Preparation, structure, and properties of new ternary rhenium arsenides and phosphides with metal-metal bondings

The M₂Re₅As₁₂ arsenides (M = Fe, Co, Ni) and the Co₂Re₅P₁₂ phosphide were synthesized. The unit cell is orthorhombic with space group Pnnm and contains two formula units. The X-ray structure of Ni₂Re₅As₁₂ was studied from three-dimensional single-crystal counter data and was refined down to R = 0.048 for 637 independent reflections. The structure can be described as built up from two different structural domains; the first one is the marcasite type and shows As---As pairs and linear Re---Re chains, the second one consists of Re₄ clusters with common edges linked to terminal Ni atoms. A nearly temperature-independent paramagnetism and p-type metallic conduction were observed from the magnetic and electrical measurements. Also observed in this new family of compounds were the resistivities along and perpendicular to the c axis and their anisotropic behavior.     

碱土金属与DBC-偶氮氯膦配位反应及配合物结构的研究

本文研究了DBC-偶氮氯膦在不同酸度下的存在形式、质子化情况及反应中的质子释放情况, 测定了钙、锶、钡与其形成的配合物的稳定常数。利用红外、激光Raman、核磁共振光谱等对所生成的配合物的结构进行了研究, 并根据实验结果和分子结构的几咱理论, 提出了碱土金属与其生成的配合物的结构。本文还就配位反应和配合物的成键情况进行了讨论。     

2D and 3D alkaline earth metal carboxyphosphonate hybrids: Anti-corrosion coatings for metal surfaces

Reactions of Mg²⁺ (1), Ca²⁺ (2), Sr²⁺ (3), or Ba²⁺ (4) salts with hydroxyphosphonoacetic acid (HPAA) at a 1:1 ratio yield M-HPAA layered coordination polymers. The crystal structures of 3 (two phases) and 4 have been determined by single crystal X-ray crystallography. Both stereoisomers (R and S) of HPAA are incorporated in the metal-HPAA materials. Synergistic combinations of Sr²⁺ or Ba²⁺ and HPAA at pH 7.3 are effective corrosion inhibitors for carbon steel, but are ineffective at pH 2.0.     

Thin-layer chromatographic behavior of rare earths on silica gel with aqueous alkaline earth metal nitrate solutions as mobile phases

The TLC behavior of all the rare earths except Pm has been surveyed on silica gel (pH 7.0) pretreated with 0.1 mol L^–1 tris(hydroxymethyl)aminomethane and 0.1 mol L^–1 HCl with aqueous nitrate solutions of alkaline earth metals as mobile phases. The R_F values of the lanthanides varied in a regular and characteristic way accompanied by the tetrad effect with increasing atomic number, and when the mobile phases were changed the R_F values of each metal decreased in the order Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺, as the crystal ionic radii of the alkaline earth metals increased. This adsorption sequence was not observed with alkali metal nitrate and alkali metal chloride mobile phases. A brief discussion concerning the effect on R_F values of the solvent cations and the adsorption mechanism is included; also presented are typical chromatograms for the separation of multi-component mixtures containing adjacent lanthanides. Received: 9 October 2000 / Revised: 20 February 2001 / Accepted: 26 February 2001     

Thin-layer chromatographic behavior of rare earths on silica gel with aqueous alkaline earth metal nitrate solutions as mobile phases

The TLC behavior of all the rare earths except Pm has been surveyed on silica gel (pH 7.0) pretreated with 0.1 mol L(-1) tris(hydroxymethyl)aminomethane and 0.1 mol L(-1) HCl with aqueous nitrate solutions of alkaline earth metals as mobile phases. The RF values of the lanthanides varied in a regular and characteristic way accompanied by the tetrad effect with increasing atomic number, and when the mobile phases were changed the RF values of each metal decreased in the order Mg2+ > Ca2+ > Sr2+ > Ba2+, as the crystal ionic radii of the alkaline earth metals increased. This adsorption sequence was not observed with alkali metal nitrate and alkali metal chloride mobile phases. A brief discussion concerning the effect on RF values of the solvent cations and the adsorption mechanism is included; also presented are typical chromatograms for the separation of multi-component mixtures containing adjacent lanthanides.     

Complexes of quinolone drugs norfloxacin and ciprofloxacin with alkaline earth metal perchlorates

The interaction of quinolone drugs Norfloxacin (NR) and Ciprofloxacin (CP) with magnesium, calcium and barium perchlorates was investigated. Solid complexes, obtained as products of this interaction, were isolated and characterized by elemental and thermal analysis, FT-IR spectral and electrical conductivity measurements. The spectral studies of the isolated complexes suggest that NR and CP act as bidentate ligands that bind through one carboxylic oxygen atom and the exocyclic carbonyl oxygen atom. The obtained results indicate the formation of the complexes of the following formulas: [M(CP)₂](ClO₄)₂·xH₂O and [M(NR)₂](ClO₄)₂·xH₂O, where M = Mg(II), Ca(II), and Ba(II).     

3D coordination polymers with vanadyl fragments and alkaline earth metal ions

The reactions of vanadyl sulfate VOSO₄·3H₂O with barium or strontium cyclopropane-1,1-dicarboxylate (MCpdc, M = Ba, Sr, H₂Cpdc = C₃H₄(COOH)₂) afforded the polymeric heterometallic complexes {[(H₂O)₈Ba₂(VO)₂(Cpdc)₄]·2H₂O}n (1) and {[(H₂O)₆Sr(VO)(Cpdc)₂]}n (2), respectively. These complexes differ in the binding mode of mononuclear vanadyl fragments with alkaline earth metal ions. Coordination polymers 1 and 2 were characterized by ESR spectroscopy.     

Encapsulating ruthenium and osmium with tris(2-aminoethyl)amine based tripodal ligands

The reaction of a series of tripodal ligands, H₃L^1,2 and L^3-6, with [M(PPh₃)₂Cl₂] (M = Ru, Os) affords a family of coordination cage compounds of the type [M^IIIL^1,2] (1-4) or [M^IIL^3-6](BPh₄)₂ (5-12). The Schiff base ligands (H₃L¹, L³, L⁵) have been synthesized by condensation of tris(2-aminoethyl)amine with salicylaldehyde, pyridine-2-aldehyde and 1-methyl-2-imidazolecarboxaldehyde. These ligands were further reduced and subsequently methylated to form the new ligands (H₃L², L⁴, L⁶). Single crystal X-ray diffraction studies of 1 and 2 show that the tripodal ligand wraps around the metal center as a hexadentate ligand to form a cage. All the synthesized compounds have been thoroughly characterized by ESI-MS, FT-IR, UV-Vis and NMR spectroscopic methods. To the best of our knowledge, this is the first ever report of osmium complexes with tris(2-aminoethyl)amine based tripodal ligands. DFT calculations were performed to obtain geometry optimized structures of all the other complexes (3-12).     

Electronic second hyperpolarizability of alkaline earth metal chains end capped with −NH2 and –CN

A comparative study of the electronic structure and second hyperpolarizability has been performed by considering alkaline earth metal-bridged chains (Be_n, Mg_n, Ca_n) end capped with NH₂ and CN groups. For the sake of comparison of the calculated second hyperpolarizability, analogous molecular species H₂N−(CC)_n−CN has also been included in the present investigation. Since the metal-metal interactions are weaker, the dispersion corrected DFT methods are employed to calculate the stability of the investigated species. Similar to the conventional donor-π-acceptor system, the longitudinal component of first- and second-hyperpolarizabilities of Mg and Ca chains increases on increasing the chain length. The highest γ_zzzz value of Mg and Ca chains (n ​= ​7) are found to be in the order 10⁷ au and 10⁸ au, respectively. Both transition moment and transition energy associated with the crucial electronic transition play a significant role in the variation of second hyperpolarizability.     

Ground and excited state complexation of ketocyanine dyes with alkaline earth metal ions

Electronic absorption and emission spectral characteristics of two ketocyanine dyes have been studied in solution in the presence of alkaline earth metal ions. Absorption spectral studies indicate complex formation between the ions and the dyes in the ground state. Values of the equilibrium constant and the enthalpy change characterizing dye (S0)-metal ion interaction have been determined from the absorption spectral data. In the presence of the metal ions the fluorescence spectrum of the dyes shows two bands pointing to the existence of two emitting species, viz., the solvated and the complexed dye in solution. Time-resolved studies of the dyes in solution containing the metal ions can be explained by a two-state model and indicate the presence of two emitting species in equilibrium. Values of the equilibrium constant for the interaction of metal ion and the dyes in the S1 state have also been estimated.     

The color reactions of sulfonazo-III isomers with lanthanum and alkaline earth metal ions

Six sulfonazo-III isomers were synthesized, and their color reactions with alkaline earth metals and lanthanum investigated. All six reagents had good sensitivities for lanthanum (? = 1.9–5.0·10⁴), but the sensitivities for alkaline earth metals were fairly low except for the barium chelate of sulfonazo-III (? = 2.8 · 10⁴). The position of the sulfo group on the phenyl ring and the symmetry of the reagent are important for the barium reactions, but of little significance for the lanthanum reactions. The effects of water-miscible solvents are also described.     

Ionophoric binding of alkaline earth metal ions (M2+) by tris-(arylazo oximato)osmium(II) anions, [OsA3]−

Summary High-yield synthetic routes to trinuclear complexes of the type [M(OsA₃)₂] (M = Mg, Ca, Sr or Ba; A = anion of arylazo oxime) by reaction of Na[OsA₃] and M(ClO₄)₂, or of [HOsA₃] with MCO₃, are described. The new complexes have been characterized on the basis of spectroscopic and physico-chemical results. The alkaline earth metal ions are held in an O₆ matrix of two facial [OsA₃]^– units, each behaving as a tridentate (O, O, O) ligand. Quantitative transport of one equivalent of M²⁺ from the aqueous to the organic (CH₂Cl₂) phase can be achieved with two equivalents of [OsA₃]^–. When the aqueous phase is acidified with two mol of H⁺, [M(OsA₃)₂] decomposes into M²⁺ and [HOsA₃], and M²⁺ returns to this phase in its free state.     

Bonding, ion mobility, and rate-limiting steps in deintercalation reactions with ThCr2Si2-type KNi2Se2

Here, we study the nature of metal-metal bonding in the ThCr(2)Si(2) structure type by probing the rate-limiting steps in the oxidative deintercalation of KNi(2)Se(2). For low extents of oxidation, alkali ions are removed exclusively to form K(1-x)Ni(2)Se(2). For greater extents of oxidation, the rate of the reaction decreases dramatically, concomitant with the extraction of both potassium and nickel to form K(1-x)Ni(2-y)Se(2). The appreciable mobility of transition metal ions is unexpected, but illustrates the relative energy scales of different defects in the ThCr(2)Si(2) structure type. Furthermore, the fully oxidized compounds, K(0.25)Ni(1.5)Se(2), spontaneously convert from the tetrahedral [NiSe(4)]-containing ThCr(2)Si(2) structure to a vacancy-ordered NiAs structure with [NiSe(6)] octahedra. From analysis of the atom positions and kinetic data, we have determined that this transformation occurs by a continuous, low-energy pathway via subtle displacements of Ni atoms and buckling of the Se sublattice. These results have profound implications for our understanding of the stability, mobility, and reactivity of ions in materials.     

混合稀土离子的毛细管电泳电导法分离检测

采用高效毛细管电泳电导检测法分离检测了稀土离子。以醋酸-醋酸钠为背景电解质,4-吗啉乙磺酸（MES）为络合剂,在24kV的高压下,7种稀土离子得到子较好的分离。考察了背景电解质的pH和浓度,络合剂的浓度,分离电压等对稀土离子分离的影响。在选定的实验条件下,7种烯土离子在10min内守成分离检测。     

Coordination chemistry of the alkaline earth metal ions with Zwitterionic forms of the Schift bases. X-Ray studies and other spectroscopic properties

The non-ionized forms of tetradentate Schiff bases NN′-ethylenebis(salicylideneimine), H₂L and NN′-propane-1,3-diylbis(salicylideneimine), H₂L′ react with hydrated alkaline earth halide and nitrate to give complexes of the type: M(H₂L)Cl₂·nH₂O [M = Mg(II), Ca(II), Sr(II); n = 0–4], M(H₂L)₂Cl₂ [M = Ca(II), Sr(II), M(H₂L)_nBr₂ [M = Ca(II), Sr(II); n = 2, 3 and Mg₂(H₂L)₃Br₄], M(H₂L)_nI₂ [M = Mg(II), Ca(II), Sr(II), Ba(II); n = 2, 3)], M(H₂L)_n(NO₃)₂ and M(H₂L′)_n(NO₁)₂[M = Mg(II), Ca(II);n = 1, 2)]. Because of distinct spectral similarities with structurally known Ca(H₂L′)(NO₃)₂ compound, the Schiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups, which carry the protons transferred from phenolic groups on complexation. Halide and nitrate are coordinated to the central metal ion except in 2:1 nitrato complexes where the presence of both ionic and coordinated nitrate groups are evident and also in 3:1 halide complexes where the presence of non-coordinated halide cannot be excluded. X-Ray powder photographs showed no marked similarities between Ca(H₂L′)(NO₃)₂ and Mg(H₂L′)(NO₃)₂ while there are some isomorphic features between the same types of halide complexes. Infrared spectra and other structural information revealed the polymeric nature of the complexes. Therefore the coordination numbers exhibited by the alkaline earth metal cations would be 4, 6 or 8 in these series of Schiff base complexes.