含羧基的三核钼原子簇

本文总结了作者研究的一组合有羧基的三核钼原子簇的结果。这些簇合物分为两类。第一类有: (C_2H_5)_4N[Mo_3(μ_3-O)(μ-O_2CH)_3(μ-Cl)_3Cl_3] (Ⅰ) (CH_3)_4N[Mo_3(μ_3-O)(μ-O_2CH)_3(μ-Cl)_3Cl_3] (Ⅱ) (CH_3)_4N[Mo_3(μ_3-O)(μ-O_2CH)_3(μ-Br)_3Cl_3] (Ⅲ) (C_5H_7S_2)[Mo_3(μ_3-O)(μ-O_2CCH_3)_3(μ-Cl)_3Cl_3] (Ⅳ) (C_5H_7S_2)[Mo_3(μ_3-O)(μ-O_2CCH_3)_3(μ-Br)_3Cl_3] (Ⅴ) (C_2H_5)_4N[Mo_3(μ_3-O)(μ-O_3CCH_3)(μ-Cl)_3X_3] (Ⅵ) (X为Cl和Br统计分布的簇合物) (C_2H_5)_4N[Mo_3(μ_3-O)(μ-O_2CCH_2CH_3)_3(μ-Cl)_3Cl_3] (Ⅶ) (C_2H_5)_4N[Mo_3(μ-O)(μ-O_2CCH_2CH_2CH_3)_3(μ-Cl)_3Cl_3] (Ⅷ) (Ⅰ)-(Ⅷ)的簇阴离子具有下述通式: [Mo_3(μ_3-O)(μ-O_2CR)_3(μ-X)_3X_3~′]~-; R=H,CH_3,CH_3CH_3,CH_2CH_2CH_2:X和X′=Cl或Br。 属于第二类型的目前只有一个,即: [(C_2H_5)_4N]_2[Mo_3(μ_3-O)(μ-O_2CCH_3)_2(μ-Cl)_3Cl_5) (Ⅸ) 本文将扼要介绍这些簇合物的合成方法,晶体和分子结构的主要特征,并对成簇规律、结构变化规律以及μ_3-O的红外光谱的指认,给予简单的讨论。     

Me3NO存在下Ru3(CO)11L的CO取代反应动力学与机理

本文研究了在Me_3NO存在下Ru_3(CO)_(11)L(L_=PPh_3,PBu_3~n)的CO取代反应动力学,并提出了可能的机理。Ru_3(CO)_(11)L中的CO被配体L取代生成Ru_3(CO)_9L_3。当L=PPh_3,r=(k_1 k_2[Me_3NO])[Ru_3(CO)_(11)L];L=PBu_3~n,r=(k_1 k_2[PBu_3~n])[Ru_3(CO)_(11)L].除了涉及简单的离解机理外,还存在着按缔合机理进行的简单CO热取代与Me_3NO对Ru_3(CO)_(11)L中羰基碳的进攻。     

新型磷-钒-氧层状化合物[H2en]2[H3O]6[Co(H2O)2(VO)8(OH)4(PO4)8]的水热合成与晶体结构

金属磷酸盐材料在吸附、离子交换、离子传导和催化剂方面有潜在的应用前景[1～5]. 近年来, 通过水热反应合成了一些A-V-P-O化合物. 在这些化合物中, A一般为碱金属或有机阳离子, 如层状结构的[H2N(C4H8)2NH2][(VO)4(OH)4(PO4)2][6] 和[H2N(C2H4)3NH2][(VO)8(HPO4)3(PO4)4*(OH)2]*2H2O[6], 一维链状结构的 [H2NCH2CH2NH3(VO)(PO4)][7], 手性双螺旋结构的 [(CH3)2NH2]K4[(VO)10(H2O)2(OH)4(PO4)7]*H2O[8]以及具有三维骨架结构的化合物 [H3N(CH2)3NH3K(VO)3(PO4)3][9], [H3N(CH2)3NH3]2[V(H2O)2(VO)6(OH)2(HPO4)3(PO4)5]*3H2O[10]和[H3N(CH2)2NH3][(VO)3(H2O)2(PO4)2(HPO4)4][11].     

甲基化戊二烯的质谱研究

本文报道了CH₃CH=C(CH₃)CH=CH₂(1)、CH₃C(CH,)=CHCH=CH₂(2)、CH₃CH=C(CH₃)C(CH₃)=CH₂(3)、CH₃C(CH₃)=CHC(CH₃)=CH₂(4)、CH₃C(CH₃)=C(CH₃)C(CH₃)=CH₂(5)和CH₃CH=CHCH=CH₂(6)的质谱,对其中的(1)、(3)、(5)化合物做了亚稳和高分辨测定,阐述了它们的断裂规律,提出了断裂机理。     

Dy_(2)O_(3),Cu_(2)O在LiF-DyF_(3)熔盐体系的溶解度研究EI北大核心CSCD

以LiF-DyF_(3)为熔盐,电解Dy_(2)O_(3),Cu_(2)O制备Dy-Cu合金过程中,明确Dy_(2)O_(3),Cu_(2)O溶解度是制定合理加料制度、提高电解效率的关键。采用等温饱和法研究了Dy_(2)O_(3),Cu_(2)O溶解平衡时间,考察了温度、DyF_(3)浓度对单一氧化物(Dy_(2)O_(3)或Cu_(2)O)及混合氧化物(Dy_(2)O_(3)与Cu_(2)O)溶解度的影响,通过最小二乘法对溶解度数据进行了拟合,建立了温度、DyF_(3)浓度与Dy_(2)O_(3),Cu_(2)O溶解度之间的数学回归方程。研究结果表明,Dy_(2)O_(3),Cu_(2)O在LiF-DyF_(3)熔盐中溶解平衡的时间分别为110,120 min,溶解反应为吸热反应。相同温度下,随熔盐中DyF_(3)浓度增大,Dy_(2)O_(3)的溶解度逐渐增大,Cu_(2)O溶解度变化较小;在温度为910~1030℃,熔盐中DyF_(3)浓度为15%~40%(摩尔分数)时,Dy_(2)O_(3),Cu_(2)O溶解度分别为0.55%~3.45%,0.39%~0.52%。     

La(NO3)3·bipy·2H2O·(B-15-C-5)电子结构和电化学键

稀土硝酸盐与双啮杂环胺配体α,α′联吡啶(bipy)的配合物研究不多.Hart 等合成了Ln(NO_3)_3(bipy)_2配合物;亦已解析了3个晶体结构:La(NO_3)_3(bipy)_2,Tb(NO_3)_3(bipy)_2,La(NO_3)3·bipy·2H_2O·(B-15-C-5)(B-15-C-5=苯并15-冠-5,).我们对La(NO_3)_3(bipy)_2的电子结构和化学键作过研究.本文利用自旋非限制适于稀土配合物计算的INDO方法研究了La(NO_3)_3·bipy·     

羧酸配体取代基对席夫碱型双核镝(Ⅲ)配合物结构和磁性的影响

以N-(2-羟基-3-甲氧基亚苄基)氨基脲(H2hms)与不同取代基的羧酸(RCOOH)为配体,合成了3例席夫碱类的中心对称双核镝基配合物[Dy2(Hhms)2(C(CH3)3COO)2(H2O)4](NO3)2(1)、[Dy2(Hhms)2(C14H9COO)2(C2H5OH)2(CH3OH)2] [ZnCl4](2...     

Ni_(x)Cu_(y)-B_(24)N_(28)催化CO_(2)氧化C_(3)H_(8)速控步骤的反应机理研究北大核心CSCD

采用密度泛函理论(DFT)研究了C_(3)H_(8)和CO_(2)在Ni_(x)Cu_(y)-B_(24)N_(28)(x+y=4,x=1、2、3、4)表面吸附及速控步骤反应机理.计算了C_(3)H_(8)、CO_(2)和相应中间体在Ni_(x)Cu_(y)-B_(24)N_(28)表面的吸附能以及6条可能路径下的反应热和活化能.计算结果表明,C_(3)H_(8)和CO_(2)在Ni_(x)Cu_(y)-B_(24)N_(28)表面是物理吸附,C_(3)H_(8)+CO_(2)→CH_(3)CHCH_(3)+OCOH是最有利的路径,其在不同催化剂表面的活化能顺序是NiCu_(3)-B_(24)N_(28)(1.42 eV)、Ni_(2)Cu_(2)-B_(24)N_(28)(1.57 eV)、Ni_(3)Cu-B_(24)N_(28)(1.62 eV)、Ni_(4)-B_(24)N_(28)(1.75 eV).由此可知,在Ni_(x)Cu_(y)-B_(24)N_(28)催化CO_(2)氧化C_(3)H_(8)的体系中,Cu含量直接影响其催化活性,即NiCu_(3)-B_(24)N_(28)用于催化CO_(2)氧化C_(3)H_(8)有一定优势.     

Synthesis and Crystal Structure of Cubane—typeMolybdenum Cluster ComplexMo4S4（DTP）4[μ—SOP（OEt）2]2

1 INTRODUCTION Trinuclear molybdenum complexes with Mo3(3-S)(-O)n(-S)3n (n = 0~3) cores have been extensively studied on their diversified reactions towards various organic ligands and many metals. Many derivatives with Mo3S4 core have been rationally synthesized from the cation precursor [Mo3S4(H2O)9]4+ and its neutral derivative Mo3(3-S)(-S)3(DTP)4(H2O)[1]. However, due to their structural lability, complexes with Mo3(3-S)(-O)n(-S)3n (n = 1~3) cores have been reported limitedl…     

膦取代的羰基铂簇的合成,结构和性质

Pt(PPh_3)_2Cl_2在碱性介质中,与一氧化碳直接进行还原及羰基化反应,得到五种膦取代的羰基铂配合物:Pt_5(μ_2-CO)_5(CO)(PPh_3)_4 1,Pt_3(μ_2-CO)_3(PPh_3)_3 2,Pt_3(μ_2-CO)_3(PPh_3)_4 3,Pt_4(μ_2-CO)_5(PPh_3)_4 4,以及Pt(Cl)(PPh_3)_2(COOCH_3) 5。经X-射线单晶衍射分析,确定了新的三核铂羰基簇2以及配合物5的分子结构。还讨论了1和5的生成机理。     

Speciation of ternary cobalt(II) phenanthroline-silica surface complexes as a function of pH and ligand steric bulk

Co(II) solution species containing 1 equiv of phenanthroline (phen), 2-methyl-1,10-phenanthroline (MMP), or 2,9-dimethyl-1,10-phenanthroline (DMP) ligand formed inner-sphere surface complexes when grafted on silica. The speciation on the silica surface depended on both the pH of the grafting solution and the steric bulk of the ligand. [Co(DMP)](2+) formed tetrahedral surface adducts exclusively, with a 1:1 ligand-Co ratio. These surface adducts were first detectable at pH values above 5.1. [Co(MMP)](2+) and [Co(phen)](2+) formed exclusively octahedral adducts on the surface with a 1:1 ligand-Co ratio at pH values below 5. The [Co(MMP)](2+) complex formed a tetrahedral adduct initially at pH 6 and increasingly as the pH was raised. The [Co(phen)](2+) complex did not produce a comparable tetrahedral surface species under any conditions. Instead, mixtures of octahedral surface species with both 1:1 and 2:1 ligand-Co ratios began to form at pH values above 6. Taken together, the results indicated that the development of tetrahedral stereochemistry was strongly influenced by steric factors in the presence of a nitrogen-donating ligand. All three phenanthroline derivatives promoted surface binding of the Co(II) ion adducts, so that maximal binding occurred at lower pH values than for binding of [Co(H(2)O)(6)](2+), which formed exclusively tetrahedral adducts.     

Electrochemical behavior of phytochelatins and related peptides at the hanging mercury drop electrode in the presence of cobalt(II) ions

Direct current voltammetry and differential pulse voltammetry have been used to investigate the electrochemical behaviour of two phytochelatins: heptapeptide (gamma-Glu-Cys)3-Gly and pentapeptide (gamma-Glu-Cys)2-Gly, tripeptide glutathione gamma-Glu-Cys-Gly and its fragments: dipeptides Cys-Gly and gamma-Glu-Cys at the hanging mercury drop electrode in the presence of cobalt(II) ions. Most interesting results were obtained with direct current voltammetry in the potential region of -0.80 V up to -1.80 V. Differential pulse voltammetry of the same solutions of Co(II) with peptides gives more complicated voltammograms with overlapping peaks, probably in connection with the influence of adsorption at slow scan rates necessarily used in this method. However, in using Brdicka catalytic currents for analytical purposes, differential pulse voltammograms seem to be more helpful. Presented investigations have shown that particularly the prewave of cobalt(II) allows distinguishing among phytochelatins, glutathione, and its fragments.     

Complex formation of nonsymmetric 1,2-diacylhydrazines with nonferrous metal ions

Complex formation of Cu(II), Co(II), Ni(II), and Zn(II) ions with nonsymmetric 1,2-diacylhydrazines (DAHs) in ammonia solutions was studied. [M(II): [DAH] ratios were found by equilibrium slope, isomolar series, and conductometric titration methods to be 1: 1 and 1: 2 for Cu(II), 2: 1 and 1: 1 for Co(II), 2: 1 and 1: 1 for Ni(II), and 1: 1 for Zn(II). Independent of the [M(II): [DAH] ratio, we have isolated only complexes of composition 1: 1 from ammonia solutions. The composition was confirmed by IR spectroscopy and elemental analyses. The solubility products of solid complexes of 1: 1 composition and the complex formation constants were calculated with considering the states of ligands and metal ions in ammonia solutions. The solubility products of the solid complexes were found to depend on the length of radical in DAHs.     

THE ROLE OF DIOXYGEN SPECIES IN THE BASE- AND COBALT-CATALYZED OXYGENATION OF HINDERED PHENOLS

Abstract— The mechanisms by which 4-substituted 2,6-di- t -butylphenols are oxygenated by base- and Co(II) Schiff base complex-catalysis into o - or p -peroxyquinols and their Co(III) complexes, respectively, have been investigated. For the base-catalyzed oxygenation, a one-step ionic mechanism involving no radical species is suggested to be the most probable one. For the formation of the peroxycobalt(III) complexes, the following stoichiometry is concluded: ArOH + Co(II) + 5/4 O₂→ peroxycobalt(III) complex + 1/2 H₂O. A mechanism involving an electron transfer between the phenols and the Co(II)-O₂ complex followed by further electron transfer between the formed phenoxy radicals and the Co(II) complex to give the corresponding phenolate anions is proposed.     

Determination of trace amounts of cobalt using 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid-Cu(II)-Co(II) competitive replacement complexation

The chromophore 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid (BPANS) has been used to sensitively complex Cu(II) and Co(II) in aqueous solution at pH 9.43. The spectral correction technique was applied to characterize the complexes, and results showed that both Cu(BPANS)2 and Co(BPANS)2 were formed. Trace Co2+ replaced the Cu(II) in the Cu-BPANS complex, so the competitive replacement complexation (CRC) was used to improve the analytical selectivity. A novel light-absorption ratio variation approach (LARVA) was described as one of the most sensitive methods. The combination of CRC and LARVA was applied to the quantitative detection of Co(II) at the ng/mL level. The limit of detection was only 2.0 ng/mL Co, and the analysis of water samples demonstrated satisfactory results.     

Electrochemical and electrocatalytic studies of the N,N′-(1R,2R)-(–)-1,2-cyclohexylenebis(salicylideneiminato)cobalt(II) complex

The electrochemical properties and catalytic activity of a Co(II) complex with the optically active Schiff base derived from (1R,2R)-(–)-cyclohexanediamine and salicylaldehyde have been studied in non-aqueous solutions. When dissolved in deoxygenated non-aqueous solutions, the complex exhibits reversible redox properties for the Co(II)/Co(III) couple. Electrochemical reduction of oxygen and oxidation of cobalt(II) was observed on cyclic voltammograms of solutions containing both dioxygen and the Schiff base-cobalt(II) complex. An anodically formed film on a platinum electrode, studied by means of X-ray photoelectron spectroscopy, revealed the presence of the oxidized Co(III) species. Cyclic voltammetry of oxygenated solutions examined after a period of time indicates an electrochemical activity of coordinated superoxo/peroxo species in the 0.7–1.1 V potential range. In the presence of 4-methyl-1-cyclohexene the cyclic voltammetry curves reveal changes similar to those caused by the removal of oxygen. The GC-MS technique was used to identify some of the products formed by the catalytic oxidation of cyclohexene and 4-methyl-1-cyclohexene. Electronic Publication     

Radiometric studies on the reaction of some metals with potassium pentacyanonitrosyl manganate

The nature and composition of complexes formed by the reaction of Fe(III), Cr(III), Zn(II), and Co(II) with potassium pentacyanonitrosyl manganate K₃ [Mn(CN)₅NO] has been investigated by radiometric method. The metals form 1∶1 complexes with K₃ [Mn(CN)₅NO], the optimum pH for maximum precipitation being 3.6 for Fe(III), 7.3 for Cr(III), 5.4 for Zn(II), and 8.3 for Co(II). The solubility of the complexes as computed from activity at maximum precipitation point follows the order: chromium complex > iron complex > cobalt complex > zinc complex. The radiometric titration curves also show the formation of colloidal precipitates with dilute Zn(II) solutions.     

Observation of an Organic Acid Mediated Spin State Transition in a Co(II)-Schiff Base Complex: An EPR, HYSCORE, and DFT Study

The interactions of a weak organic acid (acetic acid, HOAc) with a toluene solution of the Co(II)-Schiff base type complex, (R,R')-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino Co(II) (labeled [Co(1)]), was investigated using EPR, HYSCORE, and DFT computations. This activated [Co(II)(1)] system is extremely important within the context of asymmetric catalysts (notably the hydrolytic kinetic resolution of epoxides) despite the lack of detailed structural information about the nature of the paramagnetic species present. Under anaerobic conditions, the LS [Co(II)(1)] complex with a |yz, (2)A(2)? ground state is converted into a low-spin (LS) and a high-spin (HS) complex in the presence of the acid. The newly formed LS state is assigned to the coordinated [Co(II)(1)]-(HOAc) complex, possessing a |z(2), (2)A(1)? ground state (species A; g(x) = 2.42, g(y) = 2.28, g(z) = 2.02, A(x) = 100, A(y) = 120, A(z) = 310 MHz). The newly formed HS state is assigned to an acetate coordinated [Co(II)(1)]-(OAc(-)) complex, possessing an S = (3)/(2) spin ground state (species B, responsible for a broad EPR signal with g ≈ 4.6). These spin ground states were confirmed with DFT calculations using the hybrid BP86 and B3LYP functionals. Under aerobic conditions, the LS and HS complexes (species A and B) are not observed; instead, a new HS complex (species C) is formed. This complex is tentatively assigned to a paramagnetic superoxo bridged dimer (AcO(-))[Co(II)(1)···O(2)(-)Co(III)(1)](HOAc), as distinct from the more common diamagnetic peroxo bridged dimers. Species C is characterized by a very broad HS EPR signal (g(x) = 5.1, g(y) = 3.9, g(z) = 2.1) and is reversibly formed by oxygenation of the LS [Co(II)(1)]-(HOAc) complex to the superoxo complex [Co(III)(1)O(2)(-)](HOAc), which subsequently forms the association complex C by interaction with the HS [Co(II)(1)](OAc(-)) species. The LS and HS complexes were also identified using other organic acids (benzoic and propanoic acid). Thermal annealing-quenching experiments revealed the additional presence of [Co(III)(1)O(2)(-)](HOAc) adducts, corroborating the presence of species C and the presence of diamagnetic dimer complexes in the solution, such as the EPR silent (HOAc)[Co(III)(1)(O(2)(2-))Co(III)(1)](HOAc). Overall, it appears that a facile interconversion of the [Co(1)] complex, possessing a LS ground state, occurs in the presence of acetic acid, producing both HS and LS Co(II) states, prior to formation of the oxidized active form of the catalyst, [Co(III)(1)](OAc(-)).     

Cu(II)-3-(5-chlor-2-hydroxy-3-sulfophenylazo)-6-(2,4,6-tribromophenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic Acid-Co(II) binuclear complexation and its application to the selective determination of cobalt at ng/ml level.

The chromophore, 3-(5-chlor-2-hydroxy-3-sulfophenylazo)-6-(2,4,6-tribromophenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (CSTDD) was used to complex Cu(II) and Co(II) in aqueous solution at pH 9.43. A binuclear complex of Cu-CSTDD-Co was formed and showed a high selectivity for the determination of Co(II). The spectral correction technique was applied to characterize the complexes. The results showed the formation of complexes of Cu(CSTDD), Co(CSTDD)3 and Cu2(CSTDD)2Co. The quantitative analysis of Co(II) at ng/ml level was carried out by the light-absorption ratio variation approach (LARVA). The results showed that the technique is satisfactory to determine Co(II) at trace level in water samples with a detection limit of 2.3 ng/ml.     

Study of binary complexes of Cu(II), Ni(II) and Co(II) with sulfamethazine by voltammetry

Cyclic voltammetry (CV) and square-wave voltammetry (SWV) techniques have been used to study the binary complexes of Co(II), Ni(II) and Cu(II) with sulfamethazine (SMZ) at a static mercury drop electrode (SMDE) in 0.04 M Britton-Robinson (B-R) buffer. SMZ gave three peaks at 0.01, −1.32 and −1.55 V. Cu(II)-SMZ complex was recognized by a cathodic peak at −0.38 V. Ni(II)-SMZ complex was reduced at more positive potential (−0.77 V) than that of the hydrated Ni(II) ions (−1.08 V). Co(II)-SMZ complex is investigated at pH 7 and 8. The Co(II) complex at pH 7 is appeared as a shoulder at −1.19 V, whereas this peak becomes a well-separated form at pH 8. The study indicated that the SMZ serves as a catalyst in the reduction of Co(II) and Ni(II) ions. From electronic spectra data of the complexes, their stoichiometries of 1: 2 (metal-ligand) in aqueous medium are determined. The stability constants of the complexes are in agreement with the Irwing-Williams series (Co < Ni < Cu).