Bis(phosphinimino)methanide rare earth amides: synthesis, structure, and catalysis of hydroamination/cyclization, hydrosilylation, and sequential hydroamination/hydrosilylation

A series of yttrium and lanthanide amido complexes [Ln{N(SiHMe(2))2}2{CH(PPh(2)NSiMe(3))2}] (Ln=Y, La, Sm, Ho, Lu) were synthesized by three different pathways. The title compounds can be obtained either from [Ln{N(SiHMe(2))2}3(thf)2] and [CH(2)(PPh(2)NSiMe(3))2] or from KN(SiHMe(2))2 and [Ln{CH(PPh(2)NSiMe(3))2}Cl(2)]2, while in a third approach the lanthanum compound was synthesized in a one-pot reaction starting from K{CH(PPh(2)NSiMe(3))2}, LaCl3, and KN(SiHMe(2))2. All the complexes have been characterized by single-crystal X-ray diffraction. The new complexes, [Ln{N(SiHMe(2))2}2{CH(PPh(2)NSiMe(3))2}], were used as catalysts for hydroamination/cyclization and hydrosilylation reactions. A clear dependence of the reaction rate on the ionic radius of the center metal was observed, showing the lanthanum compound to be the most active one in both reactions. Furthermore, a combination of both reactions--a sequential hydroamination/hydrosilylation reaction--was also investigated.     

Optically active rhodium complexes with indenyl-linked phosphane ligands

The optically active indenyl-linked phosphane ligands (S)-[2-(3H-inden-1-yl)-1-phenylethyl]diphenylphosphane (L₁) and (S)-[2-(4,7-dimethyl-3H-inden-1-yl)-1-phenyl-ethyl]diphenylphosphane (L₂) were synthesized in three steps from (R)-1-phenylethane-1,2-diol in excellent yields. Their lithium salts reacted with [Rh(μ-Cl)(η²-CH₂CH₂)₂]₂ at −78 °C in THF affording the planar chiral complexes (S,R_pl + S_pl)-[Rh(η⁵-indenyl-CH₂CH(Ph)PPh₂-kP)(η²-CH₂CH₂)] and (S,R_pl + S_pl)-[Rh(η⁵-4,7-dimethylindenyl-CH₂CH(Ph)PPh₂-kP)(η²-CH₂CH₂)] as 61:39 and 15:85 mixtures of diastereomers. The complexes were isolated in optically pure form by column chromatography. The stereochemical configuration of one of the diastereomers was determined by X-ray crystallography. The complexation of L₂ was studied in different solvents and with several Rh precursors and diastereomeric excesses up to 76% were achieved. The ability of the chiral ligands to control the stereochemistry at the metal center was tested by oxidative addition of methyl iodide. Diastereomeric excesses greater than 98% were observed.     

Eigenvalue Distribution of Positive Definite Kernels on Unbounded Domains

We study eigenvalues of positive definite kernels of L² integral operators on unbounded real intervals. Under the assumptions of integrability and uniform continuity of the kernel on the diagonal the operator is compact and trace class. We establish sharp results which determine the eigenvalue distribution as a function of the smoothness of the kernel and its decay rate at infinity along the diagonal. The main result deals at once with all possible orders of differentiability and all possible rates of decay of the kernel. The known optimal results for eigenvalue distribution of positive definite kernels in compact intervals are particular cases. These results depend critically on a 2-parameter differential family of inequalities for the kernel which is a consequence of positivity and is a differential generalization of diagonal dominance.     

对磺酸基苯基亚甲基若丹宁光度法测定三醋酸甘油酯中的铅

本文研究了对磺酸基苯基亚甲基若丹宁与铅的显色反应,在硝酸介质中,吐温－８０存在下,ＳＢＤＲ与铅反应生成２：１稳定络合物,λｍａｘ＝５２０ｎｍ,ε＝２．９１＊１０＾４Ｌ．ｍｏｌ．ｃｍ＾－１。     

硫代亚磷酸酯抗磨添加剂的合成与应用

通过改性抗磨添加剂亚磷酸二正丁酯 (T3 0 4)合成了新型含磷润滑油抗磨添加剂———硫代亚磷酸O ,O 二 (十二烷基 )酯 (T3 1 1 ) ,其结构经元素分析和HPLC MS确认。T3 1 1与T3 0 4相比热氧化稳定性及耐久性有明显提高。T3 1 1应用于卡车及公共汽车手动变速箱齿轮油中通过了FZG齿轮机试验、L 60 1热氧化稳定性台架试验及Mack变速箱循环台架试验。     

二氧化碳在P+/P-Si半导体电极上光电化学还原的研究

1870年,Royer使用Zn电极将CO₂还原为HCOOH。近年来,人们对CO₂在几十种金属电极上的电化学还原进行了深入的研究。但普遍存在的问题是CO₂在金属电极上还原的过电位较大,导致耗电较多。     

若干"大乌型"Schiff碱配合物合成和性质的研究

由4-叔丁基2,6-二甲酰基苯酚与4-正己基-3-氨基硫脲缩合, 合成了"大乌"配体(H3BB), 它与Cu(II)、Ni(II)、Co(II)、Pb(II)、Cd(II)生成五种电中性的可溶性"大乌"配合物, 除Co(II)配合物外, 其余四种均为乙氧基桥联的双核配合物, 配体是将4-叔丁基2,6-二羟甲基苯酚用MnO2在室温下直接氧化, 得到4-叔丁基-2,6-二甲酰基苯酚, 然后再与4-正己基-3-硫代氨基脲缩合而得, 该反应步骤较少, 产量较高, 优于前人结果。用IR、UV等方法对配合物进行了表征, 并用Evans的核磁共振法研究了吡啶与Ni2BB(OEt)在轴向的作用和配合物两中心原子间的作用。这五种配合物中, 有趣的是Ni2BB(OEt)呈顺磁性, 本文对其原因作了探讨。     

二氢辅酶的电催化氧化: I: α-萘甲酰尼罗蓝修饰电极性能研究

新的电子传递中间体α-萘甲酰尼罗蓝(NNB)能强烈吸附在石墨上以构成修饰电极。在-0.5V至+0.6V(vs. SCE)电位区内, 固定化的NNB表观出相当可逆的氧化还原行为, 总反应中有2个电子和2个质子参加。在pH7.0缓冲溶液中其表面标准电位E°'为-170mV, 表观电子传递常数kg为3s^-^1。NNB对还原辅酶NADH的电化学氧化有明显催化作用, 可使氧化过电位降低550mV。NADH的电催化遵循EC机理, 催化反应步骤为速度决定步骤, 其速度常数为3×10^3dm^3.mol^-^1.s^-^1。NNB在中性和弱碱性介质中的稳定性优于其它电子传递中间体, 是有前途的电催化剂。     

亲电试剂与Et3NH[μ-CO)(μ-RS)Fe2(C))6]的反应及混合配体桥联双铁羰基配合物的合成

通过芳香酰氯, 丙烯酸酰氯或二甲基氯化膦与中间物(标题化合物)的原位反应, 合成了十一个混合配位桥联的六羰基二铁配合物, 它们的结构皆经元素分析, IR和'HNMR证实, 对于含二甲膦系列的配合物, 还测得3'PNMR谱, 并根据其'H及31PNHR数据进一步推断出这类配合物所具有的可能构象。