Interactions of thiamine with anions: (Hthiamine)(thiamine) heptaiododimercurate dihydrate and its dimethanol monohydrate

In the title compounds, 3-[(4-amino-2-methyl-5-pyrimidinio)methyl] -5-(2-hydroxyethyl)-4-methylthiazolium(2+) 3-[(4-amino-2-mcthyl-5-pyrimidinyl)methyl]-5-(2-hydroxyethyl)-4-methylthiazolium( 1+) heptaiododimercurate dihydrate, (C12H18N4OS)(C12H17N4OS)[Hg2I7]. 2H(2)O, (I), and its dimethanol monohydrate, (C12H18N4OS)(C12H17N4OS)[Hg2I7]. 2CH(3)OH . H2O (2), a crystallographic centre of symmetry in (1) or a twofold axis in (2) is imposed between the protonated and deprotonated thiamine molecules, resulting in a statistically half-occupied proton attached at N1' of the pyrimidine ring. The Hg2I73- anion, residing on the centre of symmetry in (1) or on the twofold axis in (2), interacts with two thiamine molecules, each through a C2-H ... I ... pyrimidine-ring interaction. This bridging interaction is a characteristic of thiamine in the F conformation.

Theoretical investigation of small lathanum carbide clusters

LaC2+, LaC22+, LaC3 and LaC3- clusters have been studied using B3LYP density functional method. Four isomers with C-2v, C-s, C-infinity v and D-infinity h symmetry were presented for LaC2+ and LaC22+. Meanwhile, two spin states, namely, singlet and triplet for LaC2+, doublet and quartet for LaC22+ were considered The results indicated that ring isomers with C-2v and C-s symmetry are the most stable for La-C2(+) at both spin states and for LaC22+ at quartet state. Whereas for LaC22+ at doublet state, linear isomer with C-infinity v symmetry is energetically favored, For LaC3 and LaC3- clusters,, three isomers have been presented for each cluster, that is, two ring isomers with C-2v symmetry ( in one of them, La forms two single bonds with two carbons, and in another, La forms a double bond with carbon), and one linear isomer with C-infinity v symmetry. The results revealed that the ring isomer in which La forms two single bonds with carbons is the lowest in energy.

1,4-二丙氧基-2,3二氰基萘的晶体结构

用 Siemens P4四圆衍射仪,测得了1,4-二丙氧基-2,3-二氰基萘的晶体结构。晶体属单斜晶系,空间群为 C2/C。晶格参数 a=14.987(3)A,b=10.527(2),c=11.755(2),β=118.98°(3),晶胞体积 V=1622.4(6)3,Z=4,Dc=1.205Kg/m~3,μ(MoK_α)=0.079mm~(-1),F(000)=624,T=293(2)K_o晶体结构应用直接法,解出最后的偏离因子 R=0.0554[1425个Ⅰ≥2σ(Ⅰ)衍射点]。结构分析表明,萘环的1,4和2,3位碳原子上的氢原子分别被丙氧基和氰基所取代,由于取代基的引入使萘环的结构有所改变。

Influences of acid treatments of active carbons on no reduction over carbon-supported copper oxides

Active carbon supported copper oxides were used in NO reduction. The conversions of NO reduction depends strongly on surface oxygen-containing groups on the active carbons, among them the carboxyls and lactones favored remarkably the NO reduction. However, hydrochloric acid treatment led to the decomposition of the carboxyls and lactones on C2 and C3, decreasing their reactivities for NO reduction. Concentrated HNO3 treatment of active carbon produced higher conversions of NO reduction at relatively low temperatures due to the marked increase in the amounts of the carboxyls and lactones.

Syntheses and reactions of heterometallic complexes of nickel and copper with tetrathiotungstates. The molecular structures of [Ph(4)P](2)[S2W(mu-S)(2)Ni(S-2)] and W(mu-S)(4)Cu-2(PPh(3))(4)center dot py

Reaction of [Ph(4)P]2WS4 With NiCl2 in methanol solution in the presence of NaOCH3 leads to the formation of [Ph(4)P](2) [S2W(mu-S)(2)Ni(S-2)] (I) A Similar reaction between (NH4)(2)WS4 and NiCl2 under O-2 atmosphere in the presence of Ph(4)PCl or (n)Bu(4)NCl affords [Ph(4)P](2)([(S-2)W(O)(mu-S)(2)]Ni-2] (IIa) and [(n)Bu(4)N](2)([(S-2)W(O)(mu-S)(2)]Ni-2} (IIb) Under argon the same reaction gives [Ph(4)P](2)[Ni(WS4)(2)] (IIIa) and [(n)Bu(4)N](2)[Ni(WS4)(2)] (IIIb). [Ph(4)P](2)[Ni(WOS3)(2)] (IV) and [Ph(4)P](2)[Ni(WO2S2)(2)] (V) can be prepared from the reaction of [Ph(4)P]2WOS3 and [Ph(4)P]2WO2S2 with NiCl2. Treatment of (NH4)(2)WS4 with CuCl in the presence of PPh(3) in boiling pyridine produces W(mu-S)(4)Cu-2(PPh(3))(3) (VI), which can further react with excess PPh(3) to give W(mu-S)(4)Cu-2(PPh(3))(4) . py (VII). Complex I crystallizes in the space group P2(1)/n with the cell parameters: a = 20.049(4), b = 17.010(4), c = 14.311(7) Angstrom; beta = 110.24(3)degrees and Z = 4; R = 0.058 for 4267 independent reflections. The structural study confirms that complex I contains two terminal sulfide ligands, two bridging sulfide ligands, a side-on disulfide ligand, and a planar central W(mu-S)(2)Ni four membered ring. Complex VII crystallizes in the space group C2/c with the cell parameters: a = 26.436(8), b = 20.542(6), c = 19.095(8) Angstrom; beta = 125.00(3)degrees and Z = 4; R = 0.080 for 3802 independent reflections. The structural study reveals a perfect linear arrangement of the three metal atoms Cu-W-Cu.

Synthesis and molecular structures of di- and trinuclear molybdenum complexes containing pyridine-2-thiolato (pyS) ligand

Dinuclear complexes [Mo-2(mu-pyS)(2)(CO)(4)(PPh(3))(2)] (1), [Mo-2(mu-pyS)(2)(CO)(5)(PPh(3))] (2) and a trace quality of trinuclear complex [Mo-3(mu-pyS)(2)(mu(3)-pyS)(2)(CO)(6)] (3) were obtained from the reaction of [Mo(CO)(3)(MeCN)(3)] with pyridine-2-thione (pySH) and PPh(3) in THF. The crystal structures of 1.2C(7)H(8) and 3.7 C7H8 have been determined by X-ray diffraction studies. Crystals of 1.2C(7)H(8) are monoclinic, space group C2/c and Z = 4, with a = 18.797(3), b = 11.143(4), c = 28.157(7) Angstrom, beta = 101.23(2)degrees. The structure was refined to R = 0.050 and Rw = 0.057 for 3146 observed reflections, Crystals of 3.7 C7H8 are monoclinic, space group P2(1)/a and Z = 4, with a = 13.912(2), b = 17.161(2), c = 15.577(3) Angstrom, beta = 101.17(1)degrees. The structure was refined to R = 0.046 and Rw = 0.051 for 4357 observed reflections. The molecule of 1 consists of two Mo(CO)(2)(PPh(3)) fragments linked by an Mo-Mo bond (2.974(2)Angstrom) and by two doubly-bridging pyS ligands. The compound 3 contains a bent open geometry of three molybdenum atoms (Mo(1)-Mo(2)-Mo(3) angle 122.99(3)degrees) linked by two Mo-Mo bonds (2.943(1) and 2.950(1) Angstrom) and by two doubly- and two triply-bridging pyS ligands.

The reactivity of lanthanide alkyl compounds with phenylacetylene: Synthesis and structure of [(Bu(t)Cp)(2)LnC CPh](2) (Ln=Nd, Gd)

[(Bu(t)Cp)(2)LnCH(3)](2) (Ln = Nd, Gd) react with PhC=CH to form the dimeric alkynide-bridged complexes [(Bu(t)Cp)(2)LnC=CPh](2) [Ln = Nd (I), Gd (II)]. Both compounds crystallized from toluene in the monoclinic space group C2/c. The two complexes are homologous, composed of asymmetric metal-alkynide bridges with Nd-C, Gd-C (alkynide) bond lengths of 2.602(4), 2.641(5) (I) and 2.532(6), 2.601(7) Angstrom (II), respectively. The average Nd-C (ring) and Gd-C (ring) distances are 2.746(13) and 2.703(19)Angstrom.

甲烷氧化偶联Ti-La-Li系多元氧化物催化剂的表面碱性和表面活性氧种

利用CO2-TPD方法考察了Ti-La-Li系多元氧化物催化剂的表面碱性,实验发现:C2 选择性与表面碱强度呈顺变关系,而CH4 转化率与CO2 的脱附峰面积呈顺变关系.同时,利用XPS,O2-TPD等方法对该体系催化剂的表面活性氧种进行了表征与研究,结果表明:催化剂的表面晶格氧与C2 选择性有关,表面吸附氧与甲烷转化(包括偶联和深度氧化)有关.O2 -TPD实验发现催化剂的表面存在三种氧:α( 100℃≤t≤450℃),β(450℃

四氯合锌酸二(正十一烷基铵)晶体相变的Raman光谱

用Raman光谱研究了[n-C_(11)H_(23)NH_3]_2ZnCl_4(简记为C_nZn)配合物的固-固相变.结果表明,配合物产生的固-固相变主要与烷烃链的堆积结构和分子构象变化有关.在 T_(c1)=25℃的相变是由于烷烃链的侧向堆积和分子构象的有序到部分无序变化.在中间相,分子链局部产生旁式构象.在T_(c2)=87℃的相变主要来源于烷烃链从部分构象有序到完全无序的变化.高温相形成了构象完全无序相.相应于烷烃链的“熔化”.

锂在甲烷氧化偶联多元氧化物催化剂中的作用

考察了不同Li含量对LixLa0．5Ti0．5系氧化物催化剂的甲烷氧化偶联催化性能的影响；比较了水洗前后LiLa0．5Ti0．5氧化物催化剂的催化活性，并通过XRD、IR、XPS和BET等方法时催化剂进行表征。确认了Li在含稀土、过渡金属多元氧化物中的作用。其中，表面Li的作用是缩小催化剂的比表面积，覆盖表面深度氧化活性位，提高C2选择性；体相Li的作用是部分取代Ti3+进入LaTiO3晶格形成LaTi1-yLiyO3-λ活性相，产生甲烷氧化偶联Li+－O-－Ti3+缺陷簇。（注：LixLa0．5Ti0．5和LiLa0．5Ti0．5表示该系列氧化物催化剂制备时的各金属元素的配比。用来表示催化剂的名称，并不表示实际存在的物相，以下类同，下面出现时，不再加以说明。

INTERACTIONS OF THIAMINE WITH ANIONS - STRUCTURE OF THIAMINE DITHIOCYANATE

The crystal structure analysis of {3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-5-(2-hydroxyethyl)-4-methylthiazol}ium dithiocyanate reveals that there are two types of anion bridges between the two aromatic rings of the same thiamine which adopts the usual F conformation, one of which involves a contact between H(C2) on the thiazolium ring and the hydroxy O atom from a neighbouring molecule. The crystal packing shows a novel triple helical structure formed by strongly hydrogen-bonded thiamine-SCN- molecular chains.

(η~5-C_5H_5)_2Yb(THF)_2的新合成方法及其晶体结构

双(环戊二烯基)镱(Ⅱ)四氢呋喃配合物(η~5-C_5H_5)_2Yb(THF)_2通过环辛二烯基钾(KC_8H_(11))还原(C_5H_5)_2YbCl·THF而得到,经元素分析、红外光谱表征,并测定了其晶体结构。配合物属单斜晶系,C2/c空间群,晶体学参数a=1.3564(4),b=0.9569(3),c=1.4747(6)nm;β=109.90(3)°;V=1.79975(118)nm~3;D_c=1.65·cm~(-3);μ_C=54.7cm~(-1)(Mo);F(000)=880,Z=4。最后一致性因子R=0.079,R_w=0.081。Yb~(2+)的配位数为8。

水溶液中甘氨酰替亮氨酸与Ho(ClO_4)_3和Yb(ClO_4)_3相互作用的NMR研究(英文)

本文用~(13)C NMR方法研究了水溶液中三价顺磁性稀土离子Ho~(3+)和Yb~(3+)与二肽甘氨酰替亮氨酸之间的相互作用。对稀土诱导位移中的接触位移和偶极位移进行了分离。实验表明,与羧基相连的碳核所受的接触作用很大,因此不能把镱诱导的位移直接用于肽的构象分析。在水溶液中,肽通过羧基与稀土离子配位,在弱酸性条件下肽键和氨基均不参与配位。根据结构因子确定了肽在溶液中的构象,结果表明,分子片段C1-C2-C5-C6,C2-N-C3-C4和C2-C5-C6-C8为反式,而C2-C5-C6-C7和C1-C2-N-C3成旁式。

维生素B_1-锌配合物的晶体结构

用X射线单晶衍射方法测定了ZnVB_1晶体结构。晶体属单斜晶系,空间群为C2/c;α=25.747(5),b=8.461(0),c=17.407(3)A;β=105.79(1)°,Z=8。晶体结构是用Patterson函数法与Fourier计算得到,最后的R=0.0283。金属锌离子与嘧啶环上的N(1)原子以及三个氯离子键合,形成四配位的络合物。配位多面体是稍有扭曲的四面体。Zn—Cl键的平均距离为2.266A,Zn—N键长为2.041(4)A。

C440/C540/Saf-T三元混合染料体系的荧光光谱研究

选择适当的混合染料溶液作为染料激光器的工作物质,近年来,已有一些文献报导,但大都局限于二元混合染料体系。对于三元混合染料体系国外也曾有过少量报导,诸如C102/R110/RB,C102/RB/CV,C2/C6/R6G,R6G/CV/NB等。或多或少地得到了三个波长