COMPLEXES OF Al(III) WITH HYDROXYAROMATIC LIGANDS

Abstract

In order to assess the aluminium binding ability of humic and fulvic acids, important organic soil constituents, a pH-potentiometric study was made of the proton and aluminium(III) complexes of various bi-, tri- and tetradentate catechol and salicylic acid derivatives at 25°C and at an ionic strength of 0.20moldm^?3 (KC1). The stability data revealed that at low pH the salicylate function, and at high pH the catecholate function, is preferentially bound to the aluminium ion. In the intermediate pH range, mixed hydroxo complexes and other di/oligomeric species are also formed. With an increase of the number of available coordinating sites in the molecule, the tendency to oligomeric complex formation increases, while the tendency to metal ion hydrolysis decreases.     

PREPARATION AND CHARACTERIZATION OF COBALT(III) COMPLEXES WITH SARCOSINE AND SOME TETRADENTATE LIGANDS OF THE EDDA TYPE

Abstract

Meridional geometrical isomers of cobalt(III) complexes with sarcosine (N-methylglycine) and tetradentate ligands edda (ethylenediamine-N,N′-diacetate ion), eddp (ethylenediamine-N,N′-di-3-propionate ion) and 1,3-pdda (1,3-propylenediamine-N,N′-diacetate ion) have been prepared. The edda and eddp cobalt(III) complexes were made by the reaction of sarcosine and sodium ethylenediamine-N,N′-diacetato(carbonato)cobaltate(III), and sodium uns-cis-(ethylenediamine-N,N′-di-3-propionato)(carbonato)cobaltate(III) dihydrate, respectively. The previously synthesized pdda-cobalt(III) complex with sarcosine was obtained by a new route by direct synthesis of cobalt(II) chloride hexahydrate with sarcosine and 1,3-pdda in the presents of lead(IV) oxide. Complexes were isolated chromatographically and characterized by elemental analysis, electron absorption spectra, infrared spectra and ¹H NMR spectroscopy.     

STUDIES OF THE STRUCTURE OF VANADIUM(III) COMPLEXES WITH NITROGEN CONTAINING LIGANDS IN ALCOHOLIC SOLUTIONS. I. COMPLEXES OF V(III) WITH AZOLES

Abstract

Anhydrous vanadium trichloride reacts with azoles in low concentrated ethyl alcohol solution of V(III) to produce 1:1 electrolytic complexes of the type [V (azole)₄Cl₂]⁺. Studies of the visible spectra of all the above complexes demonstrate that the vanadium(III) is octahedrally co-ordinated. The room temperature magnetic moments of the complexes (～ 2.8 B.M.) are consistant with the presence of two unpaired electrons per vanadium atom. At higher concn. of V(III) the polynuclear violet-red complexes probably are formed.     

SOLVATION OF ALUMINIUM(III) AND IRON(III) COMPLEXES OF HYDROXAMATE LIGANDS IN ALCOHOL-WATER MIXTURES

Abstract

Solubilities and derived transfer chemical potential trends are reported for several tris(hydroxamato)-aluminium(III) and iron(III) complexes in methanol-water and in t-butylalcohol-water solvent mixtures. These trends are discussed in terms of hydrophilic and hydrophobic characteristics of the peripheries of these complexes.     

以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)-Fe(Ⅲ)和Mn(Ⅱ)-Mn(Ⅱ)双核配合物的合成与磁性

基于铁和锰的双核配合物在生物氧化还原过程中的重要作用及在化学的氧化还原过程中可能做为催化剂的应用前景,本文合成了两个新的以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)双核和Mn(Ⅱ)双核配合物:[Fe_2(phen)_4(μ-CA)](ClO_4)_4·2H_2O(1)和[Mn_2(phen)_4(μ-CA)](ClO_4)_2·3H_2O(2)(phen=1,10菲咯啉;CA=氯醌酸二价阴离子)。经元素分析、IR、电子光谱及磁性等测定,对两配合物进行了表征。     

Supramolecular assemblies of two piperazine metal-organic bismuth(III) derivatives: a new precursor for the preparation of bismuth(III) oxide bromide nano-structures

Two BiBr₃ supramolecular complexes, [Bi(2-bpmp)Br_2.06Cl_0.94] (1) and [Bi(4-H₂bpmp)Br_4.29Cl_0.71]·H₂O (2) {2-bpmp = N,N′-bis(2-pyridylmethyl)piperazine and 4-bpmp = N,N′-bis(4-pyridylmethyl)piperazine}, were prepared by reaction of bismuth(III) chloride and potassium bromide with two nitrogen donor ligands under thermal gradient conditions using the branched tube method. Compounds 1 and 2 were structurally characterized by single-crystal X-ray diffraction. In monomeric 1, bismuth is coordinated by two pyridyl and piperazine nitrogens of 2-bpmp, and by three halides. Compound 2 is also monomeric but is bonded to only one pyridyl nitrogen. In both compounds, extensive hydrogen-bonding interactions lead to supramolecular networks; in 2, the hydrogen bonds are augmented by π–π stacking interactions. Thermal stabilities of both compounds were studied by thermal gravimetric and differential thermal analyses. Thermal decomposition of nanosized 1 and 2 in air produced BiOBr nanoparticles.     

STUDIES ON THE BACTERIAL ACTIVITY OF COBALT(III) COMPLEXES. PART III. COBALT(III) CARBOXYLATE COMPLEXES

Abstract

Cobalt(III) complexes of the type [Co(en)₂(chel)]X.nH₂O where en = ethylenediamine, chel = phthalato = C₆H₄CO₂)^2? ₂, maleato = (O₂CCH = CHCO₂)^2?, succinato = (O₂CCH₂CH₂CO₂)^2?, homophthalato = (O₂CC₆H₄(CH₂)CO₂)^2?, citraconato = (O₂CC(CH₃) = CHCO₂)^2?, itaconato = (CH₂ = C(CO₂)CH₂CO₂)^2?, X = NO^? ₃, Br^?, (O₂CC₆H₄CO₂H)^?, (O₂CHC = CHCO₂H)^?, (O₂C(CH₂)₂CO₂H)^?, (O₂CC₆H₄(CH₂)CO₂H)^?, (O₂CHC = C(CH₂)-CO₂H)^?, and (O₂C-CH₂?C(= CH₂)-CO₂H)^?, [Co(en)₂(malonato)]X.2H₂O (where malonato = (O₂CCH₂CO₂)^2?, X = Cl^?, Br^?, and NO^? ₃) and [Co(en)₂CO₃]Cl.2H₂O have been investigated for their bacterial activity against Escherichia coli B growing on EMB agar and in minimal glucose media both in lag and log phases. Among the most active are where chel = phthalato and homophthalato. The effects are distinct from those known for compounds of Pt, e.g., cis?[Pt(NH₃)₂Cl₂] and rhodium, e.g., trans?[Rh(C₅H₅N)₄,Cl₂].6H₂O. Antagonisms are reported.     

ESR SPECTRA OF THE SQUARE PLANAR COPPER(II) COMPLEXES WITH VARIOUS N4-MACROCYCLIC LIGANDS

Abstract

The ESR parameters were determined for copper(II) complexes with various 14-, 15- and 16-membered N₄-macrocyclic ligands. Of these ESR parameters g^‖ has the most simple relation to the covalency of the coordination bonds in the present compounds, i.e., the smaller the g^‖ value the larger the covalency. The order of covalencies derived from the g^‖ values nicely matches with that supposed from the size of macrocyclic rings and the charge of the ligands. The approach to the estimation of covalency of the coordination bonds by use of copper hyperfine coupling constant was examined, but it was found that this approach gives rather unreliable results for the present compounds.     

BINUCLEAR COMPLEXES OF IRON(III) WITH SALICYLATE LIGANDS

Abstract

Binuclear iron(III) complexes with salicylate ligands, Na₂ [Fe₂ (C₇ H₄ O₃)₄ (H₂O)₂] and Na₄ [Fe₂ (C₇H₄O₃)₄ (OH)₂], crystallize out in the pH range 1–5 and pH 5.5, respectively, from solutions containing iron(III) chloride and a slightly more than two molar proportion of sodium salicylate. Infrared and Mössbauer spectral results and magnetic moment data indicate the presence of non-linear Fe—O—Fe bridge bonds. Evidently two salicylate ligands form bridges between the two iron(III) ions through phenolic oxygen. Mössbauer spectral results indicate the absence of bridging salicylate ligands in solutions of the complex prepared by mixing iron(III) chloride and two to three-fold molar excess of salicylate ions; only mononuclear complexes exist in such solutions.     

COMPLEXES OF BINUCLEATING LIGANDS. XIII. SOLUBLE COMPLEXES OF A LIGAND WITH A BRIDGING THIOPHENOXIDE COMPONENT AND PERIPHERAL n-OCTYL SUBSTITUENTS

Abstract

The trianionic binucleating ligands formally derived from the condensation products of S-n-octyldithiocarbazate with either 2-hydroxy- or 2-mercapto-5-methylisophthalaldehyde (hereafter (L″)^3- and L^3- respectively) gave the binuclear complexes L″Ni₂ (CH₃ O), L″Ni₂ (C₆ H₅ CH₂ O), LNi₂ (C₃ H₃ N₂), LCu₂ (C₃ H₃ N₂) and LNi₂ (SR) where R=C₈H_{1 7} of CH₃.C₆ H₄ and C₃ H₃ N₂ ^?=the pyrazolate anion. These complexes were soluble in chloroform and ¹H n.m.r. data for some of them are presented. There was no evidence for significant magnetic exchange within LCu₂ (C₃ H₃ N₂). Attempts to generate LNi₂ (X) where X^?=Cl^?, Br^? or I^? gave L₂ Ni₃ in which L^3- fails to impose the intended molecular arrangement. Attempts to generate L(Pd(II))₂ (X) unexpectedly gave materials containing additional palladium, i.e. LPd₄ (CH₃ CO₂) and LPd₄ (C₃ H₃ N₂).     

VANADIUM(III) AND VANADIUM(IV) COMPLEXES WITH PYRAZINE IN ALCOHOL SOLUTION

Abstract

The V(III)-pyrazine system was examined spectroscopically in the isoamyl alcohol solution. An unstable, violet-red, binuclear vanadium(III) complex [V₂(pyraz)Cl₄]²⁺ was found to be formed. On exposure to air it was slowly converted into a sparingly soluble green vanadium(IV) compound, [VO(pyraz)OH]Cl.H₂O. This compound was examined by the analytical, spectroscopic (electronic and infra-red spectra) and magnetic methods.     

SYNTHESIS AND CHARACTERIZATION OF TRIS(ALKYLISOCYANIDE) BIS(TRIARYL-PHOSPHINE)COBALT(II) COMPLEXES

Abstract

A series of complexes having the general formula, [Co(CNR)₃(PR₃)₂]X₂, X = ClO₄, BF₄ with CNR = CNCMe₃, CNCHMe₂, CNC₆H₁₁. CNCH₂Ph and PR₃ = PPh₃, P(C₆H₄Me-p)₃, P(C₆H₄OMe-p)₃ has been synthesized and characterized. Synthesis can be achieved by reaction of [Co(CNR)₄(AsPh₃)₂]X₂ complexes with controlled excess of PR₃ ligands, and by AgClO₄/AgBF₄ oxidation of the [Co(CNR)₃(PR₃)₂]X complexes. The latter procedure is preferable. Alternate syntheses of the [Co(CNR)₃(PR₃)₂]X complexes have also been employed. Five-coordinate Co(II) complexes have not been obtained using CNCMe₃ with P(C₆H₄Me-p)₃ ligands, CNCH₂Ph with P(C₆H₄OMe-p)₃ ligands, or CNC₄H_9-n with PPh₃ ligands. [Co(CNC-Me₃)₃{P(C₆H₄Cl-p)₃}₂]ClO₄ produced only [Co{CNCMe₃)₄H₂O](ClO₄)₂ upon forced oxidation with excess AgClO₄. [Co(CNR)₃(PR₃)₂]X₂ complexes appear to undergo varying degrees of distortion from regular (i.e., D _3h symmetry) axially-disubstituted trigonal bipyramidal coordination in the solid state, as evidenced by v(-N°C) IR patterns, but to assume regular trigonal bipyramidal coordination in solution. Effective magnetic moments indicate one-electron paramagnetism, and solution electronic spectra are compatible with trigonal bipyramidal coordination.     

Preparation and molecular structures of N,N-2,2′-dipicolyl- and N,N-3,3′-dipicolyldithiocarbamato metal complexes

New iron(III) and cobalt(III) complexes, [Fe(2,2′-dpdtc)₃], [Fe(3,3′-dpdtc)₃], [Co(2,2′-dpdtc)₃], and [Co(3,3′-dpdtc)₃] (dpdtc?=?dipicolyldithiocarbamate) have been synthesized and their molecular structures and spectroscopic properties determined. The 2,2′- and 3,3′-dpdtc ligands have four donors, S, S′, N, and N′. These complexes are insoluble in water, but soluble in acidic solution. Crystal structures of these metal complexes reveal that the central metal ions have MS₆ (M?=?Fe and Co) octahedral structures and all dipicolyl groups do not coordinate.     

Thermogravimetric and spectroscopic studies on La(III) and Ce(III) complexes with some thio-schiff bases

Solid complexes of five derivatives of thio-Schiff bases with La(III) and Ce(III) ions were prepared and characterized by elemental and thermogravimetric analyses. The suggested general formula of the solid complexes is [ML₂(H₂O)X]·2H₂O, whereM=trivalent lanthanide ion,L=Schiff base andX=Cl^? or ClO ₄ ^? . Information about the water of hydration, the coordinated water molecules, the coordination chemistry and the thermal stability of these complexes was obtained and is discussed. Additionally, a general scheme of thermal decomposition of the lanthanide-Schiff base complexes is proposed.     

SYNTHESIS OF MONOSUBSTITUTED PENTAKIS(2,6-DIETHYLPHENYLISO-CYANIDE)COBALT(I) COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE LIGANDS. II. BIMETALLIC COMPLEXES

Abstract

Reaction of bidentate tertiary phosphines with excess [Co(CNR)₅]BF₄, or reaction of [Co(CNR)₄L-L]BF₄ with excess [Co(CNR)₅]BF₄, leads to bimetallic complexes of the form, [(RNC)₄CoL-LCo(CNR)₄](BF₄)₂, R = 2,6-Et₂C₆H₃, L-L = p-Ph₂PC₆H₄PPh₂, Ph₂PC═CPPh₂, Me₂PCH₂CH₂PMe₂, Ph₂PCH₂CH₂PPh₂, Ph₂PCH₂CH₂CH₂PPh₂. Comparison of the v(? N═C) IR patterns, electronic spectra, and molar conductivity values of these bimetallic complexes with data for other Co(I)-organoisocyanide complexes indicates that the two -Co(CNR)₄ moieties are almost totally independent of each other. Recorded λ_max values are the same as for the [Co(CNR)₄L-L]BF₄ complexes, but the ε values, although very large, are less than double. Λ_M values in acetone, and probably also in CH₂Cl₂, are better interpreted as twice the normal conductivity for 1:1 electrolytes than conductivity for 2:1 electrolytes.     

若干锰(Ⅲ)希夫碱配合物的合成和表征

合成了六种锰(Ⅲ)希夫碱配合物:Mn(bzacem)X(X~-=Cl~-,Br~-,I~-,NCS~-,NO_2~-)和Mn(bzacen)ClO_4·2H_2O,其中bzacen~(2-)为N,N′-二(苯甲酰丙酮缩)-乙二胺阴离子.用NMR法测定配合物在DMSO溶液中的有效磁矩值为4.46—4.63,表明为高自旋配合物,将电子光谱中的吸收带分别按配位场带、荷移带和配体带进行了归属,在配合物的红外光谱中,原配体H_2bzacen中的ν_(N-H)带消失,ν_(C-O)带移向低频,并对Mn-O、Mn-N和Mn-X的伸缩带进行了归属。     

VANADYL(IV) COMPLEXES OF SULFUR-CONTAINING LIGANDS WITH BIOLOGICAL AND PHARMACOLOGICAL RELEVANCE

Abstract

The behavior of thiosalicylic acid (H₂TSA) and 6-mercaptopurine (MP) with vanadyl(IV) cation has been studied in solution at different ligand-to-metal ratios and pH values. The preparation and characterization of VO/TSA(I) and VO/MP(II) complexes in the solid state is reported. The chemical environment of V in (I) is consistent with S and O atoms of TSA and two hydroxy bridges between two metal centers. The nearest neighbor atoms to V in (II) are S and N provided by the ligand and O atoms from hydroxyl groups. These results have been supported by physicochemical studies.     

SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF CYCLOPENTADIENYLIRON(II) COMPLEXES WITH BIS(DIPHENYLPHOSPHINO)AMINE AS LIGAND

Abstract

The synthesis and properties of new cationic iron(II) complexes of general formula [(η⁵-C₅H₅)FeL(η²-dppa)]A [A=I^?, L = CO(1); A = BF₄, L = CO(2) CH₃CN(4), η¹-dppa(5); dppa = NH(PPh₂)₂] are described. The carbonyl complex [(η⁵-C₅H₅)Fe(CO)(η²-dppa)]BF₄ is deprotonated to give the neutral complex [(η⁵-C₅H₅)Fe(CO){η²-(PPh₂)₂N}](3). All complexes have been characterized by elemental analysis and IR and NMR spectroscopies. Cyclic voltammetry of complexes 1–5 shows a diverse redox chemistry in acetonitrile solution. While the reduction of 1 and 2 leads to the formation of a dinuclear Fe(I) complex, 4 and 5 form mononuclear species of Fe(I); oxidation of metal centers of 1 and 2 is not observed and in complexes 3 and 4 the metal centers are oxidized at potentials < 1. Complex 5 in acetonitrile solution is transformed into complex 4.     

Conductance behavior of some tris(ethylenediamine)cobalt(III) complexes and their ion association in aqueous solutions

The conductance behavior of some tris(ethylenediamine)cobalt(III) complexes was studied in dilute aqueous solutions at 25°C to investigate the ion-pair formation. The thermodynamic formation constants of the ion pairs [Co(en)₃]³⁺·X^– are 28 (chloride), 28 (bromide), 19 (nitrate), and 15 (perchlorate). These values were compared with theoretical values calculated by using Bjerrum's theory of ion association. The formation constant of [Co(en)₃]³⁺·Cl^– was larger than that obtained from the spectrophotometric measurement in solutions containing perchlorate ion. This difference in the formation constants was explained by considering the contribution of ion association of the complex cation with perchlorate ion.     

SYNTHESIS OF MONOSUBSTITUTED PENTAKIS(2,6-DIETHYLPHENYLISO CYANIDE)- COBALT(I) COMPLEXES WITH BIDENTATE TERTIARY PHOSPHINE LIGANDS. I. MONOMETALLIC COMPLEXES

Abstract

Reaction of [Co(CNC₆H₃Et₂-2,6)5]BF₄ with bidentate phosphines leads to monosubstituted Co(I) complexes, [Co(CNC₆H₃Et₂-2,6)₄(L-L)]BF4, where L-L = Ph₂P(CH₂)n PPh₂, n = 1-4,6; Ph₂PCH₂-CH₂AsPh₂, Ph₂PC₆H₄PPh₂-p, Ph₂PCH[dbnd]CHPPh₂-trans. Reaction conditions are such that disubstitution would be possible, but bidentate bridging to form bimetallic complexes is not favoured. Comparison of v([sbnd]N°C) IR, electronic spectra, and molar conductivities with values for [Co(CNC₆H₃Et₂-2,6)4L]X, where X = ClO₄, BF₄; L = monodentate triarylphosphine; indicates that these new complexes must also be five-coordinate Co(I) complexes, in which the potentially bidentate phosphine ligands are coordinated through only one P atom. Structures are approximately trigonal bipyramidal in solution and the solid state, with the phosphine ligand occupying an axial position.