A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste ele...A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP-303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the surface of the CPE, yielding one peak at -0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc^(3+) is 1.0×10^(-10) mol·L^(-1) for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.展开更多
Reduced arene complexes of rare-earth metals are of great interest and importance because of their unique reactivity mimicking low-valence rare-earth metal species.Here,we present the synthesis and structural characte...Reduced arene complexes of rare-earth metals are of great interest and importance because of their unique reactivity mimicking low-valence rare-earth metal species.Here,we present the synthesis and structural characterization of a series of reduced naphthalene or anthracene complexes of mononuclear scandium with mixed C_(5)Me_(5)(Cp^(*))and amidinate ligands.Among them,the reduced anthracene complexes of mononuclear scandium have been found for the first time to undergo a rapid inter-ring rearrangement.Significantly,a reduced anthracene complex with a scandium center attached to the terminal six-membered ring of anthracene was synthesized by modulating the substituents on the amidinate ligand.The diversified two-electron redox reactions of the reduced naphthalene complex of mononuclear scandium toward cyclooctatetraene(COT),dibenzo[a,e]cyclooctene,benzophenone,1,4-diazabutadiene(DAD),isothiocyanate,and selenium were examined.The scope of two-electron redox reactions via the trivalent scandium complex with the mixed Cp^(*)/amidinate/arene ligand system is significantly expanded,and thus,these results remedy the shortcomings where it is difficult for rare-earth complexes to undergo the two-electron redox process.展开更多
This paper addresses the problem of the observation of the so-called C-C agostic interactions in cyclopropyl complexes of scandium.Three new cyclopropyl complexes of scandium based on theβ-diketiminato ligand were sy...This paper addresses the problem of the observation of the so-called C-C agostic interactions in cyclopropyl complexes of scandium.Three new cyclopropyl complexes of scandium based on theβ-diketiminato ligand were synthesized including by an intramolecular C-H bond activation reaction in one case.X-ray diffraction analysis revealed distorted cyclopropyl groups in the complexes,and the distortion could be observed in solution as well for one of the complexes thanks to the natural abundance INADEQUATE NMR spectroscopy which showed a markedly reduced J_(C-C)coupling constant.This signature of the C-C agostic interaction was further examined using DFT modelling which,together with NBO calculations,indicated that C-H and C-C agostic interactions are not exclusive but can complement each other,accounting for the distortions.The intramolecular C-H bond activation in the scandium biscyclopropyl complex was investigated by isotopic labeling experiments,which indicated a direct proton abstraction of the isopropyl group in theβ-diketiminato ligand by a cyclopropyl group.展开更多
AlMe_(3) sticks,GaMe_(3) quits.A series of Lewis acid stabilized scandium methylidenes with commercially available cyclopentadienyl ligands Cp^(R)(Cp^(R)=C_(5)Me_(5)(Cp^(*)),C_(5)Me_(4)SiMe_(3)(Cp’))were synthesized....AlMe_(3) sticks,GaMe_(3) quits.A series of Lewis acid stabilized scandium methylidenes with commercially available cyclopentadienyl ligands Cp^(R)(Cp^(R)=C_(5)Me_(5)(Cp^(*)),C_(5)Me_(4)SiMe_(3)(Cp’))were synthesized.The-salt metathesis reaction of new half-sandwich dichloride precursors Cp^(R)ScCl_(2)(μ-Cl)Li(thf)_(3) with LiAlMe_(4) and AlMe_(3) at ambient temperature yielded[Cp^(R)Sc(AlMe_(4))Cl]_(2).[Cp’Sc(AlMe_(4))Cl]_(2) was further methylated at ambient temperature to yield Cp’Sc(AlMe_(4))Me.At 70℃,the reaction of Cp^(R)ScCl_(2)(μ-Cl)Li(thf)3 with LiAlMe_(4) and AlMe_(3) led to the formation of Lewis acid stabilized Sc/Al_(2) methylidenes Cp^(R)Sc(CH_(2))(AlMe_(3))_(2).The new mixed Sc/Al/Ga methylidene Cp’Sc(CH_(2))(AlMe_(3))(GaMe_(3))was obtained from the reaction of Cp’Sc(AlMe_(4))Me with GaMe_(3).When heated,complex Cp’Sc(CH_(2))(AlMe_(3))(GaMe_(3))converted into the Sc/Al methylidene[Cp’Sc(CH_(2))_(2)AlMe]_(3) via release of the comparatively weak Lewis acid GaMe_(3) and methane.The core of trimeric[Cp’Sc(CH_(2))_(2)AlMe]_(3) can be described as a triscandacyclohexane{Sc(CH_(2))}_(3) stabilized by a trialacyclohexane{Al(CH_(2))}_(3) via Pearson hard/hard matching.Complexes Cp^(R)Sc(CH_(2))(AlMe_(3))_(2) and[Cp’Sc(CH_(2))_(2)AlMe]_(3) differ in rigidity,thermal stability and reactivities toward ketones and Lewis bases.The isolated methylidenes were analyzed by ^(1)H,^(13)C{^(1)H},^(45)Sc,and variable temperature ^(1)H NMR spectroscopy,SC-XRD,IR spectroscopy,and elemental analysis.Complexes Cp^(R)Sc(CH_(2))(AlMe_(3))_(2) feature pronounced Sc⋯HCα-agostic interactions.The reaction of Cp^(R)ScCl_(2)(μ-Cl)Li(thf)_(3) with LiAlMe_(4) and AlMe_(3) was investigated via in situ 1H and 45Sc NMR spectroscopy.展开更多
The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at el...The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at elevated temperature to give a mononuclear scandium anilido intermediate 2a, which subsequently aggregates into a binuclear scandium anilido complex 2. The mononuclear intermediate 2a reacts with alkyne or imine to provide two scandium anilido complexes 3 and 4, which contain a dianionic tetradentate NNNC ligand or a dianionic tetradentate NNNN ligand. DFT calculations on the reaction mechanism of C–N bond cleavage in 1 were also performed.展开更多
Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethylt...Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.展开更多
The title complex, [MnSc (DTPA) (H2O)2]·2H2O (DTPA is diethylenetriaminepentaacetic acid). has been synthesized in aqueous solution. Its crystal structure has been determined by four-circle X-ray diffractometer. ...The title complex, [MnSc (DTPA) (H2O)2]·2H2O (DTPA is diethylenetriaminepentaacetic acid). has been synthesized in aqueous solution. Its crystal structure has been determined by four-circle X-ray diffractometer. The crystal is monoclinic with space group P21/n. The cell parameters are as follows:α=0.7886 (3) nm, b=1.5094 (5) nm. c=1. 8162(6) nm; β=100. 32(2)°, V= 2. 121 (2) nm3 , Z= 4 , Dc =1. 75 g/cm3. In the crystal,Sc3+ ion is coordinated by five oxygen atoms and three nitrogen atoms of DTPA with coordination number eight. taking a trigondodecahedron arrangement. Mn2+ ion is coordinated by four oxygen atoms from different DTPA and two oxygen atoms from H2O molecules with coordination number six, forming an octahedron. Each Sc(DTPA) is further connected with Mn2+ ions through four carboxyl groups of DPTA serving as bridges to form a three dimensional network.展开更多
选用镉-碘化钾-罗丹明B多元络合物显色体系,分光光度法测定污水中镉的含量.研究结果表明:向待测镉标准溶液中加入1.0 mol/L硫酸溶液3.0 m L,碘化钾-抗坏血酸溶液4.0 m L和10 g/L聚乙烯醇-1750溶液2.0 m L,加入显色剂0.5 g/L罗丹明B溶液1...选用镉-碘化钾-罗丹明B多元络合物显色体系,分光光度法测定污水中镉的含量.研究结果表明:向待测镉标准溶液中加入1.0 mol/L硫酸溶液3.0 m L,碘化钾-抗坏血酸溶液4.0 m L和10 g/L聚乙烯醇-1750溶液2.0 m L,加入显色剂0.5 g/L罗丹明B溶液1.8 m L,摇匀放置10 min后,在600 nm波长处测定吸光度,镉的质量浓度在0~1.0 mg/L范围内符合朗伯-比尔定律,标准曲线相关系数R^2为0.993 3,加标回收率为98.75%~102.50%.展开更多
文摘A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP-303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the surface of the CPE, yielding one peak at -0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc^(3+) is 1.0×10^(-10) mol·L^(-1) for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.
基金work was supported by the National Key R&D Program of China(No.2021YFF0701600)the National Natural Science Foundation of China(No.21725201,21890721,and 22131001).
文摘Reduced arene complexes of rare-earth metals are of great interest and importance because of their unique reactivity mimicking low-valence rare-earth metal species.Here,we present the synthesis and structural characterization of a series of reduced naphthalene or anthracene complexes of mononuclear scandium with mixed C_(5)Me_(5)(Cp^(*))and amidinate ligands.Among them,the reduced anthracene complexes of mononuclear scandium have been found for the first time to undergo a rapid inter-ring rearrangement.Significantly,a reduced anthracene complex with a scandium center attached to the terminal six-membered ring of anthracene was synthesized by modulating the substituents on the amidinate ligand.The diversified two-electron redox reactions of the reduced naphthalene complex of mononuclear scandium toward cyclooctatetraene(COT),dibenzo[a,e]cyclooctene,benzophenone,1,4-diazabutadiene(DAD),isothiocyanate,and selenium were examined.The scope of two-electron redox reactions via the trivalent scandium complex with the mixed Cp^(*)/amidinate/arene ligand system is significantly expanded,and thus,these results remedy the shortcomings where it is difficult for rare-earth complexes to undergo the two-electron redox process.
基金National Natural Science Foundation of China(No.21732007,21890721,21821002)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB20000000)Program of Shanghai Academic Research Leader。
文摘This paper addresses the problem of the observation of the so-called C-C agostic interactions in cyclopropyl complexes of scandium.Three new cyclopropyl complexes of scandium based on theβ-diketiminato ligand were synthesized including by an intramolecular C-H bond activation reaction in one case.X-ray diffraction analysis revealed distorted cyclopropyl groups in the complexes,and the distortion could be observed in solution as well for one of the complexes thanks to the natural abundance INADEQUATE NMR spectroscopy which showed a markedly reduced J_(C-C)coupling constant.This signature of the C-C agostic interaction was further examined using DFT modelling which,together with NBO calculations,indicated that C-H and C-C agostic interactions are not exclusive but can complement each other,accounting for the distortions.The intramolecular C-H bond activation in the scandium biscyclopropyl complex was investigated by isotopic labeling experiments,which indicated a direct proton abstraction of the isopropyl group in theβ-diketiminato ligand by a cyclopropyl group.
文摘AlMe_(3) sticks,GaMe_(3) quits.A series of Lewis acid stabilized scandium methylidenes with commercially available cyclopentadienyl ligands Cp^(R)(Cp^(R)=C_(5)Me_(5)(Cp^(*)),C_(5)Me_(4)SiMe_(3)(Cp’))were synthesized.The-salt metathesis reaction of new half-sandwich dichloride precursors Cp^(R)ScCl_(2)(μ-Cl)Li(thf)_(3) with LiAlMe_(4) and AlMe_(3) at ambient temperature yielded[Cp^(R)Sc(AlMe_(4))Cl]_(2).[Cp’Sc(AlMe_(4))Cl]_(2) was further methylated at ambient temperature to yield Cp’Sc(AlMe_(4))Me.At 70℃,the reaction of Cp^(R)ScCl_(2)(μ-Cl)Li(thf)3 with LiAlMe_(4) and AlMe_(3) led to the formation of Lewis acid stabilized Sc/Al_(2) methylidenes Cp^(R)Sc(CH_(2))(AlMe_(3))_(2).The new mixed Sc/Al/Ga methylidene Cp’Sc(CH_(2))(AlMe_(3))(GaMe_(3))was obtained from the reaction of Cp’Sc(AlMe_(4))Me with GaMe_(3).When heated,complex Cp’Sc(CH_(2))(AlMe_(3))(GaMe_(3))converted into the Sc/Al methylidene[Cp’Sc(CH_(2))_(2)AlMe]_(3) via release of the comparatively weak Lewis acid GaMe_(3) and methane.The core of trimeric[Cp’Sc(CH_(2))_(2)AlMe]_(3) can be described as a triscandacyclohexane{Sc(CH_(2))}_(3) stabilized by a trialacyclohexane{Al(CH_(2))}_(3) via Pearson hard/hard matching.Complexes Cp^(R)Sc(CH_(2))(AlMe_(3))_(2) and[Cp’Sc(CH_(2))_(2)AlMe]_(3) differ in rigidity,thermal stability and reactivities toward ketones and Lewis bases.The isolated methylidenes were analyzed by ^(1)H,^(13)C{^(1)H},^(45)Sc,and variable temperature ^(1)H NMR spectroscopy,SC-XRD,IR spectroscopy,and elemental analysis.Complexes Cp^(R)Sc(CH_(2))(AlMe_(3))_(2) feature pronounced Sc⋯HCα-agostic interactions.The reaction of Cp^(R)ScCl_(2)(μ-Cl)Li(thf)_(3) with LiAlMe_(4) and AlMe_(3) was investigated via in situ 1H and 45Sc NMR spectroscopy.
基金This work was supported by the National Natural Science Foundation of China(21325210,21132002,21121062)the State Key Basic Research&Development Program(2012CB821600)the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The scandium terminal imido complex supported by a monoanionic tetradentate NNNN ligand, [LSc=N(DIPP)](L = [MeC(N(DIPP))CHC(Me)(NCH2CH2N(Me)CH2CH2NMe2]-, DIPP = 2,6-(iPr)2C6H3)(1), undergoes a C–N bond cleavage at elevated temperature to give a mononuclear scandium anilido intermediate 2a, which subsequently aggregates into a binuclear scandium anilido complex 2. The mononuclear intermediate 2a reacts with alkyne or imine to provide two scandium anilido complexes 3 and 4, which contain a dianionic tetradentate NNNC ligand or a dianionic tetradentate NNNN ligand. DFT calculations on the reaction mechanism of C–N bond cleavage in 1 were also performed.
基金Supported by the National Natural Science Foundation of China (Grant no. 20434020)the Special Fund for Major State Basic Research Project (Grant No. G2005CB623802)the Committee of Science and Technology of Zhejiang Prov-ince
文摘Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.
文摘The title complex, [MnSc (DTPA) (H2O)2]·2H2O (DTPA is diethylenetriaminepentaacetic acid). has been synthesized in aqueous solution. Its crystal structure has been determined by four-circle X-ray diffractometer. The crystal is monoclinic with space group P21/n. The cell parameters are as follows:α=0.7886 (3) nm, b=1.5094 (5) nm. c=1. 8162(6) nm; β=100. 32(2)°, V= 2. 121 (2) nm3 , Z= 4 , Dc =1. 75 g/cm3. In the crystal,Sc3+ ion is coordinated by five oxygen atoms and three nitrogen atoms of DTPA with coordination number eight. taking a trigondodecahedron arrangement. Mn2+ ion is coordinated by four oxygen atoms from different DTPA and two oxygen atoms from H2O molecules with coordination number six, forming an octahedron. Each Sc(DTPA) is further connected with Mn2+ ions through four carboxyl groups of DPTA serving as bridges to form a three dimensional network.
文摘选用镉-碘化钾-罗丹明B多元络合物显色体系,分光光度法测定污水中镉的含量.研究结果表明:向待测镉标准溶液中加入1.0 mol/L硫酸溶液3.0 m L,碘化钾-抗坏血酸溶液4.0 m L和10 g/L聚乙烯醇-1750溶液2.0 m L,加入显色剂0.5 g/L罗丹明B溶液1.8 m L,摇匀放置10 min后,在600 nm波长处测定吸光度,镉的质量浓度在0~1.0 mg/L范围内符合朗伯-比尔定律,标准曲线相关系数R^2为0.993 3,加标回收率为98.75%~102.50%.
