Extraction-spectrophotometric determination of iron(II) by ternary complex formation with pyrocatechol violet and cetyltrimethylammonium bromide

A method for iron(II) determination based on reaction with Pyrocatechol Violet to form a 1:2 binary complex at pH 5-7 is described and has been extended to an extraction-spectrophotometric procedure for the determination of iron(II) by formation of the 1:2:2 iron(II)-Pyrocatechol Violet-cetyltrimethylammonium bromide ternary complex. The molar absorptivities of the binary and ternary complexes at 595 and 605 nm are 6.55 x 10(4) and 1.35 x 10(5)1.mole(-1).cm(-1), respectively. The method has been successfully applied to the determination of iron in felspar, Portland cement and sodium hydroxide.     

Cationic cryptand complexes of tin(II)

A series of cationic cryptand complexes of tin(II), [Cryptand[2.2.2]SnX][SnX(3)] (10, X = Cl; 11, X = Br; 12, X = I) and [Cryptand[2.2.2]Sn][OTf](2) (13), were synthesized by the addition of cryptand[2.2.2] to a solution of either tin(II) chloride, iodide, or trifluoromethanesulfonate. The complexes could also be synthesized by the addition of the appropriate trimethylsilyl halide (or pseudohalide) reagent to a solution of tin(II) chloride and cryptand[2.2.2]. The complexes were characterized using a variety of techniques including NMR, Raman, and temperature-dependent M?ssbauer spectroscopy, mass spectrometry, and X-ray diffraction.     

Nickel(II) and copper(II) complexes with humic acid anions and their derivatives

Complexation of Ni(II) and Cu(II) in aqueous solutions with anions of humic acids, extracted from naturally oxidized coal, and with their hydroxymethyl derivatives is studied spectrophotometrically and potentiometrically. The complexation stoichiometry and the stability constants of the complexes are determined.     

Organic derivatives of tin (II/IV): Investigation of their structure

The structures of tin(II)-oxalate, tin(IV)Na–EDTA and tin(IV)Na₈-inositol hexaphosphate were investigated using XRD analysis. Samples were identified using the Mössbauer study, thermal analysis and FTIR spectrometry. The Mössbauer study determined two different oxidation states of tin atoms, and consequently two different tin surroundings in the end products. The tin oxalate was found to be orthorhombic with space group Pnma, a=9.2066(3) Å, b=9.7590(1) Å, c=13.1848(5) Å, V=1184.62 Å³ and Z=8. SnNa–EDTA was found to be monoclinic with space group P2₁/c₁, a=10.7544(3) Å, b=10.1455(3) Å, c=16.5130(6) Å, β=98.59(2)°, V=1781.50(4) Å³ and Z=4. Sn(C₆H₆Na₈O₂₄P₆) was found to be amorphous.     

Structural diversity of a series of chlorocadmate(II) and chlorocuprate(II) complexes based on benzylamine and its N-methylated derivatives

Protonated benzylamine and its N-methylated derivatives, [C₆H₅CH₂NH_3?n(CH₃)_n]⁺ (n?=?0?3), have been adopted as cations in chlorocadmate(II) and chlorocuprate(II) complexes, showing inorganic–organic hybrid architectures. For the Cd(II) compounds, the anionic structures vary from perovskite-type layers (n?=?0) to chains (n?=?1–3). For Cu(II) compounds, the anionic structures range from perovskite-type layers (n?=?0), chains (n?=?1) to mononuclear species (n?=?2–3). Coordination geometries of the metal ions and intermolecular interactions have been analyzed. Their dielectric properties have been measured.     

Crown ether complexes of tin(II) trifluoromethanesulfonate

The treatment of tin(II) trifluoromethanesulfonate with three differently-sized crown ethers [12]crown-4, [15]crown-5 and [18]crown-6 results in the formation of tin complexes that exhibit dramatically different structural features. The compounds are investigated using experimental techniques and density functional theory calculations.     

A novel tin (II) dithioether complex

Organotin and related tin containing compounds are a recurring motif in organometallic chemistry. Here we report a new complex resulting from the reaction of tin (II) chloride with a dithioether diallyl ether ligand created as a side product from other research in our lab. This new complex is reasonably stable and can be synthesized on the bench top with no extraordinary measures required to exclude air or moisture. Its crystal structure reveals a five coordinate pseudo-square pyramidal geometry around tin, with the ligand binding the metal through its thioether sulfurs and the chlorides bridging.     

Reactions of collman complex with tin(IV) and germanium(IV) porphyris,formation of [tin(II) and germanium(II) porphyrins] tetracarbonyliron and crystal structure of [2,3,7,8,12,13,17,18-octaethylporphinato tin(II)] tetracarbonyliron

The action of Na₂Fe(CO)₄ with tin(IV) and germanium(IV) porphyrins affords metal(II) porphyrin complexes [(por)M(II)Fe(CO)₄] (por = porphyrinate, M - Sn(II) or Ge(II)). The molecular structure of [(oep)Sn(II)Fe(CO)₄] was solved by X-ray diffraction techniques. The molecular structure of [(oep)Sn(II)Fe(CO)₄] was solved by X-ray diffraction techniques : the Sn coordination is square pyramidal with the iron in axial position (Sn-Fe = 2.492(1)Å) whereas the Fe coordination is trigonal bipyramidal. Mössbauer parameters provide convincing evidence for the formal zero oxidation state of the iron atom.     

Thermodynamics and vapor formation features of zinc(II) and tin(II) pivalates

Vapor formation of tin(II) and zinc(II) pivalates were studied using the Knudsen effusion method and mass spectrometry analysis of the gas phase. Sublimation of the tin complex is shown to be accompanied by polymerization of the condensed phase, changing its thermodynamic parameters. The vapor formation of zinc pivalate in the presence of trace amounts of water is accompanied by partial hydrolysis of the condensed phase and sublimation of the sample in the form of Zn₄O(piv)₆ and Zn₂piv₄. The absolute partial pressures and heats of sublimation of the components of the gas phase above tin and zinc complexes are calculated.     

Synthesis and characteristic studies of tin(II) and tin(IV) complexes of macrocyclic schiff bases

Equimolar reactions of tin (II) chloride, tin(IV) chloride or dimethyltin dichloride with macrocyclic Schiff bases lead to the formation of a new series of tin(II) and tin(IV) complexes. An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analysis, conductance measurements, molecular-weight determination, and electronic, IR and multinuclear magnetic resonance (¹H, ¹³C and ¹¹⁹Sn) spectral studies.     

Chlorobis(polyfluorophenyl)thallium(III) complexes and their reactions with gold(I) and tin(II) compounds

The reaction of TlCl₃ with RLi leads to complexes of the general formula TlR₂Cl (R = C₆F₅, p-C₆F₄H, m-C₆F₄H, 2,4,6-C₆F₃H₂, p-C₆FH₄ or m-CF₃C₆H₄). Some of these undergo oxidative addition reactions with gold(I) complexes to give polyfluorophenyl derivatives of the types AuR₂ClL and Au(C₆F₅)R₂(tht) (tht = tetrahydrothiophen), and with SnCl₂ to give oily materials from which stable solids of the general formula Q[SnR₂Cl₃] can be isolated by addition of QCl (Q = Et₄N or Ph₃BzP).     

A new series of dinucleating macrocyclic ligands and their complexes of zinc(II)

A new category of dinucleating macrocyclic Schiff base ligands with ring sizes from 34- to 52-membered have been synthesised employing metal template procedures involving the reaction of o-phenylenediamine with a series of α,ω-bis(3′-hydroxy-4′-formylphenyloxy)alkanes in the presence of calcium(II), barium(II) or manganese(II). The latter cations act as ‘transient’ templates for formation of the corresponding metal-free Schiff base macrocyclic ligands, H₄Lⁿ (where n signifies the number of carbons in each linking bis-alkoxy chain); the macrocycles corresponding to n = 4, 6 and 8 were isolated and characterised while, for n = 1, in which single methylene groups acts as the bridges between salicyl moieties, the cyclic product was used directly for preparation of its dinuclear complex, [Zn₂L¹], without prior isolation. Evidence for the templating role of barium in the preparation of H₄L⁶ and H₄L⁸ was obtained by isolation of the corresponding species of type H₄Lⁿ·2Ba(ClO₄)₂ (n = 6 or 8) as ‘intermediates’ before generation of the respective metal-free macrocycles. Reaction of zinc(II) acetate with the free macrocycles in methanol yielded complexes of type [Zn₂Lⁿ] in all cases. A related non-cyclic ligand, H₂L⁰ and its corresponding mononuclear complex, [ZnL⁰]·H₂O, were also synthesised and its spectral properties compared with those of the macrocyclic derivatives. The elemental analyses, ¹H NMR, IR, UV–Vis and MS spectra of the respective zinc complexes in each case were in accord with the formation of the expected 2:2 condensation product. The results of DFT calculations to probe aspects of the electronic and structural natures of both H₂L¹ and H₄L⁴ are briefly presented.     

Copper(II) complexes of thioether-substituted salcyen and salcyan derivatives and their silver(I) adducts

New syntheses are reported of 5-tert-butyl-2-hydroxy-3-methylsulfanylbenzaldehyde, 5-tert-butyl-2-hydroxy-3-phenylsulfanyl-benzaldehyde, and salcyen (H(2)L(1)-H(2)L(3)) and salcyan (H(2)L(4)-H(2)L(6))-type ligands derived from these aldehydes and from 5-tert-butyl-2-hydroxybenzaldehyde. The complexes [CuL](L(2-)=[L(1)](2-)-[L(6)](2-)) bearing sulfanyl substituents each show two distinct voltammetric ligand-based oxidations under the same conditions, the first of which is chemically reversible. The first oxidation product is much longer lived by coulometry for the salcyen than for the salcyan ligand complexes, despite the latter having a substantially lower oxidation potential. The lifetimes of all the ligand oxidation products in this system are substantially smaller than for similar compounds derived from 3,5-di(tert-butyl)-2-hydroxybenzaldehyde (Dalton Trans., 2004, 2662). Attempted chemical oxidation of the Schiff base compounds using AgBF(4) yielded instead stable silver(i) adducts. A crystal structure of one such compound showed that the Ag atom was coordinated in a slightly bent geometry by the two ligand sulfanyl groups, with two additional long-range Ag...O interactions to the phenoxide donors. EPR spectra showed that some of these silver adducts dimerise in CH(2)Cl(2), probably through basal, apical intermolecular Cu-O...Cu bridging. In contrast the parent copper(ii) complexes are all monomeric in this solvent by EPR.     

Rhodium(I) complexes with bidentate nitrogen heterocycles and their reactions with tin(II) chloride and carbon monoxide

Summary Cleavage of [{Rh(diolefin)Cl}₂] by bidentate heterocyclic chelating ligands (LL) has been studied, and diolefin neutral, ionic or ion-pair type compounds are formed depending on the ligands and/or the Rh: (LL) ratio employed. When the reactions are performed in media saturated with CO and with Rh: (LL)=21, only carbonylated ion-pair complexes are formed. The diolefin compounds react with tin(II) chloride yielding species containing trichlorostannato-groups. Subsequent reaction with CO leads to displacement of the diolefin and formation of the corresponding dicarbonyl species.     

Preparation of iron carbonyl complexes of germanium(II) and tin(II) each with a terminal fluorine atom

The reaction of β-diketiminate substituted germanium(II) and tin(II) fluorides (LGeF (1) and LSnF (2)) (L = CH{(CMe)₂(2,6-iPr₂C₆H₃N)₂}) with diiron nonacarbonyl, Fe₂(CO)₉ at room temperature, leads to the iron carbonyl complexes of germanium(II) LGeFFe(CO)₄ (3) and tin(II) LSnFFe(CO)₄ (4), respectively. Compounds 3 and 4 were characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Furthermore, both complexes (3 and 4) were investigated by X-ray structural analysis which shows that both compounds are monomeric in the solid state containing terminal fluorine atoms.     

Palladium(II) and platinum(II) dichloro complexes containing diamine-estrone derivatives

The preparation ofcis-dichloro Pt(II) andcis-dichloro Pd(II) complexes ofN-[3-hydroxyestra 1:3:5 (10)trien-17β]ethylendiamine,N-[3-hydroxyestra 1:3:5 (10)trien-17β]1,3-propylendiamine, andN-[3-hydroxyestra 1:3:5 (10)trien-17β]2-aminomethylpyridine is reported. The complexes have been characterized by chemical analysis, infrared spectroscopy and molar conductivity.