Thermolysis mechanism of samarium nitrate hexahydrate

Thermal decomposition of samarium nitrate hexahydrate Sm(NO₃)₃·6H₂O has been investigated by thermogravimetry, differential scanning calorimetry, infrared spectroscopy, and X-ray diffractometry. This is a complex process that involves slow dehydration and fast concomitant internal hydrolysis. It is markedly different from the processes described for other members of the lanthanide series. At the first stage, pyrolysis is accompanied by removal of water and nitric acid to form samarium pentahydrate Sm(NO₃)₃·5H₂O and intermediate oxonitrates containing O–Sm–OH groups. No traces of SmONO₃ were detected. It is assumed that the existence of intermediate structures with six atoms of samarium best fits the experimental results. At higher temperatures, these products undergo further degradation, lose nitrogen dioxide, water, and oxygen, and finally, after having lost lattice water, are transformed into a cubic form of samarium oxide.     

Ternary complexes of neodymium(III) and samarium(III) picrate triethylene glycol: structural, spectroscopic, and photoluminescent properties

The ternary complexation of neodymium(III) and samarium(III) with triethylene glycol (EO3) and picrate anion (Pic) were characterized by elemental analyses, FTIR (Fourier-transform infrared) spectroscopy, single crystal X-ray diffraction, and photoluminescence (PL). Both the [Nd(Pic)(H₂O)₂(NO₃)(EO3)](Pic) and [Sm(Pic)(H₂O)₂(NO₃)(EO3)](Pic)·H₂O complexes were isostructural with a ten-coordination number. In both complexes, the picrate and nitrate anions were coordinated to Ln(III) in a bidentate manner, and with the the EO3 ligand in a tetradentate manner, the addition of two water molecules maintained a ten-coordination number. The lighter lanthanide-picrate complexes formed a ten-coordination number due to the lanthanide contraction effect, acyclic polyether chain length, and number of donor oxygen atoms. The acyclic EO3 ligand affected photoluminescent intensity and its conformation on the structure of the [Ln(Pic)(NO₃)(H₂O)₂(EO3)]⁺ moiety. Photoluminescent measurement showed complex Nd(III) emissions at 403, 486, and 682?nm, with the strongest emission peak at 403?nm. Formation of these peaks occurred due to the intraligand π–π transitions of the Pic anion. The Sm(III) complex exhibited the emission characteristic of the Sm(III) ion in the red spectral region at 616.7?nm (⁴G_5/2 → ⁶H_9/2 transition), even though the ligand emissions were also observed in the PL spectrum. The emission intensity of the 4f–4f transitions in the Sm complex was significantly higher than that found in its salt. We noted that the [Sm(Pic)(H₂O)₂(NO₃)(EO3)](Pic)·H₂O complex was an excellent red-light-emitter and would be considered as a candidate material for organic light emitting diodes.     

A novel synthetic path to a luminescent,dimeric samarium complex induced by the hydrolysis of methyl pyridine-3-carboxylate

A novel path to lanthanide complexes of aromatic carboxylates controlled by the hydrolysis of the corresponding aromatic carboxylate ester has been discovered. A dimeric samarium complex of pyridine-3-carboxylate (NIC) has been obtained using methyl pyridine-3-carboxylate (MNIC) as the starting ligand. With the hydrolysis of MNIC to NIC in the presence of sodium hydroxide, samarium ions coordinate to HNIC to form [Sm(NIC)₃(H₂O)₂]₂. X-ray analysis reveals the dimeric structure formed through bridging oxygen atoms of carboxylate groups. The complex crystallizes in the monoclinic space group P2₁/c with a?=?9.668(3), b?=?11.807(3), c?=?17.512(5)?Å, β?=?92.361(3)°, V?=?1997.3(10)?ų, D _c?=?1.838?Mg?m^?3, Z?=?2, R ₁?=?0.0225. The complex exhibits strong luminescence.     

Preparation of samarimm(ii) sulfide by the reaction of samarium(II) bis[bis(trimethylsilyl)amide] with hydrogen sulfide

X-ray amorphous samarium(II) sulfide was prepared by the reaction of H₂S with samarium(II) bis[bis(trimethylsilyl)amide] (1) in THF at 10^–2 Torr. Compound1 was prepared by two methods: 1) the reaction of SmI₂ with lithium bis(trimethylsilyl)amide and 2) the reaction of samarium naphthalide with bis(trimethylsilyl)amine. SmS was transformed to the polycrystalline state with the lattice parametera = 5.92 Å by annealing at 400–500 °C.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 241–243, February, 1995.     

Thermal behavior of samarium binuclear pivalate and tris-pivalate

Kinetic analysis of the thermolysis of samarium pivalate [Sm₂(μ₂-OOCCMe₃)₄(OOCCMe₃)₂(HOOCCMe₃)₆] · HOOCCMe₃ (1) was carried out (the input data were differential scanning calorimetry (DSC) and thermogravimetry data), and a mathematic model of the process was developed that allowed us to optimize (by calculation) the conditions for formation of {Sm(OOCCMe₃)₃} _n (2) samarium tris-pivalate via thermal decomposition of complex 1. The results of the thermal study of samarium and gadolinium tris-pivalates in the temperature range of −50…+50°C are reported. Specific anomalies were found in the DSC curves and heat capacity versus temperature curves in the temperature range of 0–50°C.     

Reinvestigation of a transmetallation synthesis of bis(cyclopentadienyl)samarium(II) and formation of a new soluble cyclopentadienylsamarium(II) compound

The transmetallation reaction between (C₅H₅)₂Hg and activated samarium metal in tetrahydrofuran (thf)/ether did not give (C₅H₅)₂Sm(thf)₂ but (C₅H₅)₃Sm(thf), whilst reduction of the last compound with potassium in thf gave KSm(C₅H₅)₃, a soluble organosamarium(II) complex.     

Interaction between samarium and cobalt carbonates in aqueous medium

The Sm₂(CO₃)₃-CoCO₃-H₂O system was studied using isothermal crystallization (295 K). The compounds Sm₂(CO₃)₃ · 8H₂O, Sm₂Co₅(CO₃)₈ · 30H₂O, Sm₂Co₇(CO₃)₁₀ · 40H₂O, Sm₂Co₁₇(CO₃)₂₀ · 54H₂O, and Co(CO₃)_0.7(OH)_0.6 · 2H₂O, as well as solid solutions based on samarium carbonate and samarium cobalt double carbonates were found in the system.     

Synthesis and crystal structure of nickel(II) complex based on 2-trifluoroacetylcycloalkanone benzoylhydrazones

The reaction of ethanol solutions of benzoylhydrazones of 2-trifluoroacetylcycloalkanones (H₂L) with a solution of nickel(II) acetate in aqueous ammonia in 1 : 1 ratio gave complexes NiL · NH₃ with square structure. The composition and structure of the complexes were determined by elemental analysis, IR and 1H NMR spectroscopy, and X-ray diffraction analysis.     

Hydrophilic polymer supported nanoparticles prepared from samarium trichloride and lanthanum trichloride in liquid-phase

Nanoparticles were obtained by the reaction of SmCl₃·6H₂O with sodium borohydride (NaBH₄) in the presence of sodium polyacrylate (PAA) with average molecular weight of 5,100 as a capping polymer. The resulting colloidal solution was placed on a Cu grid and characterized by transmission electron microscope (TEM) measurement, which clearly indicated the generation of nanoparticles. The reaction of LaCl₃ with NaBH₄ in the presence of PAA led to preparation of lanthanum nanoparticles, similarly as samarium nanoparticles.     

Synthesis and Molecular Structure of Bis(ethylenediamine)acetatonickel(II)hexafluoridophosphate Complex [Ni(en)2(CH3CO2)]PF6. An Unexpected Acetylacetonato Cleavage Reaction

The title complex was synthesized by an unusual reaction between [Ni(acac)₂(H₂O)₂] and ethylenediamine in water solution. The crystal structure of 1 shows the nickel(II) core in a tetragonally distorted octahedral environment coordinated to two ethylenediamine molecules and one acetate ligand. This is the first example of a mononuclear bis(ethylenediamine)nickel(II) complex, where the oxygen atoms of the auxiliary ligand are in cis configuration. The compound exhibits an extensive association between the complex cation and the respective anion through classical N–H ··· O and N–H ··· F intermolecular hydrogen bonds, which generate a supramolecular 3D arrangement in the solid state.     

Edta-linked 5p–4f trinuclear heterometallic complex: syntheses,X-ray structure and luminescent properties

A new heterometallic antimony–samarium complex, [Sb₂(edta)₂Sm(H₂O)₄]NO_3?·?3.55H₂O (edta?=?ethylenediaminetetraacetate) (1), has been synthesized and characterized by elemental analyses (EA), Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, and X-ray crystallography. The X-ray crystal structure analysis reveals that in 1 the bridging carboxylate-O,O′ of edta^4? connects samarium(III) and antimony(III) to form 2-D sheets. The 2-D sheets are further linked by bridging carboxylates from adjacent layers, resulting in 3-D coordination polymers. Complex 1 exhibits fluorescence in the solid state at room temperature.     

Thermoanalytical investigations of tris(ethylenediamine)nickel(II) oxalate and sulphate complexes

Investigations on the thermal behaviour of [Ni(en)₃]C₂O₄·2H₂O and [Ni(en)₃]SO₄ have been carried out in air and helium atmosphere. Simultaneous TG/DTA coupled online with mass spectroscopy (MS) in helium atmosphere detected the presence of H₂, O, CO, N₂/CH₂=CH₂ and CO₂ fragments during the decomposition of tris(ethylenediamine)nickel(II) oxalate and H₂, O, NH, NH₂, NH₃ and N₂/CH₂=CH₂ fragments for tris(ethylenediamine)nickel(II) sulphate complex. The thermal events during the decomposition were monitored by temperature-resolved X-ray diffraction. In air, both the complexes give nickel oxide as the final product of the decomposition. In helium atmosphere, tris(ethylenediamine)nickel(II) oxalate gives nickel as the residue, whereas tris(ethylenediamine)nickel(II) sulphate gives a mixture of nickel and nickel sulphide phases as the final residue. Kinetic analyses of these complexes by isoconversional methods are discussed and compared.     

Square-planar nickel(II) complexes with a tridentate Schiff base and monodentate heterocycles: self-assembly to dimeric and one-dimensional array via hydrogen bonding

Square-planar nickel(II) complex with tridentate ONO-donor 4-[(2-hydroxyphenyl)imino]-2-pentanone (H₂hpac) and imidazole (Himdz) are reported. The complex was synthesized in moderate yield by reacting Ni(O₂CCH₃)₂ · 4H₂O, H₂hpac and imidazole in 1 : 1 : 1 mole ratio and characterized by elemental analysis, IR, ¹H NMR spectroscopy. An X-ray structure determination of the complex has been completed. In the solid state, a one-dimensional assembly of the [Ni(hpac)(Himdz)] molecules is formed via intermolecular hydrogen bonds between the imidazole N–H groups and the coordinated hydroxyphenyl-O atoms.     

Synthesis of new luminescent materials activated with divalent samarium

A simple technique for the preparation of powder compounds doped with divalent samarium is described. The reaction is carried out in nickel containers sealed in an inert atmosphere. The samarium impurity is introduced as samarium trifluoride SmF₃, and metallic samarium powder acts as the reducing agent to change Sm³⁺ into Sm²⁺. Using this method, samarium has been stabilized in the divalent state in various fluorides: KMgF₃, BaLiF₃, BaY₂F₈, and KY₃F₁₀. The resulting compounds show under ultraviolet or visible excitation an intense luminescence in the red region characteristic of Sm²⁺-doped materials. The emission and excitation spectra of these phosphors are presented and briefly discussed.     

Neodymium(III) tris(1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dionato)(1,10-phenanthroline): Synthesis and photophysical properties

The reaction of NdCl₃ with 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)propane-1,3-dione (HL) and 1,10-phenanthroline (Phen) in the presence of a base afforded complex [Nd(L)₃Phen] (I). Unstable solvate I · 2CH₂Cl₂ was obtained from a solution of the complex in dichloromethane, and its structure was determined by X-ray diffraction analysis. The photophysical properties of the complex were studied. Possible routes for the energy transfer in the course of photoluminescence were proposed.     

Nickel(II) complexes based on products of condensation of aroyl(perfluoroacyl)methanes with benzoylhydrazine

A series of novel complexes NiL ⁿ · NH₃ were obtained by reactions of equimolar amounts of the ligands H₂L ⁿ (prepared by condensation of aroyl(perfluoroacyl)methanes with benzoylhydrazine) as solutions in ethanol and nickel(II) acetate as a solution in aqueous ammonia. The empirical formulas and square planar structures of the complexes obtained were determined using elemental analysis, IR and ¹H NMR spectroscopy, and X-ray diffraction.     

HSAB principle and nickel(II) ion reactivity towards 1-methyhydantoin

1-Methylhydantoin and its novel nickel(II) complex [Ni(H₂O)₄(1-mhyd)₂] were prepared and identified, by elemental analysis, single crystal X-ray determination and MS methods. In addition, the complex was characterized by spectroscopic (IR, UV-Vis), magnetic and thermal techniques. The ligand reveals an interesting supramolecular architecture with both classical and non-conventional extended HB bonding networks. All rings and chains formed due to this HB bonding are embedded into the undulated pattern. A single crystal X-ray diffraction analysis of the complex shows that the nickel ion is coordinated by deprotonated hydantoin and water ligands in a N₂O₄ tetragonal arrangement. In the [Ni(H₂O)₄(1-mhyd)₂] structure both inter and intramolecular hydrogen bonds are created with the participation of water molecules.The ESI-MS method confirmed mono-nuclearity of the complex while electronic spectroscopy proved the tetragonal and pseudooctahedral geometries around the metal ion in the solid state and solution, respectively. By application of the “average environment rule”, 10Dq parameters were obtained for the hypothetical, hexa-coordinate [Ni(1-mhyd)₆] approximation or rather more realistic [Ni(1-mhyd)₃] chelate. Based on this the mhyd ligand was ranked in the spectrochemical series close to ammonia. The general consideration of the structure of the hydantoin complexes as a function of the metal ion hardness within the framework of the HSAB theory has been provided. Both the ligand and the complex were found to be non-toxic agents against breast (MCF-7), lung carcinoma epithelial (A549) and mouse fibroblasts (Balb/3T3) cancer cell lines.     

Crystal growth of Ce2O(CO3)2·H2O in aqueous solutions: Film formation and samarium doping

Crystalline cerium oxide carbonate hydrate (Ce₂O(CO₃)₂·H₂O) was grown in aqueous solutions at a low temperature of 80 °C under ambient pressure. When cerium nitrate was used as a starting material, large Ce₂O(CO₃)₂·H₂O particles were precipitated through homogeneous nucleation and subsequent fast crystal growth. In contrast, the usage of cerium chloride was found to promote the preferential precipitation of Ce₂O(CO₃)₂·H₂O on foreign substrates through heterogeneous nucleation and slow crystal growth. This phenomenon was applied to a chemical bath deposition of Ce₂O(CO₃)₂·H₂O films. Immersion of glass substrates in the solution at 80 °C for typically 24 h resulted in formation of solid films with a unique morphology like a micrometer-scale brush. It was also found that samarium could be incorporated into Ce₂O(CO₃)₂·H₂O during the crystal growth in the solutions, as evidenced by characteristic photoluminescence of Sm³⁺ in heating products of CeO₂. These results suggest that rare-earth oxide carbonate hydrates with a variety of compositions and morphologies can be synthesized from the aqueous solutions.     

Crystal structure and thermal analysis of diaquadi (1,2,4-triazol-5-one)zinc(II) ion nitrate

A new complex, diaquadi(1,2,4-triazol-5-one)zinc(II) ion nitrate formulated as {[Zn(TO)₂(H₂O)₂](NO₃)₂}_n (1) (1,2,4-triazole-5-one, abbreviated as: TO) was synthesized and characterized by elemental analysis, X-ray single crystal diffraction, infrared spectrum (IR), differential scanning calorimetry (DSC), thermogravimetric analysis and differential thermogravimetric analysis (TG-DTG). The X-ray structure analysis reveals that the complex is orthorhombic with space group Pbca and unit-cell parameters a=6.9504(2) Å; b=10.6473(3) Å; c=17.8555(5) Å. Based on the result of thermal analysis, the thermal decomposition process of the compound was derived. From measurement of the enthalpy of solution in water in 298.15 K, the standard molar enthalpy of solution of lignand TO and the complex were determined as 15.43±0.18 and 52.64±0.42 kJ mol^?1, respectively. In addition, the standard molar enthalpy of formation of TO(aq) was calculated as ?126.97±0.72 kJ mol^?1.     

Das Trihydrochlorid-monohydrat der N-(Pyrid-2-ylmethyl)ethylendiamin-N,N′,N′-triessigsäure und ihr Lanthan(III)-Komplex

The Trihydrochloride Monohydrate of N -(Pyrid-2-ylmethyl)ethylenediamine- N , N′ , N′ -triacetic Acid and its Lanthanum(III) Complex We report the results of the investigation of N-(pyrid-2-ylmethyl)ethylenediamine-N,N′,N′-triacetic acid (H₃pedta) and its complexes with rare earth metal ions. The X-ray crystal structures of H₃pedta · 3 HCl · H₂O and of the lanthanum(III) complex [La(pedta)(H₂O)] · 2 H₂O were determined. The complex forms a polymer, lanthanum(III) has coordination number 10, one water molecule is coordinated. The water degradation of H₃pedta · 3 HCl · H₂O and of the complex was investigated by thermoanalysis. Luminescence studies of the corresponding europium(III) complex in aqueous solution show three coordinated water molecules.