钬（钇）—三溴偶氮胂配合物组成和稳定常数的线性回归法测定

依据钬(钇)-三溴偶氮胂(TBA)体系吸收光谱出现等色点的特征,推断配位反应为M+nL=ML_n。提出了由光谱数据求算溶液中游离配位剂摩尔分数的计算方法,推导出两个线性回归公式,用以求算配合物组成、摩尔吸光系数、稳定常数和配位体浓度。在pH3.80的HC1-NaAc介质中,钬(钇)与TBA形成1:2配合物,摩尔吸光系数分别为1.03×10~5及1.10×10~5 1·cm~(-1)·mol~(-1),表观稳定常数(1gβ_2)分别为11.37及11.15。校正TBA的酸效应后。1gβ_2~(abs)分别为43.23及43.01。本法可在配位剂准确浓度不易得知的情况下使用。     

单核配合物溶液配位体亲核体系分光光度数据的一般处理

本文提出单核配合物溶液配位体亲核体系分光光度数据的一般处理。本法可由已知稳定常数的配合物,测定未知配合物的稳定常数,溶液组成和摩尔吸光系数;数据处理是直线外推,可见不可见光区都适用,ε也可自由选择,接续配合物的数目不受限制,选择了βi较小βj较大(硫代硫酸锌-EDTA)和βi较大βj较小(氟化铁-草酸铁)二体系进行了试验。本文提出的方法将为分光光度法研究配合物溶液提供一个新途径。     

钛与3，5－二溴水杨基荧光酮配位反应的弛豫动力学研究

用跳浓弛豫法测定了微扰体系在不同浓度［Ｔｉ￣（４＋）］时的弛豫时间τ，拟定了合理的反应机理，并根据此机理导出了１／τ的函数表达式为１／τ＝ｋ［Ｈ４Ｒ］＿０／［Ｈ３Ｏ￣＋］＿０－４ｋ·Ａ∞／ε·［Ｈ３Ｏ￣＋］０，获得了配位反应的表现稳定常数Ｋ、表观速率常数ｋ及摩尔吸光系数ε；其中所得稳定常数Ｋ的值与用平衡移动法获得的结果相吻合，进一步证明了所拟机理的合理性。     

测定配合物组成和稳定常数的平衡移动法的研究

在研究分析用的显色试剂时,需测定它们与待测金属离子所生成配合物的配位比和稳定常数。Bent依据光度法数据采用平衡移动法研究此种配合体系时,提出方程:实际应用时,由于提纯试剂或准确标定其纯度较困难,对纯度不高的试剂得方程:由式(1)、(2)以lg对lg[R](平衡时试剂的摩尔浓度c)或lgV(试剂加入体积)作图可得一直线,其斜率n即为配位比,     

钛与3,5—二溴水杨基荧光酮配位反应的驰豫动力学研究

用跳浓驰豫法测定了微扰体系在不同浓度「Ｔｉ＾４＋」时的驰豫时间τ，拟定了合理的反应是，并根据此机理导出了１／τ的函数表达式为１／τ＝ｋ「Ｈ４Ｒ」０／「Ｈ３Ｏ＾＋」０－４ｋ。Ａ∞／ε．「Ｈ３Ｏ＾＋」０，获得了配位反应的表面稳定常数Ｋ，表面速率常Ｋ及摩尔吸光系数ε；其中所得稳定常数Ｋ的值与用平衡移动法获得的结果相吻合，进一步证明了所拟机理的合理性。     

离解度—回归法测定不稳定络合物的摩尔吸光系数和稳定常数

１　引　言利用分光光度法测定络合物的摩尔吸光系数和稳定常数，通常基于饱和法。对不稳定络合物，因难以得到饱和吸收曲线，给摩尔吸光系数和稳定常数的测定带来困难。我们推导出准确求解不稳定络合物离解度的计算公式，可分别测定出不同浓度络合物溶液的离解度，利用线性回归法求出络合物的摩尔吸光系数，再由校正后的离解度求算络合物的稳定常数，可减小实验过程中的误差，提高测定结果的准确度。本法操作简便、准确度高，可适用于不同组成的络合物体系。利用本法测定了镁、钙、钡与偶氮胂Ⅰ以及钻、镍与变色酸２Ｒ络合物的摩尔吸光系数…     

在二甲基亚砜-丙酮-水溶液中[CO(SCN)n]2-n配合物的紫外分光光度研究

Lundquist,林谦次郎等都曾用分光光度法研究了钴(II)与硫氰根的配位作用.最近,孙嘉彦等采用平衡移动法研究多级配合物体系时,log[A/(A_(max)—A)]=nlog[R]+logβ_n,作图应得一条曲线,只有当[R]在适当范围内才能使曲线斜率(配位比)接近整数.鉴于文献报道对硫氰酸钴(II)配合物的研究尚未完善,我们在紫外光谱区域,用改善了的方法,测定了硫氰酸钴(II)各级配合物的稳定常数和摩尔消光系数.     

双等色点分光光度法测定络合物稳定常数

利用两种实验设计方案，获得了连续变化法吸光谱中两个等色点，由这两个波长下吸光度计算出有关物种的摩尔吸光系数及平衡组份浓度，进而计算出络合物稳定常数。     

一个简便的配合物稳定常数测定方法-Al-ECR稳定常数的测定

在配合反应体系中,当某一物种不能获得它单独存在时的吸收光谱,即得不到它的摩尔吸光系数时,测定配合物的稳定常数往往比较困难,有时甚至难以解决。Al-ECR即属于这样的体系,众多通用的饱和法不能使用。我们采用过Ingmen的方法亦未能得出合理的结果(时常出现负值)。我们曾报道利用等色点特性求取三元配合物稳定常数的方法。在这里我们利用溶液不同pH时等色点的特性,测定了Al-ECR体系的稳定常数,方法简便,所得结果比较满意。     

Tween80存在下桑色素与Fe（Ⅲ）显色反应的研究及应用

研究了在非离子表面活性剂Tweed 80存在下,3,5,7,2′,1′,五羟基黄烯酮(桑色素,Morin)与Fe(Ⅲ)显色反应的适宜条件,发现在pH 3.4～1.7的HOAc-NaOAc介质中,配合物最大吸收波长为417nm,用摩尔比法、斜率比法和平衡移动法测得配合物组成为Fe(Ⅲ):Morin=1:3。表观摩尔吸光系数为6.18×10~4,表观不稳定常数β_不=2.04×10~(-16)。方法操作简便,结果稳定,选择性好,可用于铝合金及人发中铁的测定,结果满意。     

Cyanidosilicates—Synthesis and Structure

Starting from fluoridosilicate precursors in neat cyanotrimethylsilane, Me₃Si?CN, a series of different ammonium salts [R₃NMe]⁺ (R=Et, ⁿPr, ⁿBu) with the novel [SiF(CN)₅]^2? and [Si(CN)₆]^2? dianions was synthesized in facile, temperature controlled F^?/CN^? exchange reactions. Utilizing decomposable, non‐innocent cations, such as [R₃NH]⁺, it was possible to generate metal salts of the type M₂[Si(CN)₆] (M⁺=Li⁺, K⁺) via neutralization reactions with the corresponding metal hydroxides. The ionic liquid [BMIm]₂[Si(CN)₆] (m.p.=72 °C, BMIm=1‐butyl‐3‐methylimidazolium) was obtained by a salt metathesis reaction. All the synthesized salts could be isolated in good yields and were fully characterized.     

Electron impact mass spectra of some salts of carboxylic acids with alkali (group Ia) metals

Thirteen of the salts of the alkali metals (Li, Na, K, Rb, Cs) with acetic, 2,2-dimethylpropionic, trifluoroacetic and heptafluorobutyric acid have been found to be sufficiently volatile to give mass spectra under normal electron impact conditions. The metal containing ions observed include (M=metal): [M]⁺, [MO]⁺, [MCO₂]⁺, [M₂]^+·, [M₂O]^+·, [M₂CO₂]^+· and the cluster ions [M_n (carboxylate)_n-1]⁺ for n = 2–8.     

Doubly charged benzene and isomeric dications. Fragmentation energetics and charge distributions calculated by MINDO/3 molecular orbital theory

MINDO/3 calculations for singlet and triplet doubly charged benzene [C₆H₆]²⁺ are in satisfactory agreement with the experimentally determined values of the vertical double ionization energy of benzene; calculations for straight chain isomeric structures are consistent with the observed kinetic energy release on fragmentation to [C₅H₃]⁺ and [CH₃]⁺. Symmetrical doubly charged benzene ions relax to a less symmetrical cyclic structure having sufficient internal energy to fragment by ring opening and hydrogen transfer towards the ends of the carbon chain. Fragmentation of [CH₃C₄CH₃]²⁺ to [CH₃C₄]⁺ and [CH₃]⁺ is a relatively high energy process (A), whereas both (B): [CH₃CHC₃CH₂]²⁺ to [CHC₃CH₂]⁺ and [CH₃]⁺ and (C): [CH₃CHCCHCCH]²⁺ to [CHCCHCCH]⁺ and [CH₃]⁺ may be exothermic processes from doubly charged benzene. Furthermore, the calculated energy for the reverse of process (A) is less than the experimentally observed kinetic energy released, whereas larger energies for the reverse of processes B and C are predicted. Heats of formation of homologous series [HC_n]⁺, [CH₃C_n]⁺, [CH₂C_n?2CH]⁺, [CH₃C_n?2CH₂]⁺ and [CH₂?CHC_n?3CH₂]⁺ with 1 < n < 6 are calculated to aid prediction of the most stable products of fragmentation of doubly charged cations. The homologous series [CH₂C_n?2CH]⁺ is relatively stable and may account for ready fragmentation of doubly charged ions to [C_nH₃]⁺; alternatively the symmetrical [C₅H₃]⁺ ion [CHCCHCCH]⁺ may be formed. Dicoordinate carbon chains appear to be important stabilizing features for both cations and dications.     

Kinetics and mechanism of the iodine oxidation of hydroxylamine

Studies of the stoichiometry and kinetics of the reaction between hydroxylamine and iodine, previously studied in media below pH 3, have been extended to pH 5.5. The stoichiometry over the pH range 3.4–5.5 is 2NH₂OH + 2I₂ = N₂O + 4I^? + H₂O + 4H⁺. Since the reaction is first-order in [I₂] + [I₃^?], the specific rate law, k₀, is k₀ = (k₁ + k₂/[H⁺]) {[NH₃OH⁺]₀/(1 + K_p[H⁺])} {1/(1 + K_I[I^?])}, where [NH₃OH⁺]₀ is total initial hydroxylamine concentration, and k₁, k₂, K_p, and K_I are (6.5 ± 0.6) × 10⁵ M^?1 s^?1, (5.0 ± 0.5) s^?1, 1 × 10⁶ M^?1, and 725 M^?1, respectively. A mechanism taking into account unprotonated hydroxylamine (NH₂OH) and molecular iodine (I₂) as reactive species, with intermediates NH₂OI₂^?, HNO, NH₂O, and I₂^?, is proposed.     

Association constants of dibenzo[3n + 2]crown-n ethers using steady-state fluorescence spectroscopy

The steady-state fluorescence spectra of cation complexes of fluorophore macrocyclic ethers have been studied for the estimation of 1:1 association constants, and perchlorate salts of Li⁺, Na⁺, K⁺ Rb⁺ and Pb²⁺ complexing with dibenzo[23]crown-9, dibenzo[26]crown-10, and sym-dibenzo[26]crown-10, were investigated. The fluorescence emission maximum of the free and the various ligand/cation mixtures of complexed crown ethers were measured at room temperature in AN. The concentrations of chromophore crown ether were obtained from nonlinear calibration plots. The 1:1 stoichiometry of association constants (K_ass) were calculated using the equation, 1/K_ass [L_o] = (1 − nP)ⁿ(1 − m)^m/P with linear best fit of plots depending on 1/[L_o] where P = P_C/[1 + (m − 1)P_C] and P_C is the mole fraction of n/m ratio of the complexed ligand. The association constants of cations, K_ass, displayed the cation selectivities depending on the cation radii and the macrocyclic ether size, and Pb⁺ was found to give the strongest association with such crown ethers.     

Repeller-Induced dissociation of alkyl alcohols in thermospray mass spectrometry

Six alkyl alcohols were studied using thermospray mass Spectrometry. Whereas the dominant ion in the spectrum up to a repeller potential of 120 V was [M + NH₄]⁺, above that potential [M + H]⁺ and fragment ions appeared. The fragments observed were largely due to hydrogen release from alkyl ions ([C_nH_2n+1]⁺ – H2 → [C_nH_2n-1]⁺) and loss of water or some other stable molecule from the same species. The results are compared with those from ionization of the same alcohols under electron impact and photoionization conditions and with results obtained for methanol under thermospray conditions.     

Mass spectrometry of homoadamantane derivatives

Homoadamantane derivatives can be divided into two groups according to their mass spectra. To the first group belong compounds with electron attracting substituents (COOH, CI, COOCH₃, Br); compounds with electron releasing substituents (OCH₃, OH, NH₃, NHCOCH₃) constitute the second group. The most characteristic feature of the first group compounds is the splitting off of the substituent. The hydrocarbon fragment [C₁₁H₁₇]⁺ thus formed then loses olefin molecules with the formation of corresponding ionic species C_11?nH_17?2n. The 3-substituted compounds of this group undergo thermal Wagner-Meerwein type rearrangements into adamantane derivatives, resulting in the [C₁₀H₁₅]⁺ (m/e 135) ion formation; this is the main difference between 1- and 3-substituted homoadamantanes. The series of [C_nH_2n?6X]⁺ ions (where X = OCH₃, OH, NH₂, NHCOCH₃, n = 6 to 10) are characteristic of the mass spectra of the second group compounds, the ion [C₆H₆X]⁺, [M ? C₅H₁₁]⁺ being the most abundant. The intensity ratio of [M ? C₅H₁₁]⁺ to [M ? C₄H₉]⁺ ions is 10:1 for 1-substituted and 3:1 for 3-substituted compounds of this group, allowing the location of the substituent. Some individual features of the spectra are also reported.     

Stability of crown-ether complexes with alkali-metal ions in ionic liquid-water mixed solvents

Stability constants of sodium and cesium ion complexes with 18-crown-6 (18C6) and dibenzo-18-crown-6 (DB18C6) in N-butyl-4-methyl-pyridinium tetrafluoroborate [BMP][BF₄] aqueous solutions were measured using the ²³Na and ¹³³Cs NMR technique at 23 °C. To the best of our knowledge, the estimated values of stability constants reported in this study are the first such values given for ionic liquid solutions. The cationic exchange between the free and complexed species is rapid, and only formation of the 1:1 complexes [M(18C6)]⁺ and [M(DB18C6)]⁺ (M = Na⁺, Cs⁺) were observed. The complex formation constants demonstrated a strong dependence on the [BMP][BF₄] concentration. For [M(18C6)]⁺, in solutions with a 0.33–0.70 mole fraction of water in [BMP][BF₄], lg K values are found to be more than one unit higher than the lg K values measured in pure aqueous solutions, although no information concerning the influence of [BMP][BF₄] on the complex formation selectivity could be observed. DB18C6 complexes revealed significantly lower stability under the same conditions. An extrapolation to zero water content gave the lg K = 2.42 for [Cs(18C6)]⁺ in [BMP][BF₄]. It was discovered that when added to water, [BMP][BF₄] increases the solubility of crown ethers and decreases the solubility of alkali metal nitrates. Complex formation with crown ethers enhances the solubility of alkali metal salts in [BMP][BF₄].     

Microsolvated and Chelated Butylzinc Cations: Formation,Relative Stability,and Unimolecular Gas‐Phase Chemistry

Solutions of butylzinc iodide in tetrahydrofuran, acetonitrile, and N,N‐dimethylformamide were analyzed by electrospray ionization mass spectrometry. In all cases, microsolvated butylzinc cations [ZnBu(solvent)_n]⁺, n=1–3, were detected. The parallel observation of the butylzincate anion [ZnBuI₂]^? suggests that these ions result from disproportionation of neutral butylzinc iodide in solution. In the presence of simple bidentate ligands (1,2‐dimethoxyethane, N,N‐dimethyl‐2‐methoxyethylamine, and N,N,N′,N′‐tetramethylethylenediamine), chelate complexes of the type [ZnBu(ligand)]⁺ form quite readily. The relative stabilities of these complexes were probed by competition experiments and analysis of their unimolecular gas‐phase reactivity. Fragmentation of mass‐selected [ZnBu(ligand)]⁺ leads to the elimination of butene and formation of [ZnH(ligand)]⁺. In marked contrast, the microsolvated cations [ZnBu(solvent)_n]⁺ lose the attached solvent molecules upon gas‐phase fragmentation to produce bare [ZnBu]⁺, which subsequently dissociates into [C₄H₉]⁺ and Zn. This difference in reactivity resembles the situation in organozinc solution chemistry, in which chelating ligands are needed to activate dialkylzinc compounds for the nucleophilic addition to aldehydes.     

Low-energy,low-temperature mass spectra. 10—urethanes

The 12.1 eV, 75°C electron impact mass spectra of 24 urethanes, RNHCO₂C₂H₅ [R ? H, C₂H_{2n +1} (n = 1-8), CH₂?CHCH₂, Ph, PhCH₂ and PhCH₂CH₂], and seven symmetrically disubstituted urethanes R₂NCO₂C₂H₅ (R ? C_n H_{2n + 1} (n = 1?4)) are reported and discussed. All 31 spectra show appreciable molecular ion peaks. For n ?Cn H_{2n +1} NHCO₂C₂H₅, M^{+ ˙} usually is the most abundant ion in the spectrum. A peak at m/z 102 of comparable intensity also is present; this corresponds to formal cleavage of the bond connecting the α- and β-carbon atoms in the N-alkyl group, though it is unlikely that the daughter ion has the structure [CH₂?NHCO₂C₂H₅]⁺. In the RNHCO₂C₂H₅ series, branching at the α-carbon atom enhances the relative abundance of the ion arising by notional α-cleavage at the expense of that of M^{+ ˙}. Formal cleavage of the bond between β- and γ-carbon atoms occurs to some extent for [RNHCO₂C₂H₅]⁺˙ ions; this reaction provides information on the degree of branching at the β-carbon, especially if metastable molecular ions are considered. The higher n-C_nH_{2n +1}NHCO₂C₂H₅ (n = 5?8) urethanes exhibit two other significant ions in their mass spectra. First, there is a peak at [M ? C₂H₅]⁺. Secondly, a peak is present at m/z 90; the most plausible structure for this ion is [H₂N(HO)COC₂H₅]⁺, arising by double hydrogen transfer from the alkyl group and expulsion of a [C_nH_{2n ?1}]˙ radical. Ions originating from secondary decomposition of the primary ionic species are generally of only very low abundance in these spectra.