Structure of Galactomannans from <Emphasis Type="Italic">Gleditsia delavayi</Emphasis> and <Emphasis Type="Italic">G. aquatica</Emphasis> by <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR Spectroscopy

The structure of galactomannans isolated from seeds of G. delavayi and G. aquatica was studied by ¹H and ¹³C NMR spectroscopy. It was found that the galactomannans consisted mainly of β-1-4-bound mannopyranoses, a part of which was substituted on the C-6 hydroxyl by terminal units of α-galactopyranose.__________Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 12–13, January–February, 2005.     

Molecular structure and decomposition mechanism of peracetic acid esters AcOOR (R = Me,Bu<Superscript>t</Superscript>)

The molecular structure and conformational mobility of methyl and tert-butyl esters of peracetic acid AcOOR (R = Me (1), Bu^t (2)) were studied by the ab initio MP4(SDQ)//MP2(FC)/6-31G(d,p) method and density functional B3LYP/6-31G(d,p) approach. The B3LYP calculated equilibrium conformations of the molecules are characterized by the C-O-O-C torsion angles of 93.6° (1) and 117.0° (2). Structural features of the molecules under study and a distortion of tetrahedral bond configuration at the C_α atom were explained using the natural bonding orbital approach. The standard enthalpies of formation of AcOOMe (−328.5 kJ mol⁻¹) and AcOOBu^t (−440.4 kJ mol⁻¹) were determined using the G2 and G2(MP2) computational schemes and the isodesmic reaction approach. The transition state of AcOOMe decomposition into AcOOH and formaldehyde was calculated (E _a = 122.8 kJ mol⁻¹). The thermal effects of homolytic decomposition of the peroxy esters following a concerted mechanism (Me^· + CO₂ + ^·OR) and simple homolysis of the peroxide bond (AcO^· + ^·OR) were found to be 97.5±0.3 and 155.1±0.3 kJ mol⁻¹, respectively. At temperatures below 400 K, the most probable decomposition mechanism of peroxy esters 1 and 2 involves simple homolysis of the O-O bond.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2021–2027, October, 2004.     

C-Glucosylflavonoid biosynthesis from 2-hydroxynaringenin by Desmodium uncinatum (Jacq.) (Fabaceae)

[2′,3′,5′,6′-²H₄]-2-Hydroxynaringenin is synthesised and incubated with commercially available UDP-glucose and the crude protein extract from Desmoduim uncinatum leaves. The organic extract produces isotopically labelled [2′,3′,5′,6′-²H₄]-vitexin and [2′,3′,5′,6′-²H₄]-isovitexin. Repeating the experiment with denatured protein or replacing the 2-hydroxynaringenin with [2′,3′,5′,6′-²H₄]-apigenin or [2′,3′,5′,6′-²H₄]-naringenin results in no observable incorporation. 2-Hydroxynaringenin is therefore the substrate for C-glucosylflavonoid biosynthesis in D. uncinatum.     

Preparation,Structural Characterization and the Molecular Structure of 2,3,5-Trinitro-<Emphasis Type="Italic">p</Emphasis>-xylene

2,3,5-trinitro-p-xylene (TPX) is synthesized by nitration of p-xylene in mixed acid of nitric and sulfuric acid. Single crystal of TPX is cultured from DMF solution using a slow cooling method. The compound is characterized by FT-IR, ¹H NMR and MS techniques. The crystal structure is determined by X-ray⁴ single-crystal diffraction analysis. The crystal belongs to the monoclinic system with space group P_n. Its unit cell parameters are as follows: a = 0.8271(2), b = 0.6011(1), c = 1.0487(2) nm, β = 105.42(2)^∘, V = 0.50263(2) nm³, D_c = 1.593 g/cm³, Z = 2, F(0 0 0) = 248. The molecular structures of TPX have been calculated at the B3LYP/6-31G^** and B3LYP/6-311G^** levels of theory, and its frequencies analysis have also been accomplished at the same level of theory. The thermal decomposition process of the compound was studied using DSC and TG-DTG techniques. The predicted nitro group vibrations with B3LYP/6-311G^** calculation considerably agree with the observed frequencies. The calculated results propose that the structural parameters from the theory are close to those of the crystal structure from the experiments.     

New bifunctional N-thiophosphorylated thiourea and 2,5-dithiobiurea derivatives. Crystal structures of R[C(S)NHP(S)(OiPr)2]2 (R = –N(Ph)CH2CH2N(Ph)– and –NHNH–)

A new bifunctional N-thiophosphorylated thiourea and 2,5-dithiobiurea of the common formula R[C(S)NHP(S)(OiPr)₂]₂ [R = –N(Ph)CH₂CH₂N(Ph)– (H₂L^a); –NHNH– (H₂L^b)] have been synthesized and characterized by IR, ¹H, ³¹P spectroscopy and the single crystal X-ray diffraction method. The structure of the latter compound in CDCl₃ and acetone-d₆ solutions has been discussed in comparison with the monofunctional thiosemicarbazide PhNHNHC(S)NHP(S)(OiPr)₂ (HL^c).     

Structure and stability of closo-hexaboranes and their heteroanalogs

The molecular and electronic structures of closo-hexaboranes B₆H₆ ^2–, B₆H₇ ^–, and B₆H₈ and closo-heterohexaboranes XYB₄H₄ (X = Y = CH, N; X = BH, Y = CH^–, N^–, NH, O) were studed by the ab initio (MP2(full)/6-311+G**) and density functional (B3LYP/6-311+G**) methods. The bridging H atoms in closo-hexaboranes B₆H₇ ^– and B₆H₈ can undergo facile low-barrier migrations around the boron cage (the barrier heights are about 10—15 kcal mol^–1). All heteroboranes having octahedron-like structures with hypercoordinated N and O atoms are rather stable and can be the subject of synthetic research efforts.     

ααTwo new eudesmane sesquiterpenes from Lactuca sativa var. anagustata L

Two new eudesmane sesquiterpene lactones were isolated from the stalk of Lactuca sativa var.anagustata L and their structureswere elucidated by means of spectroscopic methods,including 2D NMR(~1H-~1H COSY,HMBC and NOESY) as 1β-O-β-D-glucopyranosyl-4α-hydroxyl-5α,6β,11βH-eudesma-12,6α-olide(1) and 1β-hydroxyl-15-O-(p-methoxyphenylacetyl)-5α,6β,11βH-eudesma-3-en-12,6α-olide(2).     

Terpenes,Coumarins, and Flavones from <Emphasis Type="Italic">Acacia pennatula</Emphasis>

The chemical analysis of the acetone extract of the dried leaves from Acacia pennatula yielded triacontanol, β-sitosterol palmitate, β-sitosterol, squalene, nonaprenol, norphytane, lupenone, lupeol, daphnetin and catechin, while from the methanol extract were isolated catechin, epigallocatechin, eriodictyol, β-sitosteryl-β-D-glucopyranoside, and stigmasteryl-β-D-glucopyranoside. The structures of all these natural products were established based on their IR, ¹H, and ¹³C NMR and MS data.__________Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 240–241, May–June, 2005.     

Development of a PVC-membrane ion-selective bulk optode,for UO<Stack><Subscript>2</Subscript><Superscript>2+</Superscript></Stack> ion,based on tri-<Emphasis Type="Italic">n</Emphasis>-octylphosphine oxide and dibenzoylmethane

A novel uranyl ion-selective bulk optode membrane, incorporating tri-n-octylphosphine oxide for cation recognition and a lipophilic chromoionophore dibenzoylmethane, has been prepared. The PVC membrane composition was optimized to result in the widest working concentration range. The response range of the proposed optode is 4.1×10^–6 to 2.0×10^–4 mol L^–1 UO₂²⁺. The probe works at pH 4.0. Ion interference is low and selectivity, reproducibility, and stability are good.     

Synthesis of Schiff bases and benzylamino derivatives containing [1-B<Subscript>10</Subscript>H<Subscript>9</Subscript>NH<Subscript>3</Subscript>]<Superscript>−</Superscript> anion

Reactions of an amino derivative of the closo-decaborate anion [1-B₁₀H₉NH₃]^– with aromatic aldehydes afforded Schiff bases [1-B₁₀H₉NH=CHAr]^– (Ar=Ph, C₆H₄-2-OMe, or C₆H₄-4-NHCOMe). The reduction of the latter with sodium borohydride gave the corresponding benzylamino derivatives [1-B₁₀H₉NH₂CH₂Ar]^–.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2004–2007, September, 2004.     

Olefin epoxidation catalyzed by [Ru(TDL)(tmeda)H2O] complexes (TDL = tridentate Schiff-base ligand; tmeda = tetramethylethylenediamine)

Mixed-chelate complexes of ruthenium have been synthesized using tridentate Schiff-base ligands (TDLs) derived from condensation of 2-aminophenol or 2-aminobenzoic acid with aldehydes (salicyldehyde, 2-pyridinecarboxaldehyde), and tmeda (tetramethylethylenediamine). [Ru^III(hpsd)(tmeda)(H₂O)]⁺ (1), [Ru^III(hppc)(tmeda)(H₂O)]²⁺ (2), [Ru^III(cpsd)(tmeda)(H₂O)]⁺ (3) and [Ru^III(cppc)(tmeda)(H₂O)]²⁺ (4) complexes (where hpsd²⁻ = N-(hydroxyphenyl)salicylaldiminato); hppc⁻ = N-(2-hydroxyphenylpyridine-2-carboxaldiminato); cpsd²⁻ = (N-(2-carboxyphenyl)salicylaldiminato); cppc⁻ = N-2-carboxyphenylpyridine-2-carboxaldiminato) were characterized by microanalysis, spectral (IR and UV–vis), conductance, magnetic moment and electrochemical studies. Complexes 1–4 catalyzed the epoxidation of cyclohexene, styrene, 4-chlorostyrene, 4-methylstyrene, 4-methoxystyrene, 4-nitrostyrene, cis- and trans-stilbenes effectively at ambient temperature using tert-butylhydroperoxide (t-BuOOH) as terminal oxidant. On the basis of Hammett correlation (log k_rel vs. σ⁺) and product analysis, a mechanism involving intermediacy of a [Ru–O–OBu^t] radicaloid species is proposed for the catalytic epoxidation process.     

Ramanspektroskopische Untersuchungen an PCl5 II. Das System PCl5—ZrCl4

Raman spectra of some solid and molten PCl₅–ZrCl₄ mixtures have been recorded. ZrCl₆ ^2– complex ions accompanied by at least one more chlorozirconate species are present in the solid as well as in the melt. The newRaman frequencies are attributed to ZrCl₅ ^–, which fundamentals are given and assignment is proposed to be analogous to TiCl₅ ^–. The presence of ZrCl₆ ^2– and ZrCl₅ ^– can be explained by the equilibrium ZrCl₆ ^2–+PCl₄ ⁺ZrCl₅ ^–+PCl₅.

     

Fabrication of a novel Li<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MoO<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> film modified electrode and its application as an electrochemical sensor of iodate

A novel organic gel film modified electrode was simply and conveniently fabricated by casting Li_xMoO_y and polypropylene carbonate (PPC) onto the surface of a gold electrode. The cyclic voltammetry and amperometry studies demonstrated that the Li_xMoO_y film modified electrode has a high stability and a good electrocatalytic activity for the reduction of iodate. In amperometry, a good linear relationship between the steady current and the concentration of iodate was obtained in the range from 3×10^–7 to 1×10^–4 mol L^–1 with a correlation coefficient of 0.9997 and a detection limit of 1×10^–7 mol L^–1.     

B-frame supported bimetallics. [(PMe2ph)2PtB9H11Ru(η-PrC6H4Me)] and [(PMe2ph)2PtB9H9Ru(η-PrC6H4Me)]; an interesting pair of electron-deficient nido and closo geometries

[7,7-(PMe₂Ph)₂-9-(η⁶-^isoPrC₆H₄Me)-7,9-PtRuB₉H₁₁] has a formal closo Wadian cluster-electron count, but a nido geometry, whereas [1-(η⁶-^isoPrC₆H₄Me)-4,4-(PMe₂Ph)₂-1-4-RuPtB₉H₉], which does have a closo geometry, has a formal sub-closo cluster electron count; both compounds are formed in the reaction between [6-(η⁶-^isoPrC₆H₄Me)-nido-6 RuB₉H₁₃], KH and [PtCl₂(PMe₂Ph)₂].     

Nucleophilic addition of bifunctional sulfimidosulfides to platinum(<Emphasis Type="SmallCaps">IV</Emphasis>)-coordinated nitriles

Reactions of the platinum(IV) nitrile complexes [PtCl₄(RCN)₂] (R = Me, CH₂Ph, Ph) with 1,2- and 1,4-PhS(=NH)C₆H₄SPh in CH₂Cl₂ afforded addition products of sulfimides and coordinated nitriles, viz., the [PtCl₄{NH=C(R)N=S(Ph)(C₆H₄SPh)}₂] complexes. The latter were isolated in 75—90% yields and characterized by elemental analysis, positive-ion FAB mass spectrometry, IR spectroscopy, and ¹H and ¹³C¹H NMR spectroscopy. The temperature dependence of the ¹H NMR spectra of the model [PtCl₄{NH=C(R)N=SPh₂}₂] complexes (R = Me, Et) in CD₂Cl₂ studied in a temperature range from +40 to -70 °C demonstrated that E—Z isomerization of the ligands is a dynamic process in a range from +40 to -10 °C. The activation free energy of this process was calculated.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1618–1622, August, 2004.     

Group 9 half-sandwich complexes containing the unique P,P′-diphenyl-1,4-diphospha-cyclohexane ligand: Synthesis, X-ray structure analyses and spectroscopic studies

We wish to report the synthesis and characterization of Group 9 metal complexes with the novel P,P′-diphenyl-1,4-diphospha-cyclohexane (dpdpc) ligand. The complexes are readily prepared by direct ligand substitution reactions from the dichloro-bridged binuclear complexes, [{η⁵-Cp*M(Cl)₂}₂]. The complexes include: [η⁵-Cp*Rh(Cl)₂]₂(μ-dpdpc) (1), [η⁵-Cp*Ir(Cl)₂]₂(μ-dpdpc) (2), and [η⁵-Cp*Rh(Cl)(dpdpc)]PF₆ (3). The structures for all three complexes are supported by ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy as well as elemental analysis. The molecular structures of 1 and 3 have also been established by single-crystal X-ray analysis.     

η- and η-benzene coordination in [Ag(C6D6)3BF4]

The title complex with one η² and two η¹ deuterobenzene and one monodentate BF₄ ligands was isolated as a by-product in the reaction between [(dppe)RhCl]₂ and EtCl in C₆D₆, in the presence of AgBF₄ and its X-ray crystal structure determined.     

Layered Crystalline Barium Phenylphosphonate as Host Support for <Emphasis Type="Italic">n</Emphasis>-Alkylmonoamine Intercalation

Layered barium phosphonate, synthesized by combining the metallic salt with a phenylphosphonic acid solution, yielded Ba(HO₃PC₆H₅)₂ ·H₂O (BaPP), which gives the corresponding anhydrous compound on heating. n-Alkylmonoamines intercalation into the crystalline lamellar precursor resulted in compounds having the general formula Ba(HO₃PC₆H₅)₂ ·xH₂N(CH₂) _n CH₃ ·(1−x)H₂O (n=1–5). The intense infrared bands in the 1160–695 cm⁻¹ interval confirmed the presence of the phosphonate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns for both hydrated and anhydrous compounds. The thermogravimetric curves for both supports showed the release of water molecules and the organic moiety in distinct stages to yield a final Ba(PO₃)₂residue. An additional amine mass loss steps was observed for the corresponding aminated compounds. One isolated DSC peak found in the layered precursor compound contrasts by its absence in the anhydrous form and the ³P NMR spectrum presented one peak for attached phenylphosphonate groups centered at 12.4 ppm. An increase in carbon and hydrogen percentages for intercalated compounds followed the amine size chain with a corresponding decrease in nitrogen percentage. The interlayer distance (d) correlates linearly with the number of carbon atoms (n _c ) of the alkylamine chains, d=1467 + 62n _c and d=1688 + 60n _c , for the hydrated and anhydrous compounds, respectively, permitting inference of the interlayer distance for an unknown amine.This revised version was published online in July 2005 with a corrected issue number.     

Lithiated γ-O-functionalized propyl phenyl sulfides and sulfones of the type Li[CH(SOxPh)CH2CH2OR] (x = 0, 2). [Li{CH(SPh)CH2CH2Ot-Bu}(tmeda)] – A structurally characterized organolithium inner complex

Lithiation of O-functionalized alkyl phenyl sulfides PhSCH₂CH₂CH₂OR (R = Me, 1a; i-Pr, 1b; t-Bu, 1c; CPh₃, 1d) with n-BuLi/tmeda in n-pentane resulted in the formation of α- and ortho-lithiated compounds [Li{CH(SPh)CH₂CH₂OR}(tmeda)] (α-2a–d) and [Li{o-C₆H₄SCH₂CH₂CH₂OR)(tmeda)] (o-2a–d), respectively, which has been proved by subsequent reaction with n-Bu₃SnCl yielding the requisite stannylated γ-OR-functionalized propyl phenyl sulfides n-Bu₃SnCH(SPh)CH₂CH₂OR (α-3a–d) and n-Bu₃Sn(o-C₆H₄SCH₂CH₂CH₂OR) (o-3a–d). The α/ortho ratios were found to be dependent on the sterical demand of the substituent R. Stannylated alkyl phenyl sulfides α-3a–c were found to react with n-BuLi/tmeda and n-BuLi yielding the pure α-lithiated compounds α-2a–c and [Li{CH(SPh)CH₂CH₂OR}] (α-4a–b), respectively, as white to yellowish powders. Single-crystal X-ray diffraction analysis of [Li{CH(SPh)CH₂CH₂Ot-Bu}(tmeda)] (α-2c) exhibited a distorted tetrahedral coordination of lithium having a chelating tmeda ligand and a C,O coordinated organyl ligand. Thus, α-2c is a typical organolithium inner complex.Lithiation of O-functionalized alkyl phenyl sulfones PhSO₂CH₂CH₂CH₂OR (R = Me, 5a; i-Pr, 5b; CPh₃, 5c) with n-BuLi resulted in the exclusive formation of the α-lithiated products Li[CH(SO₂Ph)CH₂CH₂OR] (6a–c) that were found to react with n-Bu₃SnCl yielding the requisite α-stannylated compounds n-Bu₃SnCH(SO₂Ph)CH₂CH₂OR (7a–c). The identities of all lithium and tin compounds have been unambiguously proved by NMR spectroscopy (¹H, ¹³C, ¹¹⁹Sn).     

X-ray Crystal and Ab Initio Structures of 3′,5′-di-O-Acetyl-N(4)-Hydroxy-2′-Deoxycytidine and Its 5-Fluoro Analogue: Models of the N(4)-OH-dCMP and N(4)-OH-FdCMP Molecules Interacting with Thymidylate Synthase

The crystal and molecular structures of the 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine molecule and its 5-fluoro congener have been determined by X-ray single crystal diffraction. The 3′,5′-di-O-acetyl-N(4)-hydroxy-5-fluoro-2′-deoxycytidine molecule crystallizes in the space group C2 with the following unit cell parameters: a = 21.72 Å, b = 8.72 Å, c = 8.61 Å, and β = 90.42^∘. 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine also belongs to the monoclinic space group C2 and the unit cell parameters are: a = 39.54 Å, b = 8.72 Å, c = 22.89 Å, and β = 95.26^∘. The non-fluorine analogue demonstrates a rare example of crystal structure with five symmetry-independent molecules in the unit cell. All the molecules in both crystal structures have the sugar residue anti oriented with respect to the base, as well as have the N(4)-OH residue in cis conformation relatively to the N(3)-nitrogen atom. In addition to the molecular geometries from X-ray experiment, the optimized molecular geometries have been obtained with the use of theoretical ab initio calculations at the RHF/6-31G(d) level. The corresponding geometric parameters in the molecules of 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine and its 5-fluoro congener have been compared. The differences including the C(5)=C(6) bond shortening and C(4)—C(5)—C(6) angle widening in the fluorine analogue are discussed in this paper in relation to the molecular mechanism of enzyme, thymidylate synthase, inhibition by N(4)-hydroxy-2′-deoxycytidine monophosphate and its 5-fluoro congener.