- Synthesis, crystal structures and thermal properties of new ZnBr 2(pyrimidine) coordination compounds
-
Four new bromidozinc(II) coordination compounds with pyrimidine as a ligand were prepared, either in solution or by thermal decomposition reactions, and the thermal reactivity and thermodynamic stability of these compounds were investigated. These results are compared with those for the corresponding ZnI2(pyrimidine) compounds. The ligand-rich 1:2 compound dibromidobis(pyrimidine-N)zinc(II) (I) crystallizes in the monoclinic space group P21/n. In this structure the zinc atoms are coordinated by two bromido ligands and two pyrimidine ligands within distorted tetrahedra. On heating, compound I is transformed into the ligand-deficient 2:3 intermediate bis(dibromido)bis(pyrimidine-N)(μ2-pyrimidine-N,N′) dizinc(II) (II), which crystallizes in the monoclinic space group C2/c. The crystal structure consists of two ZnBr2(pyrimidine) subunits, which are connected by an additional pyrimidine ligand through μ-N,N′ coordination. Thermal decomposition of compound II leads to the formation of the ligand-deficient 1:1 compound dibromido(μ2-pyrimidine-N,N′) zinc(II) (III), which crystallizes in the orthorhombic space group Pmma. In compound III, the zinc atoms are coordinated by four bromine atoms and two pyrimidine ligands within distorted octahedra. The ZnBr2 units are connected through common edges into chains, which are linked by the pyrimidine ligands into layers. On heating, compound III is transformed into the ligand-deficient 2:1 compound (ZnBr2)2-(pyrimidine) (IV), which decomposes to give ZnBr2. Solvent-mediated conversion experiments in solution show that not all of the compounds can be prepared by treating ZnBr2 and pyrimidine in the molar ratio given by the formula of the final product. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Naether, Christian,Bhosekar, Gaurav,Jess, Inke
-
-
Read Online
- Synthesis of eight stereoisomers of pochonicine: Nanomolar inhibition of β-N-acetylhexosaminidases
-
Pochonicine, the first naturally occurring polyhydroxylated pyrrolizidine containing an acetamidomethyl group, which was isolated from Pochonia suchlasporia var. suchlasporia TAMA 87, together with its enantiomer and their C-1 and/or C-3 epimers, have been synthesized from the sugar-derived cyclic nitrones 9D and 9L, respectively. An in-depth NMR study showed that both the 1H and 13C NMR spectra of the synthetic pochonicines (1D and 1L) matched very well with those of natural pochonicine in D2O, which unequivocally determined the relative configuration of the natural product as 1D or 1L. In addition, comparison of the optical rotations of the synthetic pochonicines and that of the natural product, but more convincingly their glycosidase inhibition profiles, confirmed the absolute configuration of natural pochonicine as 1R,3S,5R,6R,7S,7aR. Thereby, the structure of natural pochonicine was unequivocally determined as (+)-(1R,3S,5R,6R,7S,7aR)-pochonicine (1D). Glycosidase inhibition experiments showed that natural pochonicine 1D and its epimers 2D, 3D, and 4D all are powerful inhibitors of hexosaminidases (five β-N-acetylglucosaminidases and two β-N-acetylgalactosaminidases) while their enantiomers 1L, 2L, 3L, and 4L are much weaker inhibitors of the same enzymes. (-)-3-epi-Pochonicine (2L) was found to be a potent and selective inhibitor of α-l-rhamnosidase. None of the compounds showed any inhibition of α-GalNAcase.
- Zhu, Jian-She,Nakagawa, Shinpei,Chen, Wei,Adachi, Isao,Jia, Yue-Mei,Hu, Xiang-Guo,Fleet, George W. J.,Wilson, Francis X.,Nitoda, Teruhiko,Horne, Graeme,Van Well, Renate,Kato, Atsushi,Yu, Chu-Yi
-
-
Read Online
- TG and TG-MS methods for studies of the reaction between metal oxide and brominated flame retardant in various atmospheres
-
TG and TG-MS measurements were used to investigate the reactivity of ZnO with HBr originating from thermal degradation of TBBPA and with SbBr3 under various atmospheres. It was found, that the HBr is an excellent brominating agent for ZnO and separates zinc as a volatile bromide (50 and 70% in He and He + 5 vol% O2, respectively) from the solid residue. In inert atmosphere the formed char plays an important role as reduction agent for remaining ZnO into metallic Zn, which vaporizes completely from the residue above 890 °C. In presence of oxygen, the char is oxidized into CO and CO2 and un-reacted ZnO remains. Bromination efficiency from thermal treatment of SbBr3 + ZnO in He is about 14% only. Such low efficiency may results from highly volatile SbBr3 sublimating from the mixture above 100 °C and its high ability to form thermally stable oxybromide compound (Sb8O11Br2). Simultaneous TG-MS measurements indicate that the presence of ZnO strongly influences the TBBPA degradation pathway and causes enhancement of char formation. Catalyzing effect of ZnO on evaporation of SbBr3 was also observed.
- Oleszek, Sylwia,Grabda, Mariusz,Shibata, Etsuro,Nakamura, Takashi
-
-
Read Online
- X-ray diffraction study of CsZn2Br5
-
CsZn2Br5 crystals are studied by X-ray diffraction. The compound crystallizes in the monoclinic system with the unit cell parameters a = 6.8880(12) ?, b = 10.4703(19) ?, c = 6.5197(9) ?, β = 108.25°, V = 446.55 ?3, ρc
- Zaitseva,Kovaleva,Fedorov
-
-
Read Online
- Revealing the structural chemistry of the group 12 halide coordination compounds with 2,2′-bipyridine and 1,10-phenanthroline
-
The coordination compounds of group 12 halides with 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen), 2[CdF2(bpy)2]·7H2O (1), [ZnI(bpy)2]+·I3 ? (2), [CdI2(bpy)2] (3), [Cd(SiF6)H2O(phen)2]·[Cd(H2O)2(phen)2]2+·F–·0.5(SiF6)2–·9H2O (4), [Hg(phen)3]2+·(SiF6)2–·5H2O (5), [ZnBr2(phen)2] (6), 6[Zn(phen)3]2+·12Br–·26H2O (7) and [ZnI(phen)2]+·I– (8), have been synthesized and characterized by X-ray crystallography, IR spectroscopy, elemental and thermal analysis. Structural investigations revealed that metal : ligand stoichiometry in the inner coordination sphere is 1 : 2 or 1 : 3. A diversity of intra- and intermolecular interactions exists in structures of 1–8, including the rare halogen?halogen and halogen?π interactions. The thermal and spectroscopic properties were correlated with the molecular structures of 1–8. Structural review of all currently known coordination compounds of group 12 halides with bpy and phen is presented.
- Swiatkowski, Marcin,Kruszynski, Rafal
-
p. 642 - 675
(2017/02/05)
-
- Molecular complexes of cobalt(II) and Zinc(II) chlorides and bromides with 1-piperidinyl dimethylcarbamodithioate (L): Crystal structures of L and [ZnLBr2]
-
Complexes of MX2(M = Co, Zn; X = Cl, Br) with 1-piperidinyl dimethylcarbamodithioate (L) of composition [MLX2] have been synthesized. The compounds have been studied by elemental analysis; X-ray diffraction; thermogravimetry; conductometry; magnetochemistry; and IR, 1H NMR, and electronic absorption spectroscopy. The ligand molecule is coordinated to the metal atoms in a bidentate chelating mode through the thione sulfur atom and the sulfenamide nitrogen atom to form a five-membered chelate ring. The structures of L and [ZnLBr2] have been determined by X-ray crystallography.
- Seifullina,Khitrich,Vologzhanina
-
p. 184 - 189
(2011/05/04)
-
- PROCESS FOR THE PREPARATION OF 3-BROMO - 4 - FLUOROBENZALDEHYDE
-
The invention relates to a process of manufacturing 3-bromo-4- fluorobenzaldehyde using zinc bromide as a catalyst.
- -
-
Page/Page column 15
(2010/08/09)
-
- Synthesis, crystal structures, and thermal properties of new [ZnX 2(2,5-dimethylpyrazine)] (X = Cl, Br, I) coordination compounds
-
Eight new halidozinc(II) coordination compounds with 2,5-dimethylpyrazine as a ligand were prepared. The reaction of ZnX2 (X = Cl, Br, I) and 2,5-dimethylpyrazine in methanol results in the formation of catena-(μ2-2,5-dimethylpyrazin
- Wriedt, Mario,Jess, Inke,Naether, Christian
-
p. 363 - 372
(2009/04/13)
-
- Investigation on the thermal decomposition some heterodinuclear Ni II-MII complexes prepared from ONNO type reduced Schiff base compounds (M II=ZnII, CdII)
-
N,N'-bis(salicylidene)-1,3-propanediamine (LH2), N,N'-bis(salicylidene)-2,2'-dimethyl-1,3-propanediamine (LDMH2), N,N'-bis(salicylidene)-2-hydroxy-1,3-propanediamine (LOH3), N,N'-bis(2-hydroxyacetophenylidene)-1,3-propanediamine (LACH2) and N,N'-bis(2-hydroxyacetophenone)-2,2'-dimethyl-1,3-propanediamine (LACDMH 2) were synthesized and reduced to their phenol-amine form in alcoholic media using NaBH4 (LHH2, LDM HH2, LOHHH2, LACHH 2 and LACDMHH2). Heterodinuclear complexes were synthesized using Ni(II), Zn(II) and Cd(II) salts, according to the template method in DMF media. The complex structures were analyzed using elemental analysis, IR spectroscopy, and thermogravimetry. Suitable crystals of only one complex were obtained and its structure determined using X-ray diffraction, NiLACH?CdBr2?DMF2, space group orthorhombic, Pbca, a=20.249, b=14.881, c=20.565 A and Z=8. The heterodinuclear complexes were seen to be of [Ni?ligand?MX 2?DMF2] structure (ligand=LH2-, LDM H2-, LOHH2-, LACH2-, LACDMH2-, M=ZnII, CdII, X=Br-, I-). Thermogravimetric analysis showed irreversible bond breakage of the coordinatively bonded DMF molecules followed by decomposition at this temperature.
- Aksu,Durmus,Sari,Emreguel,Svoboda,Fuess,Atakol
-
p. 541 - 547
(2008/10/09)
-
- Synthesis, characterization and calorimetric study of zinc group halide adducts with aniline
-
The adducts ZnCl2·2an, ZnBr2·1.5an, CdCl2·2an, CdBr2·2an, CdI2·2an, HgCl2·2an and HgBr2·2an (where an = aniline) were synthesized and characterized by elemental analysis, infrare
- da Silva Jr., Umberto G.,de Oliveira, ótom A.,de Farias, Robson F.
-
-
- A general route to α-alkyl (E)-α,β-unsaturated aldehydes
-
Bis(trimethylsilyl)-tert-butylaldimines 3 react with aldehydes in the presence of zinc bromide at room temperature to give, after hydrolysis, the desired α-alkyl α,β-ethylenic aldehydes in good yield and with very high E stereoselectivity. The reaction was believed to proceed via the α-silyl β-siloxyimines 4.
- Lahmar, Nour,Aatar, Jamaa,Ayed, Ta?cir Ben,Amri, Hassen,Bellassoued, Moncef
-
p. 3018 - 3026
(2007/10/03)
-
- Thermal decomposition kinetics of some aniline complexes of zinc group metals
-
The kinetics and mechanism of thermal decomposition of aniline complexes of zinc group metals have been studied using non-isothermal thermogravimetry. Kinetic parameters have been calculated for each of the decomposition stages using the Coats-Redfern equation. The mechanisms of the reactions have also been found out, and the rate controlling processes are found to be either random nucleation with the formation of one nucleus on each particle (Mampel equation) or phase boundary reaction with cylindrical symmetry or spherical symmetry.
- Sikha,Indrasenan
-
p. 1393 - 1402
(2007/10/03)
-
- Thermal studies and vibrational analyses of m-methylaniline complexes of Zn(II), Cd(II) and Hg(II) bromides
-
The complexes having the MBr2L2 (M: Zn, Cd and Hg; L: m-methylaniline) formulae have been prepared and characterized by their elemental analyses, thermogravimetric analyses, IR and Raman spectral studies. IR and Raman bands of the complexes have been assigned as compared with the free ligand. Coordination effects on the internal modes of m-methylaniline have been discussed. Vibrational spectra propose that the [ZnBr2(mMA)2] complex is in a tetrahedral environment around Zn(II) ion with C2v symmetry whereas Cd(II) and Hg(II) complexes have 5-coordinate polymeric bromide bridged structures.
- Golcuk,Altun,Kumru
-
p. 1841 - 1847
(2007/10/03)
-
- Empirical correlations involving calorimetric, thermogravimetric and infrared data for zinc halides adducts
-
The use of the non-isothermal Coats-Redfern method to obtain the activation energy values for the processes ZnX2·2hmpa(c) → ZnX2(c)+2hmpa(g) (X = Cl, Br, I and hmpa = hexamethylphosphoramide), by using thermogravimetric data, gave the values 44; 94 and 215 kJ mol-1 for the given sequence of halides. These values correlated to the standard molar enthalpy of formation in the condensed phase for the same sequence of adducts: - 1596, - 1532 and - 1408 kJ mol-1, respectively, providing the equation: ΔfH°m = 1.086 × Ea - 1639.738, which shows a linear correlation between the thermodynamic and kinetic parameters for such solid adducts. The IR spectroscopy data for a series of adducts of zinc halides with amides enabled the acquisition of an equation to estimate the mean metal-ligand bond enthalpy 〈D〉(M-L) values: the spectroscopic data were adjusted to the expression 〈D〉(M-L) = α + β + Δν, where αand β are related to Lewis acidity and basicity coordination features, respectively, and Δν is the difference between C=O or P=O stretching vibrations of the coordinated and uncoordinated ligands. This equation was applied for 15 adducts, showing a deviation less than 10% from the thermochemical values.
- De Farias, Robson F.,Airoldi, Claudio,Scatena Jr., Hélio
-
p. 1677 - 1681
(2008/10/08)
-
- Direct synthesis of unsaturated β-amino acids
-
Zinc bromide promoted addition of trimethylsilyl butenoate lithium enolates to aromatic aldimines. The corresponding β-amino acids were obtained in moderate to good yields as anti isomers. The reaction was believed to proceed via the zinc enolates. A tentative explanation of the selectivity in favour of the anti isomers was proposed.
- Bellassoued, Moncef,Grugier, Jér?me,Lensen, Nathalie
-
p. 172 - 177
(2007/10/03)
-
- The study of new zinc(II) aliphatic carboxylate complex compounds by methods of thermal analysis
-
Four new complex compounds were prepared by the reaction of zinc bromobutyrate and organic ligands. The general formula of the synthetized complex compounds are (2-Brbut)2Zn·L and (4-Brbut)2Zn·L2·nH2O (but=butyr
- Andogova,Gyoeryova,Nour El-Dien
-
p. 245 - 253
(2008/10/08)
-
- Allylmetallation of benzoazaheterocycles with allylic derivatives of zinc. Synthesis of 1,4-ethano-2,3-dihydroisoquinolines and allylated heterocycles
-
Allylmetallation of isoquinolines, quinoline, and quinoxaline with allylic derivatives of zinc was examined for the first time. A convenient procedure was discovered and developed for the synthesis of 1,4-ethano-2,3-dihydroisoquinolines based on the reactions of isoquinolines with allylic derivatives of zinc. This multistage process involves double allylmetallation of the heterocyclic ring followed by cyclization through intramolecular carbometallation of the C=C bond. The structures of three key derivatives of 1,4-ethano-2,3-dihydroisoquinoline were established by X-ray diffraction analysis. The reactions of quinoxaline with allyl-and methallylzinc bromide proceeded stereospecifically to form trans-2,3-diallylated 1,2,3,4-tetrahydroquinoxalines. Heating of quinoline with methallylzinc bromide in THF afforded 4-methallylquinoline in nearly quantitative yield. The initially formed 1,4-metallation product underwent aromatization through elimination of HZnBr.
- Bubnov,Pastukhov,Starikova,Ignatenko
-
p. 2172 - 2182
(2007/10/03)
-
- Thermal behaviour of new zinc(II) bromobutyrate complex compounds
-
New zinc bromobutyrate complexes of general formula ZnX2·1-2L·nH2O (X = CH2Br(CH2)2COO-; CH3CH2CHBrCOO-) containing one or two molecules of caffeine, nicotinamide and phenazone as ligands (L) were prepared. The compounds were characterized by MS-, IR- spectroscopy, chemical and thermal analysis. The thermal decomposition of hydrated compounds starts by the release of water molecules. In anhydrous compounds the loss of organic ligands takes place followed by the decomposition of the bromobutyrate anion at higher temperatures. Zinc bromide was found among the final products of thermal decomposition. Water, carbon monoxide, propylaldehyde, vinylaldehyde and formaldehyde were detected in the gaseous products of the thermally decomposed samples on heating up to 700 °C.
- Gyoeryova,Kovarova,Melnik,Andogova
-
p. 503 - 511
(2008/10/08)
-
- Synthesis and thermal behaviour of new zinc halogeno complex compounds with phenazone and nicotinamide
-
New zinc complex compounds of general formula ZnL2,X2 {X = CI, Br; L = phenazone(phen), nicotinamide(nam)} were synthesized. The new compounds were characterized by elemental analysis, IR spectroscopy and DTA, TG/DTG methods. Thermal
- Gyoryova,Balek,Melnik,El-Dien
-
p. 577 - 584
(2008/10/08)
-
- Disupersilylmetals (tBu3Si)2M and supersilylmetal halides tBu3SiMX with M = Zn, Cd, Hg: Syntheses, properties, structures [1]
-
Disupersilylmetals (tBu3Si)2Zn (colorless), (tBu3Si)2Cd (light yellow), (tBu3Si)2Hg (light yellow), and supersilylmetal halides tBu3SiZnCl(THF) (colorless), tBu3SiCdI (colorless), tBu3SiHgCl (colorless) are obtained in THF by the action of tBu3SiNa on ZnCl2, CdI2, HgCl2 in the molar ratio 2:1 and 1:1, respectively. THF can be exchanged by TMEDA under formation of tBu3SiZnCl(TMEDA), and (tBu3Si)2Zn transforms by the action of BiCl3 or BBr3 into tBu3SiZnCl (colorless) and tBu3SiZnBr (colorless), respectively. As to X-ray crystal structure analyses, the compounds (tBu3Si)2M are monomeric with a linear SiMSi framework, whereas tBu3SiZnBr and tBu3SiHgCl are tetrameric, the former with a regular, the latter with a pronounced irregular cubic M4X4 framework. The compounds are thermal stable up to 200°C (exception (tBu3Si)2Cd), photolabile, and comparatively inert for water and oxygen. The disupersilylmetals work as sources of supersilyl radicals tBu3Si (on irradiation) and as mild supersilanidation agents (e.g. (tBu3Si)2Zn/ BBr3 → tBu3SiZnBr/tBu3SiBBr2), the supersilylmetal halides as Lewis acids (formation of tBu3SiMX · donor) and electrophiles (e.g. tBu3SiHgCl/RLi → tBu3SiHgR/LiCl).
- Wiberg,Amelunxen,Lerner,Noeth,Appel,Knizek,Polborn
-
p. 1861 - 1870
(2008/10/09)
-
- Zinc Bromide: Refinement of X-ray Diffraction Data
-
The crystal data for zinc bromide (tetragonal space group D4h20-141/acd, Z = 32; a = 11.40 ± 0.02 A?, c = 21.82 ± 0.04 A?) is refined by the X-ray diffraction analysis and nuclear quadrupole resonance of 81Br. The X-ray density of zinc bromide is 4.218 g/cm3.
- Kuznetsova,Kovaleva,Fedorov
-
p. 1737 - 1738
(2008/10/08)
-
- Nicotine Complexes of Zinc(II), Cadmium(II) and Mercury(II)
-
Complexes of nicotine(nic), M(nic)nX2 (M = Zn or Cd; n = 2, X = Cl, Br, I or NCS; M = Hg, n = 1, X = Cl, Br or I) have been prepared.The conductivity measurements indicate that the complexes are nonionic.The complexes have been characterised on the basis of analytical, IR and PMR spectral, and thermal studies.
- Muralidharan, S.,Udupa, M. R.,Nagaraja, K. S.
-
-
- STUDIES ON TRANSITION-METAL PICOLINE COMPLEXES - I. PREPARATION AND THERMOANALYTICAL INVESTIGATIONS.
-
A large number of transition-metal picoline halides were prepared, and their thermal decompositions were investigated by TG, DTG, DTA and thermomicroscopy. The compounds were classified on the basis of their thermal properties and two possible mechanisms of thermal decomposition were established.
- Liptay,Borbely-Kuszmann,Nagy
-
-
- Ionic Equilibria in Aqueous Solutions of Zinc Bromide and the Related Heat Data
-
The dissociation constant of ZnBr(1+) == Zn(2+) + Br(1-) has been determined potentiometrically and has been found to be 0.2559, 0.0573, 0.0973 and 0.0339 at 5 deg C, 15 deg C, 25 deg C and 35 deg C respectively.The heat of ionisation ΔH of ZnBr(1+) = Zn(2+) + Br(1-) has been found to be +1331 +/- 100 cals/mole.
- Sinha, H. K.,Prasad, B.
-
p. 999 - 1001
(2007/10/02)
-