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1.
The anionic lanthanide‐sodium‐2,6‐di‐tert‐butyl‐phenoxide complexes [Ln(OAr)4][Na(DME)3]·DME (Ln = Nd 1 (neodymium), Sm 2 (samarium), or Gd 3 (gadolium); DME = dimethoxyethane) were synthesized by the reaction of anhydrous LnCl3 with 4 equiv of sodium‐2,6‐di‐tert‐butyl‐phenoxide NaOAr in high yields and structurally characterized. These complexes showed high catalytic activity in the ring‐opening polymerizations of ?‐caprolactone (?‐CL) and trimethylene carbonate (TMC). The catalytic activity profoundly depended on the lanthanide metals. The active order of Gd < Sm < Nd for the polymerization of ?‐CL and TMC was observed. The polymers obtained with these initiators all showed a unimodal molecular weight distribution, indicating that the [Ln(OAr)4][Na(DME)3]·DME anionic complexes could be used as single‐component initiators. The anionic complex was more efficient than the corresponding neutral complex, Ln(OAr)3(THF)2. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1210–1218, 2007  相似文献   

2.
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-((t)Bu)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 tolerance. Complexes I- III are also excellent precatalysts for addition of terminal alkynes to carbodiimides yielding a series of propiolamidines. The active sequence of Yb < Eu < Sm for metal and MeC5H4 < ArO < N(TMS)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.  相似文献   

3.
Ring‐opening polymerization of ε‐caprolactone (ε‐CL) was carried out using β‐diketiminato‐supported monoaryloxo ytterbium chlorides L1Yb(OAr)Cl(THF) (1) [L1 = N,N′‐bis(2,6‐dimethylphenyl)‐2,4‐pentanediiminato, OAr = 2,6‐di‐tert‐butylphenoxo‐], and L2Yb(OAr′)Cl(THF) (2) [L2 = N,N′‐bis(2,6‐diisopropylphenyl)‐2,4‐pentanediiminato, OAr′ = 2,6‐di‐tert‐butyl‐4‐methylphenoxo‐], respectively, as single‐component initiator. The influence of reaction conditions, such as polymerization temperature, polymerization time, initiator, and initiator concentration, on the monomer conversion, molecular weight, and molecular weight distribution of the resulting polymers was investigated. Complex 1 was well characterized and its crystal structure was determined. Some features and kinetic behaviors of the CL polymerization initiated by these two complexes were studied. The polymerization rate is first order with respect to monomer. The Mn of the polymer increases linearly with the increase of the polymer yield, while polydispersity remained narrow and unchanged throughout the polymerization in a broad range of temperatures from 0 to 50 °C. The results indicated that the present system has a “living character”. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1147–1152, 2006  相似文献   

4.
The preparation and characterization of a series of complexes of the Yb and Eu cations in the oxidation state II and III with the tetradentate N,O‐donor tripodal ligands (tris(2‐pyridylmethyl)amine (TPA), BPA? (HBPA=bis(2‐pyridylmethyl)(2‐hydroxybenzyl)amine), BPPA? (HBPPA=bis(2‐pyridylmethyl)(3.5‐di‐tert‐butyl‐2‐hydroxybenzyl)amine), and MPA2? (H2MPA=(2‐pyridylmethyl)bis(3.5‐di‐tert‐butyl‐2‐hydroxybenzyl)amine) is reported. The X‐ray crystal structures of the heteroleptic Ln2+ complexes [Ln(TPA)I2] (Ln=Eu, Yb) and [Yb(BPA)I(CH3CN)]2, of the Ln2+ homoleptic [Ln(TPA)2]I2 (Ln=Sm, Eu, Yb) and [Eu(BPA)2] complexes, and of the Ln3+ [Eu(BPPA)2]OTf and [Yb(MPA)2K(dme)2] (dme=dimethoxyethane) complexes have been determined. Cyclic voltammetry studies carried out on the bis‐ligand complexes of Eu3+ and Yb3+ show that the metal center reduction occurs at significantly lower potentials for the BPA? ligand as compared with the TPA ligand. This suggests that the more electron‐rich character of the BPA? ligand results in a higher reducing character of the lanthanide complexes of BPA? compared with those of TPA. The important differences in the stability and reactivity of the investigated complexes are probably due to the observed difference in redox potential. Preliminary reactivity studies show that whereas the bis‐TPA complexes of Eu2+ and Yb2+ do not show any reactivity with heteroallenes, the [Eu(BPA)2] complex reduces CS2 to afford the first example of a lanthanide trithiocarbonate complex.  相似文献   

5.
Treatment of Ln(NO3)3?nH2O with 1 or 2 equiv 2,2′‐bipyrimidine (BPM) in dry THF readily afforded the monometallic complexes [Ln(NO3)3(bpm)2] (Ln=Eu, Gd, Dy, Tm) or [Ln(NO3)3(bpm)2]?THF (Ln=Eu, Tb, Er, Yb) after recrystallization from MeOH or THF, respectively. Reactions with nitrate salts of the larger lanthanide ions (Ln=Ce, Nd, Sm) yielded one of two distinct monometallic complexes, depending on the recrystallization solvent: [Ln(NO3)3(bpm)2]?THF (Ln=Nd, Sm) from THF, or [Ln(NO3)3(bpm)(MeOH)2]?MeOH (Ln=Ce, Nd, Sm) from MeOH. Treatment of UO2(NO3)2?6H2O with 1 equiv BPM in THF afforded the monoadduct [UO2(NO3)2(bpm)] after recrystallization from MeOH. The complexes were characterized by their crystal structure. Solid‐state luminescence measurements on these monometallic complexes showed that BPM is an efficient sensitizer of the luminescence of both the lanthanide and the uranyl ions emitting visible light, as well as of the YbIII ion emitting in the near‐IR. For Tb, Dy, Eu, and Yb complexes, energy transfer was quite efficient, resulting in quantum yields of 80.0, 5.1, 70.0, and 0.8 %, respectively. All these complexes in the solid state were stable in air.  相似文献   

6.
Lanthanide isopropoxides supported by carbon‐bridged bisphenolate ligands of 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenoxo) {[(EDBP)Ln(μ‐OPri)(THF)2]2, where Ln is Nd ( 1 ), Sm ( 2 ), or Yb ( 3 ) and THF is tetrahydrofuran} were synthesized by protic exchange reactions in high yields with Cp3Ln compounds as raw materials, and complex 1 was structurally characterized. Complexes 1 – 3 were shown to be efficient initiators for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and 2,2‐dimethyltrimethylene carbonate (DTC). Complexes 1 – 3 could initiate the controlled polymerization of ε‐CL, and the polymerization rate was first‐order with respect to the monomer. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. End‐group analyses of the oligomers of ε‐CL and DTC showed that the polymerization underwent a coordination–insertion mechanism. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4409–4419, 2006  相似文献   

7.
Reaction of divalent Sm(OAr)2(THF)3 (Ar = C6H2tert‐Bu3‐2,4,6; THF = tetrahydrofuran) with one equivalent of azobenzene in THF and crystallization of the product in diethyl ether afforded the title complex (ArO)2(THF)2Sm(η2‐N2Ph2)·Et2O in good yield. In the complex, the N? N bond length for the azobenzene species is lengthened. The two Sm? N bonds are equivalent, and their bond lengths are intermediate between the donor bond and the single bond. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

8.
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 the compound 1,4‐bis(4‐imino‐2‐pentanone)benzene ( 1 ) (LH2) in high yield. Compound 1 reacted with (ArO)3Ln(THF)2 (ArO = 2,6‐tBu2‐4‐MeC6H2O, THF = tetrahydrofuran) in a 1:2 molar ratio in THF, after workup, to give the corresponding dilanthanide aryloxides L[Ln(OAr)2(THF)]2 [Ln = Yb ( 2 ), Y ( 3 ), Sm ( 4 ), Nd ( 5 ), La ( 6 )] in high isolated yields. Compound 1 and complexes 2 – 6 were fully characterized, including X‐ray crystal structure analyses for complexes 2 , 3 , 5 , and 6 . Complexes 2 – 6 can be used as efficient pre‐catalysts for catalytic addition of amines to carbodiimides, and the ionic radii of the central metal atoms have a significant effect on the catalytic activity with the increasing sequence of La ( 6 ) < Nd ( 5 ) ≈ Sm ( 4 ) < Y ( 3 ) ≈ Yb ( 2 ). The catalytic addition reaction with 2 showed a good scope of substrates including primary and secondary amines.  相似文献   

9.
The alcoholysis of the heteroscorpionate methyl aluminum complex (bpzmp)AlMe2 ( 1 ) (bpzmp = 2,4‐di‐tert‐butyl‐6‐(bis‐(3,5‐dimethylpyrazol‐1‐yl)methyl)phenoxo), promoted both by phenol and isopropanol, has been investigated. The reaction of 1 with phenol afforded the dimeric mono(phenoxo) derivative 2 , whereas the alcoholysis of 1 with the less acidic isopropanol involved the coordinated heteroscorpionate ligand and led to the tetrahedral complex 3 in which the aluminum atom is surrounded by one κ2‐N,O? coordinated bpzmp ligand and one η1‐O? coordinated ppzmp ligand (ppzmp = 2,4‐di‐tert‐butyl‐6‐(i‐propoxy‐(3,5‐dimethylpyrazol‐1‐yl)methyl)phenoxo). Complexes 1 – 3 have been tested in the ring opening polymerization (ROP) of L ‐lactide. The dimeric mono(phenoxo) derivative 2 was inactive in the ROP of L ‐lactide. Quite surprisingly, complex 3 was found to be active in ROP of L ‐ and rac‐lactide, showing a good molar‐mass control. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3632–3639, 2010  相似文献   

10.
The synthesis and characterization of dimeric lanthanide amides stabilized by a dianionic N‐aryloxo functionalized β‐ketoiminate ligand are described in this paper. Reactions of 4‐(2‐hydroxy‐5‐tert‐butyl‐phenyl)imino‐2‐pentanone (LH2) with Ln[N(SiMe3)2]3(µ‐Cl)Li(THF)3 in a 1:1 molar ratio in THF gave the dimeric lanthanide amido complexes [LLn{N(SiMe3)2}(THF)]2 [Ln=Nd ( 1 ), Sm ( 2 ), Yb ( 3 ), Y ( 4 )] in good isolated yields. These complexes were characterized by IR spectroscopy, elemental analysis, and 1H NMR spectroscopy in the case of complex 4 . The definitive molecular structures of complexes 1 , 3 , and 4 were determined. It was found that complexes 1 to 4 can initiate the ring‐opening polymerization of L‐lactide.  相似文献   

11.
Rare examples of amido‐iodo complexes of selected divalent lanthanides can be synthesized by using deprotonated Ap*H {Ap*H = 2,6‐diisopropylphenyl)‐[6‐(2,4,6‐triisopropylphenyl)‐pyridin‐2‐yl]‐amine} as a stabilizing ligand. Reaction of [Ap*K]n with [LnI2(thf)n] (Ln = Eu, Yb, n = 4,5) in THF leads to [Ln(Ap*)I(thf)2]2 (Ln = Eu, Yb). An attempted reduction of these divalent heteroleptic complexes with KC8 to synthesize complexes containing an unsupported Ln–Ln bond resulted in the formation of [Ln(Ap*)2(thf)2]. These lanthanide complexes were characterized by X‐ray structure analysis.  相似文献   

12.
齐民华  沈琪等 《中国化学》2002,20(6):564-569
The reaction between K(1‐C5H9C9H6) and anhydrous LnCl3 (Ln=Sm, Yb) in the molar ratio of 2:1 in THF with subsequent treatment by Na‐K alloy afforded (1‐C5H9C9H6)2Ln‐(THF)n(Ln=Sm, n=1; Ln=Yb, n=2), while the reaction of Sml2 with K(1‐C5H9C9H6) in the molar ratio of 1:2 in THF gave the anionic complex K(1‐C5H9C9H6)3Sm(THF)3. The X‐ray structure of (1‐C5H9C9H6)2Yb(THF)2 showed that central metal Yb is coordinated by two cyclopentadienyl rings of 1‐cyclopentylindenyls and two oxygen atoms from two tetrahydrofuran molecules to form pseudo‐tetrahedral coordinate geometry. All these complexes are active for the polymerization of acrylonitrile.  相似文献   

13.
The binuclear complex bis(2,6‐di‐tert‐butyl‐4‐methylphenolato)‐1κO ,2κO‐(1,2‐dimethoxyethane‐1κ2O ,O ′)bis(μ‐phenylmethanolato‐1:2κ2O :O )(tetrahydrofuran‐2κO )dimagnesium(II), [Mg2(C7H7O)2(C15H23O)2(C4H8O)(C4H10O2)] or [(BHT)(DME)Mg(μ‐OBn)2Mg(THF)(BHT)], (I), was obtained from the complex [(BHT)Mg(μ‐OBn)(THF)]2 by substitution of one tetrahydrofuran (THF) molecule with 1,2‐dimethoxyethane (DME) in toluene (BHT is O‐2,6‐t Bu2‐4‐MeC6H4 and Bn is benzyl). The trinuclear complex bis(2,6‐di‐tert‐butyl‐4‐methylphenolato)‐1κO ,3κO‐tetrakis(μ‐2‐methylphenolato)‐1:2κ4O :O ;2:3κ4O :O‐bis(tetrahydrofuran)‐1κO ,3κO‐trimagnesium(II), [Mg3(C7H7O)4(C15H23O)2(C4H8O)2] or [(BHT)2(μ‐O‐2‐MeC6H4)4(THF)2Mg3], (II), was formed from a mixture of Bu2Mg, [(BHT)Mg(n Bu)(THF)2] and 2‐methylphenol. An unusual tetranuclear complex, bis(μ3‐2‐aminoethanolato‐κ4O :O :O ,N )tetrakis(μ2‐2‐aminoethanolato‐κ3O :O ,N )bis(2,6‐di‐tert‐butyl‐4‐methylphenolato‐κO )tetramagnesium(II), [Mg4(C2H6NO)6(C15H23O)2] or Mg4(BHT)2(OCH2CH2NH2)6, (III), resulted from the reaction between (BHT)2Mg(THF)2 and 2‐aminoethanol. A polymerization test demonstrated the ability of (III) to catalyse the ring‐opening polymerization of ϵ‐caprolactone without activation by alcohol. In all three complexes (I)–(III), the BHT ligand demonstrates the terminal κO‐coordination mode. Complexes (I), (II) and (III) have binuclear rhomboid Mg2O2, trinuclear chain‐like Mg3O4 and bicubic Mg4O6 cores, respectively. A survey of the literature on known polynuclear Mgx Oy core types for ArO–Mg complexes is also presented.  相似文献   

14.
发现二价稀土配合物二 ( 2 ,6 二叔丁基 4 甲基苯氧基 )钐 [(ArO) 2 Sm (THF) 4]能较好地引发N 苯基马来酰亚胺 (N PMI)的聚合 ,溶剂对聚合的影响较大 ,在四氢呋喃中聚合转化率最高 ,且聚合转化率随单体浓度的提高而提高 ,而温度对聚合的影响不大。  相似文献   

15.
Two related compounds containing ptert‐butyl‐o‐methyl­ene‐linked phenol or phenol‐derived subunits are described, namely 5,5′‐di‐tert‐butyl‐2,2′‐di­hydroxy‐3,3′‐methyl­ene­di­benz­aldehyde, C23H28O4, (I), and 6,6′‐di‐tert‐butyl‐8,8′‐methyl­ene­bis­(spiro­[4H‐1,3‐benzo­di­oxin‐2,1′‐cyclo­hexane]), C35H48O4, (II). Both compounds adopt a `butterfly' shape, with the two phenol or phenol‐derived O atoms in distal positions. Phenol and aldehyde groups in (I) are involved in intramolecular hydrogen bonds and the two dioxin rings in (II) are in distorted half‐chair conformations.  相似文献   

16.
The molecular hydrides Ln11H2(THF)2 (Ln=Sm or Eu) were prepared by hydrogenolysis of the naphthalene complexes of divalent samarium and europium C10H8Ln(THF)2 (Ln=Sm or Eu, respectively) as well as of the stilbene derivative of samarium(II) (PhCHCHPh)Sm(DME)2 in THF at room temperature under atmospheric pressure. The resulting complexes were characterized by the data of microanalysis, IR spectroscopy, and magnetic susceptibility. Chemical properties of the complexes were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 947–945, May, 2000.  相似文献   

17.
Ring‐opening polymerization of 1‐methyltrimethylene carbonate (MTMC) initiated by highly active single‐component rare earth tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(OAr)3, Ln = La, Dy, Y] or yttrium isopropoxide [Y(OiPr)3] is reported for the first time. PolyMTMC (Mw = 8.4 × 104, molecular weight distributions = 1.5) initiated by La(OAr)3 at [MTMC]/[initiator] = 1000 was obtained with the yield over 99% in toluene within 1 h at 30 °C. Random and block copolymers of MTMC with ε‐caprolactone (CL), 2,2‐dimethyltrimethylene carbonate (DTC) or polyethylene glycol (PEG) including poly(MTMC‐r‐CL), poly(MTMC‐b‐CL), poly(MTMC‐r‐DTC), poly(MTMC‐b‐DTC), and poly(MTMC‐b‐PEG‐b‐MTMC) were synthesized. The differential scanning calorimetry results show that thermal behaviors of the polymers sensitively depend on their compositions and chain structures. Furthermore, the measurements of 1H‐1H COSY and density functional theory calculation are applied to investigate the mechanism. The polymerization of MTMC takes place according to a coordination‐insertion mechanism, and the ring is opened via acyl‐oxygen bond cleavage resulting in a Ln? O active center. There exist two ring‐opening modes of MTMC in which mode b , breaking the CH2O? CO bond, is the major pathway. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3807–3815, 2010  相似文献   

18.
The reaction of anhydrous CoCl2 with NaOAr (ArO=2,4,6‐tri‐tert‐butylphenoxo) in THF at room temperature in 1:3 molar ratio afforded anionic cobalt aryloxide [Na(THF)6][Co(OAr)3] ( 1 ). The definite structure of this complex was characterized by X‐ray single crystal diffraction. It was found that this anionic aryloxo cobalt(II) complex could effectively initiate the ring‐opening polymerization of L‐lactide both in solution and in bulk, leading to high molecular weight poly(L‐lactide).  相似文献   

19.
The ability of various rare earth borohydride and chloride complexes/n‐butylethylmagnesium systems to operate styrene chain transfer polymerization in mild conditions has been assessed. Thirteen precatalysts have been considered: the rare earth trisborohydrides Ln(BH4)3(THF)x (x = 3, Ln = Nd (1), La (2), Sm (3), x = 2, Ln = Y (4), Sc (5)), the rare earth chlorides LnCl3(THF)x (x = 3, Ln = Nd (6), La (7), Sm (8), Y (9), x = 2, Ln = Sc (10)), the mixed La(BH4)2Cl(THF)2.6 (11) and the half‐lanthanidocenes Cp*Ln(BH4)2(THF)2 (Ln = Nd (12), La (13)). Six systems were found to be active precatalysts for the polymerization of styrene. 1 , 2 , and 11 led to an efficient transmetalation of the growing polystyrene chain with the simultaneous occurrence of βH elimination, whereas 7 , 12 , and 13 led to catalyzed chain growth behavior. It is noteworthy that the catalyzed chain growth obtained with 12 and 13 occurs with significant stereoselectivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 802–814, 2010  相似文献   

20.
The oxidation of tin(IV) bis‐amidophenolate (APiPr)2Sn · THF ( I ) by bromine and iodine leads to the formation of monoradical mixed‐ligand complexes (APiPr)(ISQiPr)SnBr · THF ( II ) and (APiPr)(ISQiPr)SnI · THF ( III ) or diradical complexes (ISQiPr)2SnBr2 ( IV ) and (ISQiPr)2SnI2 ( V ), respectively [APiPr = dianion 4, 6‐di‐tert‐butyl‐N‐(2, 6‐diisopropylphenyl)‐o‐amidophenolate; ISQiPr = radical‐anion 4, 6‐di‐tert‐butyl‐N‐(2, 6‐diisopropylphenyl)‐o‐iminobenzosemiquinone], depending on the molar ratio of reagents (2:1 or 1:1). According to EPR data for compounds II and III , the unpaired electron is delocalized between both organic ligands. The EPR spectrum of IV in toluene matrix at 130 K is typical for diradical species with S = 1 with parameters D = 530 G, E = 105 G. The mixed‐ligand complexes II and III are unstable and undergo to symmetrization leading to formation of IV or V . The molecular structures of IV and V are determined by X‐ray analysis.  相似文献   

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