Valence-delocalization of the mixed-valence oxo-centered trinuclear iron propionates [Fe 2 III FeIIO(C2H5CO2)6(py)3]npy;n=0, 1.5

Mixed-valence trinuclear iron propionates [Fe ₂ ^III Fe^IIO(C₂H₅CO₂)₆(py)₃]npy, wheren=0, 1.5, were synthesized and the structure of the pyridine-solvated complex was determined by single-crystal X-ray diffraction. Mössbauer spectra of the solvated propionate complex showed a temperature-dependent mixed-valence state related to phase transitions, reaching an almost delocalized valence state at room temperature. On the other hand, the non-solvated propionate showed a remarkable change of the spectral shape related to a phase transition, remaining in a localized valence state at higher temperatures up to room temperature.     

Semi-empirical calculations on methyl substituted aromatics

The C-H and C-C types of hyperconjugation model calculated by the PPP VE SCF ASMO CI method are presented for toluene, t-butylbenzene, anilinium ion, and N-trimethyl anilinium ion. In addition a calculation was made for the anilinium ion, treating it as a perturbed toluene molecule and deriving the perturbation from potentials calculated from single center wavefunctions for CH₄ and NH₄ ⁺. The spectroscopic results of these calculations are in good agreement with experiment. However, it is concluded that for electrophilic reactions the experimental reactivities of the anilinium ion and the N-trimethyl anilinium ion should be explained not by the reactivity indices but rather by the external influences of the approaching electrophile.

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Zusammenfassung Die C-H- und C-C-Hyperkonjugation wurde mit Hilfe der PPP VE SCF ASMO CI Methode für Toluol, t-Butylbenzol, das Anilinium- und N-Trimethylaniliniumion berechnet. Außerdem wurde eine Rechnung für das Aniliniumion als gestörtes Toluol durchgeführt, wobei die Störung von Potentialen hergeleitet wurde, die von Einzentrum-Wellenfunktionen für CH₄ und NH₄ ⁺ erhalten worden waren. Die spektroskopischen Resultate dieser Berechnungen befinden sich in guter Übereinstimmung mit dem Experiment. Andererseits ergibt sich, daß für elektrophile Reaktionen die experimentellen Reaktivitäten des Anilinium- und des N-Trimethylaniliniumions nicht durch die Reaktivitätsindizes, sondern durch äußere Einflüsse des sich annähernden Agens erklärt werden sollten.

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Résumé Les modèles d'hyperconjugaison de type C-H et C-C sont calculés par la méthode PPP VE SCF ASMO CI pour le toluène, le t-butylbenzène, l'ion anilinium et l'ion N-triméthyl anilinium. De plus, un calcul de l'ion anilinium a été effectué en le considérant comme une molécule de toluène perturbée où la perturbation est obtenue à partir de fonctions d'onde monocentriques de CH₄ et NH ₄ ⁺ . Ces calculs fournissent des résultats spectraux en accord avec l'expérience. Cependant, pour les réactions électrophiles, il semble que les réactivités expérimentales de l'ion anilinium et de l'ion N-triméthyl anilinium ne doivent pas être expliquées à l'aide des indices de réactivité mais plutôt par les influences externes des réactifs électrophiles.

     

Application of fragment molecular orbital scheme to silicon-containing systems

The fragment molecular orbital (FMO) scheme has been successfully used for a variety of large-scale molecules such as proteins and nucleic acids so far. We have applied the FMO calculations to the silicon-containing systems like polysilanes. The error caused by the fragmentation was examined by the Hartree–Fock method and the second-order Møller-Plesset (MP2) perturbation method for the ground state energy. The dynamic polarizability as a linear response property was also evaluated with and without the fragmentation. A series of numerical comparisons showed that the FMO scheme is applicable to silicon-based molecules with reasonable accuracy. This implied a potential availability of FMO calculations for the issues relevant to nanoscience and nanotechnology.     

Carbon Nanosheets by Morphology‐Retained Carbonization of Two‐Dimensional Assembled Anisotropic Carbon Nanorings

Two‐dimensional (2D) carbon nanomaterials possessing promising physical and chemical properties find applications in high‐performance energy storage devices and catalysts. However, large‐scale fabrication of 2D carbon nanostructures is based on a few specific carbon templates or precursors and poses a formidable challenge. Now a new bottom‐up method for carbon nanosheet fabrication using a newly designed anisotropic carbon nanoring molecule, CPPhen, is presented. CPPhen was self‐assembled at a dynamic air–water interface with a vortex motion to afford molecular nanosheets, which were then carbonized under inert gas flow. Their nanosheet morphologies were retained after carbonization, which has never been seen for low‐molecular weight compounds. Furthermore, adding pyridine as a nitrogen dopant in the self‐assembly step successfully afforded nitrogen‐doped carbon nanosheets containing mainly pyridinic nitrogen species.     

Structure of gentiodelphin,an acylated anthocyanin isolated from Gentiana Makinoi, that is stable in dilute aqueous solution

Structure of gentiodelphin is determined to be 5, 3′-d8-O-(6-O-$\text{trans}$-caffeoylβ-D-glucosyl)-3-O-(β-D-glucosyl)delphinidin. The anthocyanin is stable in dilute neutral aqueous solution. This stabilization may be caused from intramoleculaur hydrophobic interactions among the aromatic nuclei; the anthocyanidin being sandwiched win between two caffeic acids.     

Structure of cinerarin,a tetra-acylated anthocyanin isolated from the blue garden cineraria, Senecio cruentus

Structure of cinerarin is determined to be 3-0-(6-0-malonyl-β-D-glucopyranosyl)-7-0-(6-0-(4-0-(6-0-caffeyl-β-D-glucopyranosyl)caffeyl)-β-D-glucopyranosyl)-3′-0-(6-0-caffeyl-β-D-glucopyranosyl)delphinidin.     

Compact and efficient basis sets of s- and p-block elements for model core potential method

We propose compact and efficient valence-function sets for s- and p-block elements from Li to Rn to appropriately describe valence correlation in model core potential (MCP) calculations. The basis sets are generated by a combination of split MCP valence orbitals and correlating contracted Gaussian-type functions in a segmented form. We provide three types of basis sets. They are referred to as MCP-dzp, MCP-tzp, and MCP-qzp, since they have the quality comparable with all-electron correlation consistent basis sets, cc-pVDZ, cc-pVTZ, and cc-pVQZ, respectively, for lighter atoms. MCP calculations with the present basis sets give atomic correlation energies in good agreement with all-electron calculations. The present MCP basis sets systematically improve physical properties in atomic and molecular systems in a series of MCP-dzp, MCP-tzp, and MCP-qzp. Ionization potentials and electron affinities of halogen atoms as well as molecular spectroscopic constants calculated by the best MCP set are in good agreement with experimental values.     

Molecular structure of some [1.1 ]ferrocenylruthenocenophanium (n = 1,2 polyiodides salts

Oxidation of [1.1]ferrocenylruthenocenophane with a large excess and 1.5 equivalents of iodine gives dicationic iodo[1.1]ferrocenylruthenocenophanium²⁺I₃⁻ · 0.5I₂2 (1) and monocationic [1.1]ferrocenylruthenocenophanium⁺I₃⁻ (2) salts respectively. The structures of 1 and 2 were analyzed by single-crystal X-ray diffraction studies. The crystal form of 1 is monoclinic space group C2/c, A = 21.35](5), B = 20.594(5), C = 17.397(4) Å, β = 124.17(1)°, Z = 8, and the final R = 0.068 and R_w = 0.070. The cation formulated as [Fe^III(C₅H₄CH₂C₅H₄)₂Ru^IVI]²⁺ exists in a syn-conformation as in the cases of the neutral compound. The distance between the Ru^IV and Fe^II is 4.656(4) Å, which is much shorter than the value of the neutral compound (4.792(2) Å), and the bond angle of I---Ru^IV,Fe^III is 81.26°. The dihedral angle between the two η⁵-C₅H₄ (fulvenide) rings on the Ru^IV moiety is 37.56° due to the Ru^IV---I bond (2.758(3) Å). These two rings of Fe^III and Ru^IV moieties are essentially eclipsed. The unit cell has three kinds of I₃⁻ (I_3a⁻, I_3b⁻ and I_3c⁻) and one I₂, and the formula of 1 is given as [Fe^III(C₅H₄CH₂CSH₄)₂Ru^IVI]²⁺I₃⁻ · 0.5(I₃⁻)₂ · 0.5I₂. The crystal of 2 formulated as [Fe^III(C₅H₄CH₂C₅H₄)₂Ru^II]⁺I₃⁻ is triclinic space group

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, and the final R = 0.067 and R_w = 0.068. The unit cell has two independent molecules (unit A and B); i.e. two kinds of distance between the Ru^II and Fe^III, are observed; one (A) is 4.615(3) and the other (B) is 4.647(3) α. The two η⁵-C₅H₄ rings of both Fe^III and Ru^II are essentially staggered and the dihedral angles between the rings of FcH and RcH moieties are less than 5.8°. Typical ferrocenium-type broad singlet ⁵⁷Fe-Mössbauer lines are observed for both salts (1, 2) at all temperatures.     

Nonadiabatic couplings from time-dependent density functional theory. II. Successes and challenges of the pseudopotential approximation

We present extensive calculations of nonadiabatic couplings (NACs) between the electronically ground and excited states of molecules, using time-dependent density functional theory (TDDFT) within (modified) linear response [C. Hu et al. J. Chem. Phys. 127, 064103 (2007)]. Our approach is implemented in the pseudopotential framework, with the consideration of nonlinear core corrections. The features of either the ordinary Jahn-Teller conical intersections in X(3) (X=Li, Na, K, Cu, Ag, Au) trimers, or the elliptic Jahn-Teller conical intersections in NaH(2), have been well reproduced. In particular, anticipated results for the H-H(2) collision near the avoided crossing are obtained, showing appealing improvement over the first, real-time, TDDFT calculation. The other important type of intersections, Renner-Teller glancing intersection, has also been studied for several typical molecular systems (BH(2), AlH(2), CH(2)(+), SiH(2)(+)), giving results in reasonable agreement with the theoretical model. Despite these successes, it is found that for some systems, including both Jahn-Teller and Renner-Teller systems, the pseudopotential scheme might give inaccurate results for some NAC components on nonhydrogen atoms. By trying different construction schemes of pseudopotentials, e.g., using local pseudopotentials, the results of NACs are found scheme-dependent and show improvement for some cases. Since there is much freedom in constructing ab initio nonlocal pseudopotentials, our findings on TDDFT calculation of NACs in the pseudopotential scheme might be helpful to give clues for constructing more "realistic" pseudopotentials.