堆积模型及其应用 I: 三氯化镧尿素配合物[LaCl2(urea)6].Cl分子结构的推测与测定

本根据堆积模型推测LaCl3(urea)6的实际结构为[LaCl2(urea)6]^+Cl^-, 培养了这一化合物单晶, 进行了结构测定. 本文报道了有关结果.     

堆积模型及其应用 Ⅰ.三氯化镧尿素配合物[LaCl_2(urea)_6]·Cl分子结构的推测与测定

镧系元素具有形成高配位数的特点,但由简单配位形成的多面体,最高配位数只能达到九,例如,[Ln(H_2O)_9]~(+[2])。有些从化学式来看符合九配位的化合物,如LnCl_3(H_2O)_6实际结构是八配位[LnCl_2(H_2O)_6]~(+[3])或六配位[LnCl_3(H_2O)_3]·3H_2O~[4])。这种情况促使我们对另一系列化合物LnCl_3(urea)_6~[5]产生兴趣。我们根据堆积模型推测LaCl_3(urea)_6的实际结构应当是[LaCl_2(urea)_6]~+Cl~-(见图1、2)。培养了这一化合物的单晶,进行了结构测定。本文报道有关结果。     

LaCl3-KCl熔体结构的分子动力学研究

用分子动力学计算机模拟方法研究了LaCl3-KCl熔体的结构和输运性质, 获得了熔体的偏径向分布函数、配位数、键角分布及均方位移等信息. 计算结果表明, 熔体中存在变形的八面体LaCl63-离子. K 和Cl-离子是熔体电流的主要携带迁移者, 而LaCl3浓度对熔体结构有较大的影响.     

LaCl3对欧洲李(Prunus domestica) GF43试管苗根系生长及衰老作用的影响

研究了2.5 μmol·L-1 LaCl3在GF43试管苗根系生长及衰老过程中的作用. 结果表明, LaCl3可促进GF43试管苗根系生长及干物质积累, 显著提高超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)和过氧化物酶(POD)等抗氧化酶活性, 降低超氧阴离子自由基(·O-2)产生速率、丙二醛(MDA)含量和膜透性, 对细胞膜结构具有稳定作用, 从而延缓试管苗根系的衰老进程. 此研究对解决核果类果树工厂化育苗过程中的生根及移栽问题具有一定的参考价值.     

LaCl3-KCl体结构的分子动力学研究

用分子动力学计算机模拟方法研究了LaCl3-CI熔体的结构和输运性质，获得了熔体的偏径向分布函数、配位数、键角分布及均方位移等信息。计算结果表明，熔体中存在变形的八面体LaCl6^3-离子。K^ 和Cl^-离子是熔体电流的主要携带迁移者，而LaCl3浓度对熔体结构有较大的影响。     

氯化镧对脂多糖与单核细胞的结合及CD14表达的影响

用流式细胞术检测氯化镧(LaCl3)对内毒素(LPS)与单核细胞的结合及CD14表达的影响.结果显示LPS能够与单核细胞结合,LaCl3具有抑制LPS与单核细胞结合的作用;LPS可以上调全血单核细胞表面CD14的表达,并在一定范围内呈剂量依赖关系,LaCl3对LPS上调单核细胞表面CD14的表达具有一定的抑制作用,但不能完全阻断.     

ITSTUDIES ON THE EFFECT OF UREA ON THE COMPATIBILITY OF PMMA/PVC MIXTURES IN DMF BY A DILUTE- SOLUTION VISCOMETRY METHOD

The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.     

Theory Studies on the Intermolecular Interactions of Urea Nitrate with RDX

Six fully optimized geometries of urea nitrate cation and RDX complexes have been obtained with DFT-B3LYP and MP2 methods at the 6-311++G** level. The intermolecular interaction energies have been calculated with basis set superposition error (BSSE) and zero point energy (ZPE) correction. The nature of intermolecular interaction has been revealed by the analysis of AIM and NBO. The results indicate that the greatest binding energy of urea nitrate with RDX is –82.47kJ/mol. The O–H…O and N–H…O hydrogen bonds are important intermolecular interactions of urea nitrate cation with RDX, and the origin of hydrogen bonds is the oxygen atom offering its lone-pair electrons to the σ(O-H)* or σ(O-H)* antibonding orbital. The intermolecular interactions strengthen the N–NO2 bond, leading to the reduced sensitivity of urea nitrate and RDX mixture explosive.     

稀土-锂双金属橄合物的研究(LaCl)DMECu~2-Cl)~5(u~3)Cl(La,DME)Li(THF)~2的合成及其晶体结构

本文合成了组成为(LaCl)DME(u~2-Cl)~5(u~3-Cl)(La.DME)-Li(THF)~2的新型桥式链状配合物, 并测定了晶体结构。     

添加剂对化学沉积速率的影响

基于化学镀Ni-W-P和Ni-P体系中,添加剂LaCl3、乳酸、Fe2(SO4)3、硫脲和2,2’-联吡啶的浓度对沉积速率的影响表现出较为一致的变化规律,即随添加剂浓度的增加,出现最大沉积速率的实验事实,建立了一种吸附模型并导出添加剂加速化学沉积的公式.根据该公式和实验结果进行曲线拟合,得到相当吻合的结果.由拟合结果可得到一些参数值,如吸附平衡常数等.添加剂在基体上的吸附平衡常数(K1)大于已吸附了还原剂的表面上的吸附平衡常数(K2). K1值大表明添加剂在基体表面吸附能力更强. LaCl3、硫脲和2,2’-联吡啶的K1、K2值远大于乳酸、Fe2(SO4)3的K1、K2值,这表明LaCl3、硫脲和2,2’-联吡啶的吸附能力远强于乳酸、Fe2(SO4)3的, 因此,LaCl3、硫脲和2,2’-联吡啶所引起的沉积速率峰值的浓度远小于乳酸、Fe2(SO4)3的.     

钼铁硫原子簇化合物的合成与结构化学研究II: 以Fe(SR)6为桥的双类立方烷化合物的合成及(Et4N)4[Mo2Fe7S8(SC6H4CH3-m)12].2THF的晶体结构

在乙腈溶液中(Et4N)2[Fe4(SR)10]与(Et4N)2[MoS4]反应半小时生成对氧极为敏感的系列黑色晶状化合物(Et4N)4[Mo2Fe7S8(SR)12](R=C6H5,1;R=C6H4CH3-m, 2;R=C6H4CH3-o, 3;R=C6H4CH3-ρ,4). 2.2THF晶体的分子量为2982.8, 属单斜晶系;空间群为P21/n; a=18.022(2), b=18.375(2), c=22.254(3)A; β=71.04(1)°;V=6969(2)A^3;Dc=1.424g.cm^-^3;Z=2;F(000)=3108.晶体结构用直接法解出,修正至R=0.064. 2.2THF中Mo...Mo'距离为7.234A.     

具有局部松散配位的三核钼簇合物研究:{Mo3(μ3-S)(μ-S)3[S2P(OEt)2]4.P(C6H5)3}.(O86CH2Cl2)的合成和晶体结构

本文报道了具有局部松散配位的三核钼原子簇{Mo3(μ3-S)(μ-S)[S2P(OEt)2]4.P(C6H5)3}.(0.86CH2Cl2)的合成和晶体结构.在CAD-4四圆衍射仪上用Mo Kα射线收集到I≥2σ(I)的衍射点4840个.采用重原子法和差电子密度法解出结构,并用全矩阵最小二乘法修正,最终偏离因子为0.058.簇分子的Mo-Mo键为2.731(1),2.748(1),2.753(1)A,Mo原子和三苯基膦的P原子配位键长为Mo-P2.647(3)A,显著长于一般的Mo-P共价单键.三苯基膦基团在Mo的配位多面体中处于三重桥S原子的对位,表现出与其他此类簇合物的松散配位体配位位置不同.文中概括了此类簇合物的Mo-Mo键和Mo-L的成键情况.     

MoFe3S4单立方烷原子簇研究 III: 三核链状簇合物向单立方烷簇合物的转化及MoFe3S4(Et2NCS2)5.CH3CN的结构

以Fe(DMF)6[(FeCl2)2MoS4]与Et2NCS2Na在DMF中反应实现了三核链状簇骼向单立方烷簇骼的转化, 得到了MoFe3S4(Et2NCS2)5并测定了它的晶体结构. 本文指出与配体有关的氧化还原过程及配体的配位特点对这一转化反应及其产物的影响, 同时比较了由于核心氧化态的差异而造成的簇骼结构面貌的变化.     

MoFe3S4单立方烷原子簇研究II. MoFe3S4(C5H10NCSS)5的合成与结构

六氢吡啶基二硫代甲酸钠盐、氯化亚铁及四硫代钼酸铵在二甲基甲酰胺及二氯甲烷中,经一步自兜反应,分别得到了[MoFe3S4(C5H10NCSS)5]DMF及[MoFe3S4(C5H10NCSS)5]CH2Cl2.通过X射线衍射测定了后者的晶体结构,比较了它与[MoFe3S4(Et2NCSS)5]^-结构特点的异同,同时研究了反应物摩尔比对产物的影响以及溶剂分子的置换反应.     

The cysteine radical cation: structures and fragmentation pathways

A theoretical study on the structures, relative energies, isomerization reactions and fragmentation pathways of the cysteine radical cation, [NH(2)CH(CH(2)SH)COOH].+, is reported. Hybrid density functional theory (B3LYP) has been used in conjunction with the 6-311++G(d,p) basis set. The isomer at the global minimum, Captodative-1, has the structure NH(2)C.(CH(2)SH)C(OH)(2)+; the stability of this ion is attributed to the captodative effect in which the NH(2) functions as a powerful pi-electron donor and C(OH)(2)+ as a powerful pi-electron acceptor. Ion Distonic-S-1, H(3)N(+)CH(CH(2)S.)COOH, in which the radical is formally situated on the S atom, is higher in enthalpy (DeltaH degrees (0)) than Captodative-1 by 6.1 kcal mol(-1), but is lower in enthalpy than another isomer Distonic-C-1, H(3)N(+)C.(CH(2)SH)COOH, by 8.2 kcal mol(-1). Isomerization of the canonical radical cation of cysteine, [H(2)NCH(CH(2)SH)COOH].+, (Canonical-1), to Captodative-1 has an enthalpy of activation of 25.8 kcal mol(-1), while the barrier against isomerization of Canonical-1 to Distonic-S-1 is only 9.6 kcal mol(-1). Two additional transient tautomers, one with the radical located at C(alpha) and the charge on SH(2), and the other a carboxy radical with the charge on NH(3), are reported. Plausible fragmentation pathways (losses of small molecules, CO(2), CH(2)S, H(2)S and NH(3), and neutral radicals COOH. , HSCH(2). and NH(2).) from Canonical-1 are examined.     

Cubane, cuneane, and their carboxylates: a calorimetric, crystallographic, calculational, and conceptual coinvestigation

[reaction: see text] This study is a multinational, multidisciplinary contribution to the thermochemistry of dimethyl1,4-cubanedicarboxylate and the corresponding isomeric, cuneane derivative and provides both structural and thermochemical information regarding the rearrangement of dimethyl 1,4-cubanedicarboxylate to dimethyl 2,6-cuneanedicarboxylate. The enthalpies of formation in the condensed phase at T = 298.15 K of dimethyl 1,4-cubanedicarboxylate (dimethyl pentacyclo[4.2.0.0.(2,5)0.(3,8)0(4,7)]octane-1,4-dicarboxylate) and dimethyl 2,6-cuneanedicarboxylate (dimethyl pentacyclo[3.3.0.0.(2,4)0.(3,7)0(6,8)]octane-2,6-dicarboxylate) have been determined by combustion calorimetry, delta(f) H(o)m (cr)/kJ x mol(-1) = -232.62 +/- 5.84 and -413.02 +/- 5.16, respectively. The enthalpies of sublimation have been evaluated by combining vaporization enthalpies evaluated by correlation-gas chromatography and fusion enthalpies measured by differential scanning calorimetry and adjusted to T = 298.15 K, delta(cr) (g)Hm (298.15 K)/kJ x mol(-1) = 117.2 +/- 3.9 and 106.8 +/- 3.0, respectively. Combination of these two enthalpies resulted in delta(f) H(o)m (g., 298.15 K)/kJ x mol(-1) of -115.4 +/- 7.0 for dimethyl 1,4-cubanedicarboxylate and -306.2 +/- 6.0 for dimethyl 2,6-cuneanedicarboxylate. These measurements, accompanied by quantum chemical calculations, resulted in values of delta(f) Hm (g, 298.15 K) = 613.0 +/- 9.5 kJ x mol(-1) for cubane and 436.4 +/- 8.8 kJ x mol(-1) for cuneane. From these enthalpies of formation, strain enthalpies of 681.0 +/- 9.8 and 504.4 +/- 9.1 kJ x mol(-1) were calculated for cubane and cuneane by means of isodesmic reactions, respectively. Crystals of dimethyl 2,6-cuneanedicarboxylate are disordered; the substitution pattern and structure have been confirmed by determination of the X-ray crystal structure of the corresponding diacid.     

异双核化合物PdMo(μ-Ph~2Ppy)~2(μ-CO)(CO)~2I~2.0.5CH~2Cl~2的合成和晶体结构

本文合成了新的异双核化合物PdMo(μ-Ph~2Ppy)~2(μ-CO)(CO)~2I~2.0.5CH~2Cl~2, 对它进行了表征, 并测定其晶体和分子结构。该化合物属PI空间群, a=0.9500(2), b=1.1302(2), c=1.993(1)nm, α=102.82(3),β=101.21(3), γ=94.57(2)°, D~x=1.82g/cm^3, Z=2, R=0.064。晶体结构测定表明, 该化合物具有Pd-Mo键, 键长为0.28596(9)nm。如将Pd-Mo键考虑在内, Pd原子为d^9五配位构型, Mo原子为d^5七配位构型。两者的形式氧化态均为+1。     

[Mn(H2O)4(NCS)2](18-冠-6)的分子和晶体结构

报导了[Mn(H2O)4(NCS)2](18-冠-6)单晶的X射线结构分析.它的晶体正交晶系.锰(II)与两个硫氰酸根,四个水分子配合形成顺式八面体的配位分子,并通过其中的水分子与18-冠-6以氢键结合.     

二甲亚砜-二[4,4,4-三氟-1-(2-噻吩基)-1,3-丁二酮]合铜(II)的晶体结构

制备了标题化合物单晶,确定了它的分子和晶体结构,结果表明Cu(II)与五个氧原子配位,其中之一来自沿轴向(CH3)2SO.形成略为变形的四方锥结构.在配体上的噻吩基取顺式围绕差Cu(II)原子,这可以共轭效应来解释.     

Carboranes and baskets from reaction of B4H10 with allene

The reaction of the boron hydride B4H10 with allene was studied at the CCSD(T)/6-311+G(d)//MP2/6-31G(d) level. The mechanism is surprisingly complex with 44 transition states and several branching points located. The four carboranes and one basket that have been observed experimentally are all connected by pathways that have very similar free energies of activation. In addition, two new structures, a basket (2,4-(CH2CH2CH2)B4H8, 5a) and a "classical" structure (1,4-(Me2C)bisdiborane, 7), which might be obtained from the B4H10 + C3H4 reaction under the right conditions (hot/cold, quenched, etc.) have been identified. The first branch point in the reaction is the competition between H2 elimination from B4H10 (DeltaG(298 K) = 32.2 kcal/mol) and the hydroboration of allene by B4H10 (DeltaG(298 K) = 31.3 kcal/mol). The next branch point in the hydroboration mechanism controls the formation of 2,4-(MeCHCH2)B4H8 (1) (DeltaG(298 K) = 31.5 kcal/mol) and arachno-1,2/arachno-1,3-Me2-1-CB4H7 (8 and 8a) (DeltaG(298 K) = 34.3 kcal/mol). Another branch point in the H2-elimination mechanism controls the formation of 1-Me-2,5-micro-CH2-1-CB4H7 (29) (DeltaG(298 K) = 0.1 kcal/mol) and 2,5-micro-CHMe-1-CB4H7 (25/26) (DeltaG(298 K) = 7.3 kcal/mol). Formation of 2-Me-2,3-C2B4H7, a carborane observed in the reaction of methylacetylene with B4H10, is calculated to be blocked by a high barrier for H2 elimination. All free energies are relative to B4H10 + allene. An interesting reaction step discovered is the "reverse hydroboration step" in which a hydrogen atom is transferred from carbon back to boron, which allows a CH hydrogen to shuttle between the terminal and central carbon of allene.