Copper complexes with N-aminotriazolethione azomethines: Structures and magnetochemical properties

Azomethine derivatives of 4-amino-1,2,4-triazole-3-thiones (H₂L) and their metal complexes were obtained. The stabilities of the ligand conformers were calculated using quantum-chemical techniques. Ab initio (B3LYP/LANL2DZ) calculations of the complexes in the lower singlet and triplet states were performed with full geometry optimization. The structures and magnetochemical properties of the chelate complexes obtained were examined over a wide temperature range.     

Chemical and electrochemical syntheses of the binuclear zinc and cadmium chelates based on the sterically hindered Schiff bases

Chemical and electrochemical syntheses of a series of the zinc(II) and cadmium(II) complexes were carried out on the basis of sterically hindered Schiff bases, which are the condensation products of 4,6-di-tert-butyl-2-aminophenol with the salicylaldehyde derivatives (H₂L, H₂L¹). The structures and compositions of the synthesized binuclear complexes M₂L₂ and M₂L ₂ ¹ where M = Zn(II) and Cd(II), were proved by the data of elemental analysis, IR spectroscopy, and ¹H NMR spectroscopy. The structures of the Zn₂L₂ · 2Py and Zn₂L₂ · 2DMF dimers were proved by X-ray diffraction analysis. The electrochemical dissolution of zero-valence zinc and cadmium in methanol in the presence of equimolar amounts of H₂L and H₂L¹ made it possible to isolate dimeric complexes of the corresponding metals of the composition M₂L₂ and M_{2 2} ¹ .     

Binuclear and polynuclear complexes of Schiff bases

The data on the synthesis of binuclear and polynuclear homo- and heterometallic complexes of aromatic and heterocyclic (azole) Schiff bases are summarized and systematized. Influence is revealed of the structure (nature of aldehyde and amine moieties and intermetallic bridges) of azomethine binuclear copper chelates on their magnetic characteristics. The complexes with N,N-or S,S-bridging atoms are shown to lead, in general, to ferromagnetic exchange whereas O,O-intermetal binding leads to antiferromagnetic spin-spin coupling.     

螺旋桨空化噪声连续谱仿真算法

螺旋桨空化噪声连续谱由大量空泡随机崩溃所辐射噪声叠加而成。据此,考虑到空泡初始崩溃时刻的随机性和各空泡辐射噪声频谱的相似性,对四种情况空化辐射噪声连续谱特性分别进行了理论分析表明,可依据空泡半径和初始崩溃时间的统计性质,采用蒙特卡罗方法对空化噪声连续谱波形进行仿真建模,模型参数为空泡半径期望值、差异度和随机度,分别相应于确定辐射噪声的基准波形、各空泡噪声频谱相似程度和大量空泡的随机崩溃过程。该方法输入参数物理意义明确,控制简单,能较好地仿真空化噪声连续谱的特性,仿真结果与理论分析吻合较好。     

Serendipity Virtual Elements for General Elliptic Equations in Three Dimensions

The authors study the use of the virtual element method (VEM for short) of order k for general second order elliptic problems with variable coefficients in three space dimensions. Moreover, they investigate numerically also the serendipity version of the VEM and the associated computational gain in terms of degrees of freedom.     

Complexes of azoles with acetylacetonates

A number of the most important inorganic biological systems are coordination adducts formed as a result of the axial addition of azoles to chelates of the transition metals [1].     

MAGNETIC FIELD EFFECT OF THE EUROPIUM a8S7/2-z6P7/2 LINES

The magnetic field effect of a⁸S_7/2-z⁶P_7/2 lines of ¹⁵¹Eu and ¹⁵³Eu in magnetic fields up to 66.7 mT has been studied by using laser atomic beam spectroscopy. The Zeeman level structures of the europium a⁸S_7/2 and z⁶P_7/2 states in magnetic fields were discussed. The location and intensity of the measured Zeeman transition lines were found in good agreement with the theoretical results.     

Molecular design of azomethine complexes

Data on the coordination chemistry of azomethines, which are based on the molecular design concept formulated and developed by V.I. Minkin and his disciples, are generalized and systematized. Particular attention is given to the methods for targeted synthesis of five- and/or six-membered chelates containing chalcogen atoms (S, Se, and Te) and nonstandard (heteroleptic, molecular, and supramolecular) structures. Achievements in the design of magnetically active and luminescent complexes and azomethine complex additives to lubricants are discussed.