Magnetic susceptibilities of acetylene and ethylene using frost-model wavefunctions withp-type Gaussians

There are degeneracy problems involved in the calculation of magnetic susceptibilities from Frost model wavefunctions built up from mixeds- andp-type Gaussians. Various methods are suggested to alleviate the difficulties and they are used to compute the susceptibilities of C₂H₂ and C₂H₄.     

Magnetic susceptibility of ultradispersed rutile and related Pt/TiO2 catalysts

The magnetic susceptibilities of ultradispersed rutile and catalysts 1% Pt/TiO₂ and 3% Pt/TiO₂ were measured. Rutile-based catalysts are paramagnetic, and their magnetic susceptibilities increase as the platinum content increases. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1356–1359, July, 1998.     

Magnetic susceptibilities of binary non-electrolyte mixtures

Molar magnetic susceptibilities are determined by theGouy method for the following four systems: dichloromethane + methyl acetate,n-pentane + dichloromethane,n-pentane + methyl acetate and 2-propanol +n-pentane, in whichn-pentane is a non-polar molecule and the other three are polar while 2-propanol is associated in its pure state. Excess diamagnetic susceptibilities are calculated to obtain information about possible interactions. Diamagnetic susceptibilities were related with molecular polarizabilities byBoyer-Donzelot's equation and compared with experimental results.

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Magnetische Suszeptibilitäten binärer Nicht-Elektrolyt-Mischungen

Zusammenfassung Für folgende vier Systeme wurden die molaren magnetischen Suszeptibilitäten mittels derGouy-Methode bestimmt: Dichlormethan + Methylacetat,n-Pentan + Dichlormethan,n-Pentan + Methylacetat, und 2-Propanol +n-Penten; dabei istn-Pentan ein nicht-polares Molekül, die anderen sind polar, wobei 2-Propanol zusätzlich Assoziation zeigt. Es werden Exzess-diamagnetische Suszeptibilitäten berechnet, um Informationen bezüglich möglicher Wechselwirkungen zu erhalten. Die diamagnetischen Suszeptibilitäten wurden mit den molekularen Polarisierbarkeiten über dieBoyer-Donzelot-Beziehung in Relation gesetzt und mit den experimentellen Resultaten verglichen.

     

Quantitative Structure Property Relations （QSPR） for Predicting Molar Diamagnetic Susceptibilities,xm, of Inorganic Compounds

For predicting the molar diamagnetic susceptibilities of inorganic compounds, a novel connectivity index ^mG based on adjacency matrix of molecular graphs and ionic parameter gi was proposed. The gi is defined as gi=（ni^0.5-0.91）^4·xi^0.5｜Zi^0.5, where Zi, ni, xi are the valence, the outer electronic shell primary quantum number, and the electronegativity of atom i respectively. The good QSPR models for the molar diamagnetic susceptibilities can be constructed from ^0G and ^1G by using multivariate linear regression （MLR） method and artificial neural network （NN） method. The correlation coefficient r, standard error, and average absolute deviation of the MLR model and NN model are 0.9868, 5.47 cgs, 4.33 cgs, 0.9885, 5.09 cgs and 4.06 cgs, respectively, for the 144 inorganic compounds. The cross-validation by using the leave-one-out method demonstrates that the MLR model is highly reliable from the point of view of statistics. The average absolute deviations of predicted values of the molar diamagnetic susceptibility of other 62 inorganic compounds （test set） are 4.72 cgs and 4.06 cgs for the MLR model and NN model. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an inorganic compound. Both MLR and NN methods can provide acceptable models for the prediction of the molar diamagnetic susceptibilities. The NN model for the molar diamagnetic susceptibilities appears more reliable than the MLR model.     

On CHF calculations of second-order magnetic properties using the method of continuous transformation of origin of the current density

Summary A fully analytical formulation is outlined for computing molecular magnetic susceptibilities and nuclear magnetic shieldings via a continuous change of origin of the electronic current density induced by an external magnetic field. The change of origin is described in terms of a (continuous) arbitrary shift functiond(r). Coupled Hartree-Fock second-order magnetic properties of CH₄ and CO₂ molecules have been computed, using the special choiced(r)=r as generating function. A detailed analysis of results obtained with a variety of basis sets reveals that such a method is not as good as previously suggested. Large basis sets must be used to obtain accurate magnetic properties. On the other hand, all the components of theoretical nuclear magnetic shielding evaluated via this approach are independent of the origin of the vector potential. In general, theoretical magnetic susceptibilities depend linearly on the distance between different coordinate frames, but are origin independent for centre-symmetric molecules.     

Magnetoelectric compounds with two sets of magnetic sublattices: UCrO4 and NdCrTiO5

Using magnetic and magnetoelectric (ME) powder susceptibility measurements, the low temperature magnetic properties of antiferromagnetic UCrO₄ and NdCrTiO₅ have been studied. Their Néel temperatures T_N are 44.5 and 20.5°K, respectively, the Cr³⁺ spin systems of both materials ordering cooperatively at T_N. Below T_N, the U⁵⁺ and Nd³⁺ moments are polarized due to their exchange interaction with the ordered Cr³⁺ spins. It is argued that, for both compounds, each of the two spin systems contributes to the ME susceptibilities. They are thus the first known ME materials possessing two distinct magnetic sublattices. The effective magnetic moments calculated from the magnetic susceptibilities are in good agreement with those previously reported by neutron diffraction studies.     

Theoretical studies on NLO properties of push-pull multi-cycle electro-optical polymer intermediates including thiophene ring

The second-order nonlinear optical susceptibilities βijk,βμ and third-order non-linear optical susceptibilities γijkl,<γ> of a series of the novel push-pull multi-ring electro-photo polymer intermediates have been calculated.The influences of molecular structure,donor,acceptor and the frequency of external field on P and v,and the relationship between V and the number of thiophene rings(i.e.conjugated chain length)have been studied using UNDO/SCI methods combined with sum-overstate(SOS)formula.The calculated results show that γ is proportional to 2.69 power of the chain length of the conjugated molecular bonds when the length is not quite long.     

Structural design of easy-axis magnetic anisotropy and determination of anisotropic parameters of Ln(III)-Cu(II) single-molecule magnets

Four dinuclear Ln^III? Cu^II complexes with Ln=Tb ( 1 ), Dy ( 2 ), Ho ( 3 ), and Er ( 4 ) were synthesized to investigate the relationship between their respective magnetic anisotropies and ligand‐field geometries. These complexes were crystallographically isostructural, and a uni‐axial ligand field was achieved by using three phenoxo oxygen groups. Complexes 1 and 2 displayed typical single‐molecule magnet (SMM) behaviors, of which the out‐of‐phase susceptibilities were observed in the temperature range of 1.8–5.0 K ( 1 ) and 1.8–20.0 K ( 2 ). The Cole–Cole plots exhibited a semicircular shape with α parameters in the range of 0.08–0.18 (2.6–4.0 K) and 0.07–0.24 (3.5–7.0 K). The energy barriers Δ/k_B were estimated from the Arrhenius plots to be 32.9(4) K for 1 and 26.0(5) K for 2 . Complex 3 displayed a slow magnetic relaxation below 3.0 K, whereas complex 4 did not show any frequency‐dependent behavior for both in‐phase and out‐of‐phase susceptibilities, which indicates that easy‐axis anisotropy was absent. The temperature dependence of the dc susceptibilities for the field‐aligned samples of 1 – 3 revealed that the χ_MT value continuously increased as the temperature was lowered, which indicates the presence of low‐lying Stark sublevels with the highest |J_z| values. In contrast, complex 4 displayed a smaller and temperature‐independent χ_MT value, which also indicates that easy‐axis anisotropy was absent. Simultaneous analyses were carried out for 1 – 3 to determine the magnetic anisotropy parameters on the basis of the Hamiltonian that considers B₂⁰, B₄⁰, and B₆⁰.     

两个修正的分子连接性指数用于有机物反磁磁化率的改进QSPR研究

为了预测有机物的摩尔反磁磁化率,基于分子图的连接矩阵和可变的原子价连接性指数δi’提出了一种可变的分子连接性指数mχ’ 及其逆指数mχ”。包含在δi’、 mχ’ 和mχ”定义式中的三个可变参数x、 a和y的最佳值可通过优化方法得到。当x=2.9、a=1.10、y=0.36时, 通过最佳子变量集合法可以构建一个良好的5参数模型。对721个有机物（训练集）,该模型的相关系数r、标准偏差s和平均绝对偏差分别是0.9930、4.96 cgs和3.74cgs。交叉验证说明,从统计学角度该模型具有良好的稳定性。另外该模型对另外360个有机物（测试集）摩尔反磁磁化率预测结果的平均绝对偏差为4.37cgs。结果表明本文的方法在预测有机物摩尔反磁磁化率方面比文献方法更有效。多元线性方法能得到比较理想的预测有机物摩尔反磁磁化率的模型。     

Studies under Continuous Irradiation of Photochromic Spiro[fluorenopyran‐thioxanthenes]

New indeno‐fused spiro[benzopyran‐thioxanthenes] were synthesized (see 3a – d in Scheme 3) and their photochromic properties evaluated under continuous irradiation (Table 1). When submitted to irradiation for several minutes with a Xe lamp, the system behaved as one constituted by two open colored forms with different thermal bleaching rates and different susceptibilities to degradation. An increase in irradiation time led to significant degradation and to the apparent predominance of the open colored form with the faster bleaching rate.     

Excess thermodynamic properties and vapor-liquid equilibrium data for then-butylamine+p-dioxane system at 25°C

Excess values of molar volumes, viscosities, molar enthalpies, Gibbs molar energies, surface tensions and molar diamagnetic susceptibilities were calculated at 25°C for then-butylamine+p-dioxane system. The observed deviations from the ideality were explained on the basis of intermolecular interactions. Van Laar's equations were the best in predicting activity coefficients for this system.     

Antioxidant and antimicrobial properties of Casteanea sativa Miller chestnut honey produced on Mount Etna (Sicily)

The aim of this study was the evaluation of antibacterial and antioxidant properties of Monofloral Etna Castanea sativa Miller honeys. Escherichia coli ATCC 25,922, Pseudomonas aeruginosa ATCC 27,853, Enterococcus faecalis ATCC 29,211 and Staphylococcus aureus ATCC 29,213 were investigated for their susceptibilities to two different honeys. Antioxidant activity was evaluated by ORAC, NO scavenger assays, FRAP and DPPH. Antioxidant activity and antibacterial properties were compared with chestnut honeys from different geographical areas and with Manuka honey. UPLC-MS/MS was used for major components characteri sation.     

Reconocimiento de nicotina en una hebrita de tabaco

Summary Adaption of theLuís method for the detection of nicotine to microscale, usingEmich's capillary technic proved successful, attaining identification limit of 0,03g.Applying a sub-micro steam distillation effect, the nicotine in a speck of tobacco (1 mm² and less) could still be detected by using the above reaction.Extension of the above procedure to mixtures of nicotine with substances not volatile with steam, inorganic (halides) as well as organic compounds (other alkaloids, acids, etc.) proved to be successful, even when the nicotine is present in proportions of only 1 part in 1000.

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Zusammenfassung Die Anwendung der Kapillartechnik vonEmich zum Nachweis von Nikotin nachLuís war erfolgreich und zeigte eine Erfassungsgrenze von 0,03g.Bei Anwendung einer Ultramikrodampfdestillation kann das Nikotin nach obiger Methode noch in Spuren von Tabak (1 mm² und weniger) nachgewiesen werden.Die Reaktion ist auch positiv bei Gemischen von Nikotin mit anderen, mit Wasserdampf nicht flüchtigen sowohl anorganischen (Halogenide) als auch organischen Substanzen (andere Alkaloide, Säuren etc.), selbst dann noch, wenn das Nikotin bloß im Verhältnis von 11000 vorhanden ist.

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Résumé La technique capillaire d'Emich a été utilisée avec succès pour identifier la nicotine suivant le procédé deLuís; la limite de sensibilité est alors de 0,03g. La mise en oeuvre d'un ultramicroentraînement à la vapeur permet en outre, par application de la précédente méthode, d'identifier la nicotine dans des traces de tabac (moins de 1 mm²). La réaction est également positive en présence d'autres substances non entraînables par la vapeur d'eau, qu'elles soient minérales (halogénures) ou organiques (autres alcaloïdes, acides, etc. ...) même si la proportion de nicotine n'est que de l'ordre de grandeur de 1/1000.

     

Exchange interactions in trinuclear multispin complexes [Fe 2III MIIO(p-NitPhCOO)6]?MeCN (M = Co, Ni, p-NitPhCOO- = p-benzoatenitronyl nitroxide radical)

The temperature dependences of the magnetic susceptibilities for the complexes [Fe₂^III M^IIO(p-NitPhCOO)₆]∙MeCN (M = Co, Ni, p-NitPhCOO^–= p-benzoatenitronyl nitroxide radical, MeCN = acetonitrile) revealed the existence of antiferromagnetic exchange coupling among the metal ions in the trinuclear units, as well as between these units and the free radicals in the crystal lattices of the complexes.     

Eichinvariante Berechnung des Diamagnetismus und der chemischen Verschiebung

The procedure derived in^1–4 was used to calculate the magnetic susceptibilities of a series of unsaturated hydrocarbons (propene, isobutene, 1-butene, cyclohexene, butadiene,trans-1,3,5-hexatriene). The difference between the measured and computed susceptibilities of these molecules is discussed. The discussion shows, that there is no correlation existing between the difference and the presumed delocalisation effects.

Die Ergebnisse sind Bestandteil einer der letzten Arbeiten, die von dem von uns hochverehrten, leider zu früh verstorbenen, Prof. Dr.W. Haberditzl betreut wurden.     

Magnetische Eigenschaften der ternären Phase (Fe x Ni1-x )11Se8

The partial substitution of nickel by iron in the body centered tetragonal crystal structure of the ternary compound (Fe _x Ni_1–x )₁₁Se₈ is restricted to the range of 0.04<x<0.23 at 580°C. The magnetic properties of samples with different compositions were studied by susceptibility measurements in the temperature region from 100 to 300 K. The continuous addition of Fe atoms resulted in a decreasing temperature dependence of the magnetic susceptibilities. Only for compositions withx0.14 an approximatedCurie—Weiss behaviour was observed. The Fe-rich samples (x>0.14) showed a very high constant paramagnetism which could not be interpreted asPauli paramagnetism. The evaluation of magnetic moments was based on the assumption that only the Fe atoms contribute to the temperature dependence of the magnetic susceptibilities. The actual value of the magnetic moments is supposed to be affected by magnetic interactions between neighbouring Fe atoms. The extrapolation of the magnetic moments towardsx=0 is compatible with a magnetic moment of 3.87 _B corresponding to three unpaired d-electrons per Fe atom. According to the negativeWeiss constants derived fromCurie—Weiss law antiferromagnetic interactions at low temperatures can be expected.

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Mit 3 Abbildungen     

Indice de liaison en méthode CNDO. Relation entre indice de liaison et distance de liaison

The use of p_AB = Σ_μ^A Σ_ν^B _μν S_μν as bond index in the CNDO approximation is theoretically justified as it is an elaborated form of Coulson's bond order and an approximation of Roby's shared electron density. This bond index correlates with diatomic energy E_AB, a measure of binding energy, and with interatomic distance R_AB, for several bonds involving hydrogen and atoms of the n = 2 period. As an example of utilization of p_AB bond lengths in butadiene and a series of ethylenic compounds are determined.     

Calculation of the Magnetic Properties of <Emphasis Type="Italic">d</Emphasis> and <Emphasis Type="Italic">f</Emphasis> Transition Metal Complexes in Terms of the Angular Overlap Model

The theory of the electronic structures and magnetic properties of mononuclear complexes of d and f transition metals was developed in a complete basis set of products of one-electron functions with the use of the parametrization adopted in the angular overlap model. It was demonstrated that the theory describes well the temperature dependences of the magnetic susceptibilities of these complexes and allows estimation of their detailed electronic structures.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 7, 2005, pp. 506–511.Original Russian Text Copyright © 2005 by Rakitin, Rakitina, Kalinnikov.     

Sur diverses possibilités de formation de pyrimidines à partir de formyl-3 chromone

Guanidine transforms the following: (a) 3-formylchromone into a mixture of 2-amino-5-(2-hydroxybenzoyl)pyrimidine and 2-amino-5H-[1]-benzopyrano[4,3-d]pyrimidine; (b) the diacetate of 3-methylidyne-chromone into 2-amino-5-hydroxy-5H-[1]benzopyrano[4,3-d]pyrimidine; and (c) the oxime of 3-formylchromone into 2-amino-5H-[1]benzopyrano-[4,3-d]pyrimidin-5-one. Thiourea, acetamidine and nitroguanidine can also generate pyrimidines of the same type with 3-formylchromone, the diacetate of 3-methylidynechromone or 3-(1,3-dioxolan)chromone.     

Synthesis,crystal structure and magnetism of a two-dimensional Ni(II) coordination polymer with thiocyanate anion and dehydrogen-1,10-phenanthrolin-2-ol as bridging ligands

A two-dimensional coordination polymer [Ni(μ_1,3-SCN)(μ-Pheno)(CH₃OH)] _n (where Pheno = dehydrogen-1,10-phenanthrolin-2-ol) has been synthesized and its crystal structure determined by X-ray crystallography. Adjacent Ni(II) ions are coordinated by μ_1,3-SCN^? and μ-Pheno alternately forming a two-dimensional sheet structure. The fitting of the variable-temperature magnetic susceptibilities with a binuclear nickel(II) formula reveals that there is an anti-ferromagnetic interaction between the bridging Ni(II) ions with the magnetic coupling constant 2J = ?0.67 cm^?1.