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1.
This study determined iodine value (IV) and free fatty acids (FFA) content of four different animal fat wastes and their blends using Fourier transform near-infrared spectroscopy (FT-NIR). Chemometric analysis by partial least squares (PLS) regression was used to correlate spectral data with IV and FFA reference values of the samples. The effects of four spectra pre-processing (first derivative (FD), second derivative (SD), multiplicative scatter correction (MSC) and vector normalization (VN)) methods were investigated to predict the reproducibility and robustness of the PLS-NIR model developed. A set of 70% of animal fat wastes and their blends were used for developing PLS calibration models for measuring IV and FFA content using the remaining 30% samples as an independent test set validation. The coefficient of determination (R2), the root mean square error estimation (RMSEE), and the residual prediction deviation (RPD) were used as indicators for the predictability of the PLS models. PLS-NIR models developed using first derivative and second derivative spectral preprocessing methods were the best for both IV and FFA content analysis (For IV, FD; R2 = 0.9870, RMSEE = 1.40 gI2/100 g, RPD = 8.76, SD; R2 = 0.9892, RMSEE = 1.28 gI2/100 g, RPD = 9.64 while For FFA, FD; R2 = 0.9991, RMSEE = 0.195%, RPD = 34.00, SD; R2 = 0.9993, RMSEE = 0.182%, RPD = 36.8). Overall, the results of this study demonstrate the suitability of FT-NIR spectroscopy for the quality control analysis of feedstocks for biodiesel production. 相似文献
2.
Blanka Kašná Roman Jambor Markus Schürman Klaus Jurkschat 《Journal of organometallic chemistry》2008,693(21-22):3446-3450
The syntheses are reported of the novel heteroleptic organostannylenes [2,6-(ROCH2)2C6H3]SnCl (1, R = Me; 2, R = t-Bu) and of their tungstenpentacarbonyl complexes [2,6-(ROCH2)2C6H3](X)SnW(CO)5 (3, X = Cl, R = Me; 4, X = Cl, R = t-Bu; 5, X = H, R = Me). The compounds were characterized by means of elemental analyses, 1H, 13C, 119Sn NMR spectroscopies, electrospray mass spectrometry and in case of 3 and 4 also by single crystal X-ray diffraction analysis. For the two latter compounds the substituents bound at the ether oxygen atom control the strength of intramolecular O → Sn coordination. Thus, the O–Sn distances amount to 2.391(5)/2.389(5) (3) and 2.464(3)/2.513(3) Å (4). 相似文献
3.
《Journal of organometallic chemistry》2005,690(24-25):5822-5831
Reaction between a chiral imidazole–amine precursor derived from (1R,2R)-trans-diaminocyclohexane and P1Cl (where P1 = PPh2, P(1,3,5-Me3C6H3)2, P(2,2′-O,O′-(1,1′-biphenyl), P((R)-(2,2′-O,O′-(1,1′-binaphthyl))) and P((S)-(2,2′-O,O′-(1,1′-binaphthyl)))) followed by RX (where R = nPr, iPr, CHPh2, X = Br; R = iPr, X = I), respectively, gives a selection of chiral imidazolium–phosphine compounds. Deprotonation of the imidazolium salt gives the corresponding NHC–P ligands that can be used in metal-mediated asymmetric catalytic applications. Catalytic reactions show that NHC–P ligands give a significantly greater rate of reaction for a palladium catalysed allylic substitution reaction in comparison to analogous di-NHC or NHC–imine ligands and that NHC–P hybrids are also effective for iridium catalysed transfer hydrogenation. 相似文献
4.
《Journal of organometallic chemistry》2006,691(1-2):35-44
The reaction of organoaluminum compounds containing O,C,O or N,C,N chelating (so called pincer) ligands [2,6-(YCH2)2C6H3]AliBu2 (Y = MeO 1, tBuO 2, Me2N 3) with R3SnOH (R = Ph or Me) gives tetraorganotin complexes [2,6-(YCH2)2C6H3]SnR3 (Y = MeO, R = Ph 4, Y = MeO, R = Me 5; Y = tBuO, R = Ph 6, Y = tBuO, R = Me 7; Y = Me2N, R = Ph 8, Y = Me2N, R = Me 9) as the result of migration of O,C,O or N,C,N pincer ligands from aluminum to tin atom. Reaction of 1 and 2 with (nBu3Sn)2O proceeded in similar fashion resulting in 10 and 11 ([2,6-(YCH2)2C6H3]SnnBu3, Y = MeO 10; Y = tBuO 11) in mixture with nBu3SniBu. The reaction 1 and 3 with 2 equiv. of Ph3SiOH followed another reaction path and ([2,6-(YCH2)2C6H3]Al(OSiPh3)2, Y = MeO 12, Me2N 13) were observed as the products of alkane elimination. The organotin derivatives 4–11 were characterized by the help of elemental analysis, ESI-MS technique, 1H, 13C, 119Sn NMR spectroscopy and in the case 6 and 8 by single crystal X-ray diffraction (XRD). Compounds 12 and 13 were identified using elemental analysis,1H, 13C, 29Si NMR and IR spectroscopy. 相似文献
5.
Christian Schmolke Daniel Bichler Dirk Johrendt Wolfgang Schnick 《Solid State Sciences》2009,11(2):389-394
The novel branched chain-type nitridosilicates Ce5Si3N9 and La5Si3N9 have been synthesized in a radio-frequency furnace starting from the respective metals and silicon diimide Si(NH)2 at 1625 °C for La5Si3N9 and 1650 °C for Ce5Si3N9, respectively. The structure of Ce5Si3N9 has been determined by single-crystal X-ray diffraction (Ce5Si3N9, Cmca (no. 64), a = 10.567(2) Å, b = 11.329(2) Å, c = 15.865(3) Å, V = 1899.3 Å3, Z = 8, R1 = 0.0391, 1480 independent reflections, 90 refined parameters). The structure of isotypic La5Si3N9 has been refined by the Rietveld method, starting from single-crystal data of Ce5Si3N9 (La5Si3N9, Cmca (no. 64), a = 10.647(4) Å, b = 11.414(4) Å, c = 16.030(5) Å, V = 1948.1 Å3, Z = 8, RP = 0.0348, RF2 = 0.0533). Both compounds are built up of alternating Q2- and Q3-type corner sharing SiN4 tetrahedra with additional corner sharing Q1-units attached to the Q3-tetrahedra pointing alternately in opposing directions. These zipper-like chains are intertwined in both directions perpendicular to the chain itself to form a three-dimensionally interlocked structure with the rare-earth ions situated between the chains. Magnetic measurements resulted in a ferromagnetic ground state with a magnetic moment in agreement with Ce3+. 相似文献
6.
CRTh2 receptor is an important mediator of inflammatory effects and has attracted much attention as a therapeutic target for the treatment of conditions such as asthma, COPD, allergic rhinitis and atopic dermatitis. In pursuit of better CRTh2 receptor antagonist agents, 3D-QSAR studies were performed on a series of 2-(2-(benzylthio)-1H-benzo[d]imidazol-1-yl) acetic acids. There is no crystal structure information available on this protein; hence in this work, ligand-based comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed by atom by atom matching alignment using systematic search and simulated annealing methods. The 3D-QSAR models were generated with 10 different combinations of test and training set molecules, since the robustness and predictive ability of the model is very important. We have generated 20 models for CoMFA and 100 models for CoMSIA based on two different alignments. Each model was validated with statistical cut off values such as q2 > 0.4, r2 > 0.5 and r2pred > 0.5. Based on better q2 and r2pred values, the best predictions were obtained for the CoMFA (model 5 q2 = 0.488, r2pred = 0.732), and CoMSIA (model 45 q2 = 0.525, r2pred = 0.883) from systematic search conformation alignment. The high correlation between the cross-validated/predicted and experimental activities of a test set revealed that the CoMFA and CoMSIA models were robust. Statistical parameters from the generated QSAR models indicated the data is well fitted and have high predictive ability. The generated models suggest that steric, electrostatic, hydrophobic, H-bond donor and acceptor parameters are important for activity. Our study serves as a guide for further experimental investigations on the synthesis of new CRTh2 antagonist. 相似文献
7.
《Solid State Sciences》2007,9(2):137-143
Four new magnesium containing metal–organic hybrid compounds have been synthesized in an effort to prepare low-density materials for hydrogen storage. The compounds were prepared hydrothermally and characterized using single crystal X-ray diffraction. Three of these compounds are analogs of known transition metal structures with squarate (I, Pn-3n, a = 16.276(5) Å), diglycolate (II, P212121, a = 6.860(1) Å, b = 9.993(1) Å, c = 10.884(1) Å, R1 = 0.0341), and glutarate (III, R-3, a = 10.744(2) Å, c = 28.677(5) Å, R1 = 0.0554) ligands; the fourth is a novel structure using cyclobutanetetracarboxylate (IV, Pccn, a = 9.382(1) Å, b = 14.410(2) Å, c = 8.725(1) Å, R1 = 0.0465) which contains potassium as well as magnesium cations. 相似文献
8.
N-Thioamide thiosemicarbazone derived of 2-chloro-4-hydroxy-benzaldehyde (R = H, HL1; R = Me, HL2 and R = Ph, HL3) have been prepared and their reaction with fac-[ReX(CO)3(CH3CN)2] (X = Br, Cl) in chloroform gave the adducts [ReX(CO)3(HL)] (1a X = Cl, R = H; 1a′ X = Br, R = H; 1b X = Cl, R = CH3; 1b′ X = Br, R = CH3; 1c X = Cl, R = Ph; 1c′ X = Br, R = Ph) in good yield. Complexes 1a′ and 1b’ were also obtained by the reaction of HL1 and HL3 with [ReBr(CO)5] in toluene.All the compounds have been characterized by elemental analysis, mass spectrometry (FAB), IR and 1H NMR spectroscopic methods. Moreover, the structures of HL2, HL3 and 1a·H2O were also established by X-ray diffraction. In 1a, the rhenium atom is coordinated by the sulphur and the azomethine nitrogen atoms, forming a five-membered chelate ring, as well as three carbonyl carbon and chloride atoms. The resulting coordination polyhedron can be described as a distorted octahedron.The study of the crystals obtained by slow evaporation of methanol and DMSO solutions of the adducts 1a′ and 1b, respectively, showed the formation of dimer structures based on rhenium(I) thiosemicarbazonates [Re2(L1)2(CO)6]·3H2O (2a)·3H2O and [Re2(L2)2(CO)6]·(CH3)2SO (2b)·2(CH3)2SO. Amounts of these thiosemicarbazonate complexes [Re2(L)2(CO)6] (2) were obtained by reaction of the corresponding free ligands with [ReCl(CO)5] in dry toluene.In 2a·3H2O and 2b·2(CH3)2SO the dimer structures are established by Re–S–Re bridges, where S is the thiolate sulphur from a N,S-bidentate thiosemicarbazonate ligand. In both structures the rhenium coordination sphere is similar; the dimers are in the same diamond Re2S2 face. 相似文献
9.
《Arabian Journal of Chemistry》2014,7(6):1124-1130
The electronic and molecular structures of the homoleptic Yttrium tris-guanidinates complexes Y[(NiPr)2CNR1R2]3, [R1 = R2 = Me, Et and iPr] have been investigated employing DFT calculations in order to understand the structures, bonding and energies of the interactions between Yttrium metal and guanidinate ligands. The effect of the substitution on nitrogen position of guanidinate in these complexes has been also investigated employing DFT and TDDFT calculations for six kinds of models obtained by alternative substitution of alkyl on nitrogen of the guanidinate ligands. The results reveal that the substitution position plays a crucial role in the geometric structure by affecting the torsion angle and the HOMO–LUMO transitions. The energy decomposition analysis indicates a majority of ionic bonding in all systems; the exception is in the M4 (Y[(NYR)2CNCR1R2]3; R = Et and R1 = R2 = H) which present a significant degree of covalency. 相似文献
10.
《Tetrahedron: Asymmetry》2005,16(9):1595-1602
The spontaneous resolution reaction of racemic trans-2,3-dihydro-2,3-dipyridyl-benzo[e]indole 1 with Cd(ClO4)2·6H2O in the presence of 2-butanol under solvothermal reaction conditions favors the formation of crystal 2 [P-Cd(R,R,-1)2(ClO4)2], while a similar reaction in the presence of ethanol only favors the formation of crystal 3 [M-Cd(S,S,-1)2(ClO4)2]. The crystal structural determination shows that both 2 and 3 crystallize in chiral enantiomorphous space groups (P6122 and P6522) and their structures are 1D infinite chain, and are just enantiomorphous pairs most like. The spontaneous resolution process displays estimated ee values of ca. +0.6 for 2-butanol and ca. −0.4 for ethanol. Enantiomerically pure (S,S)-trans-2,3-dihydro-2,3-dipyridyl-benzo[e]indole (S,S,-1) can be obtained through the decomposition of mechanically separated 3. Additionally (S,S,-1) also crystallizes in a chiral space group (P21). The CD (circular dichroism) spectra of both 2 and 3 in the solid state are also approximately enantiomorphous pairs. However, their fluorescent spectra in the solid state display a moderate difference in maximum emission peaks (Δλ = 19 nm). Crystal data for 2: C44H34Cl2N6O8Cd, M = 958.07, hexagonal, P6122, a = 10.5488(5), c = 68.256(4) Å, α = γ = 90°, β = 120°, V = 6577.8(6) Å3, Z = 6, Dc = 1.451 mg m−3, R1 = 0.0498, wR2 = 0.1124, μ = 0.679 mm−1, S = 0.623, Flack χ = −0.02(6). For space group P6522, R1 = 0.0670, wR2 = 0.1602, S = 0.725 with a Flack value of 1.03(7); Crystal data for 3, C44H34Cl2N6O8Cd, M = 958.07, hexagonal, P6522, a = 10.5446(3), c = 68.265(3) Å, V = 6573.3(4) Å3, Z = 6, Dc = 1.452 mg m−3, R1 = 0.0444,wR2 = 0.1002, μ = 0.679 mm−1, S = 0.558, Flack χ = 0.01(5). For space group P6122, R1 = 0.0501, wR2 = 0.1178, S = 0.599 with a Flack value of 1.00(5). The low Flack parameter indicates that the absolute configurations of 2 and 3 are stated; Crystal data for (S,S)-1, C22H17N2, M = 323.39, orthorhombic, P212121, a = 9.2598(7), b = 9.4617(8), c = 19.1452(16) Å, V = 1677.4(2) Å3, Z = 4, Dc = 1.281 mg m−3, R1 = 0.0417, wR2 = 0.1191, T = 293 K, μ = 0.077 mm−1, S = 0.862. 相似文献
11.
《The Journal of chemical thermodynamics》2007,39(7):991-1000
Cryogenic heat capacities determined by equilibrium adiabatic calorimetry from T = (6 to 350) K on Li, Na, and K disilicates in both crystalline and vitreous phases are adjusted to end member composition and the vitreous/crystal difference ascertained. The thermophysical properties of these and related phases are estimated, compared, and updated. The values at T = 298.15 K of {S∘(T) − S∘(0)}/R for stoichiometric compositions of alkali disilicate (M2O · 2SiO2): vitreous, crystal: Li, 16.30, 14.65; Na, 20.67, 19.47; and K, 23.26, 23.00. Entropy differences confirm greater disorder in the vitreous compounds compared with the crystalline compounds. The entropy data also show that disorder increases with decreasing atomic mass of the alkali ion. 相似文献
12.
《Solid State Sciences》2007,9(7):644-652
Na2Cu(PO2NH)4·7H2O and KxNa2−xCu(PO2NH)4·7H2O (x ≈ 0.5) were synthesized by gel crystallization in sodium silicate gels. The crystal structures were solved by single-crystal X-ray methods and found to be isotypic (Pnma, Z = 4; Na2Cu(PO2NH)4·7H2O: a = 627.5(2) pm, b = 1456.0(3) pm, c = 1900.5(4) pm, R1 = 0.0352; K0.47Na1.53Cu(PO2NH)4·7H2O: a = 632.2(2) pm, b = 1460.0(3) pm, c = 1936.4(4) pm, R1 = 0.0345). The P4N4 rings of the tetrametaphosphimate anion exhibit a distorted chair-2 conformation with admixtures of saddle and crown conformation. The M+ ions are six- and sevenfold coordinated by oxygen atoms, the Cu2+ ions are fivefold coordinated, respectively. The MO7 and the CuO5 units form pairs of face-sharing polyhedra, which are connected by common corners forming chains and are further interconnected by tetrametaphosphimate anions, forming a three-dimensional network structure with channels along [100] and [010]. The MO6 units form chains of face-sharing polyhedra, which are situated in the channels along [100]. Extended hydrogen bonding reinforces the three-dimensional framework structure of the compounds. 23Na-MAS NMR experiments were conducted to verify the K/Na distribution on the M sites derived from the X-ray crystal structure refinement. 相似文献
13.
《Polyhedron》2005,24(16-17):2269-2273
Two ion-pair compounds, consisting of 1-(4′-R-benzyl)pyridinium ([RBzPy]+, R = NO2 (1) and Br (2)) and [Ni(dmit)2]− (dmit2− = 2-thioxo-1,3-dithion-4,5-dithiolato), have been synthesized and structurally characterized. The anions of [Ni(dmit)2]− stack into dimers, which further construct into two-leg ladder through terminal S⋯S interactions in 1, lateral S⋯S interactions in 2. The weak H-bonding interactions of C–H⋯S were observed in 2, while only weak van de Waals interactions between anion and cations in 1. The magnetic susceptibilities measured in 2–300 K indicate AFM exchange interaction domination both two compounds. A peculiar magnetic transition at ∼100 K was observed in 1. An AFM ordering below ∼11 K was found in 2, and the best fit to magnetic susceptibility above 45 K in this compound, using a dimer model with s = 1/2, give rise to Δ/kB = 36.1 K, zJ = −0.91 K, C = 3.2 × 10−3 emu K mol−1 and χ0 = −4.0 × 10−6 emu mol−1 with g of 2.0 fixed. 相似文献
14.
M. Agostinha R. Matos Clara C.S. Sousa Victor M.F. Morais 《The Journal of chemical thermodynamics》2008,40(10):1485-1489
The standard molar energies of combustion, at T = 298.15 K, of crystalline 1,4-benzodioxan-2-carboxylic acid and 1,4-benzodioxan-2-hydroxymethyl were measured by static bomb calorimetry in an oxygen atmosphere. The standard molar enthalpies of sublimation, at T = 298.15 K, were obtained by Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the compounds in the gas phase at T = 298.15 K: 1,4-benzodioxan-2-carboxylic acid ?(547.7 ± 3.0) kJ · mol?1 and 1,4-benzodioxan-2-hydroxymethyl ?(374.2 ± 2.3) kJ · mol?1.In addition, density functional theory calculations using the B3LYP hybrid exchange–correlation energy functional with extended basis sets, 6-311G7 and cc-pVTZ, have been performed for the compounds studied. We have also tested two more accurate computational procedures involving multiple levels of electron structure theory in order to get reliable estimates of the thermochemical parameters of the compounds studied. The agreement between experiment and theory gives confidence to estimate the enthalpies of formation of other 2-R derivatives of 1,4-benzodioxan (R = –CH2COOH, –OH, –COCH3, –CHO, –CH3, –CN, and –NO2). 相似文献
15.
Masaki Kakeya Makoto Tanabe Yoshiyuki Nakamura Kohtaro Osakada 《Journal of organometallic chemistry》2009,694(14):2270-2278
Alkyl and arylplatinum complexes with 1,5-cyclooctadiene ligand, [PtR2(cod)] (R = Me, Ph, C6H4-p-CF3, C6F5), react with secondary phosphines, PHR′2 (R′ = i-Bu, t-Bu, Ph), to afford the mononuclear platinum complexes, cis-[PtR2(PHR′2)2] (1a: R = Me, R′ = i-Bu; 1b: R = Me, R′ = t-Bu; 1c: R = Me, R′ = Ph; 2a: R = Ph, R′ = i-Bu; 2b: R = Ph, R′ = t-Bu; 2c: R = R′ = Ph; 3a: R = C6H4-p-CF3, R′ = i-Bu; 3b: R = C6H4-p-CF3, R′ = t-Bu; 3c: R = C6H4-p-CF3, R′ = Ph; 4a: R = C6F5, R′ = i-Bu; 4c: R = C6F5, R′ = Ph) in 81–98% yields. Molecular structures of the complexes except for 1a, 1c and 2a were determined by X-ray crystallography. Complex 1b has a square-planar structure with Pt–C(methyl) bonds of 2.083(8) and 2.109(8) Å, while the Pt–C(aryl) bonds of 2b–c, 3a–c, 4a and 4c (2.055(1)–2.073(8) Å) are shorter than them. Thermal decomposition of 1b, 2a–c, and 3a–c releases methane, biphenyl or 4,4′-bis(trifluoromethyl)biphenyl as the organic products, which are characterized by NMR spectroscopy. The solid product of the thermal reactions of 2b and 2c were characterized as the metallopolymers formulated as [Pt(PR′2)2]n (5b: R′ = tBu; 5c: R′ = Ph), based on the solid-state NMR and elemental analyses. 相似文献
16.
《Journal of Molecular Structure》2006,780(1-3):134-142
The ability of the Generalised AMBER Force Field (GAFF) of Kollman and co-workers to model the structures of bisphosphonate ligands, C(R1)(R2)(PO32−)2, important compounds in the treatment of bone cancer, by molecular mechanics methods is evaluated. The structure of 50 bisphosphonates and nine bisphosphonate esters were predicted and compared to their crystal structures. Partial charges were assigned from a RHF/6-31G1 single point calculation at the geometry of the crystal structure. Additional parameters required for GAFF were determined using the methods of the force field’s developers. The structures were found to be well replicated with virtually all bond lengths reproduced to within 0.015 Å, or within 1.2σ of the crystallographic mean. Bond angles were reproduced to within 1.9° (0.8σ). The observed gauche or anti conformation of the molecules was reproduced, although in several instances gauche conformations observed in the solid state energy-minimised into anti conformations, and vice versa. The interaction of MDP (R1 = R2 = H), HEDP (R1 = OH, R2 = CH3), APD (R1 = OH, R2 = (CH2)2NH3+), alendronate (R1 = OH, R2 = (CH2)3NH3+) and neridronate (R1 = OH, R2 = (CH2)5NH3+) with the (001), (010) and (100) faces of hydroxyapaptite was examined by energy-minimising 20 random orientations of each ligand 20 Å from the mineral (where there is no interaction), and then at about 8 Å from the surface whereupon the ligand relaxes onto the surface. The difference in energy between the two systems is the interaction energy. In all cases interaction with hydroxyapatite caused a decrease in energy. When modelled with a dielectric constant of 78εo, non-bonded interactions dominate; electrostatic interactions become important when the dielectric constant is <10εo. Irrespective of the value of the dielectric constant used, the structure of the ligands on the hydroxyapatite surface is very similar. On the (001) face, both phosphonate groups interact near a surface Ca2+ ion. The magnitude of the exothermic interaction energy varies with molecular volume (MDP<HEDP<APD<alendronate) except for neridronate which interacts less effectively than alendronate because the long amino side chain folds in on itself and does not align with the surface of the mineral. The bisphosphonates adopt two conformations on the (010) face. In the first of these, found for MDP and 40% of the alendronate structures, both phosphonates interact with the surface and the side chain points away from the surface. Hence, the interaction energy is similar for both species. In the second conformation, adopted by the majority of ligands, one phosphonate and the Cα side chain interact with the surface. The interaction energy, the magnitude of which is very similar to that on the (001) face, increases with the molecular volume of the ligand, again with the exception of neridronate. Two conformations also occur on the (100) face. In the first conformation, only one of the phosphonate groups points towards the surface and the Cα side chain interacts with the surface; in the second conformation the Cα side chain interacts strongly with the surface and both phosphonate groups point away from the surface towards the solution. The first conformation, which is the more common, is energetically more favourable. Its magnitude is virtually insensitive to the nature of the side chain and is similar to the magnitude of the interaction energy on the other two faces. The magnitude of the second conformation increases with the size of the Cα side chain. 相似文献
17.
《Comptes Rendus Chimie》2007,10(6):469-472
The structure of Bu4NSnMe2Cl3 is found to be monomer, containing a 5-coordinated bipyramidal trigonal tin(IV) center. Crystals belong to the monoclinic space group C2/c, with unit-cell dimensions a = 26.633(4) Å; b = 9.880(2) Å; c = 21.510(2) Å; β = 114.82(2)°; Z = 8; D = 1.287 Mg/m3; R is refined to 0.0537 and Rw = 0.0642 for 3330 reflections (F > 2σ(F)). 相似文献
18.
《The Journal of chemical thermodynamics》2001,33(6):643-687
The apparent molar heat capacities Cp, φ ∘ and apparent molar volumes Vφ ∘ of Y2(SO4)3(aq), La2(SO4)3(aq), Pr2(SO4)3(aq), Nd2(SO4)3(aq), Eu2(SO4)3(aq), Dy2(SO4)3(aq), Ho2(SO4)3(aq), and Lu2(SO4)3(aq) were measured at T = 298.15 K and p = 0.1 MPa with a Sodev (Picker) flow microcalorimeter and a Sodev vibrating-tube densimeter, respectively. These measurements extend from lower molalities of m = (0.005 to 0.018) mol ·kg − 1to m = (0.025 to 0.434) mol ·kg − 1, where the upper molality limits are slightly below those of the saturated solutions. There are no previously published apparent molar heat capacities for these systems, and only limited apparent molar volume information. Considerable amounts of the R SO4 + (aq) and R(SO4)2 − (aq) complexes are present, where R denotes a rare-earth, which complicates the interpretation of these thermodynamic quantities. Values of the ionic molar heat capacities and ionic molar volumes of these complexes at infinite dilution are derived from the experimental information, but the calculations are necessarily quite approximate because of the need to estimate ionic activity coefficients and other thermodynamic quantities. Nevertheless, the derived standard ionic molar properties for the various R SO4 + (aq) and R(SO4)2 − (aq) complexes are probably realistic approximations to the actual values. Comparisons indicate that Vφ ∘ {RSO4 + , aq, 298.15K} = − (6 ± 4)cm3· mol − 1and Vφ ∘ {R(SO4)2 − , aq, 298.15K} = (35 ± 3)cm3· mol − 1, with no significant variation with rare-earth. In contrast, values of Cp, φ ∘ { RSO4 + , aq, 298.15K } generally increase with the atomic number of the rare-earth, whereas Cp, φ ∘ { R(SO4)2 − , aq, 298.15K } shows a less regular trend, although its values are always positive and tend to be larger for the heavier than for the light rare earths. 相似文献
19.
Two new hybrid materials, (C4H14N2)[MII(H2O)6](SO4)2·4H2O (MII: Co (I), Ni (II)), have been synthesised by slow evaporation method at room temperature and crystallographically characterized. They crystallise isotypically in the monoclinic system, space group P21/n, with the following unit-cell parameters a = 9.2285(3), b = 11.3333(4), c = 10.6693(4) Å, β = 109.004(2)°, Z = 2 and V = 1055.07(6) Å3 for I and a = 9.2127(2), b = 11.3182(2), c = 10.6434(2) Å, β = 109.094(1)°, Z = 2 and V = 1048.74(4) Å3 for II. The structure of the two supramolecular compounds consists of metallic cation octahedrally coordinated to six water molecules, sulfate anions, 1,4-butanediammonium cation and water molecules linked together via two types of hydrogen bonds, O–H?O and N–H?O. The two compounds are not stable at room temperature and their partial dehydration depends on the humidity of the environment. The thermal decomposition of precursors, studied by thermogravimetric analysis (TG) and temperature-dependent X-ray diffraction (TDXD), shows successive intermediate hydrates and crystalline anhydrous compounds upon dehydration. 相似文献
20.
Pavlo Solokha Serena De Negri Volodymyr Pavlyuk Adriana Saccone 《Solid State Sciences》2009,11(4):801-811
Single crystals of the Y5Cu5Mg8, Y5Cu5Mg13, Y5Cu5Mg16 and YCuMg4 compounds were synthesized by heating in a resistance furnace evacuated quartz vials containing Ta-crucibles with element pieces. SEM-EDXS analyses were performed to check phases composition. The structures were refined from X-ray single crystal diffraction data. Y5Cu5Mg8, Y5Cu5Mg13 and Y5Cu5Mg16 represent new structure types: Y5Cu5Mg8 – orthorhombic, Pmma, oP36, a = 2.63723(15), b = 0.40066(2), c = 0.74115(6) nm, Z = 2, wR2 = 0.0597, 939 F2 values, 60 variables; Y5Cu5Mg13 – orthorhombic, Cmcm, oS92, a = 0.40973(2), b = 1.92794(8), c = 2.57907(11) nm, Z = 4, wR2 = 0.1134, 1208 F2 values, 75 variables; Y5Cu5Mg16 – orthorhombic, Cmcm, oS104, a = 0.41360(8), b = 1.9239(4), c = 2.9086(6) nm, Z = 4, wR2 = 0.0760, 1383 F2 values, 84 variables. YCuMg4 crystallizes in the TbCuMg4 structure type (Cmmm, oS48, a = 1.35754(4), b = 2.03153(6), c = 0.39060(1) nm, Z = 8, wR2 = 0.0401, 661 F2 values, 45 variables). The crystal chemistry of these two-layer structures is comparatively discussed. Majority of novel compounds were characterized as members of inhomogeneous 2D intergrowth structure series of R5M5X5, X4 (Mg4) and empty Mg octahedra building blocks of general formula R5kM5kX5k + 4l + m. The common pentagonal prism derivative structural fragments around the most electropositive yttrium atoms were outlined in all these intermetallics. 相似文献