Helical ternary complexes of alkaline earth picrates with open-chain crown ether

Much attention has been paid to the amide-type open-chain crown ethers with versatile mo-lecular structures because of their characteristic physical and chemical properties. These types of ligands have been used successfully as the active materials for ion-selective electrodes and the extractants for metal ions[1—5]. Among these ligands, N,N,N′,N′-tetraphenyl-3,6,9-trioxaun- decanediamide (TTD) shows the high extractabilities for Sr2+, Ba2+ and rare earth ions and the good selectivity to…     

Heterobimetallic diethanolaminate complexes of titanium and zirconium with alkaline earth metals

Ti(OPr ⁱ )₄ or Zr(OPr ⁱ )₄ · Pr ⁱ OH react with hydrocarbon-insoluble complexes M{(OCH₂CH₂)NH(CH₂CH₂OH)}₂ (M = Mg, Ca, Sr, Ba) in a 2:1 molar ratio to yield hydrocarbon-soluble heterobimetallic diethanolaminate isopropoxide complexes [M{(OCH₂CH₂)₂NH}₂{M(OPr ⁱ )₃}₂] (M = Mg, Ca, Sr, Ba; M = Ti, Zr), which have been characterized by elemental analyses, molecular weight measurements and spectroscopic [i.r., n.m.r. (¹H and ¹³C)] studies.     

The first coordination polymers and hydrogen bonded networks containing octahedral Nb6 clusters and alkaline earth metal complexes

Three novel coordination polymers built of octahedral niobium cyanochloride clusters [Nb6Cl12(CN)6] and alkaline earth metal complexes have been prepared by reaction of aqueous solutions of (Me4N)4Nb6Cl18 and KCN with solutions of alkaline earth metal salts and 1,10-phenanthroline (phen) (1:2 molar ratio) in H2O/EtOH. The structures of [Ca(phen)2(H2O)3]2[Nb6Cl12(CN)6] x (phen)(EtOH)1.6 (1), [Ca(phen)2(H2O)2]2[Nb6Cl12(CN)6] x (phen)2 x 4H2O (2), and [Ba(phen)2(H2O)]2[Nb6Cl12(CN)6] (3) were determined by single-crystal X-ray diffraction. The three compounds were found to crystallize in the monoclinic system (space group Pn) with a = 11.5499(6) A, b = 17.5305(8) A, c = 21.784(1) A, beta = 100.877(1) degrees for 1; triclinic system (P1) with a = 12.609(4) A, b = 13.262(4) A, c = 16.645(5) A, alpha = 69.933(6) degrees, beta = 68.607(6) degrees, gamma = 63.522(5) degrees for 2; and a = 16.057(1) A, b = 16.063(1) A, c = 16.061(1) A, alpha = 86.830(1) degrees, beta = 64.380(1) degrees, gamma = 67.803(1) degrees for 3. Compounds 1 and 2 are built of cluster anions [Nb6Cl12(CN)6]4- trans-coordinated by two Ca2+ complexes via CN ligands to form neutral macromolecular units [Ca(phen)2(H2O)3]2[Nb6Cl12(CN)6] in 1 and [Ca(phen)2(H2O)2]2[Nb6Cl12(CN)6] in 2. Water of coordination and cyanide ligands form hydrogen bonded 3D and 2D frameworks for 1 and 2, respectively. The structure of 3 consists of [Nb6Cl12(CN)6]4- cluster anions and [Ba(phen)2(H2O)]2+ complexes linked through bridging cyanide ligands to form a neutral three-dimensional framework in which each barium complex is bound to three neighboring Nb6 clusters and each Nb6 cluster is linked to six Ba complexes.     

Thiomalates of alkaline earth metals

Solid state 1:1 complexes of divalent Mg, Ca, Sr and Ba with thiomalic acid(tma) have been isolated and characterised by elemental analysis, IR spectra and thermal studies. It is shown that tma coordinates to the metal ions through carboxylic oxygen atoms. Thermal studies of these complexes show that desulphurisation preceeds decarbonylation reaction leading to the formation of metal carbonates in all the cases except Mg where MgO is the end product. Thermal stability of the anhydrous thiomaltes follows the order Mg ∼ Ca > Sr > Ba. Structures have been proposed based on the information obtained from these studies.     

Synthesis and structural variations of substituted phenylamide complexes of the heavy alkaline earth metals calcium, strontium and barium

Starting material KN(H)C(6)H(3)-2,6-F(2) was prepared via a transamination reaction from KNH(2) and 2,6-F(2)C(6)H(3)NH(2) in THF and crystallized from 1,4-dioxane (diox) as the three-dimensional polymer [(diox)(1.5)K{N(H)-2,6-F(2)C(6)H(3)}.diox(0.5)](infinity) (1). The metathesis reaction of (THF)(4)CaI(2) with KN(Me)Ph in THF yields monomeric (THF)(4)Ca[N(Me)Ph](2) (2) with a nearly linear N-Ca-N moiety of 179.84(8) degrees . The metathesis reaction of (THF)(4)CaI(2) with KN(H)Mes yields trinuclear (THF)(6)Ca(3)[N(H)Mes](6) (3) with a linear Ca(3) fragment and bridging 2,4,6-trimethylphenylamido groups. The reaction of 1 with (THF)(4)CaI(2) gives dinuclear (THF)(5)Ca(2)[N(H)-2,6-F(2)C(6)H(3)](4).2THF (4) with three bridging and one terminally bound 2,6-difluorophenylamide. A similar reaction of (THF)(5)SrI(2) with KN(H)-2,6-F(2)C(6)H(3) yields dinuclear (THF)(6)Sr(2)[N(H)-2,6-F(2)C(6)H(3)](3)I.THF (5) in which the iodide anion binds terminally. This iodide ligand cannot be substituted as easily by excess KN(H)-2,6-F(2)C(6)H(3). The metathesis reaction of (THF)(5)BaI(2) with KN(H)-2,6-F(2)C(6)H(3) leads to the formation of [(THF)(2)Ba{N(H)-2,6-F(2)C(6)H(3)}(2)](infinity) (6) which crystallizes as a one-dimensional polymer with bridging 2,6-difluorophenylamide anions and additional Ba-F-bonds.     

Reactions of alkaline earth metal or al slurries with bis-cyclopentadienyl complexes of some early transition metals

Slurries of Mg, Ca, Ba and Al, prepared by cocondensation of metal vapour with volatile organic solvents, especially toluene, at –196°C, reacted at ambient temperature with some bis-cyclopentadienyl complexes of Ti, Zr, Hf, V and Cr. [TiCl₂Cp₂] (Cp = η⁵-C₅H₅) with slurries Al in hexane or toluene, or Mg or Ba, in toluene, formed [TiClCp₂]₂ accompanied by side-products. From related reactions with slurries of Mg in tetrahydrofuran (THF), [TiCl₂Cp(THF)] was obtained and with Ca-toluene slurries an unstable paramagnetic dihydrido complex of Ti(III) was observed by using ESR spectroscopy. Reactions of [TiPh₂Cp₂ with slurries of Al or Ba in toluene yielded a form of “titanocene” (TiC₁₀H₁₀) and ESR studies of these reactions revealed related paramagnetic species in solution. Reaction of slurries of Al, Mg or Ba with [TiMe₂Cp₂] produced several different paramagnetic products which were studied by ESR spectroscopy, and the reaction of metal slurries with the complexes [MR₂Cp₂] (M = Ti, R = OPh; M = Zr or Hf, R = Cl or Me), [VRCp₂] (R = Cl or Me), and [CrCp₂] are also reported.     

Synthesis of complexes containing silacyclobutane groupings and variable valence metals

Conclusions On the example of the synthesis of the complexes of 1-methyl-1-(3-pyridyl)-1-silacyclobutane with the cobalt and nickel halides it was shown that it is possible to obtain the complexes of the transition metals with heterocyeles that contain four-member ed silicon-carbon groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 135–137, January, 1973.     

Ion chromatographic determination of alkaline earth metals and some heavy metals

The method is described for ion chromatographic determination of Ba, Ca, Cd, Cu, Mn, Ni, Sr, Pb and Zn. Ethylenediammonium chloride or tartrate solutions are used as eluents with a suppressor column. The detection limits for the listed elements are (in μg l^?1): Ba 1.4, Ca 0.045, Cd 0.6, Cu 0.3, Mn 0.8, Ni 0.5, Pb 6.3, Sr 0.3, Zn 1.2. Relative standard deviations are 0.015–0.050 ar the 20 mg l^?1 level (n = 5, p = 0.95). Interferences are considered.     

The photochemistry of a bis-crown ether based on benzobis(thiazole) and its alkaline earth metal cation complexes

Irradiation of acetonitrile solutions of the bis-crown ether E,E-2,7-bis[2-(6,7,9,10,12,13,15,16-octahydro-5,8,11,14,17-pentaoxabenzocyclopentadecen-2-yl)vinyl]-benzo[1,2-d;3,4-d']bisthiazole (hereafter, 1) gives efficient E --> Z photoisomerization (initial phi(trans --> cis) = 0.48), leading to lambda(exc)-dependent quasi-photostationary states composed primarily of E,Z and E,E isomer mixtures. Further irradiation gives [2 + 2]-cycloadducts of 1. In the presence of Ba2+ ions, essentially quantitative formation of 2:2 complexes, 1(2) x (Ba2+)2 controls the photochemical outcome. E --> Z photoisomerization of the ligand is entirely suppressed and efficient intramolecular [2 + 2]-photocycloaddition in the complexes leads to cyclobutane dimers of 1 (phiCB = 0.26). The reactivity of 1 in the presence of Mg2+ ions for which 1:2 complex formation dominates gives both cis-trans photoisomerization and enhanced photocycloaddition.     

Flammability of macrocyclic polymers and their complexes with metals

The peculiarities of thermal degradation and the flammability of nitrogen-containing macrocyclic polymers have been investigated. It has been shown that the thermal and thermo-oxidative stability of these polymers depend on the structure of the macrocycle, the type of organic radicals of the main unit and the metal nature. The effect of the type of n-conjugated macromolecules, as well as of the planarity and symmetry of macrocycle, on thermal stability as well as flammability of macrocyclic polymers has been studied. Metals (Cu, Co, Ni) in the coordination sphere increase the thermal stability and decrease the thermo-oxidative degradation of macrocyclic polymers.     

Metal complex formation with dicarbonyl-ligands. Calculations on glyoxal complexes with alkali and alkaline earth metal ions

Ab initio MO SCF calculations on the complexes of Li, Na, K, Be, Mg and Ca ions with glyoxal have been performed. These calculations represent the first part of a series of theoretical investigations on the dependence of complex formation properties of ligands containing two carbonyl groups on the structure of the cordinative center. Special attention has been paid to the chelate effect, which is found to increase with increasing atomic number within the series of ions. The calculated values are compared with our recent data obtained from UV spectroscopy of ion complexes with dicarbonyl ligands.     

Extraction and photometric determination of lead with diazacrown ether dye

N,N'-Bis(2-hydroxy-5-nitrobenzyl)cryptand-22 (22-Koshland) forms yellow complexes with bivalent metal ions, and these are extractable into 1,2-dichloroethane. The overall extraction constants have been estimated for lead (10(-5.4)), copper (10(-5.6)), mercury (10(-5.8)) and cadmium (10(-8.4)). The result obtained has been applied to extraction and photometric determination of lead. The molar absorptivity at the absorption maximum (406 nm) is 4.47 x 10(4) l.mole(-1).cm(-1). The interferences from copper and mercury can be eliminated by the addition of sodium thiosulphate and the interference from cadmium can be eliminated by calculation from the absorbances at 406 and 391 nm (the cadmium complex with 22-Koshland has its absorption maximum at 391 nm). The method has been successfully applied to the determination of lead in zinc powder.     

Study of the alkaline earth metals with 8-hydroxyquinolinate derivatives

Metal complexes of calcium with 5,7-dibromo, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinolate were precipitated in aqueous ammonia and acetone medium, except for the solid state compound with 5,7-dichloro-8-hydroxyquinoline which hasn"t been obtained under these conditions. The complexes obtained through the mentioned precipitation are Ca[(C₉H₄ONBr₂)₂]₃·H₂O, Ca[(C₉H₅ONI)₂]·2H₂O and Ca[(C₉H₄ONICl)₂]·2.5H₂O. Their intermediate from the thermal decomposition found through TG/DTA curves in air indicated the presence of different kinds of calcium carbonates related to the reversibility and crystalline structure, depending on the original compounds. The initial compounds and the intermediate from the thermal decomposition were also characterized through IR spectra and X-ray diffraction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ion-selective electrode measurements for the determination of formation constants of alkali and alkaline earth metals with low-molecular-weight ligands

Formation constants of acetate, hydrogencarbonate, malonate, citrate and 1,2,3-propanetricarboxylate complexes with Na⁺, K⁺ and Ca²⁺ were determined potentiometrically using sodium, potassium and calcium selective electrodes, at 25 °C and at different ionic strengths, in the range 0 < I ≤ 1 M. Formation constants obtained by ion-selective electrode (ISE) measurements were compared with those obtained by different techniques. It has been found that the use of ISEs gives reliable results in the study of weak complexes, also under non-constant ionic strength conditions.     

Polyurethanes crosslinked by metals and their complexes with crown ether

Two types of crosslinked polyurethanes (PU) have been synthesized: (a) PU crosslinked by metal ions (Cu²⁺ and Co²⁺), and (b) PU crosslinked by the complexes of metals with crown ether. Using X-ray scattering under small and wide angles the peculiarities of the structure of networks have been investigated. It was found that PU crosslinked by the metal crown ether complexes have a looser structure because of the bulky crosslink and diminished molecular mobility of the chains between two crosslinks, as was proven by the dielectric spectroscopy method. The X-ray and IR data have allowed proposing a scheme of the structure of the crosslinked PU with various types of crosslinks. The structures discovered may be considered as similar to metal catenandes. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1379–1386, 1998     

Synthesis of novel aromatic ether polymers containing perfluorocyclobutyl and triazole units via click chemistry

The synthesis and characterization of a novel class of linear aromatic ether polymers containing perfluorocyclobutyl and triazole unites is described. These polymers were prepared from the click chemistry (the copper-catalyzed Huisgen's 1,3-dipolar cycloaddition) of new monomer 1,2-bis(4-azidomethylphenoxy) perfluorocyclobutane and bisethynyl compounds.     

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.