- Catalytic Systems Based on Chromium(III) Silylated-Diphosphinoamines for Selective Ethylene Tri-/Tetramerization
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The N-substituents on the backbone of Ph2PN(R)Si(CH3)2CH2PPh2- and [Ph2PCH2Si(CH3)2]2N(R)-type silylated-diphosphinoamine (Si-PNP) systems have been observed to have a significant impact on their catalytic performance in ethylene oligomerization reactions. Cr precatalyst 3, bearing an isopropyl (iPr) substituent, affords the most efficient catalytic system and exhibited the highest selectivity (83%) toward 1-octene (1-C8) and showed a catalytic activity of more than 76,700 g(product)·g(Cr)-1·h-1 under experimental conditions. Single-crystal analysis results revealed the influence of steric constraints around the catalytically active center and established a relationship between the product selectivity and the P-Cr-P bite angle. Furthermore, DFT calculations indicate that the catalytic system based on precatalyst 3 faces a low energy barrier in the formation of 1-C8 and therefore shows high selectivity toward the 1-C8 fraction. Modification in the backbone length may alter the binding mode of the ligands from mononuclear-bidentate (k2-P, P) to mononuclear-tridentate (k3-P, N, P), which consequently switches the ethylene tetramerization systems to ethylene trimerization systems.
- Alam, Fakhre,Zhang, Le,Wei, Wei,Wang, Jiadong,Chen, Yanhui,Dong, Chunhua,Jiang, Tao
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- Fine Tuning of the Substituents on the N-Geminal Phosphorus/Silicon-Based Lewis Pairs for the Synthesis of Z-Type Silyliminophosphoranylalkenes
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Reactions of the N-aryl(diphenylphosphanyl)aminosilane Ph2PN(Ar)SiCl3-nMen (Ar = 2,4,6-Me3C6H2, n = 0 (1a), 1 (2a), 2 (3a), 3 (4a); Ar = 2,6-iPr2C6H3, n = 0 (1b), 1 (2b), 2 (3b), 3 (4b)) with methyl propiolate and dimethyl acetylenedicarboxylate (DMAD) give two types of products, the zwitterionic heterocycles [Ph2PN(2,4,6-Me3C6H2)SiCl3](HC=CCO2Me) (5c) and [Ph2PN(Ar)SiCl3-nMen](MeO2CC=CCO2Me) (Ar = 2,4,6-Me3C6H2, n = 0 (5a), 1 (6a), 2 (7a); Ar = 2,6-iPr2C6H3, n = 0 (5b), 1 (6b), 2 (7b)) and (Z)-silyliminophosphoranylalkene ArN=P(Ph2)C(CO2Me)=C(CO2Me)SiMe3 (Ar = 2,4,6-Me3C6H2 (8a), 2,6-iPr2C6H3 (8b)). The reaction of Ph2PN(SiMe3)2 with DMAD gives only the acyclic alkene Me3SiN=P(Ph2)(MeO2C)C=C(CO2Me)SiMe3 (9), which is similar to 8a,b. In these reactions, compounds 1a-4a and 1b-4b behave as N-geminal P/Si-based Lewis pairs, which undergo a dipolar cycloaddition reaction with the alkyne. The theoretical calculations indicate that the reactions proceed through a concerted cycloaddition reaction mechanism. The stability of these heterocycles decreases as the number of the Me substituent on the pentacoordinated Si atom increases. When the Si center is substituted with three Me groups (4a,b), the heterocyclic intermediates undergo ring opening by Si-N bond cleavage and concomitant N=P bond formation resulting in 8a,b. The formation of the acyclic (Z)-alkene (8a,b and 9) can be considered as a stepwise SN2 reaction at the silicon center.
- Li, Jiancheng,Li, Yan,Purushothaman, Indu,De, Susmita,Li, Bin,Zhu, Hongping,Parameswaran, Pattiyil,Ye, Qingsong,Liu, Weiping
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- Efficient chromium-based catalysts for ethylene tri-/tetramerization switched by silicon-bridged/N,P-based ancillary ligands: A structural, catalytic and DFT study
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High performance catalysts switched by a series of silicon-bridged/N,P-based ancillary ligands have been explored. The precatalyst supported by L1 possessed a large steric bulk and exhibited a high activity of 16.8 × 106 g (mol Cr)-1 h-1 as well as a total selectivity of 99% toward 1-hexene and 1-octene. The selectivity for 1-hexene was adjustable from 59% to 88%. The catalyst bearing an L2 ligand, facilitated by a smaller steric bulk, displayed an identical activity of 13.0 × 106 g (mol Cr)-1 h-1 and a superior selectivity of 75% towards 1-octene under the appropriate conditions. The DFT calculations elucidated the reason for these excellent and tunable activities and selectivities.
- Zhang, Le,Wei, Wei,Alam, Fakhre,Chen, Yanhui,Jiang, Tao
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- Ethylene oligomerization promoted by nickel-based catalysts with silicon-bridged diphosphine amine ligands
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A series of nickel complexes [Ni(L1)Br2] (C1), [Ni(L2)Br2] (C2) and [Ni(L3)Br2] (C3) (L1 = N-isopropyl-N-(((diphenylphosphanyl)methyl)dimethylsilyl)-1,1-diphenylphosphanamine, L2 = N-cyclopentyl-N-(((diphenylphosphanyl)methyl)dimethylsilyl)-1,1-diphenylphosphanamine, L3 = N-(2,6-diisopropylphenyl)-N-(((diphenylphosphanyl)methyl)dimethylsilyl)-1,1-diphenylphosphanamine) were synthesized and characterized by elemental analysis, mass spectrometry, spectroscopy and single-crystal X-ray diffraction. L1, L2 and L3 each act as bidentate ligands. Upon activation with ethylaluminum dichloride, these complexes produce efficient catalytic systems for selective dimerization of ethylene to 1-butene, with catalytic activities of 3.45 × 107?g/(molNi·h) and 95.6% butene selectivity containing 87.6% 1-butene fraction.
- Wei, Wei,Yu, Buwei,Alam, Fakhre,Huang, Yongwang,Cheng, Shaoling,Jiang, Tao
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p. 125 - 133
(2018/10/02)
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- Sterically Tuned P-Phosphanylamino Phosphaalkenes (Me3Si)2C=PN(R)PPh2 and (iPrMe2Si)2C=PN(R)PPh2
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Deprotonation of the aminophosphanes Ph2PN(H)R 1a–1h [R = tBu (1a), 1-adamantyl (1b), iPr (1c), CPh3 (1d), Ph (1e), 2,4,6-Me3C6H2 (Mes) (1f), 2,4,6-tBu3C6H2 (Mes*) (1g
- B?rzoi, Roxana M.,Lungu, Daniela,Jones, Peter G.,Bartsch, Rainer,du Mont, Wolf-W.
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p. 381 - 390
(2018/04/09)
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- Nickel-based ethylene oligomerization catalysts supported by PNSiP ligands
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A series of nickel (II) complexes bearing silicon bridged diphosphines ligands (PNSiP) have been synthesized and characterized. All nickel precatalysts, activated with ethylaluminum dichloride (EtAlCl2), exhibited moderate to high activities for ethylene dimerization to butylene. The in situ nickel precatalysts formed by mixing N-cyclopentyl-N-((diphenylphosphanyl)dimethylsilyl)-1,1-diphenylphosphanamine (L2) with NiBr2(DME) showed high catalytic activity (2.40 × 108 g/(molNi·h)) and high product selectivity (88.6%) towards butene using methylcyclohexane as solvent at 1.0?MPa ethylene pressure and 45°C temperature, no polyethylene(PE) was observed. Ligand backbone tuning of PNSiP-based catalytic systems help in precise understanding of steric bulk variation effects on catalytic performance.
- Huang, Yongwang,Zhang, Le,Wei, Wei,Alam, Fakhre,Jiang, Tao
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p. 363 - 368
(2018/02/06)
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- Amino group combined P/Ge and P/Sn Lewis pairs: Synthesis and dipolar addition reactions to alkyne and aldehyde molecules
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Amino group combined P/Ge-based frustrated Lewis pairs (FLPs) Ph2PN(R)GeCl3 (R = 2,6-iPr2C6H3 (1), 2,4,6-Me3C6H2 (2), and C6H11 (3)) and Ph2PN(2,6-iPr2C6H3)GeMe3 (4) as well as P/Sn-based FLP Ph2PN(2,6-iPr2C6H3)SnMe3 (5) were prepared and utilized for reactions with alkyne and aldehyde molecules. Compounds 1-3 each reacted with MeO2CC≡CCO2Me to give zwitterionic cyclic vinyls [Ph2PN(R)GeCl3](MeO2CC=CCO2Me) (6-8) and compound 1 reacted with HC≡CCO2Me to give the similar compound [Ph2PN(2,4,6-Me3C6H2)GeCl3](HC=CCO2Me) (9). Compound 4 reacted with RC≡CCO2Me to afford acyclic vinyls 2,6-iPr2C6H3N=P(Ph2)C(R)=C(CO2Me)GeMe3 (R = CO2Me (10), H (11)) and 5 reacted with MeO2CC≡CCO2Me to give 2,6-iPr2C6H3N=P(Ph2)C(CO2Me)=C(CO2Me)SnMe3 (12). The reactions of 1 with CH3CH2CHO and 1,4-(CHO)2C6H4 were also investigated and yielded novel zwitterionic OCPNGe five-heteroatom cycles [Ph2PN(2,6-iPr2C6H3)GeCl3][CH(CH2CH3)O] (13) and [Ph2PN(2,6-iPr2C6H3)GeCl3][p-(OCH)C6H4CHO][Cl3GeN(2,6-iPr2C6H3)PPh2] (14). Compounds 1-14 were characterized by NMR (1H, 13C, and 31P) and CHN elemental analysis, of which 1, 7, and 10-14 were further studied by X-ray crystallography. The reactions of 4 (or 5) with RC≡CCO2Me to produce 10-12 present a novel way of obtaining the germyl (or stannyl) and iminophosphoranyl co-substituted vinyls.
- Yu, Ying,Li, Jiancheng,Liu, Weiping,Ye, Qingsong,Zhu, Hongping
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p. 6259 - 6268
(2016/04/26)
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- Structural diversity in sterically demanding diiminophosphinato alkali metal complexes
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We have prepared the new aminophosphine Ph2PNHMes 2 [Mes = mesityl (2,4,6-Me3C6H2)], and the aminoiminophosphorane Ph2P(=NMes)NHMes 4 (MesLH), and obtained the new alkali metal complexes [(
- Hawley, Andrew L.,Stasch, Andreas
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p. 257 - 270
(2015/01/30)
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- Rhodium-catalyzed transfer hydrogenation with aminophosphines and analysis of electrical characteristics of rhodium(I) complex/n-Si heterojunctions
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A series of novel neutral mononuclear rhodium(I) complexes of the P-NH ligands have been prepared starting from [Rh(cod)Cl]2 complex. Structural elucidation of the complexes was carried out by elemental analysis, IR and multinuclear NMR spectroscopic data. The complexes were applied to the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of 2-propanol as the hydrogen source. Catalytic studies showed that all complexes are also excellent catalyst precursors for transfer hydrogenation of aryl alkyl ketones in 0.1m iso-PrOH solution. In particular, [Rh(cod)(PPh2NH-C6H4-4-CH(CH 3)2)Cl] acts as an excellent catalyst, giving the corresponding alcohols in excellent conversion up to 99% (turnover frequency≤588h-1). Furthermore, rhodium(I) complexes have been used in the formation of organic-inorganic heterojunction by forming their thin films on n-Si and evaporating Au on the films. It has been seen that the structures have rectifying properties. Their electrical properties have been analyzed with the help of current-voltage measurements. Finally, it has been shown that the complexes can be used in the fabrication of temperature and light sensors. Copyright
- Aydemir, Murat,Ocak, Yusuf Selim,Rafikova, Khadichakhan,Kystaubayeva, Nurzhamal,Kayan, Cezmi,Zazybin, Alexey,Ok, Fatih,Baysal, Akin,Temel, Hamdi
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p. 396 - 404
(2014/06/09)
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- N-P bond cleavage induced ring formation of cyclosilazanes from reactions of aryl(phosphanyl)aminotrichlorosilanes with lithium alkynyls
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The aryl(silyl)aminotrichlorosilane 2,6-iPr2C6H 3N(SiMe2Ph)SiCl3 (1) and aryl(phosphanyl) aminotrichlorosilane ArN(PPh2)SiCl3 (Ar = 2,6-iPr 2C6H3
- Wang, Jinjin,Liu, Rui,Ruan, Wenqing,Li, Yan,Mondal, Kartik Chandra,Roesky, Herbert W.,Zhu, Hongping
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p. 2696 - 2703
(2014/06/24)
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- A hydrocarbon-soluble lithium hydride complex
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LiH-ghtweight: The title complex having a central (LiH)4 cube has been prepared and structurally characterized (see picture). The compound is stable towards LiH elimination at room temperature in solution, and can be employed for hydrolithiatio
- Stasch, Andreas
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supporting information; experimental part
p. 1930 - 1933
(2012/04/10)
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- Synthesis and characterization of new (N-diphenylphosphino)- isopropylanilines and their complexes: Crystal structure of (Ph 2P=S)NH-C6H4-4-CH(CH3)2 and catalytic activity of palladium(II) complexes in the Heck and Suzuki cross-coupling reactions
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Three new (N-diphenylphosphino)-isopropylanilines, having isopropyl substituent at the carbon 2- (1) 4- (2) or 2,6- (3) were preparedfromtheaminolysisof chlorodiphenylphosphine with 2-isopropylaniline, 4-isopropylanilineor2,6-diisopropylaniline, respectively, under anaerobic conditions. Oxidation of 1,2 and 3 with aqueous hydrogen peroxide, elemental sulfur or gray selenium gave the corresponding oxides, sulfides and selenides (Ph2P=E)NH-C6H4-2-CH(CH3) 2, (Ph2P=E)NH-C6H4-4- CH(CH 3)2 and (Ph2P=E)NH-C6H 4-2,6-{CH(CH3)2}2, where E = O, S, or Se, respectively. The reaction of [M(cod)Cl2] (M = Pd, Pt; cod = 1,5-cyclooctadiene) with two equivalents of 1,2 or 3 yields the corresponding monodendate complexes [M((Ph2P)NH-C6H4-2- CH(CH3)2)2Cl2], M = Pd 1d, M = Pt 1e, [M((Ph2P)NH-C6H4-4-CH(CH3) 2)2Cl2], M = Pd 2d, M = Pt 2e and [M((Ph 2P)NH-C6H4-2,6-(CH(CH3) 2)2)2Cl2], M = Pd 3d, M = Pt 3e, respectively. All the compounds were isolated as analytically pure substances and characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, representative solid-state structure of [(Ph2P S)NH-C 6H4-4-CH(CH3)2] (2b) was determined using single crystal X-ray diffraction technique. The complexes 1d-3d were tested and found to be highly active catalysts in the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes, respectively. Copyright
- Aydemir, Murat,Baysal, Akin,Guerbuez, Nevin,Oezdemir, Ismail,Guemguem, Bahattin,Oezkar, Saim,Caylak, Nagihan,Yildirim, Leyla Tatar
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experimental part
p. 17 - 24
(2010/10/02)
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- Ruthenium-catalyzed transfer hydrogenation of aromatic ketones with aminophosphine or bis(phosphino)amine ligands derived from isopropyl substituted anilines
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A series of new highly active Ru(II) complexes with two new (N-diphenylphosphino)isopropylanilines, having an isopropyl substituent at carbon 2- (1) or 2,6- (2) and two new bis(diphenylphosphino)isopropylanilines, having an isopropyl substituent at carbon
- Aydemir, Murat,Baysal, Akin
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body text
p. 1219 - 1224
(2010/04/30)
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