1,721,161 research outputs found
Theoretical study of the [Fe(CO)(2)Cp(3)(mu(3)-C-3)](+) tricarbido cation
No full textDensity functional calculations have been carried out on a trinuclear [{Fe(CO)(2)Cp}(3)(mu(3)-C-3)](+) cation, and on related C3H3+ and C-3(NH2)(3)(+) molecules in order to study the electronic structure and the bonding of the C-3(+) unit to the metal fragments in this complex. An analysis of the MOs and of the Mulliken populations has been performed in order to understand the extent of the relative sigma and pi interactions between the C-3(+) and the Fe(CO)(2)Cp fragments. The results show that the iron-cyclopropenyl bond is mainly of sigma character with a smaller, but important, pi contribution. DFT calculations were also performed on the hypothetical mononuclear [Fe(CO)(2)Cp(C3H2)](+) complex to study the relative stabilities of the possible orientations of the Fe(CO)(2)Cp fragments with respect to the C-3(+) ring and to study its rotation about the Fe-C bond
The C-C bond as shuttle of two electrons in intermolecular and intramolecular processes: a theoretical approach to molecular batteries
No full textA theoretical study of transition metal systems: molecular batteries and activation of inert molecules
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Stepwise Four- and Six-Electron Reduction of Carbon Monoxide to Oxyalkylidyne, to Carbide and Oxide, Then to Carbide over an Nb−Oxo Surface Modeled by Calix[4]arene1
No full textalpha-Sulfinyl Transition Metal Bond. 1. Naked alpha-Sulfenyl Anions and their Reactivity with Metal Carbonyls: Synthesis of Metal-Carbon Bonded alpha-Sulfenyls and alpha-Sulfenylcarbenes
No full textDeprotonation of ArSOCH3 [Ar = C6H5,1; Ar = 4-MeC6H4, 2] with KH in THF in the presence of 18-crown-6 and Kryptofix-2,2,2 led to the isolation of the respective ion-contact and ionseparated pairs: [ArS(CH2)O⋯K(18-crown-6)] [Ar = C6H5, 3; Ar = 4-MeC6H4,4]; [ArS(CH2)O⋯K-(kryptofix-2,2,2)] [Ar = C6H5, 5; Ar = 4-MeC6H4,6]. The complexation of the potassium cation in both 4 and 6 causes the complete racemization of the α-sulfinyl anion. The structures of 3 and 5 have been determined with an X-ray analysis. The reaction of 3 and 4 with [Cr(CO)5-(THF)] led to the formation of α-sulfinyl carbonylmetalates containing a CrC σ bond, in [ArS(O)CH2Cr(CO)5]−[K(18-crown-6)]+[Ar = C6H5, 7; Ar = 4-MeC6H4, 8]. The high nucleophilicity of 3 is demonstrated in the reaction with a weakly electrophilic CO in [Cr(CO)6]. The reaction gives an unprecedented metallacarbene–sulfinyl anion complex, [{(CO)5CrC(O)CHS(O)Ph}⋯{K(18-crown-6)}2], 10, in which the carbene sulfoxide fragments migrate to a carbon monoxide, forming an α-sulfinylcarbene metallacycle, [formula omitted]⋯{K(18-crown-6)}2], 11. Exhaustive silylation of the peripheral oxygens of 11 led to the corresponding silylated form 12. Crystallographic details: 3 is monoclinic, space group P21, with a = 9.025(1) Å, b = 15.799(2) Å, c = 8.579(1) Å, α = γ = 90°, β = 107.76(1)°, Z = 2, and R = 0.040; 5 is triclinic, space group P1̅, with a = 10.713(1) Å, b = 10.825(1) Å, c = 14.877(1) Å,α = 112.07(1)°, β = 112.83(1)°, γ = 80.39(1)°, Z = 2, and R = 0.067; 11 is triclinic, space group P1̅, with a = 15.251(4) Å, b = 16.774(2) Å, c = 11.833(2) Å, α = 109.75(1)° β = 110.30(2)°, γ = 85.94(1)°, Z = 2, and R = 0.049
A density functional study of (PH3)2M(eta2-C2X4) alkene complexes for the group 10 metals Ni, Pd, Pt: the effect of electron-attracting substituents
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Bis(Cyclooctatetraene) Derivatives of Zirconium(IV) and Hafnium(IV): Syntheses and Lewis Base Adducts. Crystal Structures of [Zr(eta8-C8H8)(eta4-C8H8)], [Hf{eta8-C8H6(SiMe3)2}{eta4-C8H6(SiMe3)2}], [Zr(eta8-C8H8) (eta4-C8H8) (NH3)] and [Zr(eta8-C8H8) (eta4-C8H8)(CNBut)]
No full textThe syntheses of [M(η8-C8H8)(η4-C 8H8)] (M = Zr, 2 or Hf, 3) and [M{η8-C8H6(SiMe3) 2}{η4-C8H6(SiMe 3)2}] (M = Zr, 4 or Hf, 5) are reported. The η8 and η4 bonding modes for C8H8 were established in the solid state by X-ray analyses, while in solution a single C8H8 environment was observed by 1H NMR spectroscopy even at low temperature in accord with fluxional behaviour for these compounds. Complexes 2-5 behave as Lewis acids toward tetrahydrofuran, NH3 and ButNC and the adducts [Zr(η8-C8H8)(η4-C 8H8)(NH3)] 6 and [M(η8-C8H8)(η4-C 8H8)(CNBut)] (M = Zr, 7 or Hf, 8) have been isolated and characterized by X-ray analysis. Crystallographic details: 2, monoclinic, space group P21/c, a = 13.754(1), b = 7.798(1), c = 12.753(1) Å, β = 114.02(1)°, Z = 4 and R = 0.037 for 1267 independent observed reflections; 5, orthorhombic, space group Pca21, a = 14.418(1), b = 11.285(1), c = 18.898(1) Å, Z = 4 and R = 0.036 for 2239 independent observed reflections; 6, orthorhombic, space group P212121, a = 9.815(1), b = 14.129(2), c = 9.561(1) Å, Z = 4 and R = 0.022 for 1556 independent observed reflections; 7, triclinic, space group P1, a = 11.172(1), b = 13.469(1), c = 14.303(1) Å, α = 62.80(1), β = 78.01(1), γ = 77.26(1)°, Z = 4 and R = 0.028 for 2994 independent observed reflections
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