- Arene-Metal Dimer Complexes (C6H6)2V2 and (C6H6)V2; Experiment and Xα Theory. 3
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V atoms have been shown in a previous paper (part 1) to react with one or two benzene rings in rare gas matrices to form the respective half-sandwich, (C6H6)V, or the bis(benzene)vanadium complex, (C6H6)2V, depending on the relative concentrations of the various components.In this study, at higher V atom loadings, the corresponding binuclear complexes (C6H6)V2 and (C6H6)2V2 are identified from a combination of a kinetic analysis and V atom concentration study, the results of thermal annealing, and the outcome of V and Cr atom depositions into low-temperature methylcyclohexane solutions of bis(toluene)M (M=V,Cr).Xα-SW calculations were undertaken to provide a qualitative insight into modes of bonding in metal dimer arene molecules.Simplified half-sandwich models were utilized in C6v and C2v symmetry, as implied by stable, known structural analogues.In both cases the molecular orbital divided neatly into three types.The first type related essentially to the benzene ligand itself.The second type was characterized by uniquely metal-metal bonding interactions.These interactions established a basis for inferring metal localized excitations as being at the origin of the electronic absorption spectra seen red-shifted from the main MLCT band.The third type detailed the metal-ligand bonding interactions.The C6v structure showed bonding interactions similar to those of the mono(benzene)vanadium half-sandwich.The C2v molecule showed features in common with metal atoms interacting with a benzene ring which can show latent allyl-like character.The relevance of such a structure to known vanadium dimer molecules incorporating a single fluxional benzene ring is indicated.
- Andrews, Mark P.,Ozin, Geoffrey A.
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- Bis(arene)vanadium Anions, a New Class of Organovanadium Complexes: Syntheses, Reactivity towards Carbon Oxides, and Electron Spin Resonance Investigation
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Reduction of bis(arene)vanadium((0) complexes (1) with potassium in co-ordinating ether solvents gives solutions of the corresponding bis(arene)vanadate(-1) derivatives (2a; arene= benzene) and (2b; arene= mesitylene).Solvated potassium salts were isolated in yields depending on the arene ligands and the type of procedure required.The e.s.r. spectra of the reduction mixtures both in 1,2-dimethoxyethane and hexamethylphosphoramide are discussed.Solutuons of K (2a) in tetrahydrofuran are quickly reoxidized by both carbon mono- and di-oxide to give the vanadium(0) complex (1a); C1 and C2 products are formed, the relative yields depending on the concentrations of the reactants.
- Fochi, Giovanni,Runjuan, Xu,Colligiani, Arturo
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- Structures and its dipole moments of half-sandwich type metal-benzene (1:1) complexes determined by 2-m long electrostatic hexapole
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The transition metal-benzene (1:1) complexes are synthesized by laser evaporation method followed by the size and structure selection with 2-m long electrostatic hexapole field. Electric dipole moments of half-sandwich type binary complexes for a series of the transition metals, i.e. Ti, V, Co, and Ni, with benzene molecule were determined by measuring the focusing curves, namely the dependence of the focused beam intensity upon the hexapole field strength. It is found that the dipole moments of Ti-C6H6 and V-C6H6 are larger than the ones of Co-C6H 6 and Ni-C6H6. Such large dipole moments of Ti-C6H6 and V-C6H6 can be ascribed to the strong orbital interaction due to charge transfer between the metal atom and benzene molecule.
- Imura, Kohei,Ohoyama, Hiroshi,Kasai, Toshio
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- Bis(arene)vanadium(0) complexes as a source of vanadium(II) derivatives by both disproportionation of the 6-arene)2>+ cations and oxidation of 6-arene)2>
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The 6-arene)2>+ cation (arene = benzene, toluene or mesitylene) is disproportionate to 6-arene)2 and VII compounds in ether solvents such as THF or 1,2-dimethoxyethane (DME).The extent of disproportionation depends on the nature of both the counteranion and the arene ligand.Addition of the filtered crude reaction mixtures, presumably containing the 6-arene)2> derivatives, to THF gave (arene = benzene or toluene; X = Cl or Br).For X = Cl and arene = toluene, addition to a THF solution of LiI yielded I.The atom connectivity was established for , while I was fully characterized by X-ray diffraction methods.Crystal data: I: monoclinic, space group C2/c (no.15), a 25.199(8), b 13.865(6), c 9.879(4) Angstroem, β 103.98(2) deg, V 3349.3 Angstroem3, Z = 4, Dc 1.523 g cm-3, μ 17.256 cm-1, F(000) = 1560.The vanadium(II) derivative VI2(THF)0.7 was obtained, together with 6-mesitylene)2 in the reaction of 6-mesitylene)2> with THF.By reaction of 6-mesitylene)2> with CPh3X (X = Br or I) in 1,2-dimethoxyethane (DME), the dihalides of vanadium(II), have been isolated in good yields.The crystal and molecular structure of the monomeric cis- of pseudo-octahedral geometry has been studied by X-ray diffraction methods.Crystal data: : monoclinic, space group P21/n (non-standard No.14), a 7.819(4), b 13.150(4), c 15.535(5) Angstroem, β 90.23(3) deg, V 1587.3(1) Angstroem3, Z = 4, Dc 2.017 g cm-3, μ 44.231 cm-1, F(000) = 916.
- Calderazzo, Fausto,Benedetto, Giuseppe Egidio De,Pampaloni, Guido,Moessmer, Caecilia Maichle,Straehle, Joachim,Wurst, Klaus
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- Bis-arene-vanadium anions as reducing agents towards carbon dioxide and monoxide
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A novel way of activating an alkali metal for the reduction of CO2 and CO involves dissolving potassium in tetrahydrofuran containing , to give a solution of K as the actual reducing agent.In contact with CO2 or CO, the formal V-I derivative is immediately re-oxidized to the V0 complex and C1 and C2 products are formed.
- Fochi, Giovanni
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- Neodymium(II) and dysprosium(II) iodides in the reactions with metallocenes of d-transition metals
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Heating NdI2 (1) or DyI2 (2) with vanadocene (3) in benzene at 85°C led to the formation of bis(benzene)vanadium in 10 and 24 % yields, respectively. The lanthanide products were isolated in the form of CpLnI2(THF)3 after crystallization from THF. The interaction of 2 with 3 in isopropylbenzene at 90°C yielded a mixture of (arene)2V complexes from which a small amount of bis(isopropylbenzene)vanadium was isolated. The same reaction did not occur in mesitylene. From the reaction of 2 with 3 in molten naphthalene at 100°C, the heterobimetallic cluster {[CpDy(μ-I}2]7Cp 2V(μ-I)}(4) was isolated in low yield. The reaction of Cp 2Cr with 1 or 2 in benzene at ambient temperature afforded the dimer [CpCr(μ-I)]2 (5) and a dysprosium complex, Cp2DyI (6) (in the reaction with 2). When the reaction with 2 was carried out at 80°C, along with compound 6, the -ate complex {[Cp2DyI2] -[Cp2Cr]+}(7) was crystallized from the reaction solution. Nickelocene was reduced by 2 in benzene at 80°C to nickel metal. The dysprosium product was isolated as solvent-free complex 6. Ferrocene and cobaltocene did not react with 1 and 2 in benzene. The molecular structures of compounds 4, 5, and 7 were characterized by X-ray diffraction analysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Burin, Mikhail E.,Smirnova, Marina V.,Fukin, Georgy K.,Baranov, Eugeny V.,Bochkarev, Mikhail N.
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p. 351 - 356
(2007/10/03)
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- Ferromagnetism in one-dimensional vanadium-benzene sandwich clusters
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A molecular beam of multilayer vanadium-benzene organometallic complexes Vn(C6H6)m was produced by a laser vaporization synthesis method. The magnetic moments of the complexes were measured by a molecular beam magnetic deflection technique, and were found to increase with the number of vanadium atoms in the cluster, showing that the unpaired electrons, which occupy the nonbonding dσ orbitals localized on the metal atoms, couple ferromagnetically. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition metal atoms are formally zerovalent. Copyright
- Miyajima, Ken,Nakajima, Atsushi,Yabushita, Satoshi,Knickelbein, Mark B.,Kaya, Koji
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p. 13202 - 13203
(2007/10/03)
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- A soft-landing experiment on organometallic cluster ions: Infrared spectroscopy of V(benzene)2 in Ar matrix
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Vanadium (V)-benzene cluster ions, produced by laser ablation with reaction toward benzene vapor, were size-selected and deposited into a low-temperature Ar matrix. Infrared spectrum of V1(benzene)2 in the Ar matrix was measured after one-hour deposition with the deposition energy of 20 eV. The spectrum was in agreement with both the reported spectrum and our theoretical calculations, showing that (1) V1(benzene)2, prepared in the gas-phase reaction, takes a sandwich structure and that (2) the ions were soft-landed onto the Ar matrix and were neutralized by charge transfer from a metal substrate without fragmentation.
- Judai, Ken,Sera, Kentaro,Amatsutsumi, Shin-Ichi,Yagi, Keiichi,Yasuike, Tomokazu,Yabushita, Satoshi,Nakajima, Atsushi,Kaya, Koji
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p. 277 - 284
(2008/10/08)
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- Electronic properties of organometallic metal-benzene complexes [Mn(benzene)m (M = Sc-Cu)]
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Neutral metal-benzene complexes, Mn(benzene)m (M = Sc to Cu), are produced for all of the 3d transition metals in the gas phase by using the laser vaporization method. These species are characterized by mass spectrometry, photoioniza
- Kurikawa, Tsuyoshi,Takeda, Hiroaki,Hirano, Masaaki,Judai, Ken,Arita, Tadashi,Nagao, Satoshi,Nakajima, Atsushi,Kaya, Koji
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p. 1430 - 1438
(2008/10/08)
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