999-97-3Relevant articles and documents
From Ylides to Doubly Yldiide-Bridged Iron(II) High Spin Dimers via Self-Protolysis
Yogendra, Sivathmeehan,Weyhermüller, Thomas,Hahn, Anselm W.,Debeer, Serena
, p. 9358 - 9367 (2019)
A synthetic strategy for the preparation of novel doubly yldiide bridged iron(II) high spin dimers ([(μ2-C)FeL]2, L = N(SiMe3)2, Mesityl) has been developed. This includes the synthesis of ylide-iron(II) monomers [(Ylide)FeL2] via adduct formation. Subsequent self-protolysis at elevated temperatures by in situ deprotonation of the ylide ligands results in a dimerization reaction forming the desired bridging μ2-C yldiide ligands in [(μ2-C)FeL]2. The comprehensive structural and electronic analysis of dimers [(μ2-C)FeL]2, including NMR, M?ssbauer, and X-ray spectroscopy, as well as X-ray crystallography, SQUID, and DFT calculations, confirm their high-spin FeII configurations. Interestingly, the Fe2C2 cores display very acute Fe-C-Fe angles (averaged: 78.6(2)°) resulting in short Fe···Fe distances (averaged: 2.588(2) ?). A remarkably strong antiferromagnetic coupling between the Fe centers has been identified. Strongly polarized Fe-C bonds are observed where the negative charge is mostly centered at the μ2-C yldiide ligands.
The Instability of Ni{N(SiMe3)2}2: A Fifty Year Old Transition Metal Silylamide Mystery
Faust, Michelle,Bryan, Aimee M.,Mansikkam?ki, Akseli,Vasko, Petra,Olmstead, Marilyn M.,Tuononen, Heikki M.,Grandjean, Fernande,Long, Gary J.,Power, Philip P.
, p. 12914 - 12917 (2015)
The characterization of the unstable NiII bis(silylamide) Ni{N(SiMe3)2}2 (1), its THF complex Ni{N(SiMe3)2}2(THF) (2), and the stable bis(pyridine) derivative trans-Ni{N(SiMe3)2}2(py)2 (3), is described. Both 1 and 2 decompose at ca. 25°C to a tetrameric NiI species, [Ni{N(SiMe3)2}]4 (4), also obtainable from LiN(SiMe3)2 and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of NiII to NiI and the stabilization of 4 through dispersion forces.
Ammonolysis of boron-substituted chlorosilylmethyl ortho-carborane derivatives
Izmailov,Qi, Shisheng,Markova,Vasnev
, p. 2338 - 2342 (2014)
We studied the ammonolysis of boron-substituted chlorosilylmethyl ortho-carborane derivatives and co-ammonolysis with trimethylchlorosilane. The reaction affords carboranylmethyl(organo)silanes with terminal aminosilane or trimethylsilyl groups. During ammonolysis, the bulky carboranylmethyl groups hinder the intermolecular condensation of intermediate products with aminosilane groups and favors the formation of low-molecular-weight organosilazanes not only from mono- and dichlorosilanes, but also from carboranylmethyltrichlorosilane. The Ccarborane-H groups having the acidic nature were found to be possibly involved in the formation of oligo(carboranylmethyl)silsesquiazane structure and its room-temperature structuring products.
Deoxygenation of primary amides to amines with pinacolborane catalyzed by Ca[N(SiMe3)2]2(THF)2
Gong, Mingliang,Guo, Chenjun,Jiang, Linhong,Luo, Yunjie,Yu, Chong
supporting information, p. 1201 - 1206 (2021/05/29)
Deoxygenative reduction of amides is a challenging but favorable synthetic method of accessing amines. In the presence of a catalytic amount of Ca[N(SiMe3)2]2(THF)2, pinacolborane (HBpin) could efficiently reduce a broad scope of amides, primary amides in particular, into corresponding amines. Functional groups and heteroatoms showed good tolerance in this process of transformation, and a plausible reaction mechanism was proposed.
Isolation and Reactivity Study of a Model 17-Electron Species in the Oxo Process
Takebayashi, Satoshi,Fayzullin, Robert R.
supporting information, p. 500 - 507 (2021/02/05)
[Co(L)(CO)3]2 (L = CO or PR3) catalyzed hydroformylation of olefins is among the most successful homogeneous organometallic catalysis. The bimetallic [Co(L)(CO)3]2 complex exists in equilibrium with its mononuclear 17-electron [Co(L)(CO)3] metalloradical. However, isolation of the mononuclear metalloradical is unknown, and hence the role of this species in the catalytic cycle is difficult to study. Herein, we report the isolation of [Co(L)(CO)3] using ring-expanded N-heterocyclic carbene (reNHC) ligands. Isolation of this complex enabled us to examine feasibility of putative termolecular H2 activation by the [Co(L)(CO)3] metalloradicals. The kinetic experiments revealed that [Co(reNHC)(CO)3] does not activate H2 via a previously proposed termolecular mechanism but via a bimolecular mechanism. The result obtained here will contribute to design a cobalt carbonyl complex that activates H2 under mild conditions and to develop a more energy efficient oxo process based on economical cobalt catalysts.
Preparation method of silazane
-
Paragraph 0020-0021, (2020/10/14)
The invention provides a preparation method of silazane. The preparation method comprises the following steps: carrying out a stirring reaction on monochlorosilane, alkali metal amide, a catalyst anda solvent in a reaction container completely; and after the reaction is finished, carrying out reduced pressure distillation to obtain the silazane. Compared with the prior art, the invention providesa new silazane synthesis technology, the process is simple, the yield is as high as 93.0%, and the purity can reach 93.6%.
METHOD FOR PREPARING HYDROGEN BIS(FLUOROSULFONYL)IMIDE AND METHOD FOR PREPARING LITHIUM BIS(FLUOROSULFONYL)IMIDE
-
Paragraph 0051, (2020/06/07)
A method for preparing hydrogen bis(fluorosulfonyl)imide including contacting sulfonyl fluoride with hexamethyl disilazane in an organic solvent. The disclosure also provides a method for preparing lithium bis(fluorosulfonyl)imide (LiFSI). The method includes contacting sulfonyl fluoride with hexamethyl disilazane in an organic solvent and yielding hydrogen bis(fluorosulfonyl)imide; and contacting hydrogen bis(fluorosulfonyl)imide with a lithium compound and yielding lithium bis(fluorosulfonyl)imide.
Catalytic Upgrading of Ethanol to n-Butanol via Manganese-Mediated Guerbet Reaction
Kulkarni, Naveen V.,Brennessel, William W.,Jones, William D.
, p. 997 - 1002 (2018/02/14)
Replacement of precious metal catalysts in the Guerbet upgrade of ethanol to n-butanol with first-row metal complex catalysts is highly appreciated due to their economic and environmental friendliness. The manganese pincer complexes of the type [(RPNP)MnBr(CO)2] (R = iPr, Cy, tBu, Ph or Ad) are found to be excellent catalysts for upgrading ethanol to n-butanol. Under suitable reaction conditions and with an appropriate base, about 34% yield of n-butanol can be obtained in high selectivity. A detailed account on the effect of the temperature, solvent, nature, and proportion of base used and the stereoelectronic effects of the ligand substituents on the catalytic activity of the catalysts as well as the plausible deactivation pathways is presented.
Intramolecular alkene hydroamination and degradation of amidines: Divergent behavior of rare earth metal amidinate intermediates
Zhang, Dexing,Liu, Ruiting,Zhou, Xigeng
, p. 5573 - 5581 (2018/11/20)
Direct N-H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N-alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.
Reversible Ligand-Centered Reduction in Low-Coordinate Iron Formazanate Complexes
Broere, Dani?l L. J.,Mercado, Brandon Q.,Lukens, James T.,Vilbert, Avery C.,Banerjee, Gourab,Lant, Hannah M. C.,Lee, Shin Hee,Bill, Eckhard,Sproules, Stephen,Lancaster, Kyle M.,Holland, Patrick L.
supporting information, p. 9417 - 9425 (2018/07/06)
Coordination of redox-active ligands to metals is a compelling strategy for making reduced complexes more accessible. In this work, we explore the use of redox-active formazanate ligands in low-coordinate iron chemistry. Reduction of an iron(II) precursor occurs at milder potentials than analogous non-redox-active β-diketiminate complexes, and the reduced three-coordinate formazanate-iron compound is characterized in detail. Structural, spectroscopic, and computational analysis show that the formazanate ligand undergoes reversible ligand-centered reduction to form a formazanate radical dianion in the reduced species. The less negative reduction potential of the reduced low-coordinate iron formazanate complex leads to distinctive reactivity with formation of a new N?I bond that is not seen with the β-diketiminate analogue. Thus, the storage of an electron on the supporting ligand changes the redox potential and enhances certain reactivity.
