1586-73-8Relevant articles and documents
[Fe4] and [Fe6] Hydride Clusters Supported by Phosphines: Synthesis, Characterization, and Application in N2 Reduction
Araake, Ryoichi,Sakadani, Kazuki,Tada, Mizuki,Sakai, Yoichi,Ohki, Yasuhiro
, p. 5596 - 5606 (2017)
Multiple iron atoms bridged by hydrides is a common structural feature of the active species that have been postulated in the biological and industrial reduction of N2. In this study, the reactions of an Fe(II) amide complex with pinacolborane in the presence/absence of phosphines afforded a series of hydride-supported [Fe4] and [Fe6] clusters Fe4(μ-H)4(μ3-H)2{N(SiMe3)2}2(PR3)4 (PR3 = PMe3 (2a), PMe2Ph (2b), PEt3 (2c)), Fe6(μ-H)10(μ3-H)2(PMe3)10 (3), and (η6-C7H8)Fe4(μ-H)2{μ-N(SiMe3)2}2{N(SiMe3)2}2 (4), which were characterized crystallographically and spectroscopically. Under ambient conditions, these clusters catalyzed the silylation of N2 to furnish up to 160 ± 13 equiv of N(SiMe3)3 per 2c (40 equiv per Fe atom) and 183 ± 18 equiv per 3 (31 equiv per Fe atom). With regard to the generation of the reactive species, dissociation of phosphine and hydride ligands from the [Fe4] and [Fe6] clusters was indicated, based on the results of the mass spectrometric analysis on the [Fe6] cluster, as well as the formation of a diphenylsilane adduct of the [Fe4] cluster.
Conversion of dinitrogen to tris(trimethylsilyl)amine catalyzed by titanium triamido-amine complexes
Ghana, Priyabrata,Van Krüchten, Franziska D.,Spaniol, Thomas P.,Van Leusen, Jan,K?gerler, Paul,Okuda, Jun
, p. 3231 - 3234 (2019)
By using a triaryl-Tren ligated titanium dinitrogen complex, K2[{(Xy-N3N)Ti}2(μ2-N2)] (3), prepared by two-electron reduction of [TiCl(Xy-N3N)] (1-Cl) under N2 atmosphere, catalytic fixation of molecular nitrogen to form tris(trimethylsilyl)amine was achieved under ambient conditions with a turnover number (TON) of up to 16.5 per titanium atom.
Synthesis of Dinuclear Mo?Fe Hydride Complexes and Catalytic Silylation of N2
Ishihara, Kodai,Araki, Yuna,Tada, Mizuki,Takayama, Tsutomu,Sakai, Yoichi,Sameera,Ohki, Yasuhiro
, p. 9537 - 9546 (2020)
Two transition-metal atoms bridged by hydrides may represent a useful structural motif for N2 activation by molecular complexes and the enzyme active site. In this study, dinuclear MoIV-FeII complexes with bridging hydrides, CpRMo(PMe3)(H)(μ-H)3FeCp* (2 a; CpR=Cp=C5Me5, 2 b; CpR=C5Me4H), were synthesized via deprotonation of CpRMo(PMe3)H5 (1 a; CpR=Cp*, 1 b; CpR=C5Me4H) by Cp*FeN(SiMe3)2, and they were characterized by spectroscopy and crystallography. These Mo?Fe complexes reveal the shortest Mo?Fe distances ever reported (2.4005(3) ? for 2 a and 2.3952(3) ? for 2 b), and the Mo?Fe interactions were analyzed by computational studies. Removal of the terminal Mo?H hydride in 2 a–2 b by [Ph3C]+ in THF led to the formation of cationic THF adducts [CpRMo(PMe3)(THF)(μ-H)3FeCp*]+ (3 a; CpR=Cp*, 3 b; CpR=C5Me4H). Further reaction of 3 a with LiPPh2 gave rise to a phosphido-bridged complex Cp*Mo(PMe3)(μ-H)(μ-PPh2)FeCp* (4). A series of Mo?Fe complexes were subjected to catalytic silylation of N2 in the presence of Na and Me3SiCl, furnishing up to 129±20 equiv of N(SiMe3)3 per molecule of 2 b. Mechanism of the catalytic cycle was analyzed by DFT calculations.
N2 Silylation Catalyzed by a Bis(silylene)-Based [SiCSi] Pincer Hydrido Iron(II) Dinitrogen Complex
Li, Shengyong,Wang, Yajie,Yang, Wenjing,Li, Kai,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
, p. 757 - 766 (2020)
The bis(silylene)-based SiC(sp3)Si pincer ligand N,N′-bis(LSi:)dipyrromethane [SiCH2Si] (L1; L = PhC(NtBu)2) with a C(sp3) atom anchor was synthesized, and its coordination chemistry to iron was studied. Two novel iron hydride complexes, [SiCHSi]Fe(H)(N2)(PMe3) (1) and [SiCHSi]Fe(H)(PMe3)2 (2), were synthesized in the reaction of L1 with Fe(PMe3)4 via C(sp3)-H bond activation under different inert atmospheres (N2 and argon). To the best of our knowledge, 1 and 2 are the first examples of a bis(silylene)-based hydrido pincer iron complex produced through activation of a C(sp3)-H bond. At the same time 1 is also the first example of a TM dinitrogen complex supported by a bis(silylene) ligand. The interconversion between 1 and 2 was achieved and monitored by operando IR and 31P NMR spectra to understand the transformation from 1 to 2 from the viewpoint of kinetics. To our delight, 1 could effectively catalyze silylation of dinitrogen and gave the highest turnover number so far among all the Fe-catalyzed N2 silylation systems at room temperature and under atmospheric dinitrogen.
N-Substituted hexamethyldisilazanes as new substances for the synthesis of functional films in the system Si-Ge-C-N-H
Sysoev,Nikulina,Kolontaeva,Kosinova,Titov,Rakhlin,Tsyrendorzhieva,Lis,Voronkov
, p. 2501 - 2505 (2011)
N-Organylbis(trimethylsilyl)amines of the general formula RN(SiMe 3)2 (R = Me3Si, Et3Ge) were synthesized by reaction of sodium bis(trimethylsilyl)amide with the corresponding trialkylsilyl(germyl) halide. Their IR, UV, and 1H, 13C, and 29Si NMR spectra were studied, and saturated vapor pressures and thermal stabilities were determined. The possibility of using the RN(SiMe3)2 compounds as precursors in chemical vapor deposition of films with specified composition was estimated by thermodynamic modeling. Pleiades Publishing, Ltd., 2011.
Synthesis and Reactivity of Iron– and Cobalt–Dinitrogen Complexes Bearing PSiP-Type Pincer Ligands toward Nitrogen Fixation
Imayoshi, Ryuji,Nakajima, Kazunari,Takaya, Jun,Iwasawa, Nobuharu,Nishibayashi, Yoshiaki
, p. 3769 - 3778 (2017)
Iron– and cobalt–dinitrogen complexes bearing PSiP-type pincer ligands are newly designed and prepared, on the basis of our previous proposal that iron– and cobalt–dinitrogen complexes bearing trimethylsilyl ligands are key reactive intermediates in the c
Dinitrogen Functionalization Affording Chromium Hydrazido Complex
Yin, Jianhao,Li, Jiapeng,Wang, Gao-Xiang,Yin, Zhu-Bao,Zhang, Wen-Xiong,Xi, Zhenfeng
, p. 4241 - 4247 (2019)
A series of trinuclear and dinuclear Cr(I)-N2 complexes bearing cyclopentadienyl-phosphine ligands were synthesized and characterized. Further reduction of the Cr(I)-N2 complexes generated anionic Cr(0)-N2 complexes, which could react with Me3SiCl to afford the first chromium hydrazido complex from N2 functionalization. These complexes were found to be effective catalysts for the transformation of N2 into N(SiMe3)3.
Fe-Catalyzed Conversion of N2 to N(SiMe3)3 via an Fe-Hydrazido Resting State
Piascik, Adam D.,Li, Ruohao,Wilkinson, Harry J.,Green, Jennifer C.,Ashley, Andrew E.
, p. 10691 - 10694 (2018)
The catalytic conversion of N2 to N(SiMe3)3 by homogeneous transition metal compounds is a rapidly developing field, yet few mechanistic details have been experimentally elucidated for 3d element catalysts. Herein we show that Fe(PP)2(N2) (PP = R2PCH2CH2PR2; R = Me, 1Me R = Et, 1Et) are highly effective for the catalytic production of N(SiMe3)3 from N2 (using KC8/Me3SiCl), with the yields being the highest reported to date for Fe-based catalysts. We propose that N2 fixation proceeds via electrophilic Nβ silylation and 1e- reduction to form unstable FeI(NN-SiMe3) intermediates, which disproportionate to 1Me/Et and hydrazido FeII[N-N(SiMe3)2] species (3Me/Et); the latter act as resting states on the catalytic cycle. Subsequent 2e- reduction of 3Me/Et leads to N-N scission and formation of [N(SiMe3)2]- and putative anionic Fe imido products. These mechanistic results are supported by both experiment and DFT calculations.
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Wiberg,Uhlenbrock
, p. 239,242, 246 (1974)
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Cobalt-catalyzed transformation of molecular dinitrogen into silylamine under ambient reaction conditions
Imayoshi, Ryuji,Tanaka, Hiromasa,Matsuo, Yuki,Yuki, Masahiro,Nakajima, Kazunari,Yoshizawa, Kazunari,Nishibayashi, Yoshiaki
, p. 8905 - 8909 (2015)
The first successful example of cobalt-catalyzed reduction of N2 with Me3SiCl and Na as a reductant, under ambient reaction conditions, gives N(SiMe3)3, which can be readily converted into NH3. In this reaction system, 2,2′-bipyridine (bpy) is found to work as an effective additive to improve substantially the catalytic activity. Co-N2 complexes bearing three Me3Si groups as ancillary ligands are considered to work as key reactive species based on DFT calculations. The DFT results also allow the proposal of a detailed reaction pathway for the transformation of N2 into N(SiMe3)3.
Catalytic dinitrogen reduction at the molybdenum center promoted by a bulky tetradentate phosphine ligand
Liao, Qian,Saffon-Merceron, Nathalie,Mzailles, Nicolas
, p. 14206 - 14210 (2014)
Stoichiometric reduction of N2 at a Mo center stabilized by a bulky tetradentate phosphine ligand (PP3Cy) allowed isolation of Mo-imidoamine and Mo-imido complexes. Both complexes as well as the MoII precursor are equally suitable catalysts for the synthesis of NTMS3 (TMS= trimethylsilyl) from N2, TMSCl, and electron sources. Mechanistic studies prove the involvement of a TMS radical at least in one of the catalytic steps.
An arene-tethered silylene ligand enabling reversible dinitrogen binding to iron and catalytic silylation
Bai, Yunping,Zhang, Jianying,Cui, Chunming
, p. 8124 - 8127 (2018)
An arene-tethered silylene ligand, L (L = PhC(tBuN)2SiCH2C(tBu)NAr, Ar = 2,6-iPr2C6H3), allowed the synthesis of three-coordinate Fe(ii) silylamido and piano-stool Fe(
Ketone Enolization with Sodium Hexamethyldisilazide: Solvent- And Substrate-Dependent E- Z Selectivity and Affiliated Mechanisms
Collum, David B.,Woltornist, Ryan A.
, p. 17452 - 17464 (2021/11/04)
Ketone enolization by sodium hexamethyldisilazide (NaHMDS) shows a marked solvent and substrate dependence. Enolization of 2-methyl-3-pentanone reveals E-Z selectivities in Et3N/toluene (20:1), methyl-t-butyl ether (MTBE, 10:1), N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDTA)/toluene (8:1), TMEDA/toluene (4:1), diglyme (1:1), DME (1:22), and tetrahydrofuran (THF) (1:90). Control experiments show slow or nonexistent stereochemical equilibration in all solvents except THF. Enolate trapping with Me3SiCl/Et3N requires warming to -40 °C whereas Me3SiOTf reacts within seconds. In situ enolate trapping at -78 °C using preformed NaHMDS/Me3SiCl mixtures is effective in Et3N/toluene yet fails in THF by forming (Me3Si)3N. Rate studies show enolization via mono- and disolvated dimers in Et3N/toluene, disolvated dimers in TMEDA, trisolvated monomers in THF/toluene, and free ions with PMDTA. Density functional theory computations explore the selectivities via the E- and Z-based transition structures. Failures of theory-experiment correlations of ionic fragments were considerable even when isodesmic comparisons could have canceled electron correlation errors. Swapping 2-methyl-3-pentanone with a close isostere, 2-methylcyclohexanone, causes a fundamental change in the mechanism to a trisolvated-monomer-based enolization in THF.
Cluster Supported by Redox-Active o-Phenylenediamide Ligands and Its Application toward Dinitrogen Reduction
Liang, Qiuming,Demuth, Joshua C.,Radovi?, Aleksa,Wolford, Nikki J.,Neidig, Michael L.,Song, Datong
supporting information, p. 13811 - 13820 (2021/06/27)
As prevalent cofactors in living organisms, iron-sulfur clusters participate in not only the electron-transfer processes but also the biosynthesis of other cofactors. Many synthetic iron-sulfur clusters have been used in model studies, aiming to mimic their biological functions and to gain mechanistic insight into the related biological systems. The smallest [2Fe-2S] clusters are typically used for one-electron processes because of their limited capacity. Our group is interested in functionalizing small iron-sulfur clusters with redox-active ligands to enhance their electron storage capacity, because such functionalized clusters can potentially mediate multielectron chemical transformations. Herein we report the synthesis, structural characterization, and catalytic activity of a diferric [2Fe-2S] cluster functionalized with two o-phenylenediamide ligands. The electrochemical and chemical reductions of such a cluster revealed rich redox chemistry. The functionalized diferric cluster can store up to four electrons reversibly, where the first two reduction events are ligand-based and the remainder metal-based. The diferric [2Fe-2S] cluster displays catalytic activity toward silylation of dinitrogen, affording up to 88 equiv of the amine product per iron center.
