- Catalytically Active N-Acylamidine-Zirconium Complexes: Synthesis, Structures, and Application in Ethylene Polymerization
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Three novel N-acylamidines 1a-c with varying steric bulk and substitution patterns were synthesized and thoroughly characterized by X-ray diffraction. Compounds 1a and 1b, which contain two additional binding sites located at two pyridine substituents, were treated with equimolar amounts of cyclopentadienylzirconium(IV) trichloride at room temperature. The X-ray data of the resulting coordination compounds 7a and 7b indicate the formation of five-membered metallacycles with one of the pyridine nitrogen atoms and the carbonyl oxygen atom acting as binding sites. For the complexation of ligand 1c, a different route was chosen: 1c was first deprotonated to yield the polymeric potassium compound 8 with a very complex substitution pattern based on O, N, and aromatic interactions with the potassium ions. Transmetalation of 8 with cyclopentadienylzirconium(IV) trichloride gave amidinate complex 9, which is dimeric in the solid state but exists in solution in equilibrium with monomeric species. After addition of methylaluminoxane (MAO), the three novel cyclopentadienylzirconium complexes 7a, 7b, and 9 gave active homogeneous single-site catalysts for the polymerization of ethylene. Of these three systems, 9/MAO turned out to be the most efficient one, showing activities 3-5 times higher than 7a/MAO and 7b/MAO, respectively, and producing polymers with a well-defined "monomodal" molecular weight distribution. An important feature of these materials is their broader distribution in molecular weight (PDI > 3), which is best seen in the products of reactions at 53 °C, with a "monomodal" main fraction at higher molecular weight and only small fractions of low molecular weight.
- Holtrichter-R??mann, Thorsten,H?ger, Ina,Daniliuc, Constantin-Gabriel,Fr?hlich, Roland,Bergander, Klaus,Troll, Carsten,Rieger, Bernhard,Rojas, René S.,Würthwein, Ernst-Ulrich
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- Acyclic aminocarbene-like palladium complex-catalyzed Suzuki-Miyaura reaction at low catalyst loadings
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A series of air-stable aminocarbene-like palladium(II) complexes were easily prepared by the reaction of bis-aromaticisocyanide-dichloropalladium(II) with N-arylbenzamidines. 0.1 mol % of the optimal palladium complex 3a showed excellent catalytic activity for Suzuki-Miyaura cross-coupling reaction at room temperature and the desired products were isolated in up to 98% yields. Moreover, a large-scale reaction showed that 0.01 mol % 3a was enough to catalyze the coupling reaction efficiently at room temperature to give the desired product in 93% yield.
- Fang, Yi,Wang, Shun-Yi,Ji, Shun-Jun
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supporting information
p. 9679 - 9683
(2015/12/04)
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- Copper-catalyzed aerobic aliphatic C-H oxygenation directed by an amidine moiety
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A method for the oxygenation of tertiary C-H bonds of N-alkylamidines and N-(2-alkylaryl)amidines is described that utilizes the CuBr?SMe 2/2,2′-bipyridine catalytic system under an O2 atmosphere and provides dihydrooxazoles and 4H-1,3-benzoxazines. The oxygen atom is incorporated from atmospheric molecular oxygen during the present process.
- Wang, Yi-Feng,Chen, Hui,Zhu, Xu,Chiba, Shunsuke
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supporting information; experimental part
p. 11980 - 11983
(2012/09/08)
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- Synthesis, characterization of bridged bis(amidinate) lanthanide amides and their application as catalysts for addition of amines to nitriles for monosubstituted N-arylamidines
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A series of lanthanide amide complexes supported by bridged bis(amidinate) ligand L, LLnNHAr1(DME) (L = [Me3SiNC(Ph)N(CH 2)3NC(Ph)NSiMe3], Ar1 = 2,6- iPr2C6
- Li, Wenbo,Xue, Mingqiang,Xu, Fan,Tu, Jing,Zhang, Yong,Shen, Qi
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supporting information; experimental part
p. 8252 - 8260
(2012/07/28)
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- PHOSPHINYL AMIDINE COMPOUNDS, METAL COMPLEXES, CATALYST SYSTEMS, AND THEIR USE TO OLIGOMERIZE OR POLYMERIZE OLEFINS
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N2-phosphinyl amidine compounds, N2-phosphinyl amidinates, N2-phosphinyl amidine metal salt complexes, N2-phosphinyl amidinate metal salt complexes are described. Methods for making N2-phosphinyl amidine compounds, N2-phosphinyl amidinates, N2-phosphinyl amidine metal salt complexes, and N2-phosphinyl amidinate metal salt complexes are also disclosed. Catalyst systems utilizing the N2-phosphinyl amidine metal salt complexes and N2-phosphinyl amidinate metal salt complexes are also disclosed along with the use of the N2-phosphinyl amidine compounds, N2-phosphinyl amidinates, N2-phosphinyl amidine metal salt complexes, and N2-phosphinyl amidinate metal salt complexes for the oligomerization and/or polymerization of olefins.
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Page/Page column 307
(2011/07/30)
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- Synthesis and molecular structures of lanthanocene amide complexes and their catalytic activity for addition of amines to nitriles
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Reaction of (CH3C5H4)2LnCl(THF) with NaNHAr in a 1:1 molar ratio in THF afforded the amide complexes (CH3C5H4)2LnNHAr(THF) [(Ar = 2,6-Me2C6H
- Cai, Tao,Chen, Xiaoniu,Xu, Fan,Zhang, Yong,Yao, Yingming,Shen, Qi
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experimental part
p. 3167 - 3171
(2010/01/05)
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- Addition of amines to nitriles catalyzed by ytterbium amides: An efficient one-step synthesis of monosubstituted N-arylamidines
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A one-step synthesis of monosubstituted N-arylamidinates via addition of amines to nitriles catalyzed by ytterbium amides is reported. The reactions with various substrates give the products in good to excellent yields with 5 mol % ytterbium at 100 °C under solvent-free conditions.
- Wang, Junfeng,Xu, Fan,Cai, Tao,Shen, Qi
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p. 445 - 448
(2008/09/19)
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- N-haloamidines. VII(2c). 4-Amino-5-chloroimidazoles and 4-amino-5- unsubstituted imidazoles from N-chloro-N'-arylbenzamidines and 1,1- diaminoethenes
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N-chloro-N'-arylbenzamidines react with 1,1-diaminoethenes to give in good yields 4-amino-5-chloroimidazoles. The behaviour of these compounds in some nucleophilic substitution reactions and their reduction to 4-amino 5- unsubstituted imidazoles is reported.
- Rossi,Pini
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p. 7939 - 7946
(2007/10/03)
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