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By using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and OPBE/TZVP levels, the possibility of the existence of three Fe(V) complexes, each of which contains in the inner coordination sphere porphyrazine/trans-di[benzo]porphyrazine/tetra[benzo]porphyrazine (phthalocyanine), oxygen (O2−) and fluorine (F−) ions, was shown. Key geometric parameters of the molecular structure of these heteroligand complexes are given; it is noted that FeN4 chelate nodes, and all metal-chelate and non-chelate cycles in each of these compounds, are practically planar with the deviation from coplanarity, as a rule, by no more than 0.5°. Furthermore, the bond angles between two nitrogen atoms and an Fe atom are equal to 90°, or less than this by no more than 0.1°, while the bond angles between donor atoms N, Fe, and O or F, in most cases, albeit insignificantly, differ from this value. Nevertheless, the bond angles formed by Fe, O and F atoms are exactly 180°. It is shown that good agreement occurs between the structural data obtained using the above two versions of the DFT method. NBO analysis data for these complexes are presented; it is noted that, according to both DFT methods used, the ground state of the each of three complexes under consideration may be a spin quartet or spin doublet. Additionally, standard thermodynamic parameters of formation (standard enthalpy ∆fH0, entropy S0 and Gibbs's energy ∆fG0) for the macrocyclic compounds under consideration are calculated. [ABSTRACT FROM AUTHOR]

By using the data of the DFT quantum chemical calculation in the OPBE/TZVP and B3PW91/TZVP levels, the possibility of the existence of a manganese(VI) heteroligand complex containing porphyrazine or its tetra[benzo] derivative (phthalocyanine) and two oxygen (O2−) ligands, which is still unknown for this element, is shown. The parameters of the molecular structure, multiplicity of the ground state, NBO analysis data and standard thermodynamic parameters (enthalpy ΔH0f, entropy S0f and Gibbs's energy ΔG0f of formation) of each of these metal macrocyclic compounds are presented. Additionally, it is noted that, based on the totality of structural data obtained by the above versions of the DFT method, the existence of a similar complex of manganese with di[benzo] derivative of porhyrazine and two oxygen (O2−) ligands seems doubtful. [ABSTRACT FROM AUTHOR]

The possibility of formation of heteroligand (6,6,6,6)-macrotetracyclic chelate complexes of 3d-elements (M = Cr, Mn, Fe) with trans-dibenzoporphyrazine as the (N,N,N,N)-donor ligand and two O2− anions was studied in terms of the density functional theory. The OPBE/TZVP method predicts complexation only in the systems with M = Cr, Fe. According to B3PW91/TZVP calculations, all the 3d-elements studied can form complexes with the structure of a slightly distorted octahedron and planar chelate site MN4. All six-membered metal chelate rings in the complexes are identical to one another. The key bond lengths, bond angles, and non-bond angles in the complexes were determined and the corresponding standard enthalpies, entropies, and Gibbs energies of formation were calculated. [ABSTRACT FROM AUTHOR]

The novel complex W (=O)Np 3 F has been prepared by fluorination of the corresponding chloride counterpart with AgBF 4 . The reactivity of this complex with silica dehydroxylated at 700 °C afforded a well-defined silica supported monopodal tungsten oxo trialkyl surface species (≡SiO)W (=O)Np 3 . The reaction proceeds both through silanolysis of the W-F bond and opening of a siloxane bridge, with formation of a Si-F fragment, thanks to the affinity of silicon for fluoride. The resulting surface species was characterized by elemental analysis, DRIFT, solid state NMR and EXAFS spectroscopy. This material presenting fluorine on its surface shows an enhanced catalytic activity in propylene self-metathesis compared to its monopodal counterpart (≡SiO)W (=O)Np 3 (prepared from W (=O)Np 3 Cl) suggesting that the Si-F in a close vicinity to the W decreases the electron density of the W and thus increases its reactivity towards the olefinic substrate. [ABSTRACT FROM AUTHOR]

Abstract: Mixed μ-phosphido or μ-thiolato μ-halo-dimolybdenum(III) compounds [Mo2Cp2(μ-SMe)2(μ-X)(μ-Y)] (X=PPh2, Y=Cl (1); X=SCH3, Y=Br (3), I(4)) have been studied. Syntheses and X-ray structures of the new bromo and iodo analogues of [Mo2Cp2(μ-SMe)3(μ-Cl)] (2) are reported. While preparing 3 a side-product 5 was obtained and structurally characterised as the Mo5 system [{Mo2Cp2Br(μ-O)(μ-SMe)2}2(μ-MoO4)], containing a {MoIV–MoIV–O–(MoVIO2)–O–MoIV–MoIV} unit. The influence of the bridging groups on the structures and electrochemical behaviour of the complexes [Mo2Cp2(μ-SMe)2(μ-X)(μ-Y)] 1–4 has been investigated. In MeCN–[NBu4][PF6] the first oxidation of [Mo2Cp2(μ-SMe)2(μ-PPh2)(μ-Cl)] (1) is quasi-reversible, contrasting with the essentially irreversible first oxidation of the thiolate analogue [Mo2Cp2(μ-SMe)3(μ-Cl)] (2) under similar conditions. The effects of lowering the temperature or increasing the scan rate on the oxidation of 1 were examined: the initial quasi-reversible oxidation at first became irreversible but at still higher scan rates or lower temperatures the oxidation was again quasi-reversible. This suggests that the oxidation of 1 in MeCN is followed by reversible coordination of acetonitrile to afford the species [Mo2Cp2(μ-SMe)2(μ-PPh2)(Cl)(MeCN)]+ (7 +). Cyclic voltammetry of [Mo2Cp2(μ-SMe)3(μ-Y)](Y=Br (3) or I (4)) showed two quasi-reversible diffusion-controlled oxidation steps in CH2Cl2–[NBu4][PF6] or thf–[NBu4][PF6]. In acetonitrile, the fast loss of the halide ligands results in the formation of [Mo2Cp2(μ-SMe)3(MeCN)2]+ species. [Copyright &y& Elsevier]

Abstract: A dichloro oxovanadium(V) alkoxide complex [VOCl2(OCH2CH2OCH2CH2O n Bu)] was synthesised by reaction of VOCl3 and 2-(2-butoxyethoxy)ethanol in pentane. It was characterised by IR, 1H, 13C and 51V NMR spectroscopy, mass spectrometry and elemental analysis. Single-crystal X-ray diffraction reveals a monomeric complex with all oxygen atoms of the ligand attached to the overall octahedrally coordinated vanadium atom. This complex exhibits remarkably higher activity than VOCl3 towards ethene polymerisation with diethyl aluminium chloride as co-catalyst and methyl trichloroacetate as promoter. The complex also catalyses the epoxidation of cyclooctene to cyclooctene oxide with tert-butyl hydroperoxide. [Copyright &y& Elsevier]

Based on the results of a quantum chemical calculation using the DFT method with the OPBE/TZVP and B3PW91/TZVP levels, the possibility of the existence of three cobalt heteroligand complexes containing in the inner coordination sphere porphyrazine, di[benzo]- and tetra[benzo]porphyrazine, and two oxygen (O2−) ions with probable oxidation state VI of Co, which is unknown for this element at the present time, was shown. Data on the structural parameters are presented. It was shown that CoN4 chelate nodes as well as all metal-chelate and non-chelate cycles in each of these complexes, were strictly planar. Besides, the bond angles formed by two donor nitrogen atoms and a Co atom were close or equal to 90°, while the bond angles formed by donor atoms N, Co, and O, in most cases, albeit insignificantly, differed from this value. Good agreement between the calculated data obtained using the above two versions of the DFT method was found. Standard thermodynamic parameters of formation (standard enthalpy ΔH0f, 298, entropy S0f, 298 and Gibbs's energy ΔG0f, 298) for the indicated complexes were presented too. [ABSTRACT FROM AUTHOR]

The quantum-chemical calculation of iron, cobalt and nickel heteroligand complexes with the double deprotonated form of (NNNN)-donor atomic ligand—3,7,11,15-tetraazaporphine—and two oxo ligands has been carried out. Data on the structural and standard thermodynamic parameters, NBO analysis and multiplicity of the ground states of these complexes have been presented. The given calculation has been made by using the density functional theory (DFT) method with the OPBE/TZVP basis set. Based on the results of this calculation, the possibility of the existence of oxidation state VI for the chemical elements indicated above—unusual for iron and cobalt, and for nickel, unknown at all—has been shown. [ABSTRACT FROM AUTHOR]