On the complexes of yttrium chloride with carbamide and acetamide

Data on the synthesis and the IR spectroscopic and X-ray diffraction analyses of new complexes of yttrium chloride with carbamide (Ur), [Y(Ur)₄(H₂O)₄]Cl₃ (I) and [Y(Ur)₆(H₂O)₂]Cl₃ (II), and with acetamide (AA), [Y(AA)₅(H₂O)₂]Cl₃ (III), are presented. The coordination of the ligands occurs through the oxygen atoms. For complexes I and II, the coordination polyhedra of the Y atoms are distorted tetragonal antiprisms. For structure III, the coordination polyhedron of the Y atom is a distorted pentagonal bipyramid. The coordination of four Ur molecules in complex I does not change their planar structure, and two Ur molecules in structure II have the dihedral angle N-C(O)-N different from 180°. The chloride ions are in the external sphere. Many hydrogen bonds are observed in the structures of complexes I–III.     

Ionic acetamide coordination in its complexes with rare-earth iodides

A series of [Ln(CH₃CONH₂)₄(H₂O)₄]I₃ (Ln?=?rare-earth metal) complexes was completed with seven new compounds (Ln?=?Ce, Pr, Sm, Tb, Tm, Yb, Lu); two (Ln?=?Ce, Tm) were studied by X-ray diffraction. The coordination polyhedron of eight oxygen atoms is a distorted square antiprism. No tetrad effect was found for Ln–O bond lengths. The structure is stabilized by a system of intermolecular hydrogen bonds. The most striking feature of the structures is the recently predicted ionic acetamide coordination. The acetamide molecules are non-planar (the Ln–O–C–N torsion angles are 159–170°) and Ln–O–C bond angles vary in the 146.0–156.8° range.     

Synthesis and physicochemical properties of crystalline tris(ferrocenoyl)acetonate hydrates of some rare-earth elements

Tris(ferrocenoyl)acetonates of some lanthanides were obtained by homophase synthesis. The compositions and structures of the complexes obtained were proved by elemental analysis, electronic absorption and IR spectroscopy. Their solubilities in some aprotic solvents and thermal stabilities (by the thermographic method) were determined. The thermal properties of lanthanide tris(ferrocenoyl)acetonates were compared with those of analogous lanthanide tris(acetyl)acetonates.     

Structural studies of magnetic nanoparticles doped with rare-earth elements

Magnetic nanoparticles and those doped with rare-earth metal ions having spinel structure were synthesized, possessing the average particles size of 11.3-13.4 nm. According to Mössbauer spectroscopy data it can be concluded that prepared iron oxide nanoparticles are γ-Fe₂O₃. For materials containing rare-earth elements the decrease of octahedral component surface was observed in comparison to non-doped material, what can be explained by Eu³⁺, Sm³⁺ и Gd³⁺ ions occupying the octahedral position.     

Coordination of rare-earth elements in complexes with monovacant Wells-Dawson polyoxoanions

The alpha-1 and alpha-2 isomers of the monovacant Wells-Dawson heteropolyoxoanion [P(2)W(17)O(61)](10-) are complexants of trivalent rare-earth (RE) ions and serve to stabilize otherwise reactive tetravalent lanthanide (Ln) and actinide (An) ions in aqueous solution. Aspects of the bonding of Ln ions with alpha-1-[P(2)W(17)O(61)](10-) and alpha-2-[P(2)W(17)O(61)](10-) were investigated to address issues of complex formation and stability. We present structural insights about the Ln(III) coordination environment and hydration in two types of stoichiometric complexes, [Ln(alpha-1-P(2)W(17)O(61))](7-) and [Ln(alpha-2-X(2)W(17)O(61))(2)](17-) (for Ln identical with Sm, Eu, Lu; X identical with P, As). The crystal and molecular structures of [(H(2)O)(4)Lu(alpha-1-P(2)W(17)O(61))](7-) (1) and [Lu(alpha-2-P(2)W(17)O(61))(2)](17-) (2) were solved and refined through use of single-crystal X-ray diffraction. The crystallographic results are supported with corresponding insights from XAFS (X-ray absorption fine structure) for a series of nine solid-state complexes as well as from optical luminescence spectroscopy of the Eu(III) analogues in aqueous solution. All the Ln ions are eight-coordinate with oxygen atoms in a square antiprism arrangement. For the 1:1 stoichiometric Ln/alpha-1-[P(2)W(17)O(61)](10-) complexes, the Ln ions are bound to four O atoms of the lacunary polyoxometalate framework in addition to four O atoms from solvent (water) molecules as [(H(2)O)(4)Ln(alpha-1-P(2)W(17)O(61))](7-). This structure (1) is the first of its kind for any metal complex of alpha-1-[P(2)W(17)O(61)](10-), and the data indicate that the general stoichiometry [(H(2)O)(4)Ln(alpha-1-P(2)W(17)O(61))](7-) is maintained throughout the lanthanide series. For the 1:2 stoichiometric Ln/alpha-2-[X(2)W(17)O(61)](10-) complexes, no water molecules are in the Ln-O(8) coordination sphere. The Ln ions are bound to eight O atoms-four from each of two heteropolyanions-as [Ln(alpha-2-X(2)W(17)O(61))(2)](17-). The average Ln-O interatomic distances decrease across the lanthanide series, consistent with the decreasing Ln ionic radius.     

Structural models for some crystalline and liquid crystalline polymers

Structural models for the crystalline and liquid crystalline smectic phase are presented for polymethylsiloxanes with mesogenic side groups and for some crystalline and lyotropic liquid crystalline cholesteric phases of cellulose derivatives. Optical and X-ray methods have been applied in these investigations.     

Preconcentration of some transition and rare-earth elements by Donnan dialysis

A method using Donnan dialysis for the preconcentration of some transition and rare-earth elements is described. Enrichment factors of about 20 are obtained in 1 hr. Calibration curves that are linear over 2 orders of magnitude are obtained with a relative precision of about 3% when Co(II) is used as an internal standard. The effect of aluminium in the receiver electrolyte on the interference caused by phosphate in the sample solution is discussed.     

Halide polyhydrates of some rare-earth elements: Synthesis and structures

Scandium, yttrium, lanthanum, cerium, and terbium bromides and iodides of the formulas [(H₂O)₅Sc(μ-OH)₂Sc(H₂O)₅]Br₄ · 2H₂O (I), [(H₂O)₅Sc(μ-OH)₂Sc(H₂O)₅]I₄ (II), [Y(H₂O)₈]Br₃ · 2H₂O (III), [(H₂O)₇La(μ-Br)₂La(H₂O)₇]Br₄ (IV), [Ce(H₂O)₉]I₃ (V), and [Tb(H₂O)₉]I₃ (VI) were obtained and examined using X-ray diffraction and IR and Raman spectroscopy. It was found that the compositions and structures of complexes II and III differ from the literature data. Crystallographic parameters were obtained for isostructural complexes V and VI. It was demonstrated that the conditions of the synthesis and the possibility of protolysis are decisive for the formation of polynuclear oxo and hydroxo complexes of rare-earth metal halides.     

Structural features of some organotin(IV) complexes of semi- and thio-semicarbazones

Some five- and six-coordinated di and tri-n-butyl tin(IV) semi- and thio-semi carbazates have been synthesized. The characterization of these complexes, by IR, NMR (¹H, ¹³C, ¹¹⁹Sn), ¹¹⁹Sn), ¹¹⁹Sn Mössbauer and Mass spectroscopies along with X-ray diffraction, reveals that complexes of biionic ligands of the type Bu₂Sn L″ are five-coordinated having trigonal bipyramidal geometry. However, complexes of monoionic ligands of the type Bu₂SnL′₂ are six-coordinated in a distorted cis-octahedral geometry and Bu₃SnL′ are five-coordinated with a trigonal bipyramidal structure. X-ray structural studies on the compound Bu₂Sn(O.C₆H₄.CH:N.N.CS.NH₂), show that it crystallizes in a monoclinic lattice with a = 16.90 Å, b = 9.71 Å, c = 8.60 Å, and β = 103°45′.     

Determination of some rare-earth elements by plasma-jet emission spectrometry

The effects of a magnetic field on spectral intensities in plasma-jet spectrometry were examined, and detection limits for rare-earth elements were calculated. Plasma-jet emission spectrometry was applied to the determination of lanthanum, yttrium and gadolinium in a monazite sample from which thorium had been separated. A standard addition method was used in order to improve accuracy, and the internal standard and background compensation method was applied to measurements of spectral line intensities to achieve good precision. The coefficient of variation was 1.51% for 50 μg La ml^?1.     

Structural specific features and properties of alkaline-earth and rare-earth metal borates

The review summarizes literature data on the synthesis, crystal growth conditions, structures, and physicochemical properties of alkaline-earth and rare-earth element borates. The compounds under consideration were shown to be promising for the use as materials for electronics, laser and luminescent matrices.     

Paramagnetic complexes of platinum and palladium with acetamide

Summary Direct reaction of K₂MCl₄ (M=Pt or Pd) with acetamide leads reproducibly to complexes which can be formulated as [Pt(C₂H₄ON)₂Cl]_n and Pd₄(C₂H₄ON)₇(OH)₂. Analytical and spectroscopic (i.r., n.m.r. and e.p.r.) data support the existence of polynuclear structures involving bridging ligands and partially oxidized metal centres.     

Thiocyanates of rare-earth elements with tetramethylphenanthroline

Molecular [M(NCS)₃(H₂O)(Me₄Phen)₂] · (Me₄Phen) · 0.75EtOH and anionic [H(Me₄Phen)][М(NCS)₄(Me₄Phen)₂] complexes are synthesized using thiocyanates М(NCS)₃ · 6H₂O (M = Y, Eu, Tb) and 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4Phen). The complexes are characterized by IR spectroscopy and elemental, X-ray phase, and X-ray diffraction analyses (CIF files CCDC no. 1498178–1498184). The thermoanalytical study shows that the solvate molecules Me₄Phen are localized in the internal coordination sphere of the molecular complexes at 195–250°C. The magnetic behavior of the Eu and Tb complexes is governed by the nature of the Ln ion.     

Preparation of complexes of sulfoxides of petroleum origin and tributyl phosphate with chlorides of rare-earth elements

Conclusions Conditions were found for obtaining the complexes of petroleum sulfoxides and tributyl phosphate with the chlorides of the rare-earth elements with a coordination number of 9, 7, and 6. It was established that anhydrous trisolvates are obtained by the azeotropic distillation of the water with toluene and subsequent drying of the complexes with zeolites.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2790–2792, December, 1977.     

Hexadecapropyloxy-substituted diphthalocyanine complexes of rare-earth elements: synthesis,spectroscopic and electrochemical studies

Hexadecapropyloxy-substituted diphthalocyanine complexes of rare-earth elements (REE = Lu, Tm, Sm) were synthesized. The new symmetrically substituted diphthalocyanine complexes prepared starting from 4,5-dipropyloxyphthalodinitrile (phthalogen) are characterized by better solubilities compared to the known hexadecamethyl-substituted diphthalocyanine complexes of the same REE. Spectral and electrochemical characteristics of the complexes were studied. The compounds can be used as materials for high-contrast electrochromic devices.     

New complexes of some d-electron elements with 3-methyladipic acid

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) 3-methyladipates were investigated and their qualitative composition and magnetic moments were determined. The IR spectra and powder diffraction patterns of the complexes prepared of the general formula M(C₇H₁₀O₄)·nH₂O (n=0-11) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Co, Ni) or two steps (Mn, Zn) losing all crystallization water molecules (Co, Ni) or some water molecules (Mn, Zn) and then anhydrous (Co, Ni, Cu) or hydrated complexes (Mn, Zn) decompose directly to oxides (Mn, Co, Zn) or with intermediate formation the mixture of M+MO (Ni, Cu). The carboxylate groups are bidentate (Mn, Co, Ni, Cu) or monodentate (Zn). The complexes exist as polymers. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.48, 4.49, 2.84 and 1.45 B.M., respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Oxygen isotopic exchange between carbon dioxide and some molybdates or rare-earth elements

The oxygen exchange between C¹⁸O₂ and the normal molybdates of cerium, lanthanum, praseodymium and neodymium has been studied within the temperature interval 300–500°C. The specific rates and activation energies of exchange for these molybdates were found to have similar values. The reactivity of oxygen in the molybdates studied was shown to be close to the reactivity of oxygen in MoO₃