F+ and F⁻ affinities of simple N(x)F(y) and O(x)F(y) compounds

Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for the neutral and ionic N(x)F(y) and O(x)F(y) systems using coupled cluster theory with single and double excitations and including a perturbative triples correction (CCSD(T)) method with correlation consistent basis sets extrapolated to the complete basis set (CBS) limit. To achieve near chemical accuracy (±1 kcal/mol), three corrections to the electronic energy were added to the frozen core CCSD(T)/CBS binding energies: corrections for core-valence, scalar relativistic, and first order atomic spin-orbit effects. Vibrational zero point energies were computed at the CCSD(T) level of theory where possible. The calculated heats of formation are in good agreement with the available experimental values, except for FOOF because of the neglect of higher order correlation corrections. The F(+) affinity in the N(x)F(y) series increases from N(2) to N(2)F(4) by 63 kcal/mol, while that in the O(2)F(y) series decreases by 18 kcal/mol from O(2) to O(2)F(2). Neither N(2) nor N(2)F(4) is predicted to bind F(-), and N(2)F(2) is a very weak Lewis acid with an F(-) affinity of about 10 kcal/mol for either the cis or trans isomer. The low F(-) affinities of the nitrogen fluorides explain why, in spite of the fact that many stable nitrogen fluoride cations are known, no nitrogen fluoride anions have been isolated so far. For example, the F(-) affinity of NF is predicted to be only 12.5 kcal/mol which explains the numerous experimental failures to prepare NF(2)(-) salts from the well-known strong acid HNF(2). The F(-) affinity of O(2) is predicted to have a small positive value and increases for O(2)F(2) by 23 kcal/mol, indicating that the O(2)F(3)(-) anion might be marginally stable at subambient temperatures. The calculated adiabatic ionization potentials and electron affinities are in good agreement with experiment considering that many of the experimental values are for vertical processes.     

Determinations of combustion and formation enthalpies of C_(60)and C_(70)

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Synthesis and characterization of β-diketonato- and phenoxoderivatives of mono(dizirconium-ennea-isopropoxy)copper(II)

Summary -Diketonato- and phenoxo-derivatives of mono(dizirconium-ennea-isopropoxy) copper(II), [Cu{Zr₂(OPr-i)₉}-(RCOCHCOR)] and [Cu{Zr₂(OPr-i)₉}(-OAr)], have been prepared by the interaction of K(RCOCHCOR) or KOAr (1 mol) [R = R = Me (1a); R = R = CF₃ (1b); R = Me, R = CF₃ (1c); OAr = 2,6-Me₂C₆H₃O (2a), 3,5-Me₂C₆H₃O (2b), p-ClC₆H₄O (2c)] with [Cu{Zr₂-(OPr-i) ₉}(-Cl)] (1 mol) in PhH. Alcohol interchanges of the derivative [Cu{Zr₂(OPr-i)₉}(-Cl)] have also been studied. These new compounds have been characterized by elemental analyses, i.r., electronic and e.s.r. spectra, and magnetic susceptibility measurements. The studies indicate a distorted octahedral geometry around Cu^II.     

Synthesis and Magnetic Properties of Fe(II) and Nd(III) Complexes of Poly(N-2-thiazolylacrylamide)

In recent years,the organic ferromagnets have drawn growing attention due to their characteristics of structural diversities,low density,and readily processing1-3.Design and synthesis of magnetic polymers are one of great challenges in today′s magnetic material research,and some significant achievements have been made in this field4,5.In this article,we describe the synthesis of acrylamide-type polymer with pendent thiazolyl groups(Scheme1).The as-prepared polymer exhibited better solubility …     

Investigation of Structures and Stabilities of AlmPn and AlmP(m+n=2～6)Clusters by DFT

The geometries,electronic states and energies of Alm Pn （ m + n = 2 ～ 6）neutral and anionic clusters have been investigated using the density functional theory（DFT）method of Becke’s three-parameter hybrid exchange functional with the nonlocal correlation of B3LYP. Structural optimization and frequency analyses are performed with the basis of 6-311G（ d）. The calculations predict the existence of a number of previously unknown isomers（i. e. ,Al3P_ and AlmPn （ m + n.5））. The calculations have also predicted that small AlP and（AlP）2 clusters adopt two-and three-dimensional structures characteristic of Si2 and Si4 clusters,while the structures of the larger AlP clusters are different completely from those of Sin clusters with the same electrons. The results show that the structures with the singlet have higher symmetries,while those with the doublet have lower symmetries. The vertical detachment energy of AlmPn （ m + n = 2 ～ 6）are also discused and the adiabatic electron affinities of AlmPn（m + n = 2 ～ 6）and also discussed at the same level. The results agree satisfactorily with the anion photoelectron spectroscopy of aluminum phosphide clusters reported recently by Gomez et al.     

Kinetics and mechanism of the anation of (αβ)-hydroxo(tetraethylenepentamine)cobalt(III) by thiosulfate, the base hydrolysis of the (sulfur-bonded) thiosulfato(tetraethylenepentamine)-cobalt(III) and photochemistry of oxygen and sulfur-bonded thiosulfato complexes

Summary The reaction of ()-(tetren)CoOH²⁺ with S₂O ₃ ^2- in the 7.25–8.28 pH range at 20–40 °C yielded S- (yellow) and O- (purple) bonded thiosulfato(tetren)cobalt(III) complexes, the former in larger quantities. The rate determining step is preceded by diffusion-controlled ion-pair [(tetren)CoOH²⁺,S₂O ₃ ^2- ] formation. Replacement of coordinated OH^- by S₂O ₃ ^2- is interpreted in terms of an internal conjugate base mechanism: (tetren)CoOH²⁺ (tetren-H)CoOH ₂ ²⁺ , the reactive amido conjugate base being generated by intramolecular proton transfer from the coordinated NH site.In acid medium the S-bonded (tetren)Co(S₂O₃)⁺ is highly stable to redox decomposition, in contrast to its pentaammine analogue. The complex however, undergoes base hydrolysis yielding the corresponding hydroxo complex. The rate and activation parameters for the base hydrolysis have been reported. Photolysis of O- and S-bonded isomers of [(tetren)CoS₂O₃]⁺ in acidic medium at 254 and 313 nm, respectively, yielded aquation products accompanied by some decomposition of S₂O ₃ ^2- .     

Surface Structure and Catalytic Behavior of MnO_(1+x) Radiated by Microwave

Introduction The surface structure, distribution and strength of the active centers of a catalyst would directly affect its catalytic activity and selectivity. In principle all the techniques and methods which can modify the surface and body structure of a catalyst, or influence its physicochemical properties can be used to change the activity and selectivity of a practical catalyst.     

Chemistry of natural compounds and bioorganic chemistry Synthesis of (±)-furodizinin and (±)-furodizin

The racemic forms of natural Omnoterpenoids, (±)-furodizinin and (±)-furodizin, were synthesized by cationic cyclization of the or -furylmethyl derivatives of linalool, geraniol and nerol.A. M. Moiseenkov (1936–1992), an outstanding Russian organic chemist, would have been sixty on July 6, 1996, He contributed significantly to the chemistry of terpenoids. The scientific heritage of A, M. Moiseenkov is rich and diversified. This work is devoted to the walizWon of one of his ideas. For the preliminary communication see Ref. 1.DeceasedTranslated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1842–1847, July, 1996.     

Preparation and electrical properties of Ca-doped La(2)NiO(4+δ) cathode materials for IT-SOFC

Ca-doped La(2)NiO(4+δ) is synthesized via the nitrate-citrate route. The effects of Ca substitution for La on the sinterability, lattice structure and electrical properties of La(2)NiO(4+δ) are investigated. Ca-doping is unfavorable for the densification process of La(2-x)Ca(x)NiO(4+δ) materials. The introduction of Ca leads to the elongation of the La-O(2) bond length, which provides more space for the migration of oxygen ion in La(2)O(2) rock salt layers. The substitution of Ca increases remarkably the electronic conductivity of La(2-x)Ca(x)NiO(4+δ). With increasing Ca-doping level, both the excess oxygen concentration and the activation energy of oxygen ion migration decrease, resulting in an optimization where a highest ionic conductivity is presented. Ca-doping is charge compensated by the oxidation of Ni(2+) to Ni(3+) and the desorption of excess oxygen. The substitution of Ca enhances the structural stability of La(2)NiO(4+δ) material at high temperatures and renders the material a good thermal cycleability. La(1.7)Ca(0.3)NiO(4+δ) exhibits an excellent chemical compatibility with CGO electrolyte. La(2-x)Ca(x)NiO(4+δ) is a promising cathode alternative for solid oxide fuel cells.     

Crystal Structures and Characterizations of Bis(pyrrolidinedithiocarbamato) Cu(II) and Zn(II) Complexes

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Excess Molar Volumes and Excess Viscosities of the Ternary System Diethylamine(1) + Ethyl Acetate(2) + n-Heptane(3) at 25°C

Densities and viscosities were experimentally determined in the whole range ofcomposition at 25°C for the ternary system diethylamine(1) + ethyl acetate(2)+ n-heptane(3) and for the three corresponding binary systems. Excess molarvolumes and excess viscosities were calculated for the binaries and the ternarysystems. Results were fitted and predicted with expressions from the literatureand are analyzed to gain insight about liquid mixture interactions.     

DNA-binding and photocleavage studies of metallofluorescein–porphyrin complexes of zinc(II) and copper(II)

The DNA-binding behaviors of the fluorescein?Cporphyrinatozinc(II) complex Zn(Fl-PPTPP) (Fl-PPTPP?=?5-(4-fluoresceinpropyloxy)phenyl-10,15,20-triphenylporphyrin) and fluorescein?Cporphyrinatocopper(II) complex Cu(Fl-PPTPP) with calf thymus DNA (CT-DNA) were investigated by UV?CVis absorption titrations, fluorescence spectra, viscosity measurements, thermal denaturation and circular dichroism. The results suggest that both complexes interact with CT-DNA by intercalation. In addition, their photocleavage reactions with pBR322 supercoiled plasmid DNA were investigated. Both complexes exhibit significant DNA cleavage activity, and singlet oxygen may play an important role in these reactions.     

Total Synthesis of (±)-Boschnialactone and (±)-Tetrahydroanhydrodesoxyaucubigenin

A total synthesis of (±)-boschnialactone ( 1 ) and (±)-tertahydroanhydrodesoxyaucubigenin ( 2 ) is described and trisubstitued cyclopentenoid 3 is a key intermediate.     

Experimental studies of the NaCs 5(3)Π0 and 1(a)3Σ+ states

We report high resolution measurements of 372 NaCs 5(3)Π(0)(v, J) ro-vibrational level energies in the range 0 ≤ v ≤ 22. The data have been used to construct NaCs 5(3)Π(0) potential energy curves using the Rydberg-Klein-Rees and inverted perturbation approximation methods. Bound-free 5(3)Π(0)(v, J) → 1(a)(3)Σ(+) emission has also been measured, and is used to determine the repulsive wall of the 1(a)(3)Σ(+) state and the 5(3)Π(0) → 1(a)(3)Σ(+) relative transition dipole moment function. Hyperfine structure in the 5(3)Π(0) state has not been observed in this experiment. This null result is explained using a simple vector coupling model.     

Total synthesis of (±)-maistemonine and (±)-stemonamide

The first total synthesis of polycyclic Stemona alkaloid maistemonine has been achieved. The efficient approach features a stereoselective intramolecular Schmidt reaction, a ketone-ester condensation, and a Reformatsky reaction. Additionally, another Stemona alkaloid stemonamide was divergently synthesized from a common intermediate.     

Synthesis and properties of ms- and β-substituted Pt(II) and Pt(IV) tetraphenylporphyrinates

The interaction of 5,10,15,20-tetraphenylporphyrin, 5,10,15,20-tetra-(4-chlorophenyl)porphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with platinum(II) chloride in boiling phenol has been studied. The corresponding platinum(II) porphyrinates have been synthesized; their subsequent treatment with bromine in chloroform resulted in platinum(IV) porphyrinates. The Pt(II) and Pt(IV)(Br)₂ porphyrinates have been identified by elemental analysis, electron absorption, IR, and ¹H NMR spectroscopy.     

Synthesis and characterization of sterically encumbered β-ketoiminate complexes of iron(II) and zinc(II)

The synthesis, structure, and spectroscopic signatures of a series of four-coordinate iron(II) complexes of β-ketoiminates and their zinc(II) analogues are presented. An unusual five-coordinate iron(II) triflate with three oxygen bound protonated β-ketoimines is also synthesized and structurally characterized. Single-crystal X-ray crystallographic analysis reveals that the deprotonated bis(chelate)metal complexes are four-coordinate with various degrees of distortion depending on the degree of steric bulk and the electronics of the metal center. Each of the high-spin iron(II) centers exhibits multiple electronic transitions including ligand π to π*, metal-to-ligand charge transfer, and spin-forbidden d-d bands. The (1)H NMR spectra of the paramagnetic high-spin iron(II) centers are assigned on the basis of chemical shifts, longitudinal relaxation times (T(1)), relative integrations, and substitution of the ligands. The electrochemical studies support variations in the ligand strength. Parallel mode EPR measurements for the isopropyl substituted ligand complex of iron(II) show low-field resonances (g > 9.5) indicative of complex aggregation or crystallite formation. No suitable solvent system or glassing mixture was found to remedy this phenomenon. However, the bulkier diisopropylphenyl substituted ligand exhibits an integer spin signal consistent with an isolated iron(ii) center [S = 2; D = -7.1 ± 0.8 cm(-1); E/D = 0.1]. A tentative molecular orbital diagram is assembled.     

Syntheses and Properties of Tripicolinatechromium (Ⅲ)

Chromium (Ⅲ) has been implicated as glucose tolerance factor (GTF) in the maintenance of normal lipid and carbohydrate metabolism^[1]. Several organic chromium (Ⅲ) complexes containing nicotinate, amino acids ligand which have much higher biological activity than chromic chloride have been synthesized and extensively studied^[2]. Tripicolinatechromium (Ⅲ) as a new human chromium(Ⅲ) nutritional supplement was shown to reduce the symptoms of diabetes, hyperglycemia and cholesterol significantly^[3]. Although the crystal structure and NMR spectrum of tripicolinatechromium (Ⅲ) was studied previously^[4,5], Its properties have only received little attention. In this paper, we report the studies of syntheses and properties of tripicolinatechromium(Ⅲ).     

Enantiospecific Synthesis of (–)-Cuspareine and (–)-Galipinine

An enantiospecific route to the synthesis of tetrahydroquinoline alkaloids (–)-cuspareine and (–)-galipinine is reported. Coupling of an iodide derivative of D-serine with aromatic dithianes and Pd-catalyzed intramolecular C–N coupling are the key steps in the synthesis.