Functionalized Trifluoromethyl-Containing Lithium β-Diketonate in the Synthesis of Homo- and Heteronuclear Complexes of Rare-Earth Metals

Russian Journal of Coordination Chemistry - The reactions of functionalized lithium CF3-β-diketonate (LiL) with trivalent rare-earth metal salts in methanol afford homobinuclear and...     

Electronic Structure and Chemical Bonding in β-Sialons

Using the discrete variation procedure we investigated the electronic structure, charge distributions, and chemical bonding in solid solutions of variable composition based on -Si₃N₄ with Si substituted by Al and N substituted by O (the general composition ). The electronic processes at the initial stage of SiAlON formation were studied (x = 1, 2) considering different distributions of Al–O pairs in the lattice of -Si₃N₄. The distribution mode of the dopant is found to be a more significant factor affecting the electronic structure of sialons compared to increased Al–O content; in particular, clusterization of dopant pairs leads to increased forbidden gap and splitting of the upper and lower valence bands. The results of calculations are used to interpret the systematic variations in the functional properties of -sialons depending on their chemical composition.     

ChemInform Abstract: Discrete-Variational-Xα Calculations of Buckminsterfullerene ( C60) and Fulleride X-Ray Emission Spectra

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Induced Circular Dichroism Spectra of β- and γ-Cyclodextrin Complexes with Indazolinone and Related Compounds

The magnetic circular dichroism (MCD) spectra of indazolinone, isatine, and 3-iminoisoindolinone and the induced circular dichroism (ICD) spectra of the inclusion complexes with β- or γ-cyclodextrins (CDs) have been measured. The spectra are interpreted by results of the ZINDO calculations. In the presence of cyclodextrin, the OH indazolinone tautomer is main structure that is consistent with that in the DMSO solution. The structures of the inclusion complexes are very different because of the scale of the cavity of cyclodextrin or position of quinone in molecules.This revised version was published online in July 2005 with a corrected issue number.     

Six-Nuclear Complexes of Platinum(II) and Palladium(II) with Mercamine and β-Mercaptoethanol

The platinum(II) and palladium(II) complexes [Pt₆(SCH₂CH₂NH₂)₈]Cl₄ and [Pd₆(SCH₂CH₂OH)₈ Cl₄· 5H₂O with mercamine and β-mercaptoethanol, respectively, were synthesized. It was found on the basis of the comparison of IR and X-ray electron spectra of the ligands and complexes, and also of the data of X-ray diffraction analysis that the bidentate coordination of ligands through sulfur and nitrogen atoms is realized in the platinum(II) complex. In the palladium(II) complex β-mercaptoethanol is coordinated in a mixed-mode type. In both complexes sulfur atoms of the ligands occupy a bridging position.     

Electronic Structures and Spectra of the Bases and Base Pairs of Nucleic Acids

The present paper covers electronic structures and spectra of the bases and the base pairs of nucleic acids calculated by using the INDO/S method. For free bases we give the energy levels of ground states and transition energies of low-lying excited states and discuss the band characters. The results indicate that the calculated spectra are in good agreement with experimental values. On the other hand, our calculations for A-T and G-C pairs are very beneficial to understanding hydrogen bond properties of these pairs.     

Molecular and Electronic Structure of λ3-Iminophoshines

Abstract

An analysis of main features of spatial and electronic structure of λ³-iminophoshines has been carried out on the basis of experimental X-ray structural data and results of quantum chemical calculation     

Emission Spectra of Some Heteropolytungstates Containing Europium

The emission spectra of some heteropolytungstates containing europium, K.[Eu(XW11 O39)2](X = P, Ge, As, or Ga), K17[EuCAs2W17O61)2] and K16H9EuAs4W40O140 have been investigated and the structures of these compounds are discussed. The emission spectra at room temperature are very similar to each other in terms of both the number of bands and transition frequencies, showing that they have the similar structures to those of K16[Ce(P2W17O61)2] and K12[U(GeW11O39)2].     

Stability and Structure of Silver–l-methionine Complexes

Journal of Solution Chemistry - Stability and structure of complexes between silver (I) and l-methionine (L) deduced from potentiometric and 1H NMR measurements allow to assume the prevailing of...     

Synthesis,Structure and Reactivity of Lanthanocene Complexes

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X–Ray Photoelectron Spectra and Electronic Energy Structure of Tetragonal Cu x Ni1-xTi Alloys

The electronic energy structure (EES) of Cu_0.8Ni_0.2Ti and Cu_0.6Ni_0.4Ti alloys, stoichiometric CuTi compound with a tetrahedral CuTi–type crystal lattice, and cubic NiTi was studied experimentally and theoretically. The experimental study of valence band EES was carried out by Xray photoelectron spectroscopy (XPS). The EES of both the stoichiometric compounds and the alloys was calculated using the cluster version of multiple scattering theory in a selfconsistent field approximation. The calculation and experimental results are in good agreement. The major contribution to XPS of the studied compounds is from the d states of copper and nickel. The specifics of chemical bonding in the compounds are discussed. The EES of tetragonal Cu—Ni—Ti alloys is modeled.     

Thin-Layer Chromatography of Some Monothio-β-Diketonate Complexes of Nickel,Zinc and Cobalt

Abstract

A silica gel adsorbent has been successfully used to separate three series of nickel, zinc and cobalt complexes of 1,1-difluoro-4-mercapto-4-(2′-thienyl)but-3-en-2-one, 1,1,1-trifluoro-4-mercapto-4-(2′-thienyl)but-3-en-2-one, 1,1,1-trifluoro-4-mercapto-2-(2′-naphthyl)but-3-en-2-one. For comparative purposes R_F data for the protonated ligands are also included. The ZnL₂ complexes gave R_F values in single and binary solvent systems which were similiar to the R_F values of the ligands; whereas, the NiL₂ and CoL₃ complexes gave R_F values which paralled each other in most solvents.     

The Microwave-assisted Preparation and X-Ray Structure of 3-Bromocarbazole-N-Acetic Acid

Carbazole and its derivatives have attracted the attention due to its photophysical and photochemical properties as well as biological activities1. So far considerable amounts of carbazole derivatives were prepared to probe the nature of electronic states. Among these carbazole derivatives, carbazole-9-carboxylic acids were important intermediates because the carboxylic group is an active function group for further transformation into other functions. The molecular packing modes of carboxylic …     

Synthesis, Structure and Noncovalent Interactions of Palladium(II) Complexes with N-Benzoyl-β-phenylalaninate Dianion and Aromatic Diimine

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Synthesis and CD Spectra of Chiral Molybdenum-fullerenyl Complexes with Pineno-bipyridine Ligands

The synthesis and characterization of two chiral fullerene complexes( )4in^CD-[Mo(η^2-C60)(CO)3(L^RR)]1 and (-)430^CD-[Mo(η^2-C60)(CO3)(L^SS)2 were described,the CD spectra of 1 and 2 in the visible range show Cotton effects,which are approximately of mirror image,indicating that the appended pineno-groups with opposite chirality in bipyridines can perturb the fullcrene chromophores through the molybdenum centers and lead to induced CD effects.     

Extraction and Crystal Structure of β-Sitosterol

The title compound β-sitosterol(C29H50O), an active phytosterol in many medicinal and edible plants, was characterized by X-ray diffraction analysis and extensive nuclear magnetic resonance(NMR) data. It crystallizes in monoclinic system, space group P21 with C29H50O·1/2H2O, a = 9.4226(7), b = 7.4824(9), c = 36.889(3) , V = 2597.0(4) 3, Z = 4, Dx = 1.084 g/cm3, Mr = 423.70, F(000) = 948, and μ = 0.064 mm-1. The final R = 0.0886 and wR = 0.2234 for 10157 observed reflections(I 2σ(I)). The molecular crystal structure of β-sitosterol shows relative stereochemistry of 24R-ethylcholest-5-en-3β-ol. The molecule is composed of one steroid nucleus(3 six-membered rings and 1 five-membered ring) and one sidechain of 10 carbons. There are two C29H50O molecules and one H2O molecule in a symmetrical unit, and the title compound is stacked into a special laminated structure through hydrogen bonds and van der Waal forces. The special laminated structure was first reported.     

Metal Complexes of Donor-functionalized Fluorinated β-Ketoiminates – Synthesis,Structure, and CVD Application

Six alkali metal complexes of partly-fluorinated, donor-functionalized β-ketoiminate ligands [L¹Li ( 1 ), L¹Na ( 2 ), L¹K ( 3 ), L¹Cs ( 4 ), L¹ = OC(CF₃)CHC(CH₃)NCH₂CH₂OCH₃; L²Li ( 5 ), L²Na ( 6 ), L² = OC(CF₃)CHC(CH₃)NCH₂CH₂N(CH₃)₂] were prepared and structurally characterized. Reactions of L¹Li with PtCl₂ gave the homoleptic Pt complex L¹₂Pt ( 7 ), which was characterized spectroscopically and by single-crystal X-ray diffraction and whose promising application as CVD precursor (chemical vapor deposition) is shown. Polycrystalline, pure Pt films were grown at 500 °C on SiO₂@Si(100) substrates at 10^–3 mbar and characterized by XRD, SEM, AFM, EDX and XPS.     

Theoretical Studies on Geometry, Stability and Electronic Spectra of DATB and TATB

The geometries of DATB( 1,3-diamino-2,4 ,6-trinitrobenzene) and TATB( 1,3,5-tri-amino-2,4,6-trinitrobenzene) have been optimized by M1NDO/3 method. It is found that the total energy of the molecule is rather low at the plane configuration. It is also found that the orbitals between the amino-N and its adjacent nitro-N as well as the amino-N and its adjacent nitro-N on the ring are rather close and matched in symmetry and have high orbital interaction through space, which are evidently seen from the computed results of the atomic bond index. The electronic spectra of DATB have been computed by using INDO/2-CI method, and the results are well conformed with the experimental facts. For instance, the transition from 'A' (ground state" ) to 'A' (the 7th exciled state) corresponds to the computed spectrum line(2. 48×104 cm-1) which is close to the experimental value (2. 43×104 cm-1). From a similar computation, we may predict that the major spectrum line of TATB will be 2. 75, 2. 77, 3. 28 and 3. 32×104 cm     

Alternative Synthesis and Crystal Structures of Titanocene(III)-β-Diketonate Complexes

Abstract

Reaction of titanocene prepared from Cp₂TiCl₂ and 2n-BuLi with β-diketones (β-diketone = 1-phenyl-1,3-butanedione, 1,3-diphenyl-1,3-propanedione, 3-methyl-2,4-pentanedione or 3-ethyl-2,4-pentanedione) afforded the titanocene(III) β-diketonate complex. The compounds [Ti(η⁵-Cp)₂(1-phenyl-1,3-butanedionate)] and [Ti(η⁵?Cp)₂(1,3-diphenyl-1,3-propanedionate)] have been characterized by X-ray crystallography.