金属配合物的电位溶出法研究

镉(Ⅱ)-硫氰酸根体系的稳定常数及配位数的测定前人已做了许多工作.但用电位溶出法研究Cd(Ⅱ)-NH_4SCN-NaClO_4-H_2O体系未见报道.我们在NaClO_4介质中,控制离子强度为3.00,用电位溶出法研究了这一体系.根据周端赐、张祖训推导的简单金属离子电位一时间方程:     

冠醚配合物热力学性质的研究VI. 几种冠醚配合物的CNDO/2计算

本文用CNDO/2方法从理论上探讨了碱金属离子Na^+,K^+和Cs^+与2,3-苯并-8,11,15-三甲基-18-冠-6(简称BC3-18C6)在溶液中发生的配位反应,计算了配位反应中CNDO总能量的变化,再现了量热法所得出的碱金属离子Na^+,K^+和Cs^+与BC3-18C6在溶液中生成配合物的稳定性次序:K^+>Na^+>Cs^+。所计算的配位能和配合物的水化能表明,在水溶液中碱金属水合离子与冠醚配位,形成稳定的二水配位的碱金属离子冠醚配合物[M(BC3-18GC6)(H~2O)~2]^+。碱金属离子与冠醚中的氧形成的金属-氧键不如其水合物中的金属-氧键强,碱金属离子能与冠醚配位形成稳定的配合物主要是由于配体的大环效应和配合物的溶剂化作用。     

焦磷酸盐水溶液中稳定Pr(IV)和Tb(IV)的研究

本文报道了在焦磷酸盐的碱性水溶液中用O~3氧化Pr(III)和Tb(III),从而得到Pr(IV)-P~2O~7^4^-和Tb(IV)-P~2O~7^4^-的配合物溶液,通过对溶液进行化学分析及吸收光谱的研究,证明了溶液中有Pr(IV)和Tb(IV)的存在,其持征吸收分别为λmax=365nm,摩尔消光系数ε=1205L/mol.cm;/.pr(iv)=257nm,ε=929L/mol.cm.在碱性条件下,Pr(IV)和Tb(IV)的还原反应均为拟一级反应.用动力学方法测定了不同条件下Pr(IV)和Tb(IV)的还原速率常数和半衰期,从而探讨了稳定Pr(IV)和Tb(IV)的条件.同时还测定了在反应条件下Pr(IV)/Pr(III)和Tb(IV)/Tb(III)电对的克式电位。     

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。     

稀土冠醚配合物的研究 XI: 稀土(III)硝酸盐与戊二酰双(苯并-15-冠-5)配合物的合成和性质研究

本工作合成了十五个新的镧系、钇的硝酸盐和戊二酰双(苯并-15-冠-5)的配合物,并进行了元素分析、紫外光谱、红外光谱、激光拉曼光谱、差热和热重等性质研究, 对这一系列稀土配合物的性质作了比较。     

ⅡB族金属离子-5-取代邻菲罗啉-二酮肟配体三元体系的 稳定性研究

在(35±0.1)℃,I=0.1mol·dm^-^3KNO~3条件下,用pH法测定了二酮肟配体PnAO,5-取代邻菲罗啉(5-Rphen,R=CH~3,H,Cl,NO~2)的质子化常数,Zn(Ⅱ),Cd(Ⅱ),Hg(Ⅱ)分别与PnAO和5-Rphen二元体系的稳定常数,以及Zn(Ⅱ),Cd(Ⅱ),Hg(Ⅱ)-PnAO-5-Rphen三元体系的稳定常数。实验结果表明,在上述二元、三元体系中均存在良好的直线自由能关系,并从三元配合物构型上讨论了存在线性关系的内在原因。同时,讨论了金属离子、取代基对配合物稳定性的影响。     

Are the Singularities Stable?

The spacetime singularities play a useful role in gravitational theories by distinguishing physical solutions from non-physical ones. The problem, we are studying in this paper is whether these singularities are stable. To answer this question, we have analyzed the general problem of stability of the family of the static spherically symmetric solutions of the standard Einstein-Maxwell model coupled to an extra free massless scalar field. We have obtained the equations for the axial and polar perturbations. The stability against axial perturbations has been proven.     

杂多阴离子的XPS研究 II:Keggin结构钨钼杂多酸热稳定性差异的研究

加入优级纯CsCl作内标,用其中Cs3d5/2校正荷电效应,准确地测定了HPWnMo12-n(n=0,3,6,9,12)及HXM12(X=P,As,Si,Ge;M=W,Mo)中Ols及HPM12中P2p的结合能,发现钨系中Ols的结合能比钼系中的高约0.5eV;P2p的结合能则相应地高0.8eV;同种金属的磷系杂多酸中Ols的结合能比其他杂原子中的高0.3eV。通过差热分析发现同类型杂多酸的热稳定性与阴离子中的Ols结合能呈近似平行的关系。结果表明,跟钼系杂多酸相比,钨系杂多酸中氧原子有较低的电子云密度,钨氧之间有更多的轨道重叠;含磷杂多酸跟其他杂多酸相比,金属、氧之间有更强的相互作用。     

Mechanical strength and thermal stability of magnesium silicate filled polypropylenes

Mineral fillers are widely used to improve the mechanical properties of polypropylene, but at the same time they may cause some degradation of polymer, especially if the stabilization is insufficient. Two different kinds of silicate minerals, talc and serpentinite, were used as fillers for homo- and copolypropylene, and their influence on mechanical properties and degradation was investigated. The mechanical properties of filled polypropylene were tested at room temperature using tensile and impact tests. GC-MS technique was used to characterize the degradation of compounds. The results revealed differences in the mechanical properties: talc filled polypropylene had higher tensile strength, rigidity and impact strength properties than serpentinite filled. The oxidation stability of filled polypropylene measured by the oven method showed lower values in the case of serpentinite filled polypropylene. In the beginning of pyrolysis there was no significant difference between talc and serpentinite filled polypropylene in the formation of degradation products, as was observed by GC-MS. In a slightly higher temperature and longer incubation time PP-serpentinite compound started to form more small molecular weight degradation products than PP-talc due to stronger catalytical effects of the serpentinite surfaces. The characterization methods used here provided us new information to understand the role of mineral fillers in degradation processes. The results of DSC measurement yielded information on the effects of the filler crystallization and thermal degradation. Talc, for example, was shown to be better nucleation agent than serpentinite for PP.