Gas chromatographic analysis of C1–C20 carboxylic acids esterified in aqueous solutions as isobutyl esters

Summary C₁–C₂₀ carboxylic acids have been esterified in aqueous solutions with i-butanol. Gas chromatographic analyses have been performed from a single chromatogram. It has been established that esterification in the concentration range of [H₂O]/[i-BuOH]=0.01–10.3 can be utilized for the quantitative determination of these carboxylic acids.The presence of water does not interfere in the range of [H₂O]/[i-BuOH]=0.01–1.03.In the cases of [H₂O]/[i-BuOH]>1.03, anhydrous sodium sulfate has been used for binding the water, in an amount of [Na₂SO₄]_anh./[H₂O]0.2.     

Cyclometallaphosphiniminatopxosphane (and Arsane) Complexes of “Early” and “Late” Transition Metals Derived from Novel Heterodifunctional Phosphorus and Arsenic Ligands

Abstract

A new heterodifunctional ligand system Me₃EN=PPh₂(CH₂)_nQPh₂ (E - Si, Ge; Q = P, As; n ? 1, 2) has been developed. These heterodifunctional ligands provide hard (N) and soft (P, As) base character appropriate for combination with “early” and “late” transition metals respectively to form chelate and monodentate complexes. In addition M-N [sgrave] bond formation by means of metathetical Me₃EX elimination leads to a variety of useful functionalized phosphanes. Interactions with Ti(IV), Mo(O), W(O), Pd(II), Rh(I) and Ir(I) indicate the versatility of these ligands     

Hydrothermal Synthesis and Crystal Structure of a New a-Keggin Unit-supported Cobalt Bipyridyl Complex: [Co(2,2'-BIPY)3]1.5[SiW12O40Co(2,2'-bipy)2(H2O)]·0.5H2O

A new α-Keggin unit-supported transition metal complex [Co(2,2′-bipy)₃]_1.5[SiW₁₂O₄₀Co(2,2′-bipy)₂-(H₂O)]·0.5H₂O has been hydrothermally synthesized and characterized by X-ray crystallography, showing that [Co(2,2′-bipy)₂(H₂O)]²⁺ units are covalently bonded to the α-Keggin cluster [SiW^VW^VI ₁₁O₅₀]^5?. Intermolecular hydrogen bonding interactions and short O … O contacts force the structure into an interesting one-dimensional supramolecular array. Crystals are monoclinic space group C2/c, with a = 46.676(9), b = 14.348(3), c = 26.010(5) Å, β = 90.33(3)°, V = 17419(6) ų, Z = 8.     

Syntheses,crystal structures,and characterization of seven coordination compounds based on flexible 1,1′-(1,4-butanediyl)bis(3-carboxyl-2-oxidopyridinium)

Seven coordination compounds based on 1,1′-(1,4-butanediyl)bis(3-carboxyl-2-oxidopyridinium), [CoNa(L)_1.5(C₂H₅OH)₃] (1), [Zn(L)(OH)₂]?·?4H₂O (2), [Co(L)(OH)₂]?·?2H₂O (3), [Co(L)(H₂O)] (4), [Zn(L)(H₂O)] (5), [Ni(L)(H₂O)] (6), and [Mn(L)(H₂O)] (7), have been synthesized and crystal structures have been determined by single-crystal X-ray diffraction. Compound 1 exhibits a 0-D molecular structure. Compound 2 shows a 1-D “Z” chain structure. Neighboring chains are further linked by hydrogen-bonding interactions into a 2-D supramolecular layer. Compound 3 features a 1-D “Z” chain structure. The chains are further extended into a 2-D supramolecular structure by hydrogen-bonding interactions. Compounds 4–7 are isomorphous and display 2-D (4⁴)-SQL networks. These compounds are further characterized by infrared spectra, elemental analyses, and X-ray powder diffraction. The luminescent properties of the compounds were also investigated.     

Syntheses,crystal structures,and magnetic properties of a series of Fe2Ln complexes

A family of phenoxo-bridged heterometallic Schiff base trinuclear complexes, [Fe₂LnL₂(C₃H₇COO)(H₂O)]·CH₃OH·CH₃CN·H₂O (Ln = Sm, 1; Gd, 2; Tb, 3; Dy, 4) is reported. Those complexes were afforded by “one-pot” reaction of a polydentate Schiff base ligand 2-hydroxy-3-methoxy-phenylsalicylaldimine (H₂L) with Fe(NO₃)₃·9H₂O, Ln(NO₃)₃·6H₂O and sodium butyrate (C₃H₇COONa) in a mixture of methanol and acetonitrile in the presence of triethylamine as a base. Single-crystal X-ray diffraction analysis reveals that the structures of the four complexes are isomorphic. In each complex, two anionic [FeL₂]^? units coordinate to the central lanthanide ion as a tetradentate ligand using its four phenoxo oxygens, forming a two-blade propeller-like molecular shape. Magnetic properties of 1–4 were investigated using variable temperature magnetic susceptibility, and weak ferromagnetic exchange between the Fe^III and Ln^III ions has been established for the Gd derivative. The Tb and Dy complexes show no evidence of slow relaxation behavior above 2.0 K.     

SPIN-CROSSOVER OF [Fe(Cl-BZIMPY)2](ClO4)2 INDUCED BY DEPROTONATION

Abstract

The ligand 4-Cl-2,6-bis(benzimidazol-2′-yl)-pyridine(Cl-bzimpy;H₂L) acts as a bidentate when coordinated with transition metal ions and the complex [Fe(Cl-bzimpy)₂](ClO₄)₂ was isolated as a solid. The protonation constants (logK). The free ligand and the complex were evaluated in 30:70 (v/v) H₂O:EtOH at room temperature and ionic strength of 0.13M (KCl). Coordination of the ligand to the metal ion leads to an increase of the acidity of the imino-hydrogen of the benzimidazole group. Deprotonation leads to a change in the spin-state (to the low-spin state; HS → LS transition) of the complex associated with a decrease in the spin-crossover equilibrium constant (K_sc). An opposite shift of spin-state is observed when HClO₄ is added to the complex solution, thus showing the reversibility of the process.     

COORDINATION COMPOUNDS OF NICKEL WITH TRITHIOCYANURIC ACID

Abstract

Nickel(II) complexes with a combination of trithiocyanuric acid and diamines or triamines of composition [Ni(aepa)(ttcH)(H₂O)], [Ni(dien)(ttcH)(H₂O)], [Ni(dpta)(ttcH)(H₂O)] H₂O, [Ni(phen)₂(ttcH)]H₂O, [Ni(phen)₃](ttcH)-5H₂O and [Ni(1,2-pn)₃](ttcH)-H₂O (aepa = N-(2-aminoethyl)-1,3-propanediamine,dien = diethylenetriamine,dpta = dipropylenetnamine, phen = 1,10-phenanthroline, 1,2-pn = 1,2-diaminopropane. ttcH₃ = trithiocyanuric acid) have been prepared. The compounds have been characterized by means of elemental analysis, IR and electronic spectroscopies and magnetochemical measurements. Selected complexes were studied by thermal analysis. The compounds can be characterized as distorted octahedral Ni(II) complexes. It was found that the trithiocyanuric dianion can act either as a bidentate ligand or be situated out of the coordination sphere of nickel. The crystal and molecular structure of [Ni(dpta)(ttcH)(H₂O)] H₂O was determined. Crystals are monoclinic, space group P2₁/n, with a = 20.316(4), b = 7.967(2), c = 21.401(4) Å, β = 99.23(3)°, K=3419.1(13)ų, Z = 4, T = 293 K. The nickel(II) atom is six-coordinated by three nitrogen atoms from dipropylene-triamine, nitrogen and sulphur from trithiocyanuric acid, and an oxygen atom from a water molecule in a distorted octahedral geometry.     

Construction of Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,4-benzenedicarboxylate

Three new Cd(II) complexes incorporating both 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,4-benzenedicarboxylate (bdic^2?), [CdCl(bdic)_1/2(imb)₂]_n (1), {[Cd(bdic)(imb)(H₂O)]·DMF·2H₂O}_n (2), and [Cd(bdic)(imb)]·3H₂O}_n (3), have been prepared and structurally characterized by single crystal X-ray diffraction. Bdic^2? anions connect the?Cd-imb-Cd-imb?chains leading to a 2-D structure of 1. Bdic^2?(A) and bdic^2?(B) anions link the binuclear [Cd₂(imb)₂(H₂O)₂] units forming a 2-D structure of 2. Complex 3 features a 2-D structure involving supramolecular “double-layer” motifs. IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis; 1–3 exhibit good fluorescence in the solid state at room temperature.     

Molar heat capacity and thermodynamic properties of crystalline [Nd(Glu)(H<Subscript>2</Subscript>O)<Subscript>5</Subscript>(Im)<Subscript>3</Subscript>](ClO<Subscript>4</Subscript>)<Subscript>6</Subscript>·2H<Subscript>2</Subscript>O

A complex of neodymium perchloric acid coordinated with L-glutamic acid and imidazole, [Nd(Glu)(H₂O)₅(Im)₃](ClO₄)₆·2H₂O was synthesized and characterized by IR and elements analysis for the first time. The thermodynamic properties of the complex were studied with an automatic adiabatic calorimeter and differential scanning calorimetry (DSC). Glass transition and phase transition were discovered at 221.83 and 245.45 K, respectively. The glass transition was interpreted as a freezing-in phenomenon of the reorientational motion of ClO₄⁻ ions and the phase transition was attributed to the orientational order/disorder process of ClO₄⁻ ions. The heat capacities of the complex were measured with the automatic adiabatic calorimeter and the thermodynamic functions [H _T-H _298.15] and [S _T-S _298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry (DSC).     

Syntheses and structural determination of eight-coordinate Na[YbIII(Cydta)(H2O)2] · 5H2O and [YbIII(Hegta)] · 2H2O complexes

Na[Yb^III(Cydta)(H₂O)₂] · 5H₂O (1) (H₄Cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid) and [Yb^III(Hegta)] · 2H₂O (2) (H₄egta = ethyleneglycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) were prepared and their composition and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. Complex 1 crystallized in the triclinic crystal system with space group P 1; the Yb^III is eight-coordinate by a hexadentate Cydta and two water molecules. Complex 2 is a protonated egta complex, crystallized in the monoclinic crystal system with space group P 2 ₁ /c; Yb^III is coordinated only by the octadentate Hegta ligand. Both these complexes adopt a pseudo-square antiprismatic conformation.     

Metal complexes with N-(trifluoromethylbenzyl)iminodiacetate chelators (x-3F ligands). Part I. Copper(II) chelates of p-3F,m-3F,and o-3F with or without imidazole-like ligands

Eight Cu(II) complexes with N-(p-, m- or o-trifluoromethylbenzyl)iminodiacetate chelators (x-3F ligands) have been synthesized to promote C–F/H interligand interactions involving the F₃C-group: {[Cu(μ₂-p-3F)(H₂O)]·3H₂O]}_n (1), [Cu(m-3F)(H₂O)₂] (2), [Cu(p-3F)(Him)(H₂O)] (3), [Cu(m-3F)(Him)(H₂O)] (4), [Cu(o-3F)(Him)(H₂O)] (5), [Cu₂(p-3F)₂(H5Meim)₂(H₂O)₂] (6), [Cu(m-3F)(H5Meim)(H₂O)] (7), and [Cu(o-3F)(H5Meim)(H₂O)] (8) [Him and H5Meim = imidazole and the “remote” tautomer 5-methylimidazole, respectively]. The compounds were studied by single-crystal X-ray diffraction, FT-IR, electronic spectra and coupled thermogravimetric + FT-IR methods. The conformation of the iminodiacetate chelating moiety (IDA group) is fac-NO + O(apical) in 1 and mer-NO₂ in 2–8. The fac-IDA conformation observed in 1 is related to its polymeric structure and the coordination of a O’-carboxylate donor, from an adjacent complex unit, trans to the Cu–N(IDA) bond. The mer-IDA conformation in 2 is in agreement with similar compounds with an aqua ligand trans to the corresponding Cu–N(IDA) bond. As expected, the ternary complexes 3–8 feature a mer-IDA conformation. Some of the studied complexes exhibit disorder in the –CF₃ group and C–H?F interligand interactions along with conventional N–H?O and O–H?O interactions. The thermal decomposition of all studied compounds under air flow produces variable amounts of trifluorotoluene.     

Reactivity of Aquadiethylenetriamineplatinum(II) Ion with Disulfide Moiety Cystine: A Kinetic and Mechanistic Approach

Abstract

Substitution reactions of the complex [Pt(dien)H₂O]²⁺ (where dien = diethylentriamine or 1,5-diamino-3-azapentane) with sulfur-containing L-cystine have been studied in a 1.0 × 10^?1 mol dm^?3 aqueous perchlorate medium at various temperatures (298–323 K) and 4.45 ≤ pH ≤ 2.15 using UV-vis spectroscopy. The products obtained have been characterized by their infrared and ¹H NMR datasets at various pH levels and temperatures. From infrared and ¹H NMR data, products have indicated that [Pt(dien)H₂O]²⁺ reacted with L-cystine forming a Pt–S bond at low pH. At high pH, a product complex through the Pt–N bond has been formed. All rate constants have been evaluated from nonlinear double exponential plots. The activation parameters ΔH^# and ΔS^# have been determined using the Eyring equation. The products, S_Ni, and reversible rate constants have been evaluated.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

Preparation of Aryloxy-aluminoxanes and Their Use as Activators in the Bis(imino)pyridyl Iron-catalyzed Oligomerization of Ethylene

In this study, a series of aryloxy-aluminoxanes originated directly from the hydrolysis of reaction products of AlMe_3 and phenols were synthesized, which could serve as effective polymer-retarding activators for the iron-catalyzed ethylene oligomerization.The molar ratios of [PhOH]/[AlMe_3] and [H_2O]/[Al] during the preparation were explored and their impacts on the oligomerization activity and product distribution were discussed. To obtain the effective activators with good polymer-retarding effect and relatively high activity, the optimized conditions were proposed to be [PhOH]/[AlMe_3] = 0.5 and [H_2O]/[Al] = 0.7. Various aluminoxanes with different[―OH] sources confirmed the importance of using phenols in preparing the effective polymer-retarding activators. By utilizing these aryloxy-aluminoxanes, the mass fraction of polymers in the total products could be reduced to lower than 1.0 wt%, which is much lower than that of the MAO-activated systems( 30 wt%). This is a potential benefit for the industrial application of the iron-catalyzed oligomerization process.     

Stereospecific interactions through π -conjugated systems of sulfur-bridged dinuclear Co(III)-Pd(II) and Co(III)-Pt(II) complexes of optically active penicillaminates

The reaction of trans(N)-[Co(D-pen)₂]^? (pen = penicillaminate) or trans(N)-[Co(L-pen)₂]^? with [MCl₂(L)] (M = Pd or Pt, L = 2,2′-bipyridine (bpy) or 4,4′-dimethyl-2,2′-bipyridine (dmbpy)) stereoselectively gave an optically active S-bridged dinuclear complex, [M(L){Co(D-pen)₂}]Cl · 3H₂O or [M(L){Co(L-pen)₂}]Cl · 3H₂O. The mixture of equimolar amounts of these two enantiomers in H₂O crystallizes as [M(L){Co(D-pen)₂}]_0.5[M(L){Co(L- pen)₂}]_0.5Cl · nH₂O (1cCl · 7H₂O: M = Pd, L = bpy, n = 7; 2cCl · 7H₂O: M = Pd, L = dmbpy, n = 7; 3cCl · 6H₂O: M = Pt, L = dmbpy, n = 6), in which the enantiomeric complex cations are included in the ratio of 1 : 1. In the crystals of 1cCl · 7H₂O, [Pd(bpy){Co(D-pen)₂}]⁺ (1a) and [Pd(bpy){Co(L-pen)₂}]⁺ (1b) are arranged alternately while overlapping the bpy planes along the a axis, and the π electronic systems of bpy moieties interact with each other. This is quite a contrast to the optically active 1aCl · 3H₂O or 1bCl · 3H₂O, which exist as monomers without intermolecular interactions. In crystals of 2cCl · 7H₂O and 3cCl · 6H₂O, similarly, the two enantiomeric complex cations interact with each other through the dmbpy frameworks. However, the interplane distances between the stacked π systems in these dmbpy complexes are considerably longer than in the bpy complexes. Such structural characteristics significantly reflect their diffuse reflectance spectra.     

Polymerization of tetrahydrofuran by AlEt3–H2O promoter system: Rate of propagation reaction

Kinetic studies were carried out on the polymerization of tetrahydrofuran with catalyst systems of aluminum alkyl–epichlorohydrin. As aluminium alkyl species AlEt₃, AlEt₃–H₂O (1:0.1 to 1:1.0), and “oxyaluminum ethyl” were employed. The polymerizations with these catalysts are characterized by a mechanism of stepwise addition without chain transfer or termination, which is expressed by the kinetic relation R_p = K_p[P*] ([M]–[M]_e), where [M] and [M]_e are the instantaneous and equilibrium concentrations of monomer and [P*] is the concentration of propagating species calculated from the amount and molecular weight of the product polymer. The determination of the rate constant k_p for these catalysts has shown that the polymerization rate varied considerably with the change of aluminum alkyl species, i.e., with the water-to-aluminum ratio, but the propagation rate constant itself varied very little. The variation of polymerization rate was, therefore, attributed primarily to the differences in concentration of the propagating species, i.e. the efficiency of the catalyst in forming propagating species. The catalyst efficiency was closely related to the acid strength of the aluminum alkyl species, which was estimated from the magnitude of shift of the xanthone carbonyl band in the infrared spectrum of its coordination complex with aluminum alkyl. The maximal catalyst efficiency was attained at about [H₂O]/[AlEt₃] = 0.75.     

New polynuclear compounds based on N-benzyliminodipropionic acid: solution studies,synthesis, and X-ray crystal structures

Three new polynuclear compounds based on a dicarboxylic acid ligand are reported. In particular, two Cu(II) coordination compounds, [Cu₂(H₂O)₆(Hbzlidp)₂](CF₃SO₃)₂·2H₂O (1) and [Cu(NO₃)(Hbzlidp)]_∞ (2) (bzlidp^2? = N-benzyliminodipropionate anion), and a Ni(II) dinuclear compound, [Ni₂(H₂O)₄(bzlidp)₂] (3), were synthesized and characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction. Different structures were obtained depending on the reaction conditions. The structural analyses reveal that 1 was formed by dinuclear [Cu₂(H₂O)₆(Hbzlidp)₂]²⁺ units built by two copper(II) ions joined through two Hbzlidp^? ligands, while 2 was formed by pairs of Cu(II) centers bridged by four syn,syn carboxylate groups to generate “paddle wheel” units. The dinuclear copper units are arranged in a rhombus type grid, in a 2-D layer structure. In both cases, the N was protonated and not coordinated to the metal center. Compound 3 was formed by [Ni₂(H₂O)₄(bzlidp)₂] neutral dinuclear units, with octahedral Ni(II) centers. Solution studies of the ligand–M(II) systems (M(II) = Mn, Co, Ni, Cu, Zn, Cd, and Pb) were also carried out.     

Self-assembled tetrameric H2O clusters in the crystal lattice of [Cu(μ2-OH){Ph2P(O)NP(O)Ph2-κ1O,O′}(1,10-phen-κ2N,N′)]2·2H2O

Abstract

The synthesis and characterization of the dinuclear Cu(II) complex [Cu(μ²-OH){Ph₂P(O)NP(O)Ph₂-κ¹O,O′}(1,10-phen-κ²N,N′)]₂·2H₂O (1), 1,10-phen?=?1,10-phenanthroline, is described. X-ray crystallographic studies reveal that the Cu(II) centers of 1 are bridged by two OH^? groups and are coordinated by the (O,O)?= Ph₂P(O)NP(O)Ph₂^? ligand in a monodentate fashion, unprecedented for Cu(II). The crystal lattice of 1 also contains H₂O molecules, which are involved in the formation of a hydrogen bonding network with bridging OH^? groups and noncoordinated O atoms of the (O,O) ligand. These H₂O molecules are arranged in the crystal lattice of 1 as tetrameric clusters. The packing of molecules in the structure of 1 was investigated by Hirshfeld Surface analysis.     

Isomeric organic ligand dominating polyoxometalate-based hybrid compounds: synthesis and as electrocatalysts and pH-sensitive probes

By introducing isomeric organic ligands into polyoxometalate (POM) systems, two new POM-based hybrid compounds, [Cu₆(m-pyttz)₂(H₂O)][HPMo₁₂O₄₀] (1) and [Ag₃(p-H₂pyttz)(p-Hpyttz)Cl][H₂PMo₁₂O₄₀]·6H₂O (2) (m-/p-H₂pyttz = 3-(pyrid-3/4-yl)-5(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl), have been hydrothermally synthesized and characterized. Single-crystal structural analysis shows the m-pyttz ligands link Cu^I ions to generate a two-dimensional layer with hanger-like rhombus, which is pillared by the PMo₁₂ anions in 1. Compound 2 exhibits a three-dimensional supramolecular framework, in which PMo₁₂ anions are building blocks facilitating the extension of the whole structure. The influence of the coordination modes of m-/p-H₂pyttz on the structures is discussed in detail. Furthermore, electrochemical properties of 1 and 2 have been studied and they display excellent electrocatalytic activities toward the reduction of nitrite and hydrogen peroxide and pH-dependent electrochemical behaviors.     

Synthesis, crystal and molecular structure of tetraaquabis(nicotinamide)cobalt(II) phthalate dihydrate

The coordination compound of cobalt(II) with nicotinamide [CoL₂(H₂O)₄][C₆H₄(COO)₂] · 2H₂O (I) (where L stands for nicotinamide) was synthesized and characterized by IR spectroscopy, conductometry, and thermogravimetry. The X-ray structure of complex I was determined. Crystals are monoclinic: a = 15.630(2) ?, b = 7.550(2) ?, c = 21.035(4) ?, β = 100.90(5)°, V = 2437.4(4) ?³, Z = 4, space group C2/c. The structural units of complex I are centrosymmetrical cations [CoL₂(H₂O)₄]²⁺, anions [C₆H₄(COO)₂]²⁻ (lying on axis 2), and molecules of waster of crystallization. Complex cations are packed into layers are alternate with layers containing anions and free H₂O molecules. This is a classical case of π-π-staking interactions that lead to the formation of supramolecular layered assemblies. Original Russian Text ? A.S. Antsyshkina, G.G. Sadikov, T.V. Koksharova, I.S. Gritsenko, V.S. Sergienko, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 8, pp. 1379–1384.     

ORGANIC PHOSPHORUS COMPOUNDS 70 PREPARATION AND PROPERTIES OF NEW PHOSPHORUS CONTAINING CHELATING AGENTS FOR CALCIUM AND MAGNESIUM IONS

Abstract

Dedicated to Professor Martin Schmeisser on the occasion of his 65th birthday.

Several phosphonic acids of the type H₂O₃PCH₂OCHRCO₂H, R = H, CH₃, CO₂H; [H₂O₃P(CH₂)_x]₂ Y, x = 1, 2; Y = O, S; and [o-H₂O₃P(CH₂)]₂C₆H₄ have been synthesized and their capacity to chelate with calcium has been determined.