Synthesis and characterization of the face-sharing bioctahedral [Mo2O6F3]3- anion

The face-sharing bioctahedral molybdenum(VI) oxide fluoride anion [Mo2O6F3]3- has been isolated in the new compound [Cu(3-apy)4]3(Mo2O6F3)2 (3-apy = 3-aminopyridine) and has been characterized by experimental and computational techniques. Single-crystal X-ray diffraction studies show that the structure of the [Mo2O6F3]3- anion resembles two distorted face-sharing octahedra, each with three short terminal metal-ligand bonds and three long metal-ligand-metal bridging interactions. Aspects of the electronic structure, as well as geometric comparisons of the bond lengths and angles in [Mo2O6F3]3- with those in the similarly distorted [MoO3F3]3- anion, suggest that the six terminal ligand positions of the confacial bioctahedra are occupied exclusively by oxide ligands and that the three bridging sites are occupied by fluorides. Crystal data for [Cu(3-apy)4]3(Mo2O6F3)2: trigonal space group R3 (No. 148) with hexagonal axes of a = 13.881(1) A and c = 31.783(3) A (Z = 3).     

Rhodium and ruthenium tetracarboxylate nitrosyl complexes: Electronic structure and metal-metal bond

The electronic structure of the tetracarboxylates M₂(μ-O₂CH)₄, M₂(μ-O₂CH)₄(L)₂ (M = Ru, Rh; L = H₂O, NO) was analyzed by the density functional theory with full geometry optimization. The inclusion of nitrogen oxide orbitals into the molecular orbitals forming the metal-metal bond affects all of the main characteristics of this bond and the concomitant properties. In the case of rhodium tetracarboxylates, one can consider destruction of the Rh-Rh covalent σ-bond and reorientation of two electrons from the internal region of the Rh₂(μ-O₂CH)₄ core to the outside, toward the axial ligands to give Rh-N covalent bonds. The axial coordination of nitrogen oxide in Ru₂(μ-O₂CR)₄ is accompanied by destruction of the metal-metal π-bond.     

Electronic structure of niobium-doped molybdenum disulfide nanotubes

The effect of doping transition metal disulfide nanotubes on their structural and electronic properties was studied for the first time using self-consistent band-structure calculations by the density functional tight-binding method (DFTB). The influence of partial Nb → Mo substitution in the walls of MoS₂ nanotubes of various diameters and atomic configurations (armchair and zigzag) on their electronic structure, structural parameters, and relative stability is exemplified by a series of “mixed” Mo_0.9Nb_0.1S₂ nanotubes. The electronic properties of Mo_0.9Nb_0.1S₂ nanotubes are discussed as a function of the possible types of distribution of doping Nb atoms in the tubes.     

Some reduced ternary and quaternary oxides of molybdenum. A family of compounds with strong metal-metal bonds

Several new, reduced ternary and quaternary oxides of molybdenum are reported, each containing molybdenum in an average oxidation state <4.0. All are prepared by reactions between a molybdate salt; metal oxide, if needed; and MoO₂ sealed in Mo tubes held at 1100°C for ca. 7 days. Refinement of the substructure of the new compound Ba_0.62Mo₄O₆ was based on an orthorhombic cell, witha = 9.509(2), b = 9.825(2), c = 2.853(1)Å, Z = 2 in space groupPbam; weak supercell reflections indicate the true structure hasc = 8(2.853) Å. The chief structural feature is closely related to that of NaMo₄O₆ (C. C. Torardi, R. E. McCarley,J. Amer. Chem. Soc.101, 3963 (1979)), which consists of infinite chains of Mo₆ octahedral clusters fused on opposite edges, bridged on the outer edges by O atoms and crosslinked by MoOMo bonding to create four-sided tunnels in which the Ba²⁺ ions are located. The structure of Ba_1.13Mo₈O₁₆ is triclinic,a = 7.311(1), b = 7.453(1), c = 5.726(1)Å, α = 101.49(2), β = 99.60(2), γ = 89.31(2)°,Z = 1, space groupP1¯. It is a low-symmetry, metal-metal bonded variant of the hollandite structure, in which two different infinite chains, built up from Mo₄O^2?₈ and Mo₄O^0.26?₈ cluster units, respectively, are interlinked via MoOMo bridge bonding to create again four-sided tunnels in which the Ba²⁺ ions reside. Other compounds prepared and characterized by analyses and X-ray powder diffraction data arePb_xMo₄O₆(x ～ 0.6), LiZn₂Mo₃O₈, CaMo₅O₈, K₂Mo₁₂O₁₉, and Na₂Mo₁₂O₁₉.     

Electronic structure and reactivity of organofluorine compounds

It was established on the basis of MNDO and STO-3G quantum-chemical calculations of fluoroethylenes that the fluorine atom at the vinylic position greatly stabilizes all the-MOs of the molecule on account of the accepting induction effect. The absence of additional stabilization of the-MO is due to the antiphase overlap of the free pair of the fluorine atom and the-MO. The concept of the electronic depletion of the double bond in fluorinated olefins is not confirmed by the calculations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1801–1805, August, 1989.     

Electronic structure and reactivity of organofluorine compounds

The basicity of isomeric bromoethylamines having a CF₃ substituent in the - and -positions with respect to the amino group was studied. According to potentiometric titration in H₂O, CH₃NO₂, and CH₃CN, the basicity of -trifluoromethylamines is 4–5 orders of magnitude lower than that of -trifluoromethyl isomers. Quantum-chemical calculations (AM1) showed that the decrease in the basicity of -trifluoromethylamines does not correlate with the change in the electron density at the nitrogen atom.For part 5, seeIzv. Akad. Nauk, Ser. Khim., 1992, 1334 [Bull. Russ. Acad. Sci., Div. Chem. Sci., 1992,41, 1041 (Engl. Transl.)].Deceased October 8, 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 279–281, February, 1994.     

Electronic structure of linear halogen compounds

Self consistent field molecular orbital calculations have been carried out for the ground electronic states for diatomic molecules XY, with X, Y=H, F, Cl, Br or I. Basis sets are critically discussed, and computed properties compared with experiment. The correlation between experimental ionization energies and those estimated through the use of Koopmans' theorem is given.     

Electronic structure and electronic absorption spectra of molybdenum and tungsten oxotetrachlorides

Electronic absorption spectra of the molecules MoOCl₄ and WOCl₄ have been measured and their electronic structure has been calculated on the basis of the SCF-X-SW theory in the overlapping atomic sphere model. Ionisation potentials and allowed optical transition energies have been found in the transition state approximation. The interpretation of the electronic absorption spectra of gaseous MoOCl₄ and WOCl₄ is given.     

Electronic structure,spectra, and thermodynamical functions of molybdenum pentachloride

The SCF-X -SW method in non-relativistic and quasi-relativistic versions has been used to calculate the electronic structure, ionization potentials, energies and oscillator strengths of the optical transitions in MoCl₅. The electronic absorption spectrum of the gaseous MoCl₅ has been measured. The interpretation of the photoelectron and optical spectra of MoCl₅ is given. Spinpolarization effects and relativistic corrections are discussed. The thermodynamical functions of MoCl₅ (gas) are calculated.     

Electronic band structure of tetracene-TCNQ and perylene-TCNQ compounds

The relationship between the crystal structures, band structures, and electronic properties of acene-TCNQ complexes has been investigated. We focus on the newly synthesized crystals of the charge-transfer salt tetracene-TCNQ and similar to it perylene-TCNQ, potentially interesting for realization of ambipolar transport. The band structures were calculated from first principles using density-functional theory (DFT). Despite the similarity in the crystal structures of the acene-TCNQ complexes studied here, the band structures are very different. Hole and electron transport properties are predicted to be equally good in perylene-TCNQ, in contrast to the tetracene-TCNQ, which has good transport properties for electrons only. The estimated degree of charge transfer for tetracene-TCNQ is 0.13e and for perylene-TCNQ 0.46e.     

ⅥB族金属叁键有机化合物的研究进展

本文对一类重要的ⅥB族金属叁键化合物R~2M~2(CO)~4(R为环戊二烯基及类环戊二烯基)近年来的研究成果进行了综述, 综述重点是这类化合物的官能团M≡M叁键的化学活性, 全文包括R~2M~2(CO)~4的合成及结构, M≡M叁键与亲核试剂、与碳-碳重键、与氧或与金属羰基物等试剂的反应及其应用。     

Electronic structure of molecules of diphenyl bridge compounds

Using the CNDO/2 method, we have calculated the valence electron density distribution in molecules of diphenylamine and its 13 derivatives with the substituents COOH, NO₂, OCH₃ on the aromatic rings of ionized forms of some diaryl amines, and also 4-amino- and 4-amino-4-adnitro substituted compounds with bridge groups NH, O, S, CH₂, CH=CH and analogous diphenyl derivatives. We have shown that independently of the nature of the bridge group, the principle of uncoupling of the aromatic rings is basically retained. Strong long-range effects of the substitutents along the chain of chemical bonds are not apparent. We have calculated the electrostatic molecular potential of the indicated compounds. We have established correlations between the electrostatic molecular potential and the protonization constants, the oxidation-reduction potentials of diarylamines; and also between the electrostatic molecular potential and the reaction rate constant for acylation of primary bridged amines at the amino group.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 84–88, January–February, 1985.     

Toward design of multiple-property inorganic-organic hybrid compounds based on face-sharing octahedral iodoplumbate chains

In this review article, we have illustrated the strategies developed to achieve inorganic-organic hybrid compounds with technologically important physical properties. A series of target inorganic-organic hybrid compounds have been accomplished by incorporating the functional organic components (with a large hyperpolarizability and luminophore Schiff base cation) into the highly polarizable one-dimensional (1-D) iodoplumbate chain network. The effect of substituent features in the phenyl ring of the Schiff base cation on its molecular conformation as well as the crystal packing structure of the hybrid compound will be discussed and the multiple physical properties (ferroelectricity, NLO and multiple band emission) will also be mentioned.