Attempted Reduction of Divalent Rare Earth Iodo Aminopyridinates

Rare examples of amido‐iodo complexes of selected divalent lanthanides can be synthesized by using deprotonated Ap*H {Ap*H = 2,6‐diisopropylphenyl)‐[6‐(2,4,6‐triisopropylphenyl)‐pyridin‐2‐yl]‐amine} as a stabilizing ligand. Reaction of [Ap*K]_n with [LnI₂(thf)_n] (Ln = Eu, Yb, n = 4,5) in THF leads to [Ln(Ap*)I(thf)₂]₂ (Ln = Eu, Yb). An attempted reduction of these divalent heteroleptic complexes with KC₈ to synthesize complexes containing an unsupported Ln–Ln bond resulted in the formation of [Ln(Ap*)₂(thf)₂]. These lanthanide complexes were characterized by X‐ray structure analysis.     

2,2′‐Bipyrimidine as Efficient Sensitizer of the Solid‐State Luminescence of Lanthanide and Uranyl Ions from Visible to Near‐Infrared

Treatment of Ln(NO₃)₃?nH₂O with 1 or 2 equiv 2,2′‐bipyrimidine (BPM) in dry THF readily afforded the monometallic complexes [Ln(NO₃)₃(bpm)₂] (Ln=Eu, Gd, Dy, Tm) or [Ln(NO₃)₃(bpm)₂]?THF (Ln=Eu, Tb, Er, Yb) after recrystallization from MeOH or THF, respectively. Reactions with nitrate salts of the larger lanthanide ions (Ln=Ce, Nd, Sm) yielded one of two distinct monometallic complexes, depending on the recrystallization solvent: [Ln(NO₃)₃(bpm)₂]?THF (Ln=Nd, Sm) from THF, or [Ln(NO₃)₃(bpm)(MeOH)₂]?MeOH (Ln=Ce, Nd, Sm) from MeOH. Treatment of UO₂(NO₃)₂?6H₂O with 1 equiv BPM in THF afforded the monoadduct [UO₂(NO₃)₂(bpm)] after recrystallization from MeOH. The complexes were characterized by their crystal structure. Solid‐state luminescence measurements on these monometallic complexes showed that BPM is an efficient sensitizer of the luminescence of both the lanthanide and the uranyl ions emitting visible light, as well as of the Yb^III ion emitting in the near‐IR. For Tb, Dy, Eu, and Yb complexes, energy transfer was quite efficient, resulting in quantum yields of 80.0, 5.1, 70.0, and 0.8 %, respectively. All these complexes in the solid state were stable in air.     

Specifics of luminescence of (benzoxazolyl)phenolate and (benzothiazolyl)naphtholate heterometallic Zn,Sc, Nd,Sm, Er,and Yb complexes

Heterometallic complexes Ln(L¹)₅Zn (Ln = Sc, Sm, Gd) were obtained by the reactions of silylamides Ln[N(SiMe)₂]₃ with 2-(benzoxazol-2-yl)phenol (HL¹) in the presence of diethylzinc. Similar reactions with 3-(benzothiazol-2-yl)-2-naphthol (HL²) led to the formation of complexes Ln(L²)₅Zn (Ln = Nd, Er, Gd, Yb). The introduction of the zinc-containing fragments provided a considerable increase of photo- and electroluminescence intensity of the scandium complex.     

4-Nitro and 4-chloro pyridine-N-oxide complexes of lanthanide perchlorates

Adducts of lanthanide perchlorates with 4-nitro and 4-chloro pyridine-Noxides (4-NPNO and 4-CPNO respectively) have been synthesised for the first time and characterised by analysis, electrolytic conductance, infrared, proton-NMR and electronic spectral data. The complexes are of the compositions Ln₂(NPNO)₁₅ (ClO₄)₆ (Ln = La, Pr, Nd and Gd), Tb(NPNO), (C1O₄)₆), Ln₂(NPNO)₁₃ (C1O₄)₆) (Ln = Dy, Ho, and Yb); Ln (CPNO)₈ (C10₄)₃) (Ln = La, Pr, Nd, Tb, Dy, Ho and Yb) and Ln(CPNO), (C1O₄)₃) (Ln = Sm and Gd). Conductivity and IR data provide evidence for the non-coordinated nature of the perchlorate groups. IR and NMR spectra suggest coordinationvia the oxygen of the N-oxide group. Electronic spectral shapes of the Nd⁺³ and Ho⁺³ complexes are interpreted in terms of eight-and seven-coordinate environments in the case of 4-NPNO complexes and eight-coordination in the case of 4-CPNO complexes. IR data indicate bridged structure in NPNO complexes of lanthanides other than Tb.     

Hydrothermal syntheses,crystal structures and luminescence properties of two lanthanide dinuclear complexes with hexafluoroglutarate

Two complexes [Ln₂(hfga)₂(phen)₄(H₂O)₆] · hfga · 2H₂O (H₂hfga = hexafluoroglutaric acid, phen = 1, 10-phenanthroline, Ln=Tb, 1; Eu, 2) were synthesized under hydrothermal conditions and their structures determined by X-ray crystallography. The complexes consist of dinuclear units with an inversion center. Each Ln(III) is nine-coordinate with two carboxylate oxygens from two hfga ligands, three oxygens from water and four nitrogens from two phen molecules. Two carboxylate groups of one hfga adopt monodentate coordination to Ln(III) as a long bidentate bridge linking two Ln(III) ions to form a dimer. Ln(III) ··· Ln(III) distances of 9.027(3) Å for 1 and 9.043(3) Å for 2 were observed. Both complexes emit strong fluorescence and show characteristic emission of Tb(III) and Eu(III) ions, respectively.     

Synthesis,Structures, and Luminescent Properties of Chloride and Nitrate LnIII Complexes Coordinated by tris(Pyrazolyl)methane

We report the synthesis of Ln³⁺ nitrate [Ln(Tpm)(NO₃)₃] ⋅ MeCN (Ln=Yb ( 1Yb ), Eu ( 1Eu )) and chloride [Yb(Tpm)Cl₃] ⋅ 2MeCN ( 2Yb ), [Eu(Tpm)Cl₂(μ-Cl)]₂ ( 2Eu ) complexes coordinated by neutral tripodal tris(3,5-dimethylpyrazolyl)methane (Tpm). The crystal structures of 1Ln and 2Ln were established by single crystal X-ray diffraction, while for 1Yb high resolution experiment was performed. Nitrate complexes 1Ln are isomorphous and both adopt mononuclear structure. Chloride 2Yb is monomeric, while Eu³⁺ analogue 2Eu adopts a binuclear structure due to two μ²-bridging chloride ligands. The typical lanthanide luminescence was observed for europium complexes ( 1Eu and 2Eu ) as well as for terbium and dysprosium analogues ([Ln(Tpm)(NO₃)₃] ⋅ MeCN, Ln=Tb ( 1Tb ), Dy ( 1Dy ); [Ln(Tpm)Cl₃] ⋅ 2MeCN, Ln=Tb ( 2Tb ), Dy ( 2Dy )).     

Synthesis and structure of heteroleptic triple-decker neodymium,europium, holmium,erbium, and ytterbium crown phthalocyaninates

Two series of heteroleptic crown-substituted tris(phthalocyaninate) complexes (Pc)Ln[(15C5)₄Pc]Ln(Pc) and [(15C5)₄Pc]Ln[(15C5)₄Pc]Ln(Pc), where 15C5 is 15-crown-5, (Pc²⁻) is the phthalocyaninate dianion, Ln = Nd, Eu, Ho, Er, and Yb, were prepared by the reaction of tetra-15-crown-5-phthalocyanine H₂[(15C5)₄Pc] with the corresponding lanthanide acetylacetonates and lanthanum bis(phthalocyaninate) La(Pc)₂, which was used as a phthalocyaninate dianion donor. The composition and structure of the synthesized complexes were confirmed by MALDI TOF mass spectrometry, UV-Vis absorption spectroscopy, and ¹H NMR. Complete assignment of the proton resonance signals of the paramagnetic lanthanide complexes was based on analysis of lanthanide-induced shifts.     

Complexes of Lanthanoid Nitrates with 15-Crown-5 and 18-Crown-6 Ethers

Complexes between the heavier lanthanoid nitrates Ln(NO₃)₃ and 15-crown-5 ( 1 ) and 18-crown-6 ( 2 ) ethers were isolated and characterized. Both 1:1 and 4:3 complexes are formed with each Ln(III) ion, except in the case of Gd and 2 . The thermal transformation of the 1:1 complexes into the corresponding 4:3 complexes was studied by thermogravimetry and by DSC, X-ray and vibrational data provide information about the structure of these complexes. The interaction between Ln(III) ions and ligands 1 and 2 in non-aqueous solutions is discussed on the basis of conductometric, fluorescence, UV./VIS. and ¹H-NMR. data. Only 1:1 complexes of 2 formed in solution and their formation constants range from logK_f = 4.4 (Ln = La) to 2.4 (Ln = Yb); for Eu, K_f of the 15-crown-5 and 18-crown-6 ether complexes are of the same order of magnitude. For La, Pr, Nd, Eu, Yb, a variable temperature NMR. study gave some indications about the chemical exchanges in solution. The factors which determine the stoichiometry of the complexes are discussed.     

仲丁基膦酸-2-丁基辛酯与希土固体配合物的研究

合成了仲丁基膦酸-2-丁基辛酯(HBO/BP)与希土(Ⅲ)(Ln=La, Gd, Ho, Y, Er, Yb)新的固体配合物，其组成为Ln(BO/BP)₃，对配合物的性质进行了表征。热分析表明，在空气中，热分解分两步完成，热分解产物是Ln₂P₄O₁₃。测定了配合物的红外光谱，对其主要吸收谱带进行了归属，配合物中Ln-O键具有较高的离子特性。     

Synthesis, characterization, thermal stability, reactivity, and antimicrobial properties of some novel lanthanide(III) complexes of 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene

Two series of new lanthanide(III) complexes of the type [Ln(HSAT)₂(H₂O)₃Cl₃] and [Ln(HSAT)₂(NO₃)₃], where Ln = La, Pr, Nd, Sm, Eu, Gd, Dy, Tm, Yb, or Lu, and HSAT = 2-(N-salicylideneamino)-3-carboxyethyl-4,5,6,7-tetrahydrobenzo[b]thiophene, are synthesized by the reaction of LnCl₃ or Ln(NO₃)₃ with the title ligand in ethanol. The complexes are characterized by elemental analysis, magnetic moment values, molar conductivity, IR, UV-Vis, and ¹H NMR spectral data. Two selected complexes are subject to thermogravimetric analysis, and their kinetic parameters are estimated using Coats-Redfern equation. The complex [La(HSAT)₂(NO₃)₃] underwent facile transesterification when refluxed in methanol. The ligand and some selected complexes are screened for their antimicrobial properties. Antimicrobial activities of the ligand increase on coordination with the metal ion. The text was submitted by the authors in English.     

Complexes of the Lighter Lanthanoid Nitrates with 15-crown-5 and 18-crown-6 ethers: Synthesis and characterization

Complexes of lanthanoid trinitrates Ln(NO₃)₃ with 15-crown-5 ether 1 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) and with 18-crown-6 ether 2 (Ln = La, Ce, Pr, Nd) having a 1:1 stoichiometry as well as 4:3 complexes with 2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) have been synthesized and characterized. All the isolated complexes are solvent free. At 170–220° the 1:1 complexes of 2 are quantitatively transformed into 4:3 complexes. X-Ray powder diagrams of the neodymium complexes with 2 indicate that both the 1:1 and 4:3 complexes are genuine compounds. All the 1:1 complexes show a characteristic IR. absorption band at 875–880 cm^?1 absent from both the spectra of the free ligands and of the 4:3 complexes. The spectroscopic properties (IR. and electronic spectra, fluorescence lifetimes) of the complexes and the low magnetic moments of the Ln(III) ions in the complexes with Ln = Ce-Eu are indicative of a strong interaction between the lanthanoid ions and the crown ethers 1 and 2 .     

Metallorganische Verbindungen der Lanthanoide. 93 [1]. Tetramethylcyclopentadienyl-Komplexe ausgewählter 4f-Elemente

Organometallic Compounds of the Lanthanides. 93. Tetramethylcyclopentadienyl Complexes of Selected 4f-Elements The trichlorides of lanthanum, neodymium, samarium, and terbium react with Na(C₅Me₄H) in THF to yield the homoleptic complexes Ln(C₅Me₄H)₃ [Ln = La ( 1a ), Nd ( 1b ), Sm ( 1c ), Tb ( 1d )]. On the other hand the reactions of HoCl₃, TmCl₃, and LuCl₃ with Na(C₅Me₄H) result only with formation of the dicyclopentadienyl complexes (C₅Me₄H)₂LnCl(THF) [Ln = Ho ( 2e ), Tm ( 2f ), Lu ( 2h )]. The metallocenes (C₅Me₄H)₂Ln(THF)₂ [Ln = Sm ( 3c ), Yb ( 3g )] are obtained by the reactions of LnI₂ (Ln = Sm, Yb) with Na(C₅Me₄H). The ¹H- and ¹³C-NMR spectra as well as the X-ray crystal structure of the triscyclopentadienyl complexes 1 a and 1 c are discussed.     

Solution Phase Chemistry of Lanthanide Complexes. 12. 1:1 and 1:2 Lanthanide Complexes with s-Carboxymethoxysuccinic Acid

Abstract

The solution phase coordination chemistry associated with 1:1 and 1:2 complexes of lanthanide ions with S-carboxymethoxysuccinic acid (CMOS) has been studied by spectroscopic means. The Tb(III) luminescence intensities and lifetimes were found to be sensitive towards the solution phase properties, as were the circularly polarized luminescence spectra of these complexes. It was found that below pH 6, Ln(CMOS) complexes were monomeric in nature and contained an average of 6 molecules of coordinated water. Above neutral pH, the Ln(CMOS)₂ complexes became self-associated into hydroxy-bridged, oligomeric species. The Ln(CMOS)₂ complexes were found to be oligomeric at all pH values, with ligand bridging taking place below neutral pH and hydroxy bridging taking place above neutral pH.     

Lanthanide perchlorate complexes of 4-cyano pyridine-N-oxide, 4-chloro 2-picoline-N-oxide and 4-dimethyl amino-2-picoline-N-oxide

Complexes of lanthanide perchlorates with 4-cyano pyridine-1-oxide, 4-chloro 2-picoline-1-oxide and 4-dimethyl-amino 2-picoline-1-oxide have been isolated for the first time and characterized by analysis, conductance, infrared, NMR and electronic spectra. The complexes of 4-cyano pyridine-1-oxides have the composition Ln(CyPO)₆(ClO₄)₃. 2H₂O (Ln=La, Sm, Dy and Ho); Ln(CyPO)₇ (ClO₄)₃. 2H₂O (Ln=Pr, Nd, Er and Yb); and Ln(CyPO)₅ (ClO₄)₃. 2H₂O (Ln=Gd and Tb). The complexes of 4-chloro 2-picoline-1-oxide analyse for the formulae Ln(CpicO)₆ (ClO₄)₃ (Ln=La, Pr, Nd and Ho); and Ln (CpicO)₅ (ClO₄)₃ (Ln=Er and Yb), and those of 4-dimethylamino 2-picoline-1-oxide for Ln(DMPicO)₆ (ClO₄)₃ (Ln=La and Nd); Ln(DMPicO)₇ (ClO₄)₃ (Ln=Gd, Er and Yb); and Ln(DMPicO)₈ (ClO₄)₃ (Ln=Dy and Ho).     

Thermal decomposition of lanthanide(III) complexes of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand

The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO₃)₂](NO₃), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by thermogravimetric (TG) and derivative thermogravimetric (DTG) techniques. The TG and DTG data indicated that all complexes are thermostable up to 398 K. The thermal decomposition of all Ln(III) complexes was a two-stage process and the final residues were Ln₂O₃ (Ln = La, Nd, Sm, Gd, Dy, Er), Tb₄O₇, and Pr₆ O₁₁. The activation energies of thermal decomposition of the complexes were calculated from analysis of the TG-DTG curves using the Kissinger, Friedman, and Flynn-Well-Ozawa methods.     

Structures and magnetic properties of two series of Schiff base binuclear lanthanide complexes

Until now, although there are many examples of studying the magnetic properties of Schiff base binuclear lanthanide complexes, the relationship between the structure and magnetic properties of the complexes still is worth further investigation in order to improve the magnetic properties of Schiff base lanthanide complexes. In this work, we successfully obtained two series of binuclear Ln complexes by in situ reaction of 4-diethylaminosalicylaldehyde, benzoic hydrazide and different lanthanide salts at 80°C under solvothermal conditions, namely, [Ln₂(L)₃(NO₃)₃]·CH₃CN·CH₃OH·H₂O [Ln = Dy ( 1 ), Ho ( 2 ), Gd ( 3 ) L = deprotonated 4-diethylamino salicylaldehyde benzoylhydrazine], [Ln₂(L)₄(CH₃COO)]CH₃COO·CH₃CN [Ln = Dy ( 4 ), Ho ( 5 ), Gd ( 6 )]. The complex 1 contains three Schiff base ligands L, two Dy (III) ions, and three NO₃⁻. The ligand H₁L is formed by in situ Schiff base reaction with 4-diethylaminosalicylaldehyde and benzoic hydrazide with the participation of Ln (NO₃)₃. When replacing Ln (NO₃)₃ with Ln (OAc)₃, obtained three μ₂-OAc bridged binuclear Ln (III) complexes. The magnetic study showed that complex 4 exhibits field-induced single-molecule magnet (SMM) behavior while complex 1 does not show any SMMs behavior. In addition, we have studied the magnetocaloric effect of complexes 3 and 6 , their maximum −ΔS_m values are 21.37 J kg⁻¹ K⁻¹ and 15.32 J kg⁻¹ K⁻¹, respectively, under ΔH = 7 T and T = 2 K.     

Synthesis,characterization, and DNA-binding of Ln(III) complexes with 2-hydroxybenzylidene-2-phenylquinoline-4-carbonylhydrazone

2-Hydroxybenzylidene-2-phenylquinoline-4-carbonylhydrazone (H₂L) and five Ln(III) complexes, [Ln(H₂L)(NO₃)₂]NO₃ [Ln = La (1), Pr (2), Sm (3), Eu (4), and Tb (5)], have been synthesized and characterized by ¹H NMR, elemental analysis, conductivity measurements, mass spectra, IR spectra, and UV spectra. The interaction of these complexes with calf thymus DNA was investigated by UV absorption spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy and viscosity measurements. Results suggest that these complexes bind to DNA via groove binding.     

TG-DTA study on the lanthanoid trifluoromethanesulfonate complexes

The thermal decomposition of the lanthanoid trifluoromethanesulfonate (triflate) complexes {Ln(CF₃SO₃)₃·9H₂O; Ln=La-Lu{ was studied by TG and DTA methods. From the endothermic and exothermic data of Ln(CF₃ SO₃)3·9H₂O complexes, pyrolysis behavior of the complexes is classified into three groups: 1) La-Nd salts, 2) Sm-Ho salts, 3) Er-Lu salts. It has also shown that all the final decomposition products were found to result in the formation of LnF₃. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dependence of the mutual ligand arrangement in guanidinate complexes of lanthanoids on the ligand solid angles

Mutual ligand arrangement in binuclear lanthanoid complexes of the type [Gu₂Ln(μ-H)]₂, [Gu₂Ln(μ-Cl)]₂, and Gu₂Ln(μ-Cl)₂Li(THF)₂, where Gu is a substituted guanidinato ligand, is quantitatively analyzed based on the ligand solid angle approach. In complexes of Nd, Sm, and Gd the Gu ligands shield up to 87% of the metal and the bidentate ligands on opposite metal centers are in the eclipsed arrangement; in complexes of lanthanoids with smaller ionic radii Y, Yb, and Lu the Gu ligands shield over 88.3% of the metal surface and their staggered conformation is observed. The ligand solid angle approach is illustrated and its application to describing multidentate ligands is demonstrated.     

Magnetic interactions in a series of paramagnetic Ln(III) complexes with a chelated imino nitroxide radical

The magnetic interactions in a new series of isostructural imino nitroxide radical lanthanide(III) complexes, [Ln(hfac)₃(IM2py)] (Ln = Gd–Yb: IM2py = 2-(2′-pyridyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazoline-1-oxy; hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), are examined by considering the intrinsic paramagnetic contribution of the Ln(III) ion from the corresponding [Ln(hfac)₃(pybzim)] with a diamagnetic pybzim(2-(2-pyridyl)benzimidazole) ligand; the Ln(III)–IM2py interaction being antiferromagnetic for the 4f⁷ to 4f¹³ Ln(III) complexes and negligibly small for the other complexes. This series is the first example reverse to the previous cases for the series of Ln–Cu or Ln–aminoxyl(NIT) radical (4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazoline-3-oxide-1-oxy) complexes, other than only a few examples of semiquinone Ln complexes. This reverse nature of the magnetic interaction, as compared with the NIT complexes, validates the empirical approach by O. Kahn et al. [Inorg. Chem. 38 (1999) 3692; J. Am. Chem. Soc. 122 (2000) 3413] in the spin-coupled systems for a series of Ln(III) complexes.