Recent Advances in Organic Reactions Catalyzed by Lanthanide(III) Complexes

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｎａｍｅ“ｒａｒｅｅａｒｔｈ”ａｐｐｌｉｅｓｔｏｔｈｅｌａｎｔｈａｎｉｄｅｓ ,ｙｔｔｒｉｕｍａｎｄｓｃａｎｄｉｕｍ .Ｔｈｅ 15ｅｌｅｍｅｎｔｓｏｆｌａｎｔｈａｎｉｄｅｆｒｏｍｌａｎｔｈａｎｕｍｔｏｌｕｔｅｔｉｕｍｃｏｎｓｔｉｔｕｔｅａｕｎｉｑｕｅｆａｍｉｌｙｏｆｃｌｏｓｅｌｙｒｅｌａｔｅｄｅｌｅｍｅｎｔｓ (ｔｈｅｄｉｆｆｅｒｅｎｃｅｌｙｉｎｇｉｎｔｈｅｎｕｍ ｂｅｒｏｆ 4ｆｅｌｅｔｒｏｎｓ)ｆｒｏｍｗｈｉｃｈｒｅｇｅｎｔｓｏｒｃａｔａｌｙｓｔｓｗｉｔｈ“ｔｕｎａｂ…     

Gold(III) π-Allyl Complexes

Gold(III) π-complexes have been authenticated recently with alkenes, alkynes, and arenes. The key importance of Pd^II π-allyl complexes in organometallic chemistry (Tsuji–Trost reaction) prompted us to explore gold(III) π-allyl complexes, which have remained elusive so far. The (P,C)Au^III(allyl) and (methallyl) complexes 3 and 3′ were readily prepared and isolated as thermally and air-stable solids. Spectroscopic and crystallographic analyses combined with detailed DFT calculations support tight quasi-symmetric η³-coordination of the allyl moiety. The π-allyl gold(III) complexes are activated towards nucleophilic additions, as substantiated with β-diketo enolates.     

Polynuclear Heteroligand Yb(III)–Er(III) Complexes as Potential Upconversion Materials

Russian Journal of Coordination Chemistry - The synthesis of complexes LnI(C6F5O)2 and LnCp(L)2 (Ln = Er, Yb; L = C6F5O, SONF), which are convenient precursors for the preparation of heteroligand...     

SynthesisandStructureof 1-Cyclopentylindenyl Lanthanide(II) Complexes and Their Catalytic Behavior for Polymerization of Acrylonitrile

ＩｎｔｒｏｄｕｃｔｉｏｎＧｒｅａｔｐｒｏｇｒｅｓｓｈａｓｂｅｅｎｍａｄｅｉｎｔｈｅｃｈｅｍｉｓｔｒｙｏｆｄｉ ｖａｌｅｎｔｏｒｇａｎｏｌａｎｔｈａｎｉｄｅｃｏｍｐｌｅｘｅｓ .Ａｖａｒｉｅｔｙｏｆｎｅｗｃｌａｓｓｅｓｏｆｃｏｍｐｌｅｘｅｓｈａｖｅｂｅｅｎｓｙｎｔｈｅｓｉｚｅｄａｎｄｗｉｄｅｌｙｕｓｅｄｉｎｏｒｇａｎｉｃｓｙｎｔｈｅｓｉｓａｎｄｐｏｌｙｍｅｒｃｈｅｍｉｓｔｒｙ .1 6 Ｉｔｗａｓｎｏｔｉｃｅｄｔｈａｔｍｏｓｔｏｆｔｈｅｗｏｒｋｐｕｂｌｉｓｈｅｄｉｓｆｏｃｕｓｅｄｏｎｔｈｅｃｏｍｐｌｅｘｅ…     

Cationic Gallium(III) Halide Complexes: A New Generation of π-Lewis Acids

Ga-neration X: Well-defined neutral and cationic gallium(III) halide complexes have been synthesized and evaluated in catalysis. Both the (NHC)GaX(3) /AgSbF(6) catalytic mixture and isolated (NHC)GaX(2) (+) species function as exquisite π-Lewis acids in typical GaX(3) -catalyzed reactions. The cationic complexes are more active than GaX(3) and yet more resistant to hydrolysis, which allows lower catalytic loadings and faster reactions.     

Studies on Upconversion Mechanism of ZrO_2∶Er~(3+),Yb~(3+) Nanocrystals Under Excitation at 488 and 980 nm

IntroductionWith a suitable host matrix,the rare earth( RE) dopant ions can convert the lower energyphotons into higher- energy ones.Upconversionprocess is intensively investigated in order to obtainnew powdered phosphors and visible solid- statelasers.Recently,the upconverting phosphor tech-nology ( UPT) has been applied to producing thelateral flow test strips[1,2 ] .Upconverting phosphoris the same usefull biological label as quantumdot[3 ] .RE ions,especially erbium,due to its energylev…     

A Highly Asymmetric Gold(III) η3-Allyl Complex

A highly asymmetric Au^III η³-allyl complex has been generated by treating Au(η¹-allyl)Br(tpy) (tpy=2-(p-tolyl)pyridine) with AgNTf₂. The resulting η³-allyl complex has been characterized by NMR spectroscopy and X-ray crystallography. DFT calculations and variable temperature ¹H NMR suggest that the allyl ligand is highly fluxional.     

Synthesis and Characterization of Chromium(III), Molybdenum(III), Ruthenium(III) and Osmium(III) Complexes with N2O2–Schiff Bases of 2-Hydroxy-1-Naphthaldimines

Monomolybdenum, monochromium, triosmium and triruthenium clusters, containing weakly coordinated ligands, are valuable starting materials for the preparation of a wide variety of compounds because of the ease with which these ligands can be displaced by another substrate under mild conditions. Four widely used complexes of this type are Mo(CO)₆, Cr(CO)₆, Os₃(CO)₁₂ and Ru₃(CO)₁₂ respectively. These complexes react with 2-hydroxy-1-naphthaldimines to give octahedral complexes which are characterized by elemental analyses, i.r. and u.v.–vis. spectra, molar conductances, d.t.a. and t.g.a. analyses, cyclic voltammetry, magnetic and e.s.r. measurements. The molar conductances in DMF solution indicate that the complexes are non-ionic. The i.r. spectra of complexes (3), (7) and (10) show (CO) bands due to bonded CO groups, however complexes (6) and (13) show (CO) bands due to bonded, bridged and terminal CO groups. The g ₁₁-values of the complexes indicate that they have covalent bond character. Also, the electrochemical reduction of the complexes has been discussed.     

Lanthanide Complexes with Acetylacetone and 5-(4-Nitrophenyl)-10,15,20-Triphcnylporphyrin Ligands

Sincethefirstlanthanideporphyrinwassynthesizedin1974',anumberofthisclassofporphyrinshavebeensynthesized'.Becauselanthanideionhasspecialelectronstructure,peopleareinterestedinpropertiesoflanthanideporphyrincomplexessuchascatalyticfunction,opticalstorage,etc3.Ingeneral,moresymmetricallyfunctionallanthanideporphyrinshavebeenstudied,butfewerunsymmetricallanthanideporphyrinsarereported.Nowlanthanidecomplexesofunsymmetricallymeso-substitutedphenylporphyrinacetylacetonate5-(4-nitrophenyl)-10,15,20-tr…     

Lanthanide Complexes with N,N′-Bis(2- hydroxybenzylidene)-2-hydroxyphenylmethanediamine

Complexes of lanthanides with N,N-bis(2-hydroxybenzylidene)-2-hydroxyphenylmethanediamine (H₃L) were synthesized and investigated by the elemental, IR, magnetochemical, and thermogravimetric methods. Using the data obtained, they were found to have compositions Ln₂L₂ · nH₂O and La₂L₂ · MCl₂ · 4H₂O (Ln = La³⁺, Pr³⁺, Nd³⁺, Dy³⁺, Er³⁺; M = Cu²⁺, Co²⁺, Ni²⁺; n = 4, 6). Suggestions on their structures were made. In the interval of 20–140°C, these complexes were shown to be high-resistance semiconductors.     

Slow Magnetic Relaxation in Mono- and Bimetallic Lanthanide Tetraimido-Sulfate S(NtBu)42− Complexes

Lanthanide ions are particularly well-suited for the design of single-molecule magnets owing to their large unquenched orbital angular momentum and strong spin-orbit coupling that gives rise to high magnetic anisotropy. Such nanoscopic bar magnets can potentially revolutionize high-density information storage and processing technologies, if blocking temperatures can be increased substantially. Exploring non-classical ligand scaffolds with the aim to boost the barriers to spin-relaxation are prerequisite. Here, the synthesis, crystallographic and magnetic characterization of a series of each isomorphous mono- and dinuclear lanthanide (Ln=Gd, Tb, Dy, Ho, Er) complexes comprising tetraimido sulfate ligands are presented. The dinuclear Dy complex [{(thf)₂Li(NtBu)₂S(tBuN)₂DyCl₂}₂ ⋅ ClLi(thf)₂] ( 1c ) shows true signatures of single-molecule magnet behavior in the absence of a dc field. In addition, the mononuclear Dy and Tb complexes [{(thf)₂Li(NtBu)₂S(tBuN)₂LnCl₂(thf)₂] ( 2b , c ) show slow magnetic relaxation under applied dc fields.     

Synthesis of Eu(III) and Tb(III) Complexes with Two New Amide Type Podands and Their Luminescence Properties

ＩｎｔｒｏｄｕｃｔｉｏｎＬａｎｔｈａｎｉｄｅｃｏｍｐｌｅｘｅｓｈａｖｅａｔｔｒａｃｔｅｄｍｕｃｈａｔｔｅｎｔｉｏｎｂｅｃａｕｓｅｏｆｔｈｅｉｒｉｍｐｏｒｔａｎｔａｐｐｌｉｃａｔｉｏｎｓ .1ＩｎｐａｒｔｉｃｕｌａｒＥｕ(ＩＩＩ)ａｎｄＴｂ(ＩＩＩ)ｃａｎｂｅｃｈａｒａｃｔｅｒｉｚｅｄｂｙｌｏｎｇ ｌｉｖｅｄ(ｍｓｔｉｍｅｓｃａｌｅ)ａｎｄｓｔｒｏｎｇｌｕｍｉｎｅｓｃｅｎｔｅｌｅｃｔｒｏｎｉｃａｌｌｙｅｘ ｃｉｔｅｄｓｔａｔｅｓ ,ｗｈｉｃｈｍａｋｅｓｔｈｅｍｉｍｐｏｒｔａｎｔｉｎａｎａｌｙｔｉｃａｌｃｈｅｍ…     

The Study on the Stability Constant and Species Distribution of Eu (III) and Tb (III) Complexes with BDBPH

Biomimetic hydrolysis of DNA or RNA is of increasing importance in biotechnology and medicine. The ability to cleave nucleic acids efficiently, in a non-degradative manner, and with high levels of selectivity for site or structure will be required by many applications for the manipulation of genes, the design of structural probes and the development of novel therapeutics1. There has been much interest in the development of lanthanide complexes as nucleic acid cleavage agents. It has been fou…     

Synthesis of Aryl-Manganese(III) Fluoride Complexes via α-Fluorine Elimination from CF3 and Difluorocarbene Generation

We report the synthesis of cyclometalated monoaryl Mn^III fluoro complexes using bis(trifluoromethyl)zinc reagent, Zn(CF₃)₂(DMPU)₂, under mild conditions via a reaction pathway that involves initial transmetalation followed by α-fluorine elimination. The formation of difluorocarbene in these reactions was detected by trapping experiments. Such facile difluorocarbene generation from Mn^III results in moderate enhancement of difluoropropanation and difluoropropenation of alkenes and alkynes using Zn(CF₃)₂(DMPU)₂ at lower temperature (20–60 °C) and short reaction time, suggesting potential application of manganese(III) perfluoroalkyl complexes as reactive species for carbene transfer reactivity.     

Exploring the reactions of β-amyloid (Aβ) peptide 1-28 with Al(III) and Fe(III) ions

The reactions of human β-amyloid peptide 1-28 (Aβ28) with Al(III) and Fe(III) ions were investigated by (1)H NMR and electrospray ionization mass spectrometry (ESI-MS) under pH conditions close to physiological ones. (1)H NMR titrations, performed in the 5.3-8.0 pH range, revealed that no measurable amounts of Aβ28-Al(III) or Aβ28-Fe(III) adducts are formed; such metal adducts could not be obtained even by changing a number of experimental conditions, e.g., temperature, buffer, nature of the salt, etc. These observations were later confirmed by ESI-MS. It is thus demonstrated that Aβ28, at physiological pH, is not able to form binary complexes with Al(III) and Fe(III) ions of sufficient stability to compete with metal hydroxide precipitation. The biological implications of these findings are discussed in the frame of current literature.     

Thermodynamics of Formation of Ru(III) and Ru(IV)-μ-Peroxo Complexes

Abstract

Reaction of one half and one equivalents of H₂O₂ with K[Ru^III(pdta-H)Cl].2H₂O gives rise to the μ-peroxo complexes [Ru^III (pdta-H)]₂H₂O₂ and [Ru^IV(pdta-H)]₂O₂, respectively. Equilibrium constants for the formation of the various peroxo species were determined between pH 3-11, in the temperature range 283-313 K and with μ = 0.10 M in KC1. The existence of the various peroxo species was substantiated by potentiometry, spectrophotometry and electrochemical studies. Thermodynamic quantities associated with the formation of the (pdta)Ru^III and (pdta)Ru^IV-μ-peroxo species and their hydrolysis products are reported.     

C−H Bond Activation by Iridium(III) and Iridium(IV) Oxo Complexes

Oxidation of an iridium(III) oxo precursor enabled the structural, spectroscopic, and quantum-chemical characterization of the first well-defined iridium(IV) oxo complex. Side-by-side examination of the proton-coupled electron transfer thermochemistry revealed similar driving forces for the isostructural oxo complexes in two redox states due to compensating contributions from H⁺ and e⁻ transfer. However, C−H activation of dihydroanthracene revealed significant hydrogen tunneling for the distinctly more basic iridium(III) oxo complex. Our findings complement the growing body of data that relate tunneling to ground state properties as predictors for the selectivity of C−H bond activation.     

A Local D4h Symmetric Dysprosium(III) Single-Molecule Magnet with an Energy Barrier Exceeding 2000 K**

Three six-coordinate Dy^III single-molecule magnets (SMMs) [Dy(O^tBu)₂(L)₄]⁺ with local D_4h symmetry are obtained by optimizing the equatorial ligands. One of the compounds with L=4-phenylpyridine shows an energy barrier (U_eff) of 2075(11) K, which is the third largest U_eff, and the first U_eff>2000 K for SMMs with axial-type symmetry so far. Ab initio analysis indicates that the exceptional uniaxial magnetic anisotropy is deeply related to the axially compressed octahedral geometry. This work provides a new insight into the local D_4h symmetry for high-performance SMMs.     

Hydrothermal Syntheses and Crystal Structures of Three Lanthanide(Ⅲ) Complexes Based on Carboxyl Derivatives of 1 ,10-Phenanthroline

Three lanthanide(III) complexes [Ln(4-NCP)(1,4-BDC)]n·xn H2O(Ln = Pr(1), Sm(2), Nd(3). 4-HNCP = 2-(4-carboxyphenyl)imidazo(4,5-f)(1,10)phenanthroline, 1,4-H2 BDC = benzene-1,4-dicarboxylic acid) have been hydrothermally synthesized and characterized via elemental analysis, infrared spectrometry and single-crystal X-ray diffraction. Structural analyses revealed that complexes 1~3 possess similar porous three-dimensional frameworks with the point symbol {4~(12)·6~3}. Meanwhile, complexes 1~3 exhibit excellent thermal stabilities and complex 2 exhibits characteristic luminescent property.