- Cooperative metal-ligand reactivity and catalysis in low-spin ferrous alkoxides
-
This report describes examples of combined Fe- and O-centered reactivity of Fe(P2O2)(CO)2 (1), where P2O2 is the diphosphinoglycolate (Ph2PC6H4CHO)22-
- Chu, Wan-Yi,Zhou, Xiaoyuan,Rauchfuss, Thomas B.
-
-
Read Online
- Hydrosilylation of Aldehydes and Ketones Catalyzed by a 2-Iminopyrrolyl Alkyl-Manganese(II) Complex
-
A well-defined and very active single-component manganese(II) catalyst system for the hydrosilylation of aldehydes and ketones is presented. First, the reaction of 5-(2,4,6-iPr3C6H2)-2-[N-(2,6-iPr2C6H3)formimino]pyrrolyl potassium (KL) and [MnCl2(Py)2] afforded the binuclear 2-iminopyrrolyl manganese(II) pyridine chloride complex [Mn2{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}2(Py)2(μ-Cl)2] 1. Subsequently, the alkylation reaction of complex 1 with LiCH2SiMe3 afforded the respective (trimethylsilyl)methyl-Mn(II) complex [Mn{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}(Py)CH2SiMe3] 2 in a good yield. Complexes 1 and 2 were characterized by elemental analysis, 1H NMR spectroscopy, Evans' method, FTIR spectroscopy, and single-crystal X-ray diffraction. While the crystal structure of complex 1 has been identified as a binuclear entity, in which the Mn(II) centers present pentacoordinate coordination spheres, that of complex 2 corresponds to a monomer with a distorted tetrahedral coordination geometry. Complex 2 proved to be a very active precatalyst for the atom-economic hydrosilylation of several aldehydes and ketones under very mild conditions, with a maximum turnover frequency of 95 min-1, via a silyl-Mn(II) mechanistic route, as asserted by a combination of experimental and theoretical efforts, the respective silanes were cleanly converted to the respective alcoholic products in high yields.
- Cruz, Tiago F. C.,Veiros, Luís F.,Gomes, Pedro T.
-
supporting information
p. 1195 - 1206
(2022/01/11)
-
- N-Heterocyclic Carbene Complexes of Nickel, Palladium, and Iridium Derived from Nitron: Synthesis, Structures, and Catalytic Properties
-
The mesoionic compound (1,4-diphenyl-1,2,4-triazol-4-ium-3-yl)phenylazanide, commonly referred to as Nitron, has been employed as a "crypto-NHC"to afford 1,2,4-triazolylidene compounds of nickel, palladium, and iridium. Specifically, Nitron reacts with NiBr2, PdCl2, and [Ir(COD)Cl]2 to afford the N-heterocyclic carbene complexes (NitronNHC)2NiBr2, (NitronNHC)2PdCl2, and (NitronNHC)Ir(COD)Cl, respectively. The lattermost compound reacts with (i) CO to afford the dicarbonyl compound (NitronNHC)Ir(CO)2Cl and (ii) CO, in the presence of PPh3, to afford the monocarbonyl compound (NitronNHC)Ir(PPh3)(CO)Cl. Structural studies on (NitronNHC)Ir(COD)Cl and (NitronNHC)Ir(CO)2Cl indicate that NitronNHC has a stronger trans influence than does Cl; furthermore, IR spectroscopic studies on (NitronNHC)Ir(CO)2Cl indicate that NitronNHC is electronically similar to the structurally related Enders carbene but is less electron donating than imidazol-2-ylidenes with aryl substituents. Significantly, the NitronNHC ligand affords catalytic systems, as illustrated by the ability of (NitronNHC)Ir(CO)2Cl to effect (i) the dehydrogenation of formic acid, (ii) aldehyde hydrosilylation, (iii) dehydrocoupling of hydrosilanes and alcohols, and (iv) ketone reduction via transfer hydrogenation.
- Quinlivan, Patrick J.,Loo, Aaron,Shlian, Daniel G.,Martinez, Joan,Parkin, Gerard
-
p. 166 - 183
(2021/02/05)
-
- Heavier Alkaline-Earth Catalyzed Dehydrocoupling of Silanes and Alcohols for the Synthesis of Metallo-Polysilylethers
-
The dehydrocoupling of silanes and alcohols mediated by heavier alkaline-earth catalysts, [Ae{N(SiMe3)2}2?(THF)2] (I–III) and [Ae{CH(SiMe3)2}2?(THF)2], (IV–VI) (Ae=Ca, Sr, Ba) is described. Primary, secondary, and tertiary alcohols were coupled to phenylsilane or diphenylsilane, whereas tertiary silanes are less tolerant towards bulky substrates. Some control over reaction selectivity towards mono-, di-, or tri-substituted silylether products was achieved through alteration of reaction stoichiometry, conditions, and catalyst. The ferrocenyl silylether, FeCp(C5H4SiPh(OBn)2) (2), was prepared and fully characterized from the ferrocenylsilane, FeCp(C5H4SiPhH2) (1), and benzyl alcohol using barium catalysis. Stoichiometric experiments suggested a reaction manifold involving the formation of Ae–alkoxide and hydride species, and a series of dimeric Ae–alkoxides [(Ph3CO)Ae(μ2-OCPh3)Ae(THF)] (3 a–c, Ae=Ca, Sr, Ba) were isolated and fully characterized. Mechanistic experiments suggested a complex reaction mechanism involving dimeric or polynuclear active species, whose kinetics are highly dependent on variables such as the identity and concentration of the precatalyst, silane, and alcohol. Turnover frequencies increase on descending Group 2 of the periodic table, with the barium precatalyst III displaying an apparent first-order dependence in both silane and alcohol, and an optimum catalyst loading of 3 mol % Ba, above which activity decreases. With precatalyst III in THF, ferrocene-containing poly- and oligosilylethers with ferrocene pendent to- (P1–P4) or as a constituent (P5, P6) of the main polymer chain were prepared from 1 or Fe(C5H4SiPhH2)2 (4) with diols 1,4-(HOCH2)2-(C6H4) and 1,4-(CH(CH3)OH)2-(C6H4), respectively. The resultant materials were characterized by NMR spectroscopy, gel permeation chromatography (GPC) and DOSY NMR spectroscopy, with estimated molecular weights in excess of 20,000 Da for P1 and P4. The iron centers display reversible redox behavior and thermal analysis showed P1 and P5 to be promising precursors to magnetic ceramic materials.
- Hill, Michael S.,Mahon, Mary F.,Manners, Ian,Morris, Louis J.,S. McMenamy, Fred,Whittell, George R.
-
supporting information
p. 2954 - 2966
(2020/03/04)
-
- Photoactivated silicon-oxygen and silicon-nitrogen heterodehydrocoupling with a commercially available iron compound
-
Silicon-oxygen and silicon-nitrogen heterodehydrocoupling catalyzed by the commercially available cyclopentadienyl dicarbonyl iron dimer [CpFe(CO)2]2 (1) under photochemical conditions is reported. Reactions between alcohols and PhSi
- Cibuzar, Michael P.,Hammerton, James,Reuter, Matthew B.,Waterman, Rory
-
supporting information
p. 2972 - 2978
(2020/03/13)
-
- Synthesis of dialkoxydiphenylsilanes via the rhodium-catalyzed hydrosilylation of aldehydes
-
The commercially available rhodium(I) complex [RhCl(CO)2]2 (1) was shown to be an effective catalyst for the reduction of carbonyls with organosilanes under mild conditions. This study focusses on the hydrosilylation of aldehydes with diphenylsilane leading to the isolation of a series of dialkoxydiphenylsilanes with low catalytic loading of complex 1.
- Nogues, Christophe,Argouarch, Gilles
-
supporting information
(2019/09/10)
-
- Zerovalent Nickel Compounds Supported by 1,2-Bis(diphenylphosphino)benzene: Synthesis, Structures, and Catalytic Properties
-
Zerovalent nickel compounds which feature 1,2-bis(diphenylphosphino)benzene (dppbz) were obtained via the reactivity of dppbz towards Ni(PMe3)4, which affords sequentially (dppbz)Ni(PMe3)2 and Ni(dppbz)2. Furthermore, the carbonyl derivatives (dppbz)Ni(PMe3)(CO) and (dppbz)Ni(CO)2 may be obtained via the reaction of CO with (dppbz)Ni(PMe3)2. Other methods for the synthesis of these carbonyl compounds include (i) the formation of (dppbz)Ni(CO)2 by the reaction of Ni(PPh3)2(CO)2 with dppbz and (ii) the formation of (dppbz)Ni(PMe3)(CO) by the reaction of (dppbz)Ni(CO)2 with PMe3. Comparison of the ν(CO) IR spectroscopic data for (dppbz)Ni(CO)2 with other (diphosphine)Ni(CO)2 compounds provides a means to evaluate the electronic nature of dppbz. Specifically, comparison with (dppe)Ni(CO)2 indicates that the o-phenylene linker creates a slightly less electron donating ligand than does an ethylene linker. The steric impact of the dppbz ligand in relation to other diphosphine ligands has also been evaluated in terms of its buried volume (%Vbur) and steric maps. The nickel center of (dppbz)Ni(PMe3)2 may be protonated by formic acid at room temperature to afford [(dppbz)Ni(PMe3)2H]+, but at elevated temperatures, effects catalytic release of H2 from formic acid. Analogous studies with Ni(dppbz)2 and Ni(PMe3)4 indicate that the ability to protonate the nickel centers in these compounds increases in the sequence Ni(dppbz)2 3)2 3)4; correspondingly, the pKa values of the protonated derivatives increase in the sequence [Ni(dppbz)2H]+ 3)2H]+ 3)4H]+. (dppbz)Ni(PMe3)2 and Ni(PMe3)4 also serve as catalysts for the formation of alkoxysilanes by (i) hydrosilylation of PhCHO by PhSiH3 and Ph2SiH2 and (ii) dehydrocoupling of PhCH2OH with PhSiH3 and Ph2SiH2.
- Neary, Michelle C.,Quinlivan, Patrick J.,Parkin, Gerard
-
p. 374 - 391
(2018/01/10)
-
- Silanol Compound, Composition, and Method for Producing Silanol Compound
-
The purpose of the present invention is to provide silanol compounds that can be used as raw materials of siloxane compounds and the like, and a composition of the silanol compounds, as well as to provide a production method that makes it possible to produce silanol compounds at excellent yield. A composition comprising 5 mass % to 100 mass % of a silanol compound represented by Formulas (A) to (C) can be prepared by devising to produce silanol compounds under water-free conditions, to produce silanol compounds in a solvent having the effect of suppressing the condensation of silanol compounds, and to perform other such processes, the composition being able to be used as a raw material or the like of siloxane compounds because the silanol compounds can be stably present in the resulting composition.
- -
-
Paragraph 0161
(2017/07/14)
-
- Dehydrogenative Coupling of Hydrosilanes and Alcohols by Alkali Metal Catalysts for Facile Synthesis of Silyl Ethers
-
Cross-dehydrogenative coupling (CDC) of hydrosilanes with hydroxyl groups, using alkali metal hexamethyldisilazide as a single-component catalyst for the formation of Si-O bonds under mild condition, is reported. The potassium salt [KN(SiMe3)2] is highly efficient and chemoselective for a wide range of functionalized alcohols (99% conversion) under solvent-free conditions. The CDC reaction of alcohols with silanes exhibits first-order kinetics with respect to both catalyst and substrate concentrations. The most plausible mechanism for this reaction suggests that the initial step most likely involves the formation of an alkoxide followed by the formation of metal hydride as active species.
- Harinath, Adimulam,Bhattacharjee, Jayeeta,Anga, Srinivas,Panda, Tarun K.
-
p. 724 - 730
(2017/05/31)
-
- Nickel nanoparticles supported on graphene as catalysts for aldehyde hydrosilylation
-
Nickel nanoparticles (NPs) supported on different undoped or doped with N or B graphenes (Gs) have been tested as catalyst for the hydrosilylation of aldehydes to obtain the corresponding siloxanes with high conversion and good selectivity in short reaction time. The different Gs employed were obtained by pyrolysis under inert atmosphere of alginate or chitosan, modified or not with boric acid. Then the metal NPs obtained by polyol reduction method using ethylene glycol were adsorbed on Gs. The Ni-containing G catalysts were characterized by electron microscopy, XPS and Raman spectroscopy. The scope of the Ni/G catalyst includes aliphatic and aromatic aldehydes as well as a variety of hydrosilanes.
- Blandez, Juan F.,Esteve-Adell, Iván,Primo, Ana,Alvaro, Mercedes,García, Hermenegildo
-
-
- Dehydrogenative coupling of alcohols and carboxylic acids with hydrosilanes catalyzed by a salen-Mn(v) complex
-
A Mn(v)-salen complex was found to be an effective catalyst for the dehydrogenative coupling of hydroxyl groups with hydrosilane. The reaction conditions were optimized with different silanes and efficient dehydrogenative coupling was achieved by using triethoxysilane and diphenylsilane. Various alcohols and phenols and a limited number of carboxylic acids were converted into the corresponding silyl ethers and silyl esters. A range of functional groups such as chloro, nitro, methoxy, carbonyl and carbon-carbon multiple bonds are tolerated in the reaction.
- Vijjamarri, Srikanth,Chidara, Vamshi K.,Rousova, Jana,Du, Guodong
-
p. 3886 - 3892
(2016/06/14)
-
- In a method of manufacturing a condition anhyride silanolated
-
PROBLEM TO BE SOLVED: To provide a method capable of synthesizing silanol under an anhydrous condition and a mild condition, adapting to substrates having various substituents, and producing siloxanes freely at an excellent yield, while having high structure controllability.SOLUTION: By a hydrogen addition reaction in which benzyloxy-substituted silanes are used as a silanol precursor, and a metal in the group 9 or 10 on the periodic table or a metal compound is used as a catalyst, corresponding silanols can be produced safely and easily at a high yield under an anhydrous condition and a mild condition, and especially object silanols can be isolated easily by using a carbon-carrying catalyst.
- -
-
Paragraph 0029
(2018/03/24)
-
- Mononuclear Heteroscorpionate Zwitterionic Zinc Terminal Hydride: Synthesis, Reactivity, and Catalysis for Hydrosilylation of Aldehydes
-
Treatment of heteroscorpionate zinc benzyloxy complex LZnOBn (1, L = (MePz)2CP(Ph)2NPh, MePz = 3,5-dimethylpyrazolyl) with phenylsilane (PhSiH3) gave a zinc hydride complex LZnH (2) containing a rare terminal hydride fragment. X-ray diffraction analysis and the DFT calculation confirm the zwitterionic structure of complex 2. The stoichiometric reaction of 2 with CS2 readily afforded a dithioformate complex LZnSCH(S) (3) of the C = S insertion into the Zn-H product. Moreover, complex 2 was an efficient catalyst for the hydrosilylation reaction of a series of silanes and aldehydes under mild conditions, featuring excellent functional group tolerance. The preliminary mechanistic study revealed that both zinc benzyloxy complex 1 and zinc hydride complex 2 were involved in the hydrosilylation process as the reaction intermediates. (Chemical Equation Presented).
- Mou, Zehuai,Xie, Hongyan,Wang, Meiyan,Liu, Na,Yao, Changguang,Li, Lei,Liu, Jingyao,Li, Shihui,Cui, Dongmei
-
p. 3944 - 3949
(2015/09/01)
-
- Hydrosilylation of Aldehydes and Ketones Catalyzed by a Terminal Zinc Hydride Complex, [κ3-Tptm]ZnH
-
Tris(2-pyridylthio)methyl zinc hydride, [κ3-Tptm]ZnH, is an effective catalyst for multiple insertions of carbonyl groups into the Si-H bonds of PhxSiH4-x (x = 1, 2). Specifically, [κ3-Tptm]ZnH catalyzes the insertion of a variety of aldehydes and ketones into the Si-H bonds of PhSiH3 and Ph2SiH2 to afford PhSi[OCH(R)R′]3 and Ph2Si[OCH(R)R′]2, respectively. The mechanism for hydrosilylation is proposed to involve insertion of the carbonyl group into the Zn-H bond to afford an alkoxy species, followed by metathesis with the silane to release the alkoxysilane and regenerate the zinc hydride catalyst. Multiple insertion of prochiral ketones results in the formation of diastereomeric mixtures of alkoxysilanes that can be identified by NMR spectroscopy.
- Sattler, Wesley,Ruccolo, Serge,Rostami Chaijan, Mahnaz,Nasr Allah, Tawfiq,Parkin, Gerard
-
p. 4717 - 4731
(2015/10/28)
-
- E-H Bond Activations and Hydrosilylation Catalysis with Iron and Cobalt Metalloboranes
-
An exciting challenge in transition metal catalyst design is to explore whether earth-abundant base metals such as Fe, Co, and Ni can mediate two-electron reductive transformations that their precious metal counterparts (e.g., Ru, Rh, Ir, and Pd) are better known to catalyze. Organometallic metalloboranes are an interesting design concept in this regard because they can serve as organometallic frustrated Lewis pairs. To build on prior studies with nickel metalloboranes featuring the DPB and PhDPBMes ligands in the context of H2 and silane activation and catalysis (DPB = bis(o-diisopropylphosphinophenyl)phenylborane, PhDPBMes = bis(o-diphenylphosphinophenyl)mesitylborane), we now explore the reactivity of iron, [(DPB)Fe]2(N2), 1, and cobalt, (DPB)Co(N2), 2, metalloboranes toward a series of substrates with E-H bonds (E = O, S, C, N) including phenol, thiophenol, benzo[h]quinoline, and 8-aminoquinoline. In addition to displaying high stoichiometric E-H bond activation reactivity, complexes 1 and 2 prove to be more active catalysts for the hydrosilylation of ketones and aldehydes with diphenylsilane relative to (PhDPBMes)Ni. Indeed, 2 appears to be the most active homogeneous cobalt catalyst reported to date for the hydrosilylation of acetophenone under the conditions studied.
- Nesbit, Mark A.,Suess, Daniel L. M.,Peters, Jonas C.
-
p. 4741 - 4752
(2015/10/28)
-
- Nonhydrolytic synthesis of silanols by the hydrogenolysis of benzyloxysilanes
-
The hydrogenolysis of benzyloxysilanes was smoothly catalyzed by Pd/C in THF to give corresponding silanols under nonhydrolytic conditions. The reaction proved to be applicable to various benzyloxysilanes giving silanemonools, diol, and triol.
- Igarashi, Masayasu,Matsumoto, Tomohiro,Sato, Kazuhiko,Ando, Wataru,Shimada, Shigeru
-
supporting information
p. 429 - 431
(2014/04/17)
-
- Ruthenium catalyzed selective hydrosilylation of aldehydes
-
A chemoselective hydrosilylation method for aldehydes is developed using a ruthenium catalyst [(Ru(p-cymene)Cl2)2] and triethylsilane; a mono hydride bridged dinuclear complex [{(η6-p- cymene)RuCl}2(μ-H-μ-Cl)] a
- Chatterjee, Basujit,Gunanathan, Chidambaram
-
supporting information
p. 888 - 890
(2014/01/06)
-
- Cesium carbonate catalyzed chemoselective hydrosilylation of aldehydes and ketones under solvent-free conditions
-
Cs2CO3 has been found to be an efficient and chemoselective catalyst for reduction of aldehydes and ketones to alcohols with one equivalent of Ph2SiH2 as the reductant under solvent-free conditions. Most of the aldehydes employed can be effectively hydrosilated quantitatively to give the corresponding silyl ethers in 2 h at room temperature, whereas the hydrosilylation of ketones proceeded smoothly at 80 °C. The catalyst system tolerates a number of functional groups including halogen, alkoxyl, olefin, ester, nitro, cyano, and heteroaromatic groups; the selective hydrosilylation of aldehydes in the presence of ketone can be effectively controlled by temperature; and hydrosilylation of α,β-unsaturated carbonyls resulted in the 1,2-addition products. The catalytic hydrosilylation of suitable dicarbonyls can be applied to the synthesis of poly(silyl ether)s with a high molecular weight and narrow molecular distribution. A general and practical protocol for the hydrosilylation of aldehydes and ketones under solvent free conditions by using a Cs 2CO3/Ph2SiH2 system is presented. Most of the aldehydes employed can be effectively hydrosilylated quantitatively to give the corresponding silyl ethers in 2 h at room temperature, whereas the reactions with ketones proceed smoothly at 80 °C.
- Zhao, Mengdi,Xie, Weilong,Cui, Chunming
-
p. 9259 - 9262
(2014/08/05)
-
- A remarkably active iron catecholate catalyst immobilized in a porous organic Polymer
-
A single-site, iron catecholate-containing porous organic polymer was prepared and utilized as a stable and remarkably active catalyst for the hydrosilylation of ketones and aldehydes. In some instances, catalyst loadings of 0.043-2.1 mol % [Fe] were sufficient for complete hydrosilylation of aldehydes and ketones within 15 min at room temperature. The catalyst can be recycled at least three times without a drop in catalytic activity. This system is an example of an immobilized homogeneous catalyst with no homogeneous analogue.
- Kraft, Steven J.,Sanchez, Raul Hernandez,Hock, Adam S.
-
p. 826 - 830
(2013/07/25)
-
- Highly efficient large bite angle diphosphine substituted molybdenum catalyst for hydrosilylation
-
Treatment of the complex Mo(NO)Cl3(NCMe)2 with the large bite angle diphosphine, 2,2′-bis(diphenylphosphino)diphenylether (DPEphos) afforded the dinuclear species [Mo(NO)(PaP)Cl 2]2[μCl]2 (PaP = DPEph
- Chakraborty, Subrata,Blacque, Olivier,Fox, Thomas,Berke, Heinz
-
p. 2208 - 2217
(2013/10/22)
-
- Synthesis and catalytic reactivity of bis(alkylzinc)-hydride-di(2- pyridylmethyl)amides
-
Direct zincation of dipicolylamin (DPA) and alcohols (MeOH, iPrOH, tBuOH) with dialkylzinc gives bis(alkylzinc)alkoxide-di(2-pyridylmethyl)amides {alkyl = methyl (1, 2), trimethylsilylmethyl (3), bis-(trimethylsilyl)methyl (4), alkoxide=OMe, OiPr, OtBu} possessing a central four-membered Zn2NO unit. Treatment of these alkoxides 1-4 with arylsilanes leads to an exchange of the (μ-OR') moiety, yielding the corresponding hydrides [(RZn) 2(μ-H){μ-N(CH2Py)2}] {R=Me (6), CH 2SiMe3 (7), CH(SiMe3)2 (8)}. Hydride 6 reacts with tBuNH2 to form the corresponding amide [(MeZn) 2{μ-N(H)tBu}{μ-N(CH2Py)2}] (5) and adds acetone to yield 2 again. The trimethylsilyl-substituted derivative 7 undergoes spontaneous conversion to form the pentanuclear zinc hydride-bridged dimer [{Me3SiCH2Zn}4{Zn(μ-H)4}{μ-N- (CH2Py)2}2] (9). The new hydride complexes were characterized in solution and in the solid state including single-crystal X-ray analysis of 8 and 9. Both hydrides 6-8 and alkoxides 1-4 were found to catalyze the hydrosilylation of aldehydes and ketones effectively. The variation of the zinc-bound alkyl group facilitates control over the catalyst reactivity by steric and electronic means. In order to achieve a deeper insight into the mechanism and the role of the cocatalytic Zn(II) centers, extensive DFT calculations were performed. In the two-step catalytic process the ketone first coordinates to one catalytic center of 6 and thus cleaves a Zn-(μ-H) bond. A subsequent intramolecular hydride transfer leads to the formation of the bridged dinuclear zinc alkoxide being the most stable species in this cycle. In the second half of the cycle, possessing the highest activation barrier, the silane inserts into a Zn-O bond, forming a six-membered ring with a Zn[μ-(H-Si-O)]Zn moiety. Consecutive cleavage of the Si-HZn and Zn-O bonds regenerates the zinc hydride 6 along with the formation of the silyl ether. NMR spectroscopic studies support these findings.
- Kahnes, Marcel,Goerls, Helmar,Gonzalez, Leticia,Westerhausen, Matthias
-
experimental part
p. 3098 - 3108
(2010/10/04)
-
- Silver-catalyzed hydrosilylation of aldehydes
-
Silver triflate, either alone or in the presence of an appropriate phosphine or NHC ligand, has been shown to catalyze the chemoselective hydrosilylation of aromatic and aliphatic aldehydes to yield silyl ethers, thus representing the first systematic app
- Wile, Bradley M.,Stradiotto, Mark
-
p. 4104 - 4106
(2007/10/03)
-