Theoretical investigation of ytterbium trichelates compounds

Theoretical studies on ytterbium trichelates, Yb(L)₃(L = trifluoromethanesulfonate (OTF), perchlorate (ClO₄), p‐toluenesulfonic (TOS), nitrobenzenesulfonic (NBSA), and dodecylsulfate (DOS), are carried out using density functional theory method at the PW91/TZP level, for the first time. All ligands are bidentate and the compounds exhibit a distorted trigonal prismatic structure, with a maximum twist angle obtained for ytterbium p‐toluenesulfonic compound Yb(TOS)₃. The quantum theory of atoms in molecules (AIM) and energy decomposition analysis reveal the dominant ionic character in ytterbium–oxygen bonding with a little covalent character. According to the Pearson terminology, the Yb(NBSA)₃complex reveals the higher acidity. © 2012 Wiley Periodicals, Inc.     

示波极谱法连续测定稀土氧化物中铕和镱

研究表明,除铕及镱外,用极谱法难以测定其它稀土元素。Laitinen等曾以0.1M氯化铵为支持电解质,在pH5～6下以经典极谱法测铕和镱,其半波电位分别为-0.671和-1.415伏。其后亦有人以氯化钙、氯化钾作底液,用经典极谱法测铕和镱。本文介绍以示波极     

Synthesis and properties of mono- and bis[2-(dimethylaminomethyl)]cymantrenyl derivatives of ytterbium

The reaction of [2-(dimethylaminomethyl)]cymantrenyl]lithium with ytterbium diiodide affords [2-(dimethylaminomethyl)cymantrenyl]ytterbium iodide or bis[2-(dimethylaminomethyl)cymantrenyl]ytterbium depending on the ratio of the starting reactants. Reactions of these complexes with a series of electrophiles (H₂O, Me₃SiCl, MeCOCl, HgCl₂, PhCOCl) were studied and the corresponding derivatives of cymantrene were prepared in high yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No.3, pp. 531–533, March, 1994.     

Complexes of lanthanide ions with dibenzodioxatetraazamacrocyclic ligands

Efficiency of luminescence of europium and ytterbium ions in complexes with three 16-membered dibenzodioxatetraazamacrocycles was estimated.     

Efficient Synthesis of 1,5‐Benzodiazepine Derivatives by Ytterbium Trichloride–Catalyzed Condensation of o‐Phenylenediamine and Ketones

1,5‐Benzodiazepines are synthesized in good to excellent yields by ytterbium trichloride (YbCl₃)–catalyzed condensation of o‐phenylenediamine and ketones under mild and solvent‐free conditions. The Lewis acid–type catalyst, ytterbium trichloride, is found to be water stable and reusable.     

三氯化镱催化丙烯酸酯与呋喃成环反应的研究

D iels-A lder反应具有立体专一性和很好的区域选择性,已被大量应用于天然有机化合物、香料、药物等的合成中。一般说来,D iels-A lder反应在加热条件下即能发生,但加热往往导致反应的区域选择性和立体专一性下降,而研究表明,路易斯酸催化下的D iels-A lder反应在不同程度上表现出或反应速度加快,或产率提高,或条件温和,尤其是区域选择性和立体专一性得到提高等良好特性。呋喃类化合物由于呋喃环所具有的芳香性而较难与一般的亲双烯发生D iels-A lder反应。如呋喃和丙烯酸甲酯在加热条件下反应2~3个月,产率只能达到50%,且反应温度的提高…     

Ytterbium (II) Hydride as a Powerful Multielectron Reductant

A dimeric β-diketiminato ytterbium(II) hydride affects both the two-electron aromatization of 1,3,5,7-cyclooctatetraene (COT) and the more challenging two-electron reduction of polyaromatic hydrocarbons, including naphthalene (E⁰=−2.60 V). Confirmed by Density Functional Theory calculations, these reactions proceed via consecutive polarized Yb−H/C=C insertion and deprotonation steps to provide the respective ytterbium (II) inverse sandwich complexes and hydrogen gas. These observations highlight the ability of a simple ytterbium(II) hydride to act as a powerful two-electron reductant at room temperature without the necessity of an external electron to initiate the reaction and avoiding radicaloid intermediates.     

Chemoselective Synthesis of Asymmetrical Carbonate from Alcohol and Dimethyl Carbonate Catalyzed by Ytterbium(III) Triflate

Catalyzed by ytterbium(III) triflate, asymmetrical carbonate can be chemoselectively synthesized from alcohols and dimethyl carbonate (DMC) in moderate to good yield under the mild conditions.     

Ytterbium Coordination Polymer with Four Different Coordination Numbers：The First Structural Characterization of Lanthanide Phthalate Complex

The novel ytterbium coordination polymer is a t4wo-dimensional framework in which the central metal ions have four different coordination numbers and form four kinds of coordination poly-hedra,The four kinds of coordination polyhedra connect into infinite chains by sharing oxygen atoms.     

配合物(ArO)2Yb(NPh2)2K(THF)4(Ar=C6H2-t-Bu3-2,4,6)的合成、分子结构和催化行为

Reaction of anhydrous YbC13 with 2 equiv, of sodium 2,4,6-tri-tert-butylphenoxide (ArONa, Ar=C6H2-t-Bu3-2,4,6) and 2 equiv, of potassium diphenyl amide in THF afforded the first bis(aryloxo) amido-lanthanide complex of (ArO)2Yb(NPh2)2K(THF)4 (1). In 1, the ytterbium and potassium were bridged via diphenyl amido ligands.The ytterbium metal center was coordinated to two oxygen atoms of aryloxide ligands and two nitrogen atoms of diphenyl amido ligands in a conventional distorted tetrahedral fashion, while the potassium interacted in η^2-fashion with two phenyl rings of the diphenyl amido ligands besides four THF molecules. 1 displayed moderate catalytic activities for the polymerization of methyl methacrylate and acrylonitrile.     

Carbon‐bridged Tri(cyclopentadiene): Synthesis and Coordination with Ytterbium

Reaction of a mixture of 1,1‐bis(cyclopentadienyl)cyclohexane and pentamethylenefulvene with metallic sodium in THF led to a mixture of cyclohexylidene‐bridged bis(cyclopentadienyl) sodium and two‐cyclohexylidene‐bridged tri(cyclopentadienyl) sodium. Reaction of the salt solutions with anhydrous YbCl₃ in THF afforded a ytterbium complex mixed‐ligated by bridged bis(cyclopentadienide) and bridged tri(cyclopentadienide).     

Reactivity of ytterbium in liquid ammonia

A solution of metallic ytterbium in liquid ammonia reacts readily with various carbonyl complexes of metals to form the corresponding lanthanide carbonylmetallates. The reaction of an excess of Yb in liquid NH₃ with [CpFe(CO)₂]₂ gave (THF)₄Yb[Fe(CO)₂Cp]₂ in 42% yield. It was suggested that the resulting complex contains two equivalent Yb−Fe bonds. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1883–1885, October, 1997.     

Allylation of Diselenides,Aldehydes and Ketones with Ytterbium/Allyl Bromide System

In the presence of methyliodide, ytterbium can react with allyl bromide smoothly to form allylytterbium bromide, which further reacts with diselenides, aldehydes and ketones to afford allylselenides and homoallylic alcohols respectively in good yields under mild and neutral conditions.     

Synthesis, properties, and reactivity of the stilbene complex of ytterbium (PhCH=CHPh)Yb(THF)2. Crystal structure of (2,4,6-But 3C6H2O)2Yb(THF)3

The stilbene complex of ytterbium (PhCH=CHPh)Yb(THF)₂ (1) was prepared by the reaction of YbI₂(THF)₂ with a twofold excess of (PhCH=CHPh)⁻ Li⁺. Based on the data of IR and ESR spectroscopy and on the results of magnetic measurements, compound1 was characterized as a complex of divalent ytterbium with the stilbene dianion. The reactivity of complex1 toward different types of reagents was studied. The structure of the product of the reaction of1 with 2,4,6-tri(tert-butyl)phenol (2,4,6-Bu^t ₃C₆H₂O)₂Yb(THF)₃ was established by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2345–2350, November, 1998.     

Ligand preferences in ytterbium ions complexation with carboxylate-based metal-organic frameworks

Two coordination polymers of ytterbium were synthesized by employing 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid (H₃TATB), 4,4′,4-benzene-1,3,5-triyl-tribenzoic acid (H₃BTB), and 3,5-pyridinedicarboxylic acid (3,5-PDC) ligands and were characterized by single-crystal X-ray diffraction analysis. Reaction of ytterbium(III) chloride in the presence of H₃BTB and 3,5-PDC ligands gives preferred complexation with the 3,5-PDC ligand, producing [Yb₂(3,5-PDC)(ClO₄)₃][NH(Me)₃] (1). However, under exactly the same reaction conditions, reaction of ytterbium(III) chloride in the presence of 3,5-PDC and H₃TATB resulted in complexation with H₃TATB to form [(CH₃)₂NH₂][Yb₄(TATB)₄(HCO₂)(H₂O)₂]·3H₂O (2). The crystal structure results showed a layered structure for 1 and a metal-organic framework structure for 2. This indicates that the complexation preference of the ytterbium ion is H₃TATB ≥ 3,5-PDC ≥ H₃BTB. Conversely, the uncomplexed ligand in the metal-organic framework (2) is an auxiliary agent during the synthesis, which shows polytopic linker controls crystal properties, to form suitable crystals for single-crystal structure determination. The prepared coordination compounds were used as heterogeneous catalysts in an oxidation amidation reaction with different aldehydes and benzylamine hydrochloride.     

1H,4H-1,4-diborabuckminsterfullerene with pyridine molecules and ytterbium endo-atom

The competition between the ytterbium endo-atom and the pyridine exo-molecules as nucleophiles interacting with the electron-deficient 1H,4H-1,4-diborabuckminsterfullerene was studied using the quantum chemical DFT PBE0 method. The equilibrium structural parameters, dipole moments, IR spectra, and exothermic effects of the formation of the C₅₈B₂•Py₂ adduct and the endohedral Yb@C₅₈B₂•Py₂ complex were determined. The concept of the state of oxidation/reduction of an atom in a chemical compound has been clarified. The localization of the ytterbium(II) under a pair of equivalent carbon atoms bonded to boron(III) atoms is predicted. The introduction of ytterbium(II) into the adduct cavity weakens exo-bonds with pyridine molecules without changing the oxidation state of boron(III). Each nitrogen atom retains a lone electron pair, coordinated by a boron(III). The ytterbium(II) endo-atom retains 14 electrons in f states.     

Erlenmeyer Synthesis for Azlactones Catalyzed by Ytterbium(III) Triflate under Solvent‐Free Conditions

A series of 4‐arylidene‐2‐phenyl‐5(4)‐oxazolones were synthesized from cyclodehydration–condensation of hippuric acid, aromatic aldehydes, and acetic anhydride catalyzed by ytterbium(III) triflate under mild conditions in excellent yields.     

Asymmetric Hetero Diels‐Alder Reaction of Chiral Imines with Danishefsky's Diene Catalyzed by Yb(OTf)3

Reaction of chiral imines with Danishefsky's diene in the presence of a catalytic amount (20 mol%) of ytterbium triflate afforded the corresponding hetero Diels‐Alder adducts with a moderate to good diastereoselectivity.     

Etherification of Ferrocenyl Alcohol by Highly‐efficient Ytterbium Triflate

Nucleophilic substitution of ferrocenyl alcohols with various aliphatic alcohols in the presence of a catalytic amount of ytterbium triflate [Yb(OTf)₃] was studied. It was found the unsymmetrical ferrocenyl ethers could be easily obtained in excellent yields when the reactions were performed in primary and secondary alcohols. However, in other organic non‐alcoholic solvents such as acetonitrile, the formation of symmetrical ferrocenyl ethers rather than unsymmetrical ones was observed.     

A Novel Divalent Ytterbium Complex Supported by a Bridged Diamide Ligand: Synthesis and Structure of [{Me2Si(NPh)2Yb(THF)2}(μ3‐Cl)(μ4‐Cl){Li(THF)}2]2·2THF

The reaction of anhydrous YbCl₃ with 1 equiv. of Li₂Me₂Si(NPh)₂ in THF, after workup, yielded a ytterbium(III) chloride [{Me₂Si(NPh)₂Yb}(μ₂‐Cl)(TMEDA)]₂·3PhMe ( 1 ) (TMEDA=tetramethylethanediamine). The same reaction followed by treatment with Na‐K alloy afforded a new ytterbium(II) complex supported by a bridged diamide with four coordinated LiCl molecules, [{Me₂Si(NPh)₂Yb(THF)₂}(μ₃‐Cl)(μ₄‐Cl){Li(THF)}₂]₂·2THF ( 2 ) in high yield. Both complexes were structurally characterized by X‐ray analysis to be dimers. Complex 1 was a chlorine‐bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me₂Si(NPh)₂Yb(THF)₂]‐(μ₃‐Cl)[Li(THF)]₂ moieties were connected with each other by two μ₄‐Cl bridges to form a "chair‐form" framework.