18641-08-2

Upstream product

• 694-53-1 phenylsilane 
• 100-51-6 benzyl alcohol 
• 100-52-7 benzaldehyde 
• 98-13-5 Phenyltrichlorosilane 
• 766-08-5 methylphenylsilane 

Relevant academic research and scientific papers

A cationic zinc hydride cluster stabilized by an N-heterocyclic carbene: Synthesis, reactivity, and hydrosilylation catalysis

The trinuclear cationic zinc hydride cluster [(IMes)3Zn3H4 (THF)](BPh4)2 (1) was obtained either by protonation of the neutral zinc dihydride [(IMes)ZnH2]2 with a Bronsted acid o

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.

POCN Ni(ii) pincer complexes: Synthesis, characterization and evaluation of catalytic hydrosilylation and hydroboration activities

A series of iminophosphinite POCN pincer Ni(ii) complexes, (POCN)NiMe and (POCN)NiLn(BX4) (L = CH3CN, n = 0, 1; X = F, Ph, C6F5), have been developed and subjected to catalytic hydrosilylation of alkenes, aldehydes and ketones and hydroboration of carbonyl compounds. The stoichiometric reactivity of (POCN)NiMe and (POCN)Ni(BF4) with PhSiH3 and HBPin suggests that catalytic reactions proceed via the hydride intermediate (POCN)NiH. With regard to reactions with HBPin, efficient and mild hydroboration of a variety of carbonyl compounds, including highly chemoselective hydroboration of benzaldehyde in the presence of other common potent reductive functional groups, such as alkenes, alkynes, esters, amides, nitriles, nitro compounds and even ketones, and the first example of base metal catalyzed hydroboration of amides, including mild direct hydroborative reduction of primary and secondary amides to borylated amines were demonstrated for (POCN)NiMe.

Bench-Stable Cobalt Pre-Catalysts for Mild Hydrosilative Reduction of Tertiary Amides to Amines and Beyond

The readily synthesized and bench-stable cobalt dichloride complex (dpephos)CoCl2 is employed as a pre-catalyst for a diversity of silane additions to unsaturated organic molecules, including the normally challenging reduction of amides to amines. With regard to hydrosilative reduction of amides even more effective and activator free catalytic systems can be generated from the bench-stable, commercially available Co(acac)2 and Co(OAc)2 with dpephos and PPh3 ligands. These systems operate under mild conditions (100 °C), with many examples of room temperature transformations, presenting a first example of mild cobalt-catalyzed hydrosilylation of amides.

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.

Surprisingly high sensitivity of copper nanoparticles toward coordinating ligands: Consequences for the hydride reduction of benzaldehyde

Functionalized copper nanoparticles are widely used as catalysts; however, identification of the catalytically active species remains a challenge. In this study we investigate hydride-assisted reduction reactions with special focus on the structural evolution of copper nanoparticles in the presence of phosphine and nitrogen-based ligands. These compounds are commonly used as stabilizing agents, and therefore are important in the context of other catalytic reactions as well. In particular, we investigate the case of tri-n-butylphosphine. Our findings show that ultrasmall nano-objects are formed as key intermediates to produce catalytically active species in the hydrosilylation of benzaldehyde into the corresponding silyl alcohol. Moreover, we found that the strength of the hydride donor is essential for the formation of the active catalysts. Therefore, this work unveils the previously overlooked high sensitivity of copper nanoparticles toward coordinating ligands in the context of catalysis.

Mechanistic Investigation of Bis(imino)pyridine Manganese Catalyzed Carbonyl and Carboxylate Hydrosilylation

We recently reported a bis(imino)pyridine (or pyridine diimine, PDI) manganese precatalyst, (Ph2PPrPDI)Mn (1), that is active for the hydrosilylation of ketones and dihydrosilylation of esters. In this contribution, we reveal an expanded scope for 1-mediated hydrosilylation and propose two different mechanisms through which catalysis is achieved. Aldehyde hydrosilylation turnover frequencies (TOFs) of up to 4900 min-1 have been realized, the highest reported for first row metal-catalyzed carbonyl hydrosilylation. Additionally, 1 has been shown to mediate formate dihydrosilylation with leading TOFs of up to 330 min-1. Under stoichiometric and catalytic conditions, addition of PhSiH3 to (Ph2PPrPDI)Mn was found to result in partial conversion to a new diamagnetic hydride compound. Independent preparation of (Ph2PPrPDI)MnH (2) was achieved upon adding NaEt3BH to (Ph2PPrPDI)MnCl2 and single-crystal X-ray diffraction analysis revealed this complex to possess a capped trigonal bipyramidal solid-state geometry. When 2,2,2-trifluoroacetophenone was added to 1, radical transfer yielded (Ph2PPrPDI·)Mn(OC·(Ph)(CF3)) (3), which undergoes intermolecular C-C bond formation to produce the respective Mn(II) dimer, [(μ-O,Npy-4-OC(CF3)(Ph)-4-H-Ph2PPrPDI)Mn]2 (4). Upon finding 3 to be inefficient and 4 to be inactive, kinetic trials were conducted to elucidate the mechanisms of 1- and 2-mediated hydrosilylation. Varying the concentration of 1, substrate, and PhSiH3 revealed a first order dependence on each reagent. Furthermore, a kinetic isotope effect (KIE) of 2.2 ± 0.1 was observed for 1-catalyzed hydrosilylation of diisopropyl ketone, while a KIE of 4.2 ± 0.6 was determined using 2, suggesting 1 and 2 operate through different mechanisms. Although kinetic trials reveal 1 to be the more active precatalyst for carbonyl hydrosilylation, a concurrent 2-mediated pathway is more efficient for carboxylate hydrosilylation. Considering these observations, 1-catalyzed hydrosilylation is believed to proceed through a modified Ojima mechanism, while 2-mediated hydrosilylation occurs via insertion.

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.

Hydridosilylamido complexes of Ta and Mo isolobal with Berry's zirconocenes: Syntheses, β-Si-H agostic interactions, catalytic hydrosilylation, and insight into mechanism

The syntheses of novel Group 5 and Group 6 hydrosilylamido complexes of the type R(ArN)M{N(tBu)SiMe2-H}X (M = Ta, R = Cp; M = Mo, R = ArN; X = Cl, H, OBn, Me) are described. The various substituents in the X position seem to play the

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).