Reaction of aryl azides with tris(trimethylsilyl)silyllithium: Synthesis of tmeda or thf adducts of [Li{N(Ar)Si(SiMe3)3}] and 1,4-trimethylsilyl migration from oxygen to nitrogen

Reaction of ArN₃ (Ar = Ph, p-MeC₆H₄, 1-naphthyl) with [Li{Si(SiMe₃)₃}(thf)₃] yielded lithium amides [Li{N(Ar)Si(SiMe₃)₃}L] (L = tmeda or (thf)₂). Similar treatment of o-phenylene diazide with 2 equiv. of [Li{Si(SiMe₃)₃}(thf)₃] formed dilithium diamide complex 4. Reaction between o-Me₃SiOC₆H₄N₃ and [Li{Si(SiMe₃)₃}(thf)₃] afforded, via 1,4-trimethylsilyl migration from oxygen to nitrogen, [Li{OC₆H₄{N(SiMe₃)Si(SiMe₃)₃}-2}]₂ (5). The structures of complexes 3 and 5 have been determined by single crystal X-ray diffraction techniques.     

镍螺旋化合物及其杂银配位聚合物的设计合成与结构

采用两个易扭转异构的双三齿有机配体，双吡啶二甲基-6,6′-二酰肼-2,2′-连吡啶(H₂L¹)和双吡啶二乙基-6,6′-二酰肼-2,2′-连吡啶(H₂L²)，和金属镍离子组装得到2个金属螺旋体(helicate)，Ni₂(HL¹)₂(PF₆)(BF₄)(CH₃OH)(H₂O)₂ (1)和Ni₂(HL²)(H₂L²)(ClO₄)₃(C₂H₅OH)(CH₃OH)H₂O)₃ (2),并测定了它们的晶体结构。同时由配体H₂L³出发,通过逐级组装的方法,得到一个镍-银杂金属的配位聚合物Ni₂Ag₂(HL³)₂(ClO₄)₂(CH₃CN)₃ (3)。单晶结构表明，配位聚合物3中配体H₂L³首先与镍离子组装成分子盒化合物(molecular box)，该结构单元进一步通过Ag离子与分子盒外围N原子配位，使分子盒互相串连成一维配位聚合物3，分子盒聚集体沿c方向伸展成一维链结构，链与链之间相互平行，进一步堆积成二维孔道结构。     

Determination of bromine and iodine in biological and environmental materials using epithermal neutron activation analysis

Epithermal neutron activation analysis (ENAA) was applied to the determination of the contents of bromine and iodine in 40 biological and environmental standard reference materials and Chinese diets. Boron nitride (BN) for solid samples and BN+Cd for liquid samples were adopted as shield material. Irradiation was carried out in inner and outer irradiation sites in a Miniature Source Reactor (MNSR) for solid and liquid samples, respectively. The 443 keV photopeak of ¹²⁸I and the 616 keV photopeak of ⁸⁰Br were used. The precision of measurement (relative standard deviation) is 2∼6% for contents of iodine of more than 100 ng/g and 8∼12% in the 20∼100 ng/g range in solid samples, and 12∼18% at less than 100 ng/ml in liquid samples. For bromine, the precision of measurement is 2–8% for solid samples and lower than 13% for liquid samples. The detection limits under experimental conditions varied between 10∼30 ng/g, 55∼95 ng/g and 25∼68 ng/g for iodine and 50∼150 ng/g, 200∼450 ng/g and 100∼300 ng/g for bromine in ENAA with BN shield in inner irradiation sites, with Cd shield and BN+Cd shield in outer irradiation sites, respectively. Received: 13 June 1996 / Revised: 2 September 1996 / Accepted: 19 September 1996     

气相中Cu+和Zn+与CS2反应的计算研究

以Cu⁺和Zn⁺与CS₂反应作为第一过渡金属离子与CS₂反应的范例体系. 采用密度泛函UB3LYP/6-311+G^*方法计算研究了第一过渡金属离子在基态和激发态与CS₂反应的反应机理. 全参数优化了反应势能面上各驻点的几何构型, 用频率分析方法和内禀反应坐标(IRC)方法对过渡态进行了验证. 并用UCCSD(T)/6-311G^*方法对各驻点作了单点能量校正. 在Cu⁺与CS₂反应中, 计算了单重态初始中间体¹IM1到三重态插入型中间体³IM2的反应交叉势能面. 确定了第一过渡金属离子与CS₂的反应为插入-消去反应, 找到了基态和激发态金属离子与CS₂反应的主要通道.     

Coordination complexes of 2-(4-quinolyl)nitronyl nitroxide with M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)]: syntheses, crystal structures, and magnetic characterization

Three new complexes of the formula M(2)L(2) derived from 2-(4-quinolyl)nitronyl nitroxide (4-QNNN) and M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)], (4-QNNN)(2).[Mn(hfac)(2)](2) (1), (4-QNNN)(2).[Co(hfac)(2)](2).2H(2)O (2), and (4-QNNN)(2).Cu(hfac)(2).Cu'(hfac)(2) (3), were synthesized and characterized structurally as well as magnetically. Complexes 1 and 2 are four-spin complexes with quadrangle geometry, in which both the nitrogen atoms of quinoline rings and oxygen atoms of nitronyl nitroxides are involved in the formation of coordination bonds. For complex 3, however, the nitrogen atoms of quinoline rings are coordinated with Cu(II) ion to afford a three-spin complex, which is further linked to another molecule of Cu(hfac)(2) (referred to as Cu'(hfac)(2)) to form a 1D alternating chain. The magnetic behaviors of the three complexes were investigated. For complex 1, as the nitronyl nitroxides and Mn(II) ions are strongly antiferromagnetically coupled, consequently its temperature dependence of magnetic susceptibility was fitted to the model of spin-dimer with S = 2, yielding the intradimer magnetic exchange constant of J = -0.82 cm(-1). For complex 2, the temperature dependence of the magnetic susceptibility in the T > 50 K region was simulated with the model of two-spin unit with S(1) = 3/2 and S(2) = 1/2, leading to J = -321.9 cm(-1) for the magnetic interaction due to Co(II).O coordination bonding, D = -16.3 cm(-1) (the zero-field splitting parameter), g = 2.26, and zJ = -3.8 cm(-1) for the magnetic interactions between Co(II) ions and nitronyl nitroxides through quinoline rings and those between nitronyl nitroxides due to the short O.O short contacts. The temperature dependence of magnetic susceptibility of 3 was approximately fitted to a model described previously affording J(1) = -6.52 cm(-1) and J(2) = 3.64 cm(-1) for the magnetic interaction between nitronyl nitroxides and Cu(II) ions through the quinoline unit via spin polarization mechanism and the weak O.Cu coordination bonding, respectively.     

Determination of isotopic ratios of osmium and ruthenium in meteorites by pretreatment and radiochemical neutron activation analysis

The isotopic abundance ratios of¹⁹⁰Os/¹⁸⁴Os and⁹⁶Ru/¹⁰²Ru for the metal phases of the Jilin and Taonan stone meteorites were determined by pretreatment and radiochemical neutron activation analysis. All experimental factors affecting Os and Ru isotopic ratios were discussed, including sampling, standard, irradiation, separation and counting. The statistical errors of measurement for the¹⁹⁹Os/¹⁸⁴Os ratio can be controlled within 1%. The experimental results indicate that the statistically significant anomalies of the¹⁹⁰Os/¹⁸⁴Os and⁹⁶Ru/¹⁰²Ru ratios have not been found relative to the terrestrial Os and Ru standards.     

钨(Ⅵ)-钼(Ⅵ)-鲁米诺化学发光反应测定钨

本文研究以钨(Ⅵ)形成钨钼杂多酸与鲁米诺反应,产生化学发光测定钨的方法及条件。在pH1.6静置溶液,钨钼杂多酸迅速形成,具有很高的氧化活性。测定钨的灵敏度达到0.084ng/ml,钨浓度从1×10~(-10)～1×10~(-5)g/ml范围内具有线性关系。通过巯基棉分离富集,用于天然水及岩矿样品中痕量钨的测定,均获得满意结果。     

适合低PH范围测量的新型中性载体膜PH电极的研究

本文设计合成了一种在低ＰＨ范围对氢离子有很好Ｎｅｒｎｓｔ响应的新型中性载体－Ｎ，Ｎ－二辛基菸酰胺，并把它制成ＰＶＣ膜ＰＨ电极，测试了该电极的线性范围、选择性、稳定、重现性和内阻等各项性能参数，并试验了电极抗氢氟酸腐蚀的能力，该该电极用于氢氟酸的电离常数测定时获得了满意的结果。     

2,6-二乙酰吡啶类双希夫碱配合物的研究——Ⅰ.VO(Ⅱ)、Mn(Ⅱ)、Fe(Ⅱ)和Fe(Ⅲ)配合物的合成和表征

制备了由2,6-二乙酰吡啶与肼基硫代甲酯衍生的希夫碱C_5H_3N[CH=NN=C(S)XR]_2(X=S,R=CH_3,C_6H_5CH_2;X=O,R=C_6H_5CH_2)。离析出类型为MC_5H_3N[CH=NN=C(S)XR]_2(M=VO~(2 )、Mn~(2 )和Fe~(2 ))和FeC_5H_3N[CH=NN=C(S)SR]_2Cl的希夫碱配合物。希夫碱及其配合物为元素分析、红外、可见一紫外光谱以及磁化率测量所表征,结果与所提出的Mn~(2 )、Fe~(2 )及Fe~(3 )配合物的结构一致.在VO(Ⅱ)配合物的情况,则形成多聚体,其结构为: -(N_3S_2)V-O-V(N_3S_2)-O-V(N_3S_2)-.     

Evaluation of the homogeneity of the environmental standard reference material — esturine sediment SRM 1646 by INAA and SRXRF

The distribution homogeneities of 13 elements (As, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Rb, Sc, Sm and Th) in the esturine sediment SRM1646 have been evaluated by INAA and synchronous radiation-based X-ray fluorescence spectrometry in the range of sampling amounts from 10 μg to 20 mg. The experimental results reveal that the homogeneities of the elements studied relate to their species and sampling amount. The sampling constants of these elements have been calculated.