首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 609 毫秒
1.
New hexamethylenetetramine complexes of antimony and bismuth trichloride were synthesized through a solid phase reaction of hexamethylenetetramine and antimony or bismuth trichloride. The formula of the complex is MCl3(C6H12N4)2⋅H2O (M=Sb, Bi).The crystal structure of the complexes belongs to monoclinic system and the lattice parameters: a=1.249 nm, b=1.4583 nm, c=1.6780 nm andβ=91.78° for SbCl3(C6H12N4)2⋅H2O and a=1.3250 nm, b=1.3889 nm, c=1.7449 nm and β=98.94° for BiCl3(C6H12N4)2⋅H2O. Far-infrared spectra reveal that the antimony or bismuth ion is coordinated by the nitrogen atom of the hexamethylenetetramine. The thermal analysis also demonstrates the complex formation between the antimony or bismuth ion and hexamethylenetetramine. The intermediate and final residues in the thermal decomposition process have been analyzed to check the pyrolysis reaction. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

2.
It is demonstrated by means of collisionally activated decomposition (CAD) that [C3H5O]+ originating from metastable [C4H8O] ions are either acylium [C2H5CO]+ (a) or hydroxycarbenium [CH2CHCHOH]+ (b). Butanone gives exclusively a but 2-methyl-2-propen-1-ol, 2-buten-1-ol, 3-buten-1-ol, butanal and 2-methylpropanal lead to ion b. Both structures a and b are produced from 3-buten-2-ol. These results are discussed in conjunction with experimental and calculated (MINDO/3) thermodynamic data.  相似文献   

3.
The thermal decomposition process of mixtures of CoC2O4⋅2H2O (COD) or Co(HCOO)2⋅2H2O (CFD) or [Co(NH3)6]2(C2O4)3⋅4H2O (HACOT) with activated carbon was studied with simultaneous TG–DTG–DTA measurements under non-isothermal conditions in argon and argon/oxygen admixtures. The results show that the thermal decomposition of the studied mixtures in Ar proceeds in the same manner. It begins with the salt decomposition to Comet+CoO mixture followed by (T>680 K) the simultaneous reduction of CoO to Cometand carbon degasification. The final product of the thermal decomposition of COD-C and CFD-C mixtures, identified by XRD, is β-Co. Cobalt contents determined in the final products fall in the range 71–78 mass%. The rest is amorphous residual carbon. In Ar/O2 admixtures the end product is Co3O4 with ash admixture. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

4.
Hydrazinium oxydiacetate salts of formulae N2H5(Hoda)⋅H2oda, N2H5(Hoda) and (N2H5)2oda (H2oda=oxydiacetic acid) and complexes of the types, M(oda)⋅2N2H4xH2O (where M=Co, Ni and Cd; x=0 for Co and Ni;x=1 for Cd) and Zn(oda)⋅N2H4⋅H2O have been prepared and characterized by analytical, spectral, thermal and X-ray powder diffraction data. IR data document the existence of N2H+ 5 ion in the simple salts and the bidentate coordination of both hydrazine and dianion in the complexes. Complete decomposition of hydrazinium salts takes place via oxydiacetic acid intermediate. Cobalt and nickel complexes decompose in a single step, whereas zinc and cadmium complexes decompose through hydrazinate intermediates. However, all the metal complexes yield metal oxide as the final residue. Isomorphic nature of the cobalt and nickel complexes is evident from XRD data. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

5.
New mixed-ligand complexes of general formulae Mn(4-bpy)(CCl3COO)2⋅H2O, Ni(4-bpy)2(CCl3COO)2⋅2H2O and Zn(4-bpy)2(CCl3COO)2⋅2H2O (where 4-bpy=4,4’-bipyridine) were obtained and characterized. The IR spectra, conductivity measurements and other physical properties of these compounds were discussed. The central atoms M(II) form coordinate bonds with title ligands. The thermal behaviour of the synthesized complexes was studied in air. During heating the complexes decompose via different intermediate products to Mn3O4, NiO and ZnO; partial volatilization of ZnCl2was observed. A coupled TG-MS system was used to the analysis of the principal volatile thermal decomposition products of Mn(II) and Ni(II) complexes. The principal volatile mass fragments correspond to: H2O+, OH+, CO+ 2, HCl+, Cl+ 2, CCl+ and other. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

6.
The solid state thermal behavior of trans-[Co(bpb)(amine)2]NCS⋅H2O complexes where (bpb)=[N,N’-bis(2-pyridinecarboxamido-N)-1,2-benzene], and amine=pyrrolidine (prldn)(1), and benzylamine (bzlan) (2), and trans-[Co(bpb)(piperidine)2]ClO4⋅H2O (3) (mixed with KSCN), has been studied using thermoanalytical techniques, infrared spectroscopy, and pyrolysis coupled to both infrared and mass spectrometry, PY/FTIR and PY/MS. The deamination-anation reaction is clearly observed for all three complexes. The estimated values of E a for the deamination-anation are: E a(1)=246.8 kJ mol−1, E a(2)=255.7 kJ mol−1, E a(3)=234.7 kJmol−1. The trend in E a values is rationalized based on the ligand field strength of the amines and the structural effects. A novel decarbonylation of the amide CO group from the equatorial ligand is observed after the release of one amine molecule. This process has been monitored for complex (1) by FTIR in the carbonyl region and by mass spectrometry for the detection of CO2 at 280°C. The activation energy of this process is estimated for complex (1) (662.5 kJ mol−1). The reaction scheme for the observed reactions is proposed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

7.
By diffusion in gel medium new complexes of formulae: Nd(btc)⋅6H2O, Gd(btc)⋅4.5H2O and Er(btc)·5H2O (where btc=(C6H3(COO)3 3−) were obtained. Isomorphous compounds were crystallized in the form of globules. During heating in air atmosphere they lose stepwise water molecules and then anhydrous complexes decompose to oxides. Hydrothermally synthesized polycrystalline lanthanide trimellitates form two groups of isomorphous compounds. The light lanthanides form very stable compounds of the formula Ln(btc)⋅nH2O (where Ln=Ce−Gd and n=0 for Ce; n=1 for Gd; n=1.5 for La, Pr, Nd; n=2 for Eu, Sm). They dehydrate above 250°C and then immediately decomposition process occurs. Heavy lanthanides form complexes of formula Ln(btc)⋅nH2O (Ln=Dy−Lu). For mostly complexes, dehydration occurs in one step forming stable in wide range temperature compounds. As the final products of thermal decomposition lanthanide oxides are formed.  相似文献   

8.
 In order to calculate more accurately the enthalpies of formation, ΔH f°(298 K), for large molecules using the CBS-4M method, a new formulation of the empirical higher-level correction to the energy is proposed: ΔE=a|S|2 i i I i i +b(n α+n β)+cΔ<S 2>+Σn i d i . The new methodology (CBS-4MB) applied to a set of 114 molecules of different size significantly decreases the mean absolute deviation from 3.78 to 2.06 kcal/mol. Received: 7 February 2001 / Accepted: 5 April 2001 / Published online: 13 June 2001  相似文献   

9.
The protonation constants for oxidized glutathione, H i−1L(4−i+1)−, K i H=[H i L(4−i)−]/[H i−1L(4−i+1)−][H+] i=1,2,…,6 have been measured at 5, 25 and 45 °C as a function of the ionic strength (0.1 to 5.4 mol⋅[kg(H2O)]−1) in NaCl solutions. The effect of ionic strength on the measured protonation constants has been used to determine the thermodynamic values (K i H0) and the enthalpy (ΔH i ) for the dissociation reaction using the SIT model and Pitzer equations. The SIT (ε) and Pitzer parameters (β (0), β (1) and C) for the dissociation products (L4−, HL3−, H2L2−, H3L, H4L, H5L+, H6L2+) have been determined as a function of temperature. These results can be used to examine the effect of ionic strength and temperature on glutathione in aqueous solutions with NaCl as the major component (body fluids, seawater and brines).  相似文献   

10.
The low-energy fragmentation characteristics of the [H3,C,N,O2] isomers [H3CNO2] (a), [H2C?N(O)OH] (b), [H3CONO] (c), [HC(O)NHOH] (d) and [HC(OH)?NOH] (e) were studied in detail by metastable ion mass spectrometry. In agreement with most earlier observations, appearance energy measurements established the potential energy surface of the isomers a, b and c, showing the intricate interrelations between them. It was concluded that a isomerizes into b prior to fragmentation by loss of ·OH and H2O and into c before loss of ·H and H3CO· moreover, the reverse reactions do not take place on the metastable time-frame. The dominant metastable process for isomers d and e (obtained via HCN loss from glyoxime) was generation of [H2NOH]. For isomer e this process was proposed to involved a rate-determining isomerization into d. It was concluded that isomers d and e do not intercommunicate with ions a, b and c prior to fragmentation. Neutralization-reionization mass spectrometry indicated that the enol form of formohydroxamic acid as well as the keto counterpart are stable in the gas phase.  相似文献   

11.
Thermal decomposition processes of selected chemicals used as food preservatives such as sodium formate, sodium propionate, sodium nitrates(V and III) and sodium sulphate(IV) were examined by the derivatographic method. Based on the curves obtained, the number of decomposition stages and characteristic temperatures of these compounds have been found. Mass decrements calculated from TG curves ranged from 28.9% for sodium formate to 77.8% for sodium nitrate(V), while sodium sulphate showed a mass increment of 5.6%. Kinetic parameters such as activation energy (E a ), frequency factor (A ) and reaction order (n ) were calculated from TG, DTG and T curves. Sodium formate shows the highest values of E a and A which amount to 171.7 kJ mol–1 and 5.8⋅1014 s–1 , respectively, while the lowest ones, E a =28.2 kJ mol–1 and A =3.65⋅102 s–1 belong to sodium nitrate(V). This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

12.
The complexes of α-alanine-salicylal Schiff base of magnesium (α-ASSM), β-alanine-salicylal Schiff base of magnesium (β-ASSM) and taurine-salicylal Schiff base of magnesium (TSSM) were synthesized. The formulae of the complexes are Mg[OC6H4CHNCH(CH3)COO]·2H2O, Mg[OC6H4CHNCH2CH2COO]·2H2O and Mg[OC6H4CHNCH2CH2SO3]·2H2O. The crystal structure belongs to orthorhombic system with the lattice parameters: a=1.6954 nm, b=2.0873 nm and c=2.3037 nm for the β-ASSM, to orthorhombic system with the lattice parameters: a=1.5586 nm, b=1.8510 nm and c=2.6240 nm for the β-ASSM, to monoclinic system with the lattice parameters: a=1.3232 nm, b=1.4960 nm, c=2.1543 nm and β=98.04° for the TSSM, respectively. The results of the thermal decomposition processes and infrared spectra of the complexes show that the complexes may possess different coordination structures.  相似文献   

13.
李悦生 《高分子科学》2011,29(5):627-633
Mono salicylaldiminato vanadium(Ⅲ) complexes(1a-1f)[RN = CH(ArO)]VCl2(THF)2(Ar = C6H4(1a-1e),R = Ph,1a;R = p-CF3Ph,1b;R = 2,6-Me2Ph,1c;R = 2,6-iPr2Ph,1d;R = cyclohexyl,1e;Ar = C6H2tBu2(2,4),R = 2,6-iPr2Ph, 1f) and bis(salicylaldiminato) vanadium(Ⅲ) complexes(2a-2f)[RN = CH(ArO)]2VCl(THF)x(Ar = C6H4(2a-2e),x = 1 (2a-2e),R = Ph,2a;R =p-CF3Ph,2b;R = 2,6-Me2Ph,2c;R = 2,6-iPr2Ph,2d;R = cyclohexyl,2e;Ar = C6H2tBu2(2,4),R = 2,6-iPr2Ph,x = 0,2f) have been evaluated as the active catalysts for ethylene/1-hexene copolymerization in the presence of Et2AlCl.The ligand substitution pattern and the catalyst structure model significantly influenced the polymerization behaviors such as the catalytic activity,the molecular weight and molecular weight distribution of the copolymers etc.The highest catalytic activity of 8.82 kg PE/(mmolV·h) was observed for vanadium catalyst 2d with two 2,6-diisopropylphenyl substituted salicylaldiminato ligands.The copolymer with the highest molecular weight was obtained by using mono salicylaldiminato vanadium catalyst 1f having ligands with tert-butyl at the ortho and para of the aryloxy moiety.  相似文献   

14.
X-ray crystal structure determinations together with density functional theory (DFT) calculations in vacuo and NMR studies in solution have been carried out for 4-MeOC6H4CONPriOH 2a and 3,5-(NO2)2C6H3CONPriOH 2b. The results were compared with that for the respective N-methyl benzohydroxamic acids. For crystal structures as well as for DFT-optimized geometries of 2 (both isomers) in vacuo, the effect of substituents in aromatic ring manifested by changing of charges is inconspicuous. Studies of potential energy surfaces showed that libration barrier around ω 1 = 0° is low enough to make electron conjugation feasible, and that for 2b rotation barrier around C(O)N bond is higher by 6 kcal/mol and additionally, that rotation around N–C bond is hindered. A careful analysis of low-temperature 1H NMR spectra confirmed the greater stability of Z-2a, the greater rigidity of E-2b and the influence of solvent on both isomers population. Despite solvent-dependent conformational alteration, both 2a and 2b crystallize exclusively as E isomers from ethyl acetate solution. Correlations of absolute 1H, 13C, and 15N shielding calculations with experimental data were also analyzed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

15.
The new mixed ligand complexes with formulae Co(4-bpy)2L2⋅2H2O (I), Cu(4-bpy)2L2⋅H2O (II) and Cd(4-bpy)L2⋅H2O (III) (4-bpy=4,4'-bipyridine, L=CCl3COO) were prepared. Analysis of the IR spectra indicate that 4-bpy is coordinated with metal ions and carboxylates groups bond as bidentate chelating ligands. The electronic spectra are in accordance with pseudo-octahedral environment around the central metal ion in the Co(II) and Cu(II) complexes. The thermal decomposition of the synthesized complexes was studied in air. A coupled TG-MS system was used to analyse the principal volatile thermal decomposition products of Co(II) and Cu(II) complexes. Corresponding metal oxides were identified as a final product of pyrolysis with intermediate formation of metal chlorides. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Three new complex compounds of general formula Zn{4-ClC6H3-2-(OH)COO}2L2nH2O (where L=thiourea (tu), nicotinamide (nam), caffeine (caf), n=2,3), were prepared and characterized by chemical analysis, IR spectroscopy and their thermal properties were studied by TG/DTG, DTA methods. It was found that the thermal decomposition of hydrated compounds starts with the release of water molecules. During the thermal decomposition of anhydrous compounds the release of organic ligands take place followed by the decomposition of salicylate anion. Zinc oxide was found as the final product of the thermal decomposition performed up to 650°C. RTG powder diffraction method, IR spectra and chemical analysis were used for the determination of products of the thermal decomposition.  相似文献   

17.
Few novel mixed ligand copper(II) complexes of the type [Cu(L)(Cl)2(H2O)], [Cu(L)2]Cl2, [Cu(L)L1] and [Cu(L)(phen)H2O]Cl2 (where L is the ligand obtained from the condensation of N-(2-aminoethyl)-1,3-propanediamine with m-nitrobenzaldehyde (La)/o-chlorobenzaldehyde (Lb)/benzaldehyde (Lc)/p-methoxybenzaldehyde (Ld)/p-hydroxybenzaldehyde (Le)/furfuraldehyde (Lf)/pyrrole-2-carboxaldehyde (Lg); L1 is another ligand obtained from the condensation of anthranilic acid with salicyaldehyde; phen = 1,10-phenanthroline) have been synthesized and characterized by the spectral and analytical techniques. From these data, it is found that the ligands adopt distorted octahedral geometry on metalation with Cu(II) ion. The XRD data indicate that the complexes are polycrystalline with nanosized grains. The SEM images of [Cu(La)phen(H2O)]Cl2 and [Cu(Lf)2]Cl2 complexes show that they have leaf and cauliflower like morphology. The in vitro biological screening effects of the investigated compounds have been tested against the bacteria such as Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aeruginosa and Staphylococcus aureus and fungi such as Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the well diffusion method. A comparative study of MIC values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. An electrochemical study of the copper complexes containing electron withdrawing substituted ligands reveals that they prefer to bind to DNA in Cu(II) rather than Cu(I) oxidation state.  相似文献   

18.
A series of indole- and carbazole-substituted pyridinium iodide salts has been synthesized and characterized. X-ray analysis revealed that the iodide salt of the indole-substituted cation (E)-4-(1H-indol-3-yl­vinyl)-N-methyl­pyridinium (IMPE+), C16H15N2+·I, (I), has two polymorphic modifications, (Ia) and (Ib), and a hemihydrate structure, C16H15N2+·I·0.5H2O, (II). Until now, only one crystal modi­fication has been identified for the (E)-4-(9-ethyl-9H-carbazol-3-yl­vinyl)-N-methyl­pyridinium (ECMPE+) iodide salt, C22H21N2+·I, (III). Crystals of (Ia) and (Ib) comprise stacks of antiparallel cations with iodide anions located in the channels between the stacks. Due to the presence of the water mol­ecules, the packing in (II) is quite different to that found in (Ia) and (Ib), and positional disorder involving a statistical superposition of two rotamers of IMPE+, with different orientations of the indole fragment, was found. Crystals of (III) contain two independent ECMPE+ rotamers with different orientations of their carbazole substituents. The cations are packed in stacks, with the iodide anions located in the channels between the stacks. In (III), the iodide was found to be disordered over two sites, with occupancies of 0.83 and 0.17.  相似文献   

19.
Dissociative electron ionization of diethyl dithiophosphate (I) and O,O′-diethyl methylphosphonothioate (II) generates moderately abundant m/z 81 ions of composition [P, O, S, H2]+. From tandem mass spectrometry experiments and theoretical calculations at the B3LYP/6-31G(d,p), G2, and G2 (MP2) levels it is concluded that the majority of the ions have the structure of HS-P-OH+ (1a +) and it is separated by high-energy barriers from its isomers P(= S)OH2+ (1b +), P(= O)SH2+ (1c +), HP(= S)OH+ (1d +), and HP(= O)SH+ (1e +). Low-energy (metastable) ions 1a + dissociate via losses of H2O and H2S to yield m/z 63 (PS+) and m/z 47 (PO+) product ions, respectively. These reactions involve isomerization of 1a + into the stable isomers 1b + and 1c +. Neutralization-reionization experiments confirm the theoretical prediction that radical 1a · is a stable species in the gas-phase. Variable-time NR experiments indicated that only a small fraction of metastable 1a · radicals dissociate in the 0.4–4.6 μs time window, while most dissociations occurred on a shorter time scale. RRKM calculations were performed to investigate unimolecular dissociation kinetics of 1a · which were found to be in agreement with the fragmentation observed in the NR spectrum. The 70-eV electron ionization of (I) and diethyl chlorothiophosphate (III) yields m/z 97 ions, predominantly of the structure S = P(OH)2+ (2a +). This conclusion follows from tandem mass spectrometry experiments and theoretical calculations. The calculations predict that (2a +) is separated by high-energy barriers from its isomers O = P(SH)OH+ (2b +), S = P(= O)OH2+ (2c +), and O = P(= O)SH2+ (2d +). Neutralization-reionization experiments confirmed that 2a · radical is a kinetically stable species on the time scale of up to 5 μs, which is in agreement with ab initio calculations. However, owing to a mismatch of Franck-Condon factors a large fraction of 2a · dissociates by loss of SH· yielding O=P-OH.  相似文献   

20.
Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation of the thermal behaviour and structure of the complexes Mg(pc)(na)3⋅3H2O (I), Mg(pc)(py)2⋅2H2O (II),Mg(pc)(pic)2⋅2H2O (III) and Mg(pc)(caf)2⋅4H2O (IV), where pc=2,6- pyridinedicarboxylate, na=nicotinamide,py=pyridine, pic=γ-picoline and caf=caffeine. The thermal decomposition of these compounds is multi-stage processes. The chemical composition of the complexes, the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. Schemes of destruction of these complexes are suggested. Heating of these compounds first resulted in a release of water molecules. In complexes I, II and IV the loss of the molecular ligands (na, py and caf) occur (on the TG curves) in one step (-2na, -2py and -2caf) and in complex III in two steps (-pic, -pic). The final product of the thermal decomposition was MgO. The thermalstability of the complexes can be ordered in the sequence: IV<I<III<II. Nicotinamide, pyridine, γ-picoline and caffeine were co-ordinated to Mg(II) through the N atom of the respective heterocyclic ring. IR data suggested a unidentate co-ordination of carboxylates to Mg(II) in complexes I–IV. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号