Rapid and efficient one-pot synthesis of octahydroquinazolinone derivatives using lanthanum oxide under solvent-free condition

A simple, efficient and cost-effective method for the synthesis of octahydroquinazolinone derivatives using dimedone, urea/thiourea and aromatic aldehydes using lanthanum oxide as a catalyst under solvent free condition in microwave irradiation is reported. The present method does not involve any hazardous organic solvents. This catalyst has promising features for the reaction response such as the shortest reaction time, excellent product yields, simple work-up procedure and purification of products by non-chromatographic methods.     

Structural characterization of methanol substituted lanthanum halides

The first study into the alcohol solvation of lanthanum halide [LaX₃] derivatives as a means to lower the processing temperature for the production of the LaBr₃ scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H₂O)₇](Br)₂}₂ (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H₂O)₇(MeOH)₂](Br)₃ (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH₂, crystals of [Ca(MeOH)₆](Br)₂ (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr_2.75·5.25(MeOH)]^+0.25 [LaBr_3.25·4.75(MeOH)]^−0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr₃ in MeOH forming the 8-coordinated [LaBr₃(MeOH)₅] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX₃ derivatives were isolated as [(MeOH)₄(Cl)₂La(μ-Cl)]₂ (6) and [La(MeOH)₉](I)₃·MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (¹³⁹La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4–6 were slightly higher in comparison to their hydrated counterparts.     

Synthesis and characterization of the reduction properties of cobalt-substituted lanthanum orthoferrites

Perovskite-related materials of composition LaFe_1−xCo_xO₃ have been prepared by conventional calcination methods. The temperature programmed reduction profiles indicate that the incorporation of cobalt renders the materials more susceptible to reduction when treated in a flowing mixture of hydrogen and nitrogen. The reduction processes have been examined by ⁵⁷Fe Mössbauer spectroscopy and Fe K-edge-, Co K-edge- and La L_III-edge XANES and EXAFS. The results show that in iron-rich systems the limited reduction of iron and cobalt leads to the segregation of discrete metallic phases without destruction of the perovskite structure at temperatures up to 1200°C. In materials where x?ca.0.5 the reduction of Co³⁺ to Co⁰ precedes complete reduction of Fe³⁺ and the segregation of alloy and metal phases is accompanied by destruction of the perovskite structure.     

Morphology-controlled nonaqueous synthesis of anisotropic lanthanum hydroxide nanoparticles

The preparation of lanthanum hydroxide and manganese oxide nanoparticles is presented, based on a nonaqueous sol-gel process involving the reaction of La(OiPr)₃ and KMnO₄ with organic solvents such as benzyl alcohol, 2-butanone and a 1:1 vol. mixture thereof. The lanthanum manganese oxide system is highly complex and surprising results with respect to product composition and morphology were obtained. In dependence of the reaction parameters, the La(OH)₃ nanoparticles undergo a shape transformation from short nanorods with an average aspect ratio of 2.1 to micron-sized nanofibers (average aspect ratio is more than 59.5). Although not directly involved, KMnO₄ plays a crucial role in determining the particle morphology of La(OH)₃. The reason lies in the fact that KMnO₄ is able to oxidize the benzyl alcohol to benzoic acid, which presumably induces the anisotropic particle growth in [0 0 1] direction upon preferential coordination to the ±(1 0 0), ±(0 1 0) and ±(−110) crystal facets. By adjusting the molar La(OiPr)₃-to-KMnO₄ ratio as well as by using the appropriate solvent mixture it is possible to tailor the morphology, phase purity and microstructure of the La(OH)₃ nanoparticles. Postsynthetic thermal treatment of the sample containing La(OH)₃ nanofibers and β-MnOOH nanoparticles at the temperature of 800 °C for 8 h yielded polyhedral LaMnO₃ and worm-like La₂O₃ nanoparticles as final products.     

Synthesis and characterization of lanthanum chloranilate complex: application to spectrophotometric determination of anions

Lanthanum chloranilate complex has been synthesized and characterized using different techniques like Infrared spectroscopy and CHN analysis. It has been used for the development of spectrophotometric method of determination of anions like fluoride, EDTA and iodate. The determination is based on the reaction of these anions with the lanthanum ion in the chloranilate complex resulting in the liberation of an equivalent amount of chloranilate anion, the colour of which was measured. The experimental conditions, which affect the optical density, are studied to get maximum sensitivity. Interference studies were carried out with various ions. The method has been applied to the determination of these ions in actual samples viz. EDTA in detergents and iodate in salt.     

(Diphenylphosphinoethyl)cyclopentadienyl complexes of yttrium and lutetium: synthesis and structure

The reaction of LnCl₃·xTHF with Na(C₅H₄CH₂CH₂PPh₂) followed by the in situ reaction with Na₂(C₁₄H₁₀) afforded the (C₅H₄CH₂CH₂PPh₂)Ln(C₁₄H₁₀)L complexes (Ln = Y or Lu and L = THF or DME). The structure of (C₅H₄CH₂CH₂PPh₂)Lu(C₁₄H₁₀)(DME) was established by X-ray diffraction. In solution, there is an equilibrium between the complexes with the coordinated and uncoordinated phosphorus atom. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1687–1689, September, 2007.     

新型二茂稀土烃硫基配合物的合成与表征

本文用三茂基稀土[(C~5H~5)~3Ln(Ln=Ho(1)，Yb(2)，La(3)，Y(4)]与等摩尔的2-巯基嘧啶(HSC:NCH:CHCH:N·)在四氢呋喃溶剂中于室温下反应，合成了四个对空气敏感的二茂稀土嘧啶巯基配合物。产物经元素分析、红外光谱及质谱鉴定确定其组成为：(C~5H~5)~2LnSC:NCH:CHCH:N·THF[Ln=Ho(1)，Yb(2)，La(3)，Y(4)]。     

Phosphinic platinum complexes with 8-thiotheophylline derivatives: synthesis, characterization, and antiproliferative activity

The platinum mixed-phosphine complexes (SP-4,2)-[PtCl(8-MTT)(PPh3)(PTA)] (2) and cis-[Pt(8-MTT)2(PPh3)(PTA)] (3) (MTTH2 = 8-(methylthio)theophylline, PTA = 1,3,5-triaza-7-phosphaadamantane) have been prepared from the precursor cis-[PtCl2(PPh3)(PTA)] (1), which has been fully characterized by X-ray diffraction determination. Antiproliferative activity tests indicated that the presence of one lipophilic PPh3 and one hydrophilic PTA makes 1-3 more active than the analogues bearing two PPh3 or two PTA. The reactivity of cis-[PtCl2(PPh3)2], cis-[PtCl2(PTA)2], and cis-[PtCl2(PPh3)(PTA)] with the bis(thiopurines) bis(S-8-thiotheophylline)methane (MBTTH2), 1,2-bis(S-8-thiotheophylline)ethane (EBTTH2), and 1,3-bis(S-8-thiotheophylline)propane (PBTTH2) has also been investigated. New binuclear complexes have been prepared and identified by spectroscopic techniques and their antiproliferative activities on T2 and SKOV3 cell lines evaluated.     

Diorganotin complexes of carboxylates: synthesis and characterization

Diorganotin complexes of monoisopropyl and monomethyl nadiate, succinate, and phthalate were synthesized and characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, and ¹¹⁹Sn NMR spectroscopic techniques. The spectroscopic investigation demonstrated that carboxylate is bidentate in the diorganotin complexes. On the basis of ¹ J(¹¹⁹Sn–¹³C) and ² J(¹¹⁹Sn–¹H) values, C–Sn–C bond angles were also calculated. The newly synthesized complexes were also screened for their antibacterial activities against Gram-positive and Gram-negative pathogenic strains of bacteria.     

Uranyl(VI) and lanthanum(III) thio-diglycolamides complexes: Synthesis and structural studies involving nitrate complexation

New tri-functional ligands of the type R₂NCOCH₂SCH₂CONR₂ (where R = iso-propyl, n-butyl or iso-butyl) were prepared and characterized. The coordination chemistry of these ligands with uranyl and lanthanum(III) nitrates was studied by using the IR, ¹HNMR and elemental analysis methods. Structures for the compounds [UO₂(NO₃)₂(ⁱPr₂NCOCH₂SCH₂CONⁱPr₂)] [UO₂(NO₃)₂(ⁱBu₂NCOCH₂SCH₂CONⁱBu₂)], [La(NO₃)₃(ⁱPr₂NCOCH₂SCH₂CONⁱPr₂)₂] and [La(NO₃)₃(ⁱBu₂NCOCH₂SCH₂CONⁱBu₂)₂] were determined by single crystal X-ray diffraction. These structures show that the ligand acts as a bidentate chelating ligand and bonds through both the carbamoyl groups to the uranyl and lanthanum(III) nitrate groups. Solvent extraction studies show that the ligand can extract the uranyl ion from the nitric acid medium but does not show any ability to extract the americium (III) ion.     

The energetics of lanthanum tantalate materials

Lanthanum tantalates are important refractory materials with application in photocatalysis, solid oxide fuel cells, and phosphors. Soft-chemical synthesis utilizing the Lindqvist ion, [Ta₆O₁₉]⁸⁻, has yielded a new phase, La₂Ta₂O₇(OH)₂. Using the hydrated phase as a starting material, a new lanthanum orthotantalate polymorph was formed by heating to 850 °C, which converts to a previously reported LaTaO₄ polymorph at 1200 °C. The stabilities of La₂Ta₂O₇(OH)₂ (LaTa−OH), the intermediate LaTaO₄ polymorph (LaTa-850), and the high temperature phase (LaTa-1200) were investigated using high-temperature oxide melt solution calorimetry. The enthalpy of formation from the oxides were calculated from the enthalpies of drop solution to be −87.1±9.6, −94.9±8.8, and −93.1±8.7 kJ/mol for LaTa−OH, LaTa-850, and LaTa-1200, respectively. These results indicate that the intermediate phase, LaTa-850, is the most stable. This pattern of energetics may be related to cation-cation repulsion of the tantalate cations. We also investigated possible LnTaO₄ and Ln₂Ta₂O₇(OH)₂ analogues of Ln=Pr, Nd to examine the relationship between cation size and the resulting phases.     

Rhodium-carbonyl complexes with a quinolyl functionalized Cp-ligand: synthesis and photochemical activation

Dicarbonyl[η⁵-2,3,4,5-tetramethyl-1-(8-quinolyl)cyclopentadienyl]rhodium(I) (1) was prepared by the reaction of [Rh(CO)₂Cl]₂ with 2,3,4,5-tetramethyl-1-(8-quinolyl)cyclopentadienyl-potassium. Irradiation of 1 in chloroform or dichloromethane as solvent leads to the formation of dichloro[η⁵-2,3,4,5-tetramethyl-1-(8-quinolyl)cyclopentadienyl]rhodium(III) (2). When Rh₆(CO)₁₆ is present, the cluster adds to the 8-quinolyl-cp-rhodium fragment and the compound [η⁵-2,3,4,5-tetramethyl-1-(8-quinolyl)cyclopentadienyl]rhodium-di-μ-carbonyl-hexarhodiumtetradecacarbonyl (3) is formed in 65% yield. The coordination sphere of the rhodium(III) atom in compound 2 and of the rhodium(I) atom in 3 is completed by a coordination of the quinolyl moiety. This was revealed by NMR spectroscopy as well as by X-ray analyses.     

New nano-particle La(III) supramolecular compound as a precursor for preparation of lanthanum oxybromide-, hydroxide-, and oxide-nanostructures

Nano-particles of a new La(III) supramolecular compound [La(4,4′-bipy)(H₂O)₂(NO₃)_3.75Br_0.25] · (4,4′-Hbipy) (1), have been synthesized from reaction of 4,4′-bipy with La(NO₃)₃ and NaBr by the sonochemical method. For the first time LaOBr, La(OH)₃ and La₂O₃ nano-structures were prepared from [La(4,4′-bipy)(H₂O)₂(NO₃)_3.75Br_0.25] · (4,4′-Hbipy) (1) by calcination at 400, 500, and 700°C, respectively. The structure of 1 was determined by X-ray crystallography and the nano-structures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Thermal stabilities of nano and crystal samples of 1 were studied and compared with each other.     

Preparation and properties of yttrium,lanthanum and lanthanide 2,4-dinitrobenzoates

Summary The conditions of the formation of rare earth 2,4-dinitrobenzoates were studied and their quantitative composition and solubilities in water at 298 K determined (their solubilities are of the order of 10^–2 mol dm^–2). The IR and X-ray spectra for the hydrated and dehydrated complexes were recorded. All complexes are crystalline compounds. The condition of thermal decomposition of the complexes were also investigated. On heating above 573 K the complexes were found to decompose explosively and undergo a melting process at the same time. Accordingly, the thermal decomposition for the complexes was carried out in the temperature range 273–573 K. The thermal stability data reveal them to dehydrate in one step and the crystallization water molecules to be bound in various ways. From the obtained results it appears that during the dehydration process no isomerisation of the nitro group to nitrito occurs.

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Herstellung und Eigenschaften von Y-, La- und Lanthaniden-2,4-Dinitrobenzoaten

Zusammenfassung Die Bedingungen zur Darstellung von Y-, La-, und Lanthaniden-2,4-dinitrobenzoaten wurden untersucht. Ihre quantitative Zusammensetzung und ihre Wasserlöslichkeit bei 298 K wurden bestimmt (die Löslichkeit ist in der Größenordnung 10^–2 mol dm^–3). Die Infrarot- und Röntgenspektren der erhaltenen Komplexe sowie der dehydratisierten wurden gemessen und dabei festgestellt, daß es sich um kristalline Verbindungen handelt. Das thermische Verhalten der Komplexe wurde ebenfalls untersucht: sie zerfallen über 573 K explosiv und schmelzen zugleich. Der thermische Zerfall der 2,4-Dinitrobenzoate wurde im Temperaturbereich von 273–573 K untersucht. Aus der thermischen Analyse ergibt sich, daß die Komplexe und die Kristallwassermoleküle in einer Stufe dehydratisiert werden und verschiedenartig gebunden sind. Es wurde festgestellt, daß die Y-, La-, und Lanthaniden-2,4-Dinitrobenzoate bei Temperaturzunahme oder im Dehydratisierungsprozeß keiner Umgruppierung in entsprechenden Nitritoverbindungen unterliegen.

     

Copper (II) complexes of sterically hindered o-diphenol derivatives: synthesis, characterization and microbiological studies

Cu (II) complexes with the sterically hindered diphenol derivatives 3,5-di(tert-butyl)-1,2-benzenediol (I), 4,6-di(tert-butyl)-1,2,3-benzenetriol (II) and the sulfur-containing 4,6-di(tert-butyl)-3-(2-hydroxyethylsulfanyl)-1,2-benzenediol (III) and 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid (IV) have been synthesized and characterized by elemental analysis, TG/DTA, FT-IR, ESR, XPS, XPD and conductivity measurements. Compounds I–III can coordinate in their singly deprotonated forms and act as bidentate ligands. These compounds yield Cu (II) complexes of the stoichiometry Cu(L)₂, which have square planar geometry (g_| > g_⊥ > g_e). Unlike them, compound IV behaves as a terdentate ligand, and its complex Cu(L^IV)₂ has distorted octahedral geometry. According to ESR data, only the Cu(L^II)₂ complex contains a very small amount of phenoxyl radicals. Antimicrobial activities of these ligands and their respective Cu (II) complexes have been determined with respect to Gram-positive and Gram-negative bacteria, as well as on yeasts. Their phytotoxic properties against Chlorella vulgaris 157 were also examined.     

A microcalorimetric determination of the thermodynamics of formation of the monoand bi-sulfato complexes of lanthanum in aqueous solutions between 25 and 55°C

Using a differential microcalorimeter, the formation constants and enthalpies of formation of the mono- and bi-sulfato complexes of lanthanum ion have been evaluated for aqueous acidic solutions over a temperature range of 25 to 55°C.     

Polynuclear rhodium complexes of phenothiazines: synthesis and characterization

Polynuclear complexes of RH^II and RH^III with fiveN-alkylphenothiazines as principal ligands have been prepared. The complexes were characterized by their elemental analyses, molar conductivities, and spectral data. The molecular formulae of the new complexes are as follows: [Rh₃(PTZ)₂(OH₂)₂Cl₈]Cl, where PTZ=chlorpromazine or promethazine; [Rh₃(EP)₂(OH₂)₂Cl₈][Rh(OH₂)₂Cl₄], where EP=ethopropazine; [Rh₄(TF)₂(OH₂)₅Cl₉]Cl·H₂O, where TF=trifluoperazine; and [Rh₂(TC)₃(OH₂)Cl₆]. H₂O, where TC=2-chlorophenothiazine. A tentative structure for each of the complexes is proposed. TMC 2627     

Sigma-borane complexes of iridium: synthesis and structural characterization

Reaction of NaBH4 with (tBuPOCOP)IrHCl affords the previously reported complex (tBuPOCOP)IrH2(BH3) (1) (tBuPOCOP = kappa(3)-C6H3-1,3-[OP(tBu)2]2). The structure of 1 determined from neutron diffraction data contains a B-H sigma-bond to iridium with an elongated B-H bond distance of 1.45(5) A. Compound 1 crystallizes in the space group P1 (Z = 2) with a = 8.262 (5) A, b = 12.264 (5) A, c = 13.394 (4) A, and V = 1256.2 (1) A(3) (30 K). Complex 1 can also be prepared by reaction of BH3 x THF with (tBuPOCOP)IrH2. Reaction of (tBuPOCOP)IrH2 with pinacol borane gave initially complex 2, which is assigned a structure analogous to that of 1 based on spectroscopic measurements. Complex 2 evolves H2 at room temperature leading to the borane complex 3, which is formed cleanly when 2 is subjected to dynamic vacuum. The structure of 3 has been determined by X-ray diffraction and consists of the (tBuPOCOP)Ir core with a sigma-bound pinacol borane ligand in an approximately square planar complex. Compound 3 crystallizes in the space group C2/c (Z = 4) with a = 41.2238 (2) A, b = 11.1233 (2) A, c = 14.6122 (3) A, and V = 6700.21 (19) A(3) (130 K). Reaction of (tBuPOCOP)IrH2 with 9-borobicyclononane (9-BBN) affords complex 4. Complex 4 displays (1)H NMR resonances analogous to 1 and exists in equilibrium with (tBuPOCOP)IrH2 in THF solutions.