Search

The (C3H6N6)0.67V2O5 hybrid nanorods are synthesized through the self-assembly of melamine organic molecules confined by V2O5 layers and used as cathode material in the lithium-ion battery. The prepared hybrid overcomes the irreversible structure puckering problem of LixV2O5 when excess Li+, x > 1, is intercalated. It demonstrates that layered oxides combined with selective organic moieties forming an ordered structure can significantly reduce the lattice stress and structure puckering problems during lithium intercalation/deintercalation process thereby extending their cycle reversibility in the wide potential range from 1.9 to 3.5 V and reaching to x = 2 of Lix(C3H6N6)0.67V2O5. The hybrid material developed in this work tackles the structure puckering problem of V2O5 layers and opens the door for studying new battery system with greater ionic radii, such as Na+, Mg2+ and Al3+.

Polymorphic cytochrome P-450 1A2, N-acetyltransferase 1, and 2 are important enzymes involved in the biotransformation of aromatic and heterocyclic amines known as carcinogens for colorectal cancer. A hospital-based study was designed to investigate the association between colorectal cancer and cytochrome P-450 1A2, N-acetyltransferase 1, and N-acetyltransferase 2, with the interaction of meat consumption.

Subacute nonsuppurative cholangitis (cholangitis lenta) is an uncommon yet important histological finding in liver biopsies from pediatric liver transplant recipients. The histopathological features include proliferation of bile ductules at the edges of portal tracts, inspissated bile within dilated bile ductules, absence of acute inflammation within ducts or ductules, and normal structure of interlobular bile ducts.

The syntheses of bisdithiocarbamates from diamines and CS2are described, and possible complications in these reactions explained. Ethylenebisdithiocarbamate was prepared from ethylenediamine and CS2in basic solution, but the same reaction using o-phenylenediamine led to a cyclization product, o-phenyleneimidazolidine-2-thione or benzimidazolidine-2-thione. In these reactions, if slightly insufficient amounts of CS2are used, bisdithiocarbamates will not be formed; instead, the cyclization reactions will occur, leading to the formation of thiones. Crystallographic studies were carried out for disodium ethylenebisdithiocarbamate and imidazolidine-2-thione or ethylenethiourea. The hexahydrate crystals of the former, Na2[S2CNHCH2CH2NHCS2]•6H2O, F.W. 364.42, are triclinic with a = 5.766(1), b = 7.212(1), c = 10.074(1) Å, α = 88.53(1), β = 98.41(1), γ = 105.50(1)°, V = 399.3(1) Å3, and Z = 1. The structure was determined from 2259 unique reflections, (2θ[Mo-Kα] < 65°) to an Rfactor of 0.022. The bisdithiocarbamate ion has a center of symmetry between the two CH2groups, and therefore the two NCS22−groups are separated as far apart as possible. Each Na+ion is octahedrally surrounded by five water molecules with Na … O distances ranging from 2.373 to 2.446 Å, and a sulphur atom of the thiocarbamate group with Na … S = 3.060 Å. The two C—S bonds of the CS2−group are 1.710(1) and 1.727(1) Å, and . Crystals of imidazolidine-2-thione, (CH2NH)2CS, are monoclinic, with a = 5.800(1), b = 14.516(3), c = 5.780(1) Å, β = 101.33(2)°, V = 477.2(2) Å3, and Z = 4. This structure, first determined thirty years ago, has been refined by full-matrix least-squares to R = 0.031, using 975 new Mo-Kα data.

Methyl,2-mercaptopyrimidinatomercury(II) was synthesized from methylmercuric hydroxide and 2-mercaptopyrimidine in aqueous solution. The crystal is orthorhombic with a = 4.063(2), b = 9.901(4), c = 18.808(15) Å, Dm = 2.88(1), Z = 4, Dc = 2.867 g cm−3, space group P212121. The structure was solved by the heavy atom method using 605 diffractometer measured reflections. The final Rfactor was 0.069. The key bond lengths and angles are: Hg—S, 2.39(2) Å, Hg—CH3, 2.13(6) Å, 174°. The CH3HgS— group bends out of the plane of the pyrimidine ring and the Hg atom interacts rather strongly with one of the ring nitrogens with an Hg—N distance of 2.83 Å. However, the Hg … N interaction is very labile in solution, since the two hydrogen atoms in the metapositions are equivalent from the 1H nmr spectra in both CDCl3and DMSO solutions. The solution of the compound is not optically active.

X-ray diffraction studies have revealed that K4UO2(CO3)3is isostructural with (NH4)4UO2(CO3)3; the crystal is monoclinic with a = 10.247(3), b = 9.202(2), c = 12.226(3) Å, β = 95.11(2)°, Z = 4, and space group C2/c. Three carbonate anions are arranged in bidentate fashion in the equatorial plane of UO22+; one of these occupies a C2site and the other two occupy C1sites. All carbonates are significantly distorted from D3hsymmetry. The binding of carbonates to uranyl is strong and thus the lattice can be considered to be composed of [UO2(CO3)3]4−anions and K+cations. The Raman and infrared spectra exhibit fewer lines than predicted for such a crystal. Tentative assignments are suggested for the more prominent bands of the constituent polyatomic species.

Nitrosonium pentanitratoholmate(III), (NO)2Ho(NO3)5, was prepared from holmium metal and dinitrogen tetroxide in anhydrous ethyl acetate. Its crystals are monoclinic with a = 8.094, b = 11.979, c = 14.170 Å and β = 104.7°,Z= 4, space group P21/c. The structure was solved by the heavy-atom method and refined by full matrix least-squares methods to an Rvalue of 0.085 for 1514 observed reflections measured on the G.E. XRD-6 diffractometer. The structure consists of one Ho(NO3)52−and two NO+ions. The holmium is 10-coordinated by five essentially symmetric bidentate nitrate groups which arrange themselves in a trigonal bipyramidal fashion around the metal with a mean Ho—O distance of 2.45 Å. The two NO+ions per metal occupy slightly different environments and give rise to two i.r. bands at 2250 and 2285 cm−1, attributable to the (N, O+) stretching vibration. The mean N—O distance within these ions is 1.00 Å.

The reaction between mercury(II) chloride and thiosemicarbazide (1:2 molar ratio) in ethanol–water (1:1 by volume) gave, almost quantitatively, dichlorobis(thiosemicarbazide)-mercury(II), HgCl2(tsc)2. There was a trace of unidentified black material as a side product. The crystals of HgCl2(tsc)2are orthorhombic with a = 8.675(7), b = 8.123(6), c = 15.786(11) Å, Z = 4, and space group Pbcn. The HgCl2(tsc)2molecule in the crystal has a twofold axis and the mercury atom is bonded to two chlorine atoms at 2.841(3) Å, and two sulfur atoms at 2.417(3) Å, in a highly distorted tetrahedron. The bond angles are: S—Hg—S = 160.7(1)°; Cl—Hg—Cl = 96.6(1)°; S—Hg—Cl = 89.5(1)° (twice) and 103.4(1)° (twice). However, if the close contacts, were counted, the coordination around the Hg atom would be an approximate octahedron.

Reaction of mercury(II) iodide with tetraethylthiuramdisulfide in chloroform and ethanol mixed solvent produced bis(iodo-N,N-diethyldithiocarbamatomercury(II)) and diiodotetraethylthiuramdisulfidemercury(II), HgI2.TETD. The crystal of HgI2.TETD is orthorhombic with a = 13.101(9), b = 13.999(9), c = 22.742(15) Å; space group Pbca. The structure was solved with 1960 observed reflections measured by a G.E. XRD-6 diffractometer. The final Rfactor was 0.064. The mercury atom is four-coordinated with two identical Hg—I distances of 2.668(1) Å and two Hg—S distances of 2.670(7) and 2.737(7) Å. The coordination is tetrahedral.

Air oxidation of Mo2(S2CNEt2)6 in chloroform yielded a disordered crystalline form of tetrakisdiethyldithiocarbamatomolybdenum(V) isohexamolybdate, [Mo(S2CNEt2)4]2 Mo6O19, which is monoclinic, space groupC2/c,a=28.61(2),b=25.74(2),c=12.892(7) Å,ß=115.26(4)°, andZ=4. The structure, refined from 2167 observed MoKa reflections to anR factor of 0.12, consists of discrete Mo(S2CNEt2)4+ cations and Mo6O192- anions. One of the two cations per asymmetric unit is located on a two-fold axis, whereas the other is randomly distributed over two general sites. The two “half” Mo(V) atoms in the two disordered molecules are separated by 1.60(2) Å. The anion is located at a center of symmetry. This phase exhibits different IR, UV, and visible spectra from those of the ordered phase, though both belong to the same space group. The IR spectrum of the product has characteristic features of dithiocarbamate complexes. However, the splitting of theµs(CS) band in the 1000 cm-1 region, a triplet ofµas(CS) at about 600 cm-1, and a shoulder of theµ(MS) band in the 350–370 cm-1 region suggest a highly complex mode of bonding between Mo and dithiocarbamate. Many bands attributable to Mo-O(t) (terminal) and Mo-O(b) (bridge) were observed, indicating substantial deviation of the anion from idealizedOh symmetry.

Oxidation of Mo2[S2CN(C2H5)2]6 with iodine in a 1:2 molar ratio yielded the complex MO[S2CN(C2H5)2]4 I3, for which magnetic susceptibility, NMR, IR, UV/visible spectra, and single crystal X-ray structure are reported. Crystals of Mo[S2CN(C2H5)2]4 I3 are monoclinic, space groupC2/c (No. 15),a=26.242(7),b=7.003(1),c=20.447(3) Å,Do=1.97,Z=4,Dc=1.890 g cm-3. The structure was determined from 1909 observed reflections and refined by blocked cascade least squares to anR factor of 0.042. The core of the cation, Mo[S2CN(C2H5)2]4+, is dodecahedral with approximate point symmetryD2d (¯42m). The eight S atoms coordinated to the Mo center can be divided into two sets, each forming a distorted tetrahedron. The set constituting a flattened tetrahedron has a mean Mo-S distance of 2.545(2) Å, whereas the set that forms an elongated one has a mean value of 2.500(2) Å. The oxidation state of +5 for the molybdenum atom is supported by the thioureide band [v(RNC)] at 1507 cm-1, which lies between those of similar Mo(IV) and Mo(VI) complexes.

Reaction of mercuric iodide with N,N,N′,N′-tetraethylthiuramdisulfide (TETD), gave bis(iodo-N,N-diethyldithiocarbamatomercury(II)) and diiodo-N,N,N′,N′-tetraethylthiuramdisulfidemercury(II). The crystal of the former was mono-clinic with a = 7.645(3), b = 7.787(4), c = 18.005(7) Å and β = 102.08(4)°. The space group was P21/c, with two dimeric molecules per unit cell. Diffractometer measured intensities of 1727 observed reflections were used to determine the structure; the final Rfactor being 0.059. The mercuric ion was three-coordinated with two Hg—S distances of 2.422(4) and 2.644(4) Å and one Hg—I distance of 2.641(1) Å. The dimer had a centre of symmetry and formed an eight-membered ring.

Reactions of tetraethylthioperoxydicarbonic diamide with methylchloromercury(II) gave two kinds of products of formula CH3—Hg[S2CN(C2H5)2] and Hg[S2CN(C2H5)2]2. The latter exists in two crystal forms as reported by Iwasaki who obtained these compounds by other reactions. The former compound is a colorless monoclinic crystal with a = 7.155, b = 7.757, c = 18.248 Å, and β = 96.1°.In methyl N,N-diethyldithiocarbamato mercury(II), the mercury is two-coordinated with CH3—Hg and Hg—S bond distances of 2.04(3) and 2.418(7) Å respectively in a linear fashion. The angle C—Hg—S is 171.2°. The molecule is planar with both CH3— of the ethyl groups bending toward one side of the plane. Two molecules around the centre of symmetry are loosely bridged by two sulfur atoms forming a group and the bridging Hg … S distances are 2.964 (intramolecular) and 3.147 Å (intermolecular). There are two bands between 970 and 1000 cm−1due to C=S and these bands become broad upon coordination. The band is at 522 (ir) and 528 (Raman) cm−1.

Complexes Hg[CH3SCH2CH(NH2)COO]2and Hg[CH3CH2SCH2CH2CH(NH3COO]2(ClO4)2obtained from reactions of yellow HgO with S-methyl-L-cysteine and ethionine respectively have been characterized by X-ray diffraction methods. The former is monoclinic, space group P21, with a = 13.790(4), b = 4.994(1), c = 9.898(2) Å, and β = 106.20(2)°. The Rand Rwfactors were 0.063 and 0.075 respectively for 980 independent reflections. The S-methyl-L-cysteine complex is N,O bonded with two Hg—N bond lengths of 2.16(3) and 2.13(3) Å and . There are eight distances within the range of 2.54–3.75 Å. The three shortest of these are distributed in an equatorial plane with respect to the N—Hg—N moiety. The Hg—O bond length of 2.54(2) Å is associated with the chelate ligand.The ethionine complex is triclinic, space group with a = 11.376(7), b = 12.009(8), c = 9.495(6) Å, α = 94.74(6), β = 108.01(5), and γ = 71.78(5)°. The Rand Rwvalues for all 3526 reflections were 0.083 and 0.10 respectively but Rbecame 0.058 for only observed reflections (I > 3 σ(I)). The Hg2+is bonded to two sulfur, Hg—S = 2.436(5) and 2.537(4) Å, and two oxygen, Hg—O = 2.28(1) and 2.259(9) Å, atoms in a distorted tetrahedron. The Hg2+–carboxylate interactions are stronger in the S-bonded than the N-bonded complex probably indicating a preference for Hg–amine coordination. At low pH when the amino group is protonated, Hg–thioether coordination becomes important for S-substituted amino acids.

Reactions of L-tryptophan and D,L-homocysteine with mercury(II) halides in acidic ethanol/water solutions result in the formation of bis(L-tryptophanium) trichloromercurate(II) (TPTC) and bis(D,L-homocysteine thiolactonium) tetrabromomercurate(II) (HTTB) respectively. Their crystal structures consist of halide-bridged polymeric chains of quasi HgX3−units. The coordination geometry around Hg(II) in both anions is distorted trigonal bipyramidal. There are no chemical bonds between the amino acid cations and the mercury(II) ions. TPTC is monoclinic, space group P21, with a = 16.688(5), b = 5.626(1), c = 14.022(5) Å, β = 108.17(3)°. The structure was solved and refined from 2433 independent counter measured reflections to an Rfactor of 0.062. The two independent tryptophan molecules per asymmetric unit form a single cation via a strong hydrogen bond between the carboxylate groups. Thus the compound can be represented by MHgCl3where M is the cation. One of the three Cl−ions is strongly bonded to one Hg(II) ion and weakly bonded to two other Hg(II) ions. In addition to the three short Hg—Cl distances of 2.403(3), 2.376(4), and 2.614(4) Å, there are two long Hg—Cl bonds of 2.833(4) and 2.888(4) Å to each Hg(II), from the weakly bridged chloride ions. HTTB is orthorhombic, space group Pnmawith a = 8.068(3), b = 24.985(7), and c = 8.828(3) Å. The structure was refined to an Rvalue of 0.066 for 819 observed reflections (I ≥ 3σ(I)), however, inclusion of unobserved reflections did not change the parameters. The homocysteine free base used in the reaction was lactonised under the experimental conditions to a thiolactonium ion. There are three relatively short Hg—Br interactions (2.566(3) twice, 2.662(4) Å) within the distorted trigonal bipyramidal stereochemistry of each mercury atom and two longer Hg—Br bonds (2.917(6) and 3.087(5) Å). The polymeric, anion chains arrange in layers on the mirror planes (y = ±1/4) with these layers sandwiched by two layers of cations.

Ammonium dithiocarbamate, H2NCS2NH4, decomposes easily but the anion forms a stable mercury(II) complex, the crystals of which are orthorhombic with a = 7.851(3), b = 17.565(7), c = 12.051(3) Å, and space group Pbca. The structure was solved by the Patterson method and refined by the full-matrix least-squares method to an Rof 0.038 for 781 reflections. The structure consists of layers of two-dimensional polymeric networks. The dimeric subunits in the layer containing two each of mutually connected Hg atoms and dithiocarbamates are further linked by other bridging dithiocarbamates forming a sheet-like structure. Each Hg atom bonds to four S atoms from four separate dithiocarbamates with Hg—S distances of 2.499(4), 2.508(4), 2.533(4), and 2.629(4) Å. The ir bands observed were: ν(NH2), 3320, 3220, 3125; δ(NH2), 1600; ν(C—N), 1395; ρr(NH2), 1172; and v(C—S), 840 cm−1. The mass spectrum of this polymeric compound gave peaks corresponding to Hg, S2, CNH2, HNCS, S, CS2, S5, S4, S3, and S8in the order of their intensities.

Dibromobis(thiosemicarbazide)mercury(II), HgBr2(tsc)2, is isostructural with dichlorobis-(thiosemicarbazide)mercury(II). The crystal is orthorhombic with a = 8.825(9), b = 8.587(11), c = 15.939(22) Å, Z = 4, space group Pbcn. Some bond lengths and angles are: Hg—Br = 2.860(4) Å, Hg—S = 2.45(1) Å, C—S = 1.76(4) Å and . In both HgCl2(tsc)2and HgBr2(tsc)2, the configuration of the coordinated thiosemicarbazide (tsc) is the same as that of the free molecule. The ir and Raman (R) spectra for the complexes and tsc in the region 300–1600 cm−1are very similar. The strong band at 800 (807 R) cm−1in the tsc due to v(C—S) is shifted to 773 (796 R), 777 (796 R), and 660 (680 R) cm−1for HgCl2−(tsc)2, HgBr2(tsc)2, and HgCl2(tsc) correspondingly. A strong band at 368 (R) cm−1present uniquely for HgCl2(tsc) can be assigned to v(Hg—N), The halides in HgX2(tsc)2are bonded to one mercury(II) ion and weakly bridged to a neighboring molecule with Hg … Cl = 3.250(3) Å and Hg…Br = 3.436(4) Å. As a result, two Raman bands due to Hg—X are expected. For HgCl2(tsc)2, the two Raman bands occur at 236 and 166 cm−1, whereas for HgBr2(tsc)2, one was observed at 190 cm−1but the other was masked by lattice modes. In HgCl2(tsc), the two Hg—Cl bonds are different and bands at 220 and 190 cm−1are assigned to v(Hg—Cl)t.

This is a review of an article entitled"Relying on Accumulated Labor for Capital Construction in Farmland and Water Conservation: An Investigation of Three Production Brigades in I-shui County," which appeared in Ching-chi yen-chiu, 1965, No. 9. The article is the result of a long and much investigated field study of Ta-chai Collective Farm conducted by the agronomy section of the Economic Research Institute in Shantung Province. The economic analysis of the production activities in Ta-chai is excellent and is indeed worth reading.

The reaction between mercury (II) chloride and N,N′-dimethylethylenebisdithiocarbamate gave a white precipitate. In an attempted recrystallization from an aqueous–ethanol solution, a cyclic thiourea-type compound, N,N′-dimethyl-2-imidazolidinethione, was obtained. The crystals of this compound are monoclinic, a = 10.388(2), b = 6.139(1), c = 12.291(4) Å, β = 118.64(2), and space group P21/c. The non-hydrogen atoms of the molecule are planar and the C=S bond length is 1.673(4) Å. The structure was refined by full-matrix least-squares from 642 independent reflections measured on an automatic diffractometer to Rand Rwof 0.053 and 0.068, respectively.

A pale yellow crystal obtained from reaction of HgBr2and tetraethylthiuram disulfide (TETD) has the composition of HgBr2•Hg[S2CN(C2H5)2]2. TETD was reduced to dithiocarbamate. The molecules are polymeric chains with HgBr2and Hg2+alternately bridging to dithiocarbamate ions and vice versa. The crystal is monoclinic: a = 10.421(7), b = 15.244(13), c = 14.649(8) Å, β = 113.3(1)°; space group P21/c. The final Rfactor for 2085 observed reflections is 0.083. There are two types of coordination geometries for the mercury(II) ions in the crystal: the coordination for one is digonal with two short Hg—S distances of 2.385(11) and 2.365(10) Å. The coordination for the other is tetrahedral with two Hg—S, 2.552(10) and 2.569(10) Å, and two Hg—Br, 2.640(4) and 2.552(7) Å, bonds. The average C=S distance is 1.72(4) Å.

Thiosemicarbazidedichloromercury(II) was synthesized in an ethanol–water solution by keeping the molar ratio of HgCl2and thiosemicarbazide (tsc) at 1:1. The crystal is monoclinic: a = 8.966(11), b = 6.817(9), c = 12.092(14) Å, β = 100.3(1)°, and space group P21/cwith four molecules per unit cell. The tsc is a bidentate ligand in this complex with Hg—S = 2.417(6) Å, Hg—N = 2.51(2) Å. The mercury atom is trigonal pyramidally four-coordinated, with two Hg—Cl distances of 2.366(6) and 2.770(5) Å. When the tsc is coordinated to the mercury(II) ions, the chemical shift of the 1H atoms on the NH2and NH groups shift to a lower field.

The single-crystal study of Sb2Tl7confirms the work of Morral and Westgren. The crystal is cubic with a = 11.618(6) Å and space group of Im3m. There are 54 atoms per unit cell. It is the only known example of this structure type which can be considered as a true superlattice of CsCl. The structure was determined using 106 observed reflections measured on a G.E. XRD-6 diffractometer. The final Rand Rwwere 0.097 and 0.060, respectively. The Tl–Tl distances range from 3.21 to 3.55 Å and the mean Sb-Tl distance is 3.27 Å. There is no Sb–Sb contact in the structure

Dibromotetraethylthiuramdisulfidemercury(II) is one of the products of the reaction between mercury(II) bromide and tetraethylthiuram disulfide (TETD). The crystals are orthorhombic with a = 13.050(5), b = 13.593(7), c = 22.373(12) Å; space group Pbca. The compound is isostructural with the iodo analogue. The final Rfactor using 1421 observed reflections is 0.10. Mean bond lengths are: Hg—Br = 1.504(6) Å, Hg—S = 2.66(1) Å. The coordination geometry for mercury(II) is tetrahedral.