- Synthesis and Reactivity of NNNNN-Pincer Multidentate Pyrrolyl Rare-Earth-Metal Amido-Chloride or Dialkyl Complexes
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The NNNNN-pincer multidentate pyrrolyl rare-earth-metal amido-chloride complexes {η1:κ3-2,5-[CH3N(CH2CH2)2NCH2]2C4H2N}RECl[N(SiMe3)2] (RE = Y (2a), Sm (2b), Dy (2c), Er (2d), Yb (2e)) were synthesized by one step from reactions of [(Me3Si)2N]3RE(μ-Cl)Li(T
- Cui, Peng,Du, Jun,Huang, Zeming,Sheng, Weiming,Wang, Shaowu,Wei, Yun,Xu, Xiaolong,Zhang, Lijun,Zhang, Xiuli,Zhou, Shuangliu,Zhu, Xiancui
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supporting information
p. 4525 - 4534
(2020/12/22)
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- 2-Picolylamino(diphenylphosphinoselenoic)amide supported zinc complexes: Efficient catalyst for insertion of N–H bond into carbodiimides, isocyanates, and isothiocyanate
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We report here the hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by zinc complexes supported by the ligand 2-picolylamino-(diphenylphosphinoselenoic)amide [{(Ph2P-(?Se)}2NCH2(C5H4N)] (1). A series of zinc complexes [κ2-{(Ph2P-(?Se)}2NCH2(C5H4N)ZnX2] [(X?Cl (2), Br (3a), I (4)] were prepared from ligand 1 and the corresponding zinc dihalide in a 1:1 molar ratio at 60°C in a chloroform solvent. The reaction of ligand 1 and ZnBr2 in methanol yielded another zinc complex [κ2-{(Ph2P-(?Se)}2NCH2(C5H4N)ZnBr2(CH3OH)] (3b). The molecular structures of compounds 3a, 3b, and 4 were established through single-crystal X-ray diffraction analyses. The solid-state structures of all the complexes revealed a κ2- chelation through pyridine nitrogen and selenium atoms of ligand 1 to the zinc ion. Complex 2 proved to be a competent pre-catalyst for the addition of the amine N–H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanate and phenylisothiocyanate in toluene solvents, which proceeded rapidly at room temperature with 5 mol% catalyst loading to yield (up to 99%) the corresponding derivatives of urea and thio-urea. However, a temperature of 90°C was needed for the hydroamination of N,N′ dicyclohexylcarbodiimide. We also report the most plausible mechanism of the hydroamination reaction.
- Harinath, Adimulam,Bano, Kulsum,Ahmed, Shakil,Panda, Tarun K.
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supporting information
p. 23 - 32
(2017/09/25)
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- Highly Active Dinuclear Titanium(IV) Complexes for the Catalytic Formation of a Carbon-Heteroatom Bond
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A series of mononuclear titanium(IV) complexes with the general composition κ3-[R{NHPh2P(X)}2Ti(NMe2)2] [R = C6H4, X = Se (3b); R = trans-C6H10, X = S (4a), Se (4b)] and [{κ2-N(PPh2Se)2}2Ti(NMe2)2] (6b) and two dinuclear titanium(IV) complexes, [C6H4{(NPh2PS)(N)}Ti(NMe2)]2 (3c) and [{κ2-N(PPh2Se)}Ti(NMe2)2]2 (6c), are reported. Dinuclear titanium(IV) complex 6c acts as an efficient catalyst for the chemoselective addition of an E-H bond (E = N, O, S, P, C) to heterocumulenes under mild conditions. The catalytic addition of aliphatic and aromatic amines, alcohol, thiol, phosphine oxide, and acetylene to the carbodiimides afforded the corresponding hydroelemented products in high yield at mild conditions with a broader substrate scope. The catalytic efficiency of the dinuclear complex depends on the cooperative effect of the TiIV ions, the systematic variation of the intermetallic distance, and the ligand's steric properties of the complex, which enhances the reaction rate. Most interestingly, this is the first example of catalytic insertion of various E-H bonds into the carbodiimides using a single-site catalyst because only the titanium-mediated insertion of E-H into a C-N unsaturated bond is reported to date. The amine and alcohol insertion reaction with the carbodiimides showed first-order kinetics with respect to the titanium(IV) catalyst as well as substrates. A most plausible mechanism for hydroelementation reaction is also proposed, based on the spectroscopic data of the controlled reaction, a time-course study, and the Hammett plot.
- Bhattacharjee, Jayeeta,Harinath, Adimulam,Banerjee, Indrani,Nayek, Hari Pada,Panda, Tarun K.
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supporting information
p. 12610 - 12623
(2018/10/09)
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- An amidato divalent ytterbium cluster: Synthesis and molecular structure, its reactivity to carbodiimides and application in the guanylation reaction
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A divalent ytterbium amidate 1 ([Yb3L6]·2C7H8 for short) was synthesized via amine-elimination of Yb[N(SiMe3)2]2(TMEDA) with an amide proligand N-2,6-diisopropylphenylbenzamide HL (L = 2,6-iPr2C6H3NC(O)Ph) and structurally characterized to be a trinuclear symmetric cluster. Further studies on the reduction of iPrNCNiPr by complex 1 provide Yb(iii) complex 2 in hexane-THF ([(YbL2)2(μ-NiPrCNiPr)][YbL3(THF)]·C7H8), which is composed of two subunits in a unit cell, one is a bridged Yb(iii) carbene, just the same as complex 4 ([(YbL2)2(μ-NiPrCNiPr)]·3C7H8) obtained in the same reaction in toluene, and the other is a homoleptic monomeric Yb(iii) amidate (YbL3). It is also found that complex 2 decomposed to complex 3 ([YbL3]2·2C7H8) and 4 at 90 °C in toluene. Complexes 1-4 were confirmed by X-ray structure determination. Furthermore, complex 4 was proved to be a more active species than its precursor 1 in the catalytic addition of amines to carbodiimides. Finally, complex 1 was found to be an excellent pre-catalyst for the guanylation reaction with a wide scope of substrates.
- Gong, Chao,Ding, Hao,Lu, Chengrong,Zhao, Bei,Yao, Yingming
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p. 6031 - 6038
(2017/07/10)
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- Zinc catalyzed Guanylation reaction of Amines with Carbodiimides/ Isocyanate leading to Guanidines/Urea derivatives formation
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We report the highly chemo-selective catalytic addition of N–H bonds from various aromatic amines to carbodiimides and isocyanates using (Ar-BIAO)ZnCl2 complexes [Ar-BIAO = N-(aryl)imino-acenapthenone, Ar = 2,6-Me2C6H3 (1), 2,4,6 Me3C6H2 (2), 2,6-iPr2C6H3 (3)] as the pre-catalyst to prepare guanidine and urea derivatives in 55-90% yield. The complex 3 showed higher catalytic activity than analogous complexes 1 and 2 under similar reaction conditions. The catalytic guanylation of N–H bonds with heterocumulenes displays a broad substrate scope. The amines having electron donating groups underwent higher conversion than the amines having electron withdrawing groups to afford corresponding guanidine or urea derivatives. A possible mechanism involving penta-coordinated zinc transition state for the catalytic reaction is presented. [Figure not available: see fulltext.]
- Bhattacharjee, Jayeeta,Sachdeva, Mitali,Banerjee, Indrani,Panda, Tarun K
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p. 875 - 881
(2016/07/06)
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- Hydroamination of carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(IV) complex
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The hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex as a precatalyst is reported here. The titanium(iv) complex [{Ph2P(Se)NCH2CH2NPPh2(Se)}Ti(NMe2)2] (1) was synthesised by the reaction of tetrakis-(dimethylamido)titanium(iv) [Ti(NMe2)4] with [{Ph2P(Se)NHCH2CH2NHPPh2(Se)}] in toluene at ambient temperature. Titanium complex 1 proved to be a competent pre-catalyst for the addition of an amine N-H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanates and phenylisothiocyanates in toluene solvents proceeding rapidly at room temperature with 5 mol% catalyst loadings to yield the corresponding urea and thio-urea derivatives up to 99%. However, ambient temperature was needed for hydroamination of 1,3-dicyclohexylcarbodiimide. The amine addition reactions with isocyanates showed first order kinetics with respect to catalyst 1 as well as substrates. The most plausible mechanism for the hydroamination reaction was established by isolating 1,1-dimethylphenyl urea as a side product.
- Bhattacharjee, Jayeeta,Das, Suman,Kottalanka, Ravi K.,Panda, Tarun K.
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supporting information
p. 17824 - 17832
(2016/11/18)
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- Synthesis and characterization of bis(amidate) rare-earth metal amides and their application in catalytic addition of amines to carbodiimides
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Two new bis(amidate) lanthanide amides {LLn[N(SiMe3)2]·THF}2 (H2L = N,N′-(cyclohexane-1,2-diyl)-bis(4-tert-butylbenzamide); Ln = Sm(4), Yb(5)), which were prepared by the treatment of the bridged amide proligand H2L with Ln[N(SiMe3)2]3 in tetrahydrofuran, had been characterized by single-crystal X-ray diffraction and elemental analyses. Both complexes 4 and 5 and the three known isomorphs {LRE[N(SiMe3)2]·THF}2 (RE = La(1), Nd(2), Y(3)) were successfully employed in the addition of amines to carbodiimides for the first time and were found to be efficient catalysts in the transformation at 60°C under solvent-free conditions. The Nd-based catalyst 2 showed the highest reactivity and provided various guanidines with good functional group tolerance in high to excellent yields.
- Cheng, Hao,Xiao, Yang,Lu, Chengrong,Zhao, Bei,Wang, Yaorong,Yao, Yingming
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p. 7667 - 7671
(2015/10/12)
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- Catalytic addition of amines to carbodIImides by bis(β-diketiminate)lanthanide(II) complexes and mechanistic studies
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Reduction reactions of bis(β-diketiminate)lanthanide(iii) chlorides formed in situ by reactions of anhydrous LnCl3 with 2 equiv. of sodium salt of the β-diketiminate ligand in THF with a Na/K alloy afforded a series of bis(β-diketiminate)lanthanide(ii) complexes LnL2(THF)n (L = L26-Me2 = [N(2,6-Me2C6H3)C(Me)]2CH-, n = 1, Ln = Eu (1); L = L2,4,6-Me3 = [N(2,4,6-Me3C6H2)C(Me)]2CH-, n = 1, Ln = Eu (2); L = L2,6-iPr2 = [N(2,6-iPr2C6H3)C(Me)]2CH-, n = 0, Ln = Eu (3), Sm (4); L = L2,6-ipr2Ph = [(2,6-iPr2C6H3)NC(Me)CHC(Me)N(C6H5)]-, n = 0, Ln = Eu (5), Yb (6); L = L2-Me = [N(2-MeC6H4)C(Me)]2CH-, n = 1, Ln = Yb (7)) in high yields. All the complexes, especially the complexes of SmII (4) and EuII (5), were found to be excellent pre-catalysts for catalytic addition of amines to carbodiimides to multi-substituted guanidines with a wide scope of substrates. The activity depends both on the central metals and the ligands with the active sequence of YbII II and EuII II and L2,6-Me2 2,4,6-Me3 ~ L2,6-iPr2 2,6-ipr2Ph for the ligands. The mechanistic study by the isolation of guanidinate species and their reactivity revealed that EuII monoguanidinate complexes Eu(L2,6-Me2)[(C6H5N)C(NHCy)(NCy)](DME) (8) and Eu(L2,6-ipr2Ph)[(C6H5N)C(NHCy)(NCy)](THF)2 (9) should be the key active intermediates for the systems with EuII complexes and a YbIII bis(guanidinate) complex Yb(L2-Me)[(C6H5N)C(NHCy)(NCy)]2 (11) for the system using a YbII complex.
- Xue, Mingqiang,Zheng, Yu,Hong, Yubiao,Yao, Yingming,Xu, Fan,Zhang, Yong,Shen, Qi
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supporting information
p. 20075 - 20086
(2015/12/01)
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- Phenylene-bridged β-Ketoiminate Dilanthanide Aryloxides: Synthesis, Structure, and Catalytic Activity for Addition of Amines to Carbodiimides
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The synthesis and reactivity of a series of bimetallic lanthanide aryloxides stabilized by a p-phenylene-bridged bis(β-ketoiminate) ligand is presented. The reaction of 1,4-diaminobenzene with acetylacetone in a 1:2.5 molar ratio in absolute ethanol gave
- Hong, Yubiao,Zheng, Yu,Xue, Mingqiang,Yao, Yingming,Zhang, Yong,Shen, Qi
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supporting information
p. 1230 - 1237
(2015/06/30)
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- Bridged bis(amidinate) lanthanide aryloxides: Syntheses, structures, and catalytic activity for addition of amines to carbodiimides
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Various lanthanide aryloxide complexes supported by bridged bis(amidinate) ligand L, LLnOAr(DME) (L = Me3SiNC(Ph)N(CH2) 3NC(Ph)NSiMe3, DME = dimethoxyethane, Ln = Y, Ar = 2,6-(Me)2C6H3
- Tu, Jing,Li, Wenbo,Xue, Mingqiang,Zhang, Yong,Shen, Qi
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supporting information
p. 5890 - 5901
(2013/07/19)
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- β-Diketiminatoytterbium aryloxides: Synthesis, structural characterization, and catalytic activity for addition of amines to carbodiimides
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The steric effect of an aryloxido group on the synthesis and molecular structures of ytterbium aryloxides supported by β-diketiminato ligand L (L = [N(2,6-Me2C6H3)C(Me)]2CH -) is reported. Reactions o
- Cai, Ling-Xia,Yao, Ying-Ming,Xue, Ming-Qiang,Zhang, Yong,Shen, Qi
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p. 366 - 372
(2013/07/28)
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- Influence of Schiff base and lanthanide metals on the synthesis, stability, and reactivity of monoamido lanthanide complexes bearing two Schiff bases
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The monoamido lanthanide complexes stabilized by Schiff base ligand L 2LnN(TMS)2 (L = 3,5-But2-2-(O)- C6H2CH=N-8-C9H6N, Ln = Yb (1), Y (2), Eu (3), Nd (4), and La (5))
- Han, Fubin,Teng, Qiaoqiao,Zhang, Yong,Wang, Yaorong,Shen, Qi
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experimental part
p. 2634 - 2643
(2011/06/18)
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- Activation of carbodiimide and transformation with amine to guanidinate group by Ln(OAr)3(THF)2 (Ln: Lanthanide and yttrium) and Ln(OAr)3(THF)2 as a novel precatalyst for addition of amines to carbodiimides: Inf
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Reaction of Ln(OAr1)3(THF)2 (Ar 1= [2,6-(tBu)2- 4-MeC6H2] with carbodiimides (RNCNR) in toluene afforded the RNCNR coordinated complexes (Ar 1O)3Ln(NCNR) (R = iPr (iso
- Cao, Yang,Du, Zhu,Li, Wenbo,Li, Junmei,Zhang, Yong,Xu, Fan,Shen, Qi
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experimental part
p. 3729 - 3737
(2011/07/07)
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- Heterobimetallic dianionic guanidinate complexes of lanthanide and lithium: Highly efficient precatalysts for catalytic addition of amines to carbodiimides to synthesize guanidines
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A series of heterobimetallic dianionic guanidinate complexes of lanthanide and lithium, [Li(THF)(DME)]3Ln[μ- η2η1(iPrN)2C(NC 6H4p-R)]3 [R=Cl, Ln=Nd (I), Y (II), La (III); R=H, Ln=Nd (IV)] were synthesized and fully characterized. These complexes were found to be highly efficient precatalysts for the addition of various primary and secondary amines, and aromatic and aliphatic diamines to carbodiimides to give the corresponding monoguanidine and biguanidine derivatives under mild condition (at 25-60 °C), which provides an efficient way for the synthesis of biguanidines compounds. The activity depends on the central metals and ligands: La>Nd>Y for the metals and [(iPrN) 2C(NC6H4p-Cl)]2->[( iPrN)2C(NC6H5)]2- for the ligands were observed.
- Zhang, Xingmin,Wang, Chuanyong,Qian, Cunwei,Han, Fubin,Xu, Fan,Shen, Qi
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experimental part
p. 8790 - 8799
(2011/12/02)
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- Ytterbium triflate: A highly active catalyst for addition of amines to carbodiimides to N,N′,N″-trisubstituted guanidines
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(Chemical Equation Presented) Ytterbium triflate was found to be efficient catalyst for addition of amines to carbodiimides to N,N′,N″- trisubstituted guanidines with a wide scope of amines under solvent-free condition.
- Zhu, Xuehua,Du, Zhu,Xu, Fan,Shen, Qi
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supporting information; experimental part
p. 6347 - 6349
(2009/12/08)
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- Divalent lanthanide complexes: Highly active precatalysts for the addition of N-H and C-H bonds to carbodiimides
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(Chemical Equation Presented) Various divalent lanthanide complexes with the formula LnL2(sol)x (L = N(TMS)2, sol = THF, x = 3, Ln = Sm (I), Eu (II), Yb (III); L = MeC5H4, sol = THF, x = 2, Ln = Sm (IV); L = ArO(Ar = [2,6-(tBu)2-4- MeC6H2]), sol = THF, x = 2, Ln = Sm (V)), especially complexes I-III, serve as excellent catalyst precursors for catalytic addition of various primary and secondary amines to carbodiimides, efficiently providing the corresponding guanidine derivatives with a wide range of substrates under solvent-free condition. The reaction shows good functional groups tolerence. Complexes I-III are also excellent precatalysts for addition of terminal alkynes to carbodiimides yielding a series of propiolamidines. The active sequence of Yb 5H4 2 for ligand around the metal was observed for both reactions. The first step in both reactions was supposed to include the formation of a bimetallic bisamidinate samarium species originating from the reduction-coupling reaction of carbodiimide promoted by lanthanide(II) complex. The active species is proposed to be a lanthanide guanidinate and a lanthanide amidinate.
- Du, Zhu,Li, Wenbo,Zhu, Xuehua,Xu, Fan,Shen, Qi
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supporting information; experimental part
p. 8966 - 8972
(2009/04/06)
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