism for the alcoholysis reaction of (HMe 2 Si) 3 CH.…”

Section: Resultsmentioning

confidence: 99%

Reactions of tris(dimethylsilyl)methane and polymers containing si—h groups with various hydroxy compounds under aerobic and mild conditions

Safa

Tofangdarzadeh

Ayenadeh

2008

Heteroatom Chemistry

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Tris(dimethylsilyl)methane, (HMe2Si) 3 −CH, reacts with n‐propyl, iso‐propyl, n‐butyl, s‐butyl, iso‐butyl, n‐pentyl, s‐pentyl, n‐hexyl alcohol, and phenol in the presence of chloroplatinic acid (H2PtCl6ċ6H2O) in air to give products (ROMe2Si)3CH (where R is n‐propyl, iso‐propyl, n‐butyl, s‐butyl, iso‐butyl, n‐pentyl, s‐pentyl, n‐hexyl, phenyl). Similar reactions with benzyl alcohol and acetic acid lead to the unexpected products, (PhCH2)2O and HC(Me2SiOSiMe2)3CH, respectively. The compound (n‐BuOMe2Si)3CSiMe2H was made from (n‐BuOMe2Si)3CH by treatment with lithium diisopropylamide, followed by quenching with HMe2SiCl. The homopolymer poly{(4‐chloromethyl)styrene} and copolymers with styrene (in 1:1 and 1:3 mol ratio) were synthesized by free radical polymerization, and (HMe2Si)3C groups were linked to them by nucleophilic substitution reactions between (HMe2Si)3CLi and the chloromethyl groups of the polymer side chains. The resulting functional polymers containing Si—H bonds reacted with various alcohols in the presence of chloroplatinic acid under heterogeneous conditions. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:365–376, 2008; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/hc.20440

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Section: Resultsmentioning

confidence: 99%

Reactions of tris(dimethylsilyl)methane and polymers containing si—h groups with various hydroxy compounds under aerobic and mild conditions

Safa

Tofangdarzadeh

Ayenadeh

2008

Heteroatom Chemistry

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“…However, these early studies provided only limited details of the electrophilic silicon intermediates involved in catalysis. [57][58][59][60] Subsequent improvements in synthetic techniques (e.g. use of fluorinated aryl borate or carborane anions) and analytical techniques (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Many of these catalysts feature a cationic metal center that enhances their ability to impart electrophilic character to the silicon center of a coordinated silane. [57] However, there are some examples in which this type of mechanism was implicated for neutral metal complexes such as 14 [58] and 15. [59] For the neutral Ni(II) based catalyst 14, it was noted that Si-H oxidative addition was unlikely since the ligand used was not expected to stabilize the unfavorable Ni(IV) oxidation state.…”

Section: Reviewmentioning

confidence: 99%

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Electrophilic Activation of Silicon–Hydrogen Bonds in Catalytic Hydrosilations

2017

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Hydrosilation reactions represent an important class of chemical transformations and there has been considerable recent interest in expanding the scope of these reactions by developing new catalysts. A major theme to emerge from these investigations is the development of catalysts with electrophilic character that transfer electrophilicity to silicon via Si-H activation. This type of mechanism has been proposed for catalysts ranging from Group 4 transition metals to Group 15 main group species. Additionally, other electrophilic silicon species, such as silylene complexes and η 3 -H2SiRR' complexes, have been identified as intermediates in hydrosilation reactions. In this Review, different types of catalysts are compared to highlight the range of hydrosilation mechanisms that feature electrophilic silicon centers, and the importance of these catalysts to the development of new hydrosilation reactions is discussed.

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“…22 A number of reaction mechanisms have been proposed, including alcohol attack on η 2 -hydrosilane or silyl hydride transition-metal complexes formed via oxidative addition steps. 7,13,14 In contrast, copperand gold-catalyzed silane alcoholyses are proposed to involve discrete metal hydride and metal-alkoxide intermediates (no MÀSi bond). 18,20 In situ generated zinc(II) catalysts are also proposed to follow this mechanism.…”

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confidence: 99%

Coordinatively Saturated Tris(oxazolinyl)borato Zinc Hydride-Catalyzed Cross Dehydrocoupling of Silanes and Alcohols

et al. 2011

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The four-coordinate zinc compound ToMZnH (1, ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate) catalyzes selective alcoholysis of substituted hydrosilanes. The catalytic reaction of PhMeSiH2 and aliphatic alcohols favors the monodehydrocoupled product PhMeHSi-OR. With the aryl alcohol 3,5-C6H3Me2OH, the selectivity for mono(aryloxy)hydrosilane PhMeHSiOC6H3Me2 and bis(aryloxy)silane PhMeSi(OC6H3Me2)2 is controlled by relative reagent concentrations. Reactions of secondary organosilanes and diols provide cyclic bis(oxo)silacycloalkanes in high yield. The empirical rate law for the ToMZnH-catalyzed reaction of 3,5-dimethylphenol and PhMeSiH2 is −d[PhMeSiH2]/dt = k′obs [ToMZnH]1 [3, 1,2 Our interest in the catalytic preparation of alkoxysilanes was inspired by our interactions with Prof. Victor Lin, as we sought to synthesize precursors for advanced silica-based functionalized nanomaterials for catalytic applications. Silyl ethers are also important building blocks in organosilicon chemistry and in synthetic organic chemistry as protecting groups.3 The reaction of chlorosilanes and alcohols provides a straightforward route to SiÀO bonds. However, the HCl byproduct of these reactions must be trapped with base, and this method is not useful for syntheses that require neutral conditions. The degree of condensation is difficult to control when more than one SiÀCl group is present in the silicon substrate. Furthermore, chlorosilanes are water sensitive and must be kept rigorously anhydrous prior to use. Catalytic SiÀH bond alcoholysis (eq 1) can avoid these problems, giving H 2 as the byproduct and bypassing acid formation and/or basic conditions. Organosilanes are not hydrolytically sensitive (in the absence of a catalyst), and catalysts can control selectivity. -hydrosilane or silyl hydride transition-metal complexes formed via oxidative addition steps. 7,13,14 In contrast, copperand gold-catalyzed silane alcoholyses are proposed to involve discrete metal hydride and metal-alkoxide intermediates (no MÀSi bond). 18,20 In situ generated zinc(II) catalysts are also proposed to follow this mechanism.23 However, these zinc, copper, and gold catalysts are generated in situ, the catalytic speciation is unknown, and the turnover-limiting step has not been established.Zinc(II) catalysts are particularly interesting, given the low cost, favorable biocompatibility, and high natural abundance of this main group metal. Although zinc hydrides are presumed intermediates in hydrosilane alcoholysis, the catalytic activity of the few isolable, monomeric, terminal zinc hydrides is not developed. 24À28

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Silane alcoholysis by a nickel(II) complex in a N, O, S ligand environment

Cited by 68 publications

References 2 publications

Reactions of tris(dimethylsilyl)methane and polymers containing si—h groups with various hydroxy compounds under aerobic and mild conditions

Reactions of tris(dimethylsilyl)methane and polymers containing si—h groups with various hydroxy compounds under aerobic and mild conditions

Electrophilic Activation of Silicon–Hydrogen Bonds in Catalytic Hydrosilations

Coordinatively Saturated Tris(oxazolinyl)borato Zinc Hydride-Catalyzed Cross Dehydrocoupling of Silanes and Alcohols

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