New cobalt(II) complexes with cyanuric acid

New cobalt(II) complexes with cyanuric acid C₃H₃N₃O₃ (L), namely, [CoL₂(OH₂)₂]Cl₂ · 4H₂O, [CoL₂(OH₂)₂]SO₄ · 3H₂O, and [CoL₂(OH₂)₂](NO₃)₂, were synthesized. The IR absorption spectra (400–4000 cm^?1) of these compounds and the initial ligand, their X-ray diffraction patterns, thermograms, and thermogravigrams were examined. The electric conductivity of their aqueous and methanolic solutions was studied. The individual character of the synthesized complexes was proved. The coordination mode of the acido groups was determined.     

Cobalt(II) complexes with hydantoin

Complexes of Co(II) with hydantoin (L, C₃H₄N₂O₂) have been synthesized. The complexes had the following compositions: [CoL₂(OH₂)₂](NO₃)₂ · 2H₂O, [CoL₂(OH₂)₂]Cl₂ · 3H₂O, and [CoL₂(OH₂)₂]SO₄ · 2H₂O. The individual character of the synthesized compounds are proved by the study of the IR absorption spectra (400–4000 cm^?1) of all the compounds and the initial ligand, as well as the X-ray diffraction patterns, thermograms, and thermogravigrams of the synthesized compounds. The coordination modes of the ligand and acido groups are revealed. The properties of the synthesized compounds are characterized.     

Synthesis, characterization and electro-spectroelectrochemical studies of four macrocyclic Schiff-base Co(II) complexes having N2O2 set of donor atoms

Four macrocyclic Schiff-base cobalt complexes, [CoL¹][NO₃]₂ · 3H₂O, [CoL²][NO₃]₂ · 4H₂O, [CoL³][NO₃]₂ · 4H₂O and [CoL⁴][NO₃]₂ · 2H₂O, were synthesized by reaction of salicylaldehyde derivatives with 1,4-bis(3-aminopropoxy)butane or (±)-trans-1,2-diaminocyclohexane and Co(NO₃)₂ · 6H₂O by template effect in methanol. The metals to ligand ratio of the complexes were found to be 1:1. The Co(II) complexes are proposed to be tetrahedral geometry. The macrocyclic Co(II) complexes are 1:2 electrolytes as shown by their molar conductivities (Λ_M) in DMF (dimethyl formamide) at 10^?3 M. The structure of Co(II) complexes is proposed from elemental analysis, Ft-IR, UV–visible spectra, magnetic susceptibility, molar conductivity measurements and mass spectra. Electrochemical and thin-layer spectroelectrochemical studies of the complexes were comparatively studied in the same experimental conditions. The electrochemical results revealed that all complexes displayed irreversible one reduction processes and their cathodic peak potential values (E _pc) were observed in around of ?1.14 to 0.95 V. It was also seen that [CoL¹][NO₃]₂ · 3H₂O and [CoL²][NO₃]₂ · 4H₂O exhibited one cathodic wave without corresponding anodic wave but, [CoL³][NO₃]₂ · 4H₂O and [CoL⁴][NO₃]₂ · 2H₂O showed one cathodic wave with corresponding anodic wave, probably due to the presence of different ligand nature even if the complexes have the same N₂O₂ donor set. In view of spectroelectrochemical studies [CoL³][NO₃]₂ · 4H₂O showed distinctive spectral changes in which the intensity of the band (λ = at 316 nm, assigned to n → π* transitions) decreased and a new broad band in a low intensity about 391 nm appeared as a result of the reduction process based on the cobalt center in the complex.     

2,4′-Bipyridyl complexes with cobalt(II) and nickel(II)

Summary Complexes of empirical formulae [ML₂Cl₂(OH₂)₂], [CoL₂Br₂(OH₂)₂]L·4H₂O, [NiL₂Br₂(OH₂)₂]L₂·2H₂O, [ML₂(OH₂)₄]L₂(NO₃)₂ and [ML₄(OH₂)₂](ClO₄)₂·2H₂O (M = Co^II, Ni^II, L = 2,4-bipyridyl) were synthesized and characterized by elemental and spectral analyses. The thermal decomposition of the complexes was also investigated.Author to whom all correspondence should be directed.     

Thermal behaviour of new Cu(II) complexes with Schiff bases functionalised with 1,3,5-triazine moieties as potential antibacterial agents

New complexes of type [Cu(L¹)₂(OH₂)]·4H₂O (1), [Cu(L²)(OH₂)]·0.5H₂O (2) and [Cu₃(L³)₂(OH₂)₃]·0.5H₂O (3) were synthesized by [1 + 1], [1 + 2] and [1 + 3], respectively, template condensation of 2,4,6-triamino-1,3,5-triazine and salicylic aldehyde in the presence of copper(II). The features of complexes have been established from microanalytical, IR and UV–Vis data. The thermal analyses have evidenced the thermal intervals of stability and also the accompanying thermodynamic effects. Processes as water elimination and oxidative degradation of the organic ligands were observed. After water elimination, complexes revealed a similar thermal behaviour. The final product of decomposition was copper(II) oxide as powder X-ray diffraction indicated.     

Water‐soluble and Halogen‐free Hexaammine Complexes of Metal Ions of Group 9 – Synthesis,Crystal Structures,and Vibrational Spectra

Reaction of [M(NH₃)₆]Cl₃ (M = Co, Rh, Ir) and [Ir(NH₃)₅(OH₂)]Cl₃ with (NH₄)₂C₂O₄ · H₂O in aqueous solution resulted in the isolation of [M(NH₃)₆]₂(C₂O₄)₃ · 4 H₂O and [Ir(NH₃)₅(OH₂)]₂(C₂O₄)₃ · 4 H₂O, respectively. The complexes have been characterized by X‐ray crystallography, IR and UV/VIS spectroscopy. The isomorphous compounds crystallize in the orthorhombic space group Pnnm (No. 58). Four molecules of crystal water are involved in an extended three‐dimensional hydrogen bonding network. The librational modes of the lattice water around 600 cm^–1 allow the characterization of [Ir(NH₃)₆]₂(C₂O₄)₃ · 4 H₂O and [Ir(NH₃)₅(OH₂)]₂(C₂O₄)₃ · 4 H₂O, respectively, by IR spectroscopy. The band around 600 cm^–1 shows a significant frequency shift in the IR spectra of the hexaammine and aquapentaammine complex of iridium(III) and, by that, a distinction is possible.     

Zum Komplexbildungsverhalten der 5,6-Dihalogen-7-oxa-bicyclo[2.2.1]heptan-2,3-dicarbonsäure gegenüber 3d-Übergangsmetallen

Complex Formation of 5,6-Dihalogeno-7-oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic Acid with 3d Transition Elements Carboxylate complexes of bivalent manganese, cobalt, nickel and copper with 5,6-dichloro- and 5,6-dibromo-7-oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic acid ( 3 and 4 ) have been prepared. For cobalt and nickel two types of complexes are formed: [ML^3/4(H₂O)₃] · H₂O and [ML^3/4(H₂O)₂], the latter is thermodynamically more stable. Manganese and copper form only complexes [MnL^3/4] and [CuL^3/4(H₂O)₂], respectively. The stereochemical configuration of the compounds have been deduced from their spectroscopic and magnetic properties. The metal atoms have been found to be in an octahedral environment. The stability constants of the complexes have been determined by potentiometric measurements. The thermal decomposition of the complexes has been studied by thermogravimetry and differential thermal analysis. The complexes of 3 are thermally more stable than the corresponding ones of 4 . The X-ray structure analysis of [CoL³(H₂O)₃] · H₂O shows a monomeric structure of the complex within the crystal and an octahedral coordination of the metal ion. The dicarboxylate anion acts as a tridentate ligand, the other octahedral sites are occupied by three water molecules. The chlorine atoms are not involved in the network of hydrogen bonds within the crystal packing.     

The role of water molecules in formation of heterometallic palladium acetate complexes with cerium and neodymium

The reactions of palladium(II) acetate with neodymium(III) and cerium(III) acetates in acetic acid containing a specified amount of water have been studied. The following homo- and heterometallic complexes have been synthesized and characterized by X-ray diffraction: Nd₂(μ-OOCMe)₂(μ,η²-OOCMe)₂(η²-OOCMe)₂(HOOCMe)₂(OH₂)₂ · 4HOOCMe, [Pd(μ-OOCMe)₄Ce(OH₂)₂(μ,η²-OOCMe)]₂ · 2HOOCMe · 6H₂O, [Pd(μ-OOCMe)₄Ce(OH₂)₂(μ,η²-OOCMe)]₂ · 14H₂O, [Pd(μ-OOCMe)₄M(HOOCMe)₂(OH₂)₂]⁺ [Pd(μ-OOCMe)₄M(μ-OOCMe)₄Pd]⁻ · 2MeCOOH · 1.5H₂O (M = Nd, Ce), and {[Pd(μ-OOCMe)₄Ce(OOCMe)₄]₂ [Pd₄(μ-OOCMe)₄]₂(μ₄-O)₈CePd₄}(OH)₃ · 27H₂O. From kinetic and structural data and optical spectra of reaction solutions, the conclusion was drawn that hydrolytic processes play a decisive role in complexation reactions.     

Two Light-Metal Dihydrogenisocyanurate Hydrates Linked by Diagonal Relationship: Syntheses,Crystal Structures,and Vibrational Spectra of Li[H2N3C3O3]·1.75 H2O and Mg[H2N3C3O3]2·8 H2O

Single-crystalline materials of Li[H₂N₃C₃O₃] · 1.75 H₂O and Mg[H₂N₃C₃O₃]₂ · 8 H₂O were obtained by dissolving stoichiometric amounts of the respective carbonates with cyanuric acid in boiling water followed by gentle evaporation of excess water after cooling to room temperature. Even though both of these compounds crystallize in the triclinic space group P1 according to X-ray structure analyses of their colorless and transparent single crystals, they adopt two new different structure types. Li[H₂N₃C₃O₃] · 1.75 H₂O exhibits the unit-cell parameters a = 884.71(6) pm, b = 905.12(7) pm, c = 964.38(7) pm, α = 67.847(2)°, β = 62.904(2)° and γ = 68.565(2)° (Z = 4), whereas the lattice parameters for Mg[H₂N₃C₃O₃]₂ · 8 H₂O are a = 691.95(5) pm, b = 1055.06(8) pm, c = 1183.87(9) pm, α = 85.652(2)°, β = 83.439(2)° and γ = 79.814(2)° (Z = 2). In both cases, the singly deprotonated isocyanuric acid forms monovalent anions consisting of cyclic [H₂N₃C₃O₃]^– units, which are arranged in ribbons typical for most hitherto known monobasic isocyanurate hydrates. The structures are governed by the oxophilic strength of the respective cation which means that they fulfil their oxophilic coordination requirements either solely with water molecules ([Mg(OH₂)₆]²⁺ for Mg²⁺) or with crystal water and one or two direct coordinative contacts to carbonyl oxygen atoms (O_(cy)) of [H₂N₃C₃O₃]^– anions ([(Li(OH₂)_2–3(O_(cy)1–2]⁺ for Li⁺). In both structures occur dominant hydrogen bonds N–H ··· O within the anionic [H₂N₃C₃O₃]^– ribbons as well as hydrogen bonds O–H ··· O between these ribbons and the hydrated Li⁺ and Mg²⁺ cations.     

Air-stable μ2-hydroxyl bridged cationic binuclear complexes of zirconocene perfluorooctanesulfonates: their structures,characterization and application

Three air-stable zirconocene perfluoro-octanesulfonates were successfully synthesized by treatment of C₈F₁₇SO₃Ag with (RCp)₂ZrCl₂ [R?=?H, n-Bu, t-Bu]. According to X-ray analysis, they have μ²-hydroxyl bridged cationic binuclear structures: (i) [CpZr(OH₂)₃]₂(μ²-OH)₂(OSO₂C₈F₁₇)₄·2THF·4H₂O (1a·2THF·4H₂O), (ii) [n-BuCpZr(OH₂)₃]₂(μ²-OH)₂(OSO₂C₈F₁₇)₄·6H₂O (2a·6H₂O), and (iii) [t-BuCpZr(OH₂)₃]₂(μ²-OH)₂(OSO₂C₈F₁₇)₄·2C₃H₆O·8H₂O (3a·2C₃H₆O·8H₂O). The ligands of water and organic molecules in the complexes originated from the moist air and solvent during their recrystallization. These complexes were characterized with different techniques, and found to show water tolerance, air/thermal stability as well as strong Lewis acidity. Moreover, the complexes showed highly catalytic activity in various reactions of CC bond formation. With good recyclability, they should find wide applications in organic chemistry.     

Mononuclear and binuclear lanthanide(III) complexes: syntheses,structural, photophysical and thermal properties

Six new Ln(III) complexes viz., [Gd(tptz)(SCN)₃(CH₃OH)₂OH₂]·CH₃OH (1), [Eu(tptz)(SCN)₃(CH₃OH)₂OH₂]·CH₃OH (2), [Tb(tptz)(SCN)₃(OH₂)₃]₄ (3), [Gd(tptz)(OBz)₂(μ-OBz)OH₂]₂·2H₂O (4), [OH₂(OBz)₂(tptz)Eu₁(μ-OBz)₂Eu₂(tptz)(OBz)₂OH₂]·CH₃OH·7H₂O (5), and {[Tb₁(tptz)(OBz)₂(μ-OBz)]₂·[Tb₂(tptz)(OBz)₃CH₃OH]₂}·2CH₃OH·4H₂O (6) (Ln = Gd, Eu, Tb; tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine; BzONa = sodium benzoate), have been synthesized and characterized by physicochemical methods including single-crystal X-ray crystallography. The X-ray studies demonstrate that 1–3 are mononuclear, whereas 4–6 are binuclear. The photophysical properties of 1–6 have been studied with ultraviolet absorption and emission spectral studies. Their thermal properties have been studied by thermogravimetric (TG) and derivative thermogravimetric analysis (DTG), demonstrating that the final product after decomposition was Ln₂O₃ for all these complexes.     

Polynuclear rhodium complexes of phenothiazines: synthesis and characterization

Polynuclear complexes of RH^II and RH^III with fiveN-alkylphenothiazines as principal ligands have been prepared. The complexes were characterized by their elemental analyses, molar conductivities, and spectral data. The molecular formulae of the new complexes are as follows: [Rh₃(PTZ)₂(OH₂)₂Cl₈]Cl, where PTZ=chlorpromazine or promethazine; [Rh₃(EP)₂(OH₂)₂Cl₈][Rh(OH₂)₂Cl₄], where EP=ethopropazine; [Rh₄(TF)₂(OH₂)₅Cl₉]Cl·H₂O, where TF=trifluoperazine; and [Rh₂(TC)₃(OH₂)Cl₆]. H₂O, where TC=2-chlorophenothiazine. A tentative structure for each of the complexes is proposed. TMC 2627     

Ten complexes constructed by two reduced Schiff base tetraazamacrocycle ligands: syntheses,structures, magnetic and luminescent properties

Ten new complexes, [Cu₂(L¹)(NO₃)₂]·2H₂O (1), [Cu₄(L¹)₂]·4ClO₄·H₂O (2), [Cu₂(L¹)(H₂O)₂]·(adipate) (3), [Cu₆(L¹)₂(m-bdc)₄]·2DMF·5H₂O (4), [Cu₂(L¹)(Hbtc)]·5H₂O (5), [Cu₂(L¹)(H₂O)₂]·(ntc)·3H₂O (6), [Co₂(L²)]·[Co(MeOH)₄(H₂O)₂] (7), [Co₃(L²)(EtOH)(H₂O)] (8), [Ni₆(L²)₂(H₂O)₄]·H₂O (9) and [Zn₄(L²)(OAc)₂]·0.5H₂O (10), have been synthesized. 1 displays a [Cu₂(L¹)(NO₃)₂] monomolecular structure. 2 shows a supramolecular chain including [Cu₂L¹]²⁺. In 3, two Cu(II) ions are connected by L¹ to form a [Cu₂(L¹)(H₂O)₂]²⁺ cation. In 4, the m-bdc anions bridge Cu(II) ions and L¹ anions to form a layer. Both 5 and 6 display 3-D supramolecular structures. 7 consists of both [Co₂L²]^2? and [Co(MeOH)₄(H₂O)₂]²⁺ units. 8 and 9 show infinite chain structures. In 10, Zn(II) dimers are linked by L² to generate a 3-D framework. The magnetic properties for 4 and 8 and the luminescent property for 10 have been studied.     

Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Four Cu^II and Co^II complexes–[Cu(L₁)Cl₂(H₂O)]3/2H₂O · 1/2EtOH, [Cu(L₁)₂Cl₂]6H₂O, [Co(L₁)Cl₂]3H₂O · EtOH, and [Co₂(L₁)(H₂O)Cl₄]1.5H₂O · EtOH (L₁ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L₁)I₂(H₂O)]6H₂O, [Cu(L₁)₂I₂]6H₂O, [Co(L₁)I(H₂O)₂]I · 2H₂O, and [Co₂(L₁)I₄(H₂O)₃]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for Cu^II or oxidation of Co^II. Oxidation of Co^II to Co^III complexes was only observed on the dissolution of Co^II complexes in d₆-DMSO in air while warming. The isolated solid complexes (Cu^II and Co^II) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, ¹H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML₂ complexes. In binuclear complexes, L is tridentate toward one Co^II and bidentate toward the second Co^II in [Co₂(L₁)Cl₄]2.5H₂O · EtOH and [Co₂(L₁)I₄(H₂O)₃]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around Cu^II and high-spin octahedral and square-pyramidal geometry around Co^II.     

Synthesis,spectroscopic, and thermal analyses of trinuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with some sulfa derivatives

New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, ¹H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and ¹H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn₂L¹(AcO)₂(H₂O)₆] (1), [Co₂(L¹)₂(H₂O)₈] (2), [Ni₂L¹(AcO)₂(H₂O)₆] (3), [Mn₃L²(AcO)₃(H₂O)₉] (5), [Co₃L²(AcO)₃(H₂O)₉] · 4H₂O (6), [Ni₃L²(AcO)₃(H₂O)₉] · 7H₂O (7), [Mn₃L³(AcO)₃(H₂O)₆] (9), [Co₂(HL³)₂(H₂O)₈] · 4H₂O (10), [Ni₃L³(AcO)₃(H₂O)₉] (11), [Mn₃L⁴(AcO)₃(H₂O)₉] · H₂O (13), [Co₂(HL⁴)₂(H₂O)₈] · 5H₂O (14), and [Ni₃L⁴(AcO)₃(H₂O)₉] (15) while [Zn₂L¹(AcO)₂(H₂O)₂] (4), [Zn₃L²(AcO)₃(H₂O)₃] · 2H₂O (8), [Zn₃L³(AcO)₃(H₂O)₃] · 3H₂O (12), and [Zn₃L⁴(AcO)₃(H₂O)₃] · 2H₂O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]⁺ and fragments supporting the formulation.     

Interaction of uranyl monoaquadiformate with diaza-18-crown-6 in aqueous ethanol

The reaction of {[UO₂(HCOO)₂(H₂O)]} with diaza-18-crown-6 (DA18C6 = C₁₂H₂₆O₄N₂) in aqueous ethanol in the presence of formic acid yields the complexes {[DA18C6H₂]·[UO₂(HCOO)₃]₂} (I), [DA18C6H₂]·[UO₂(HCOO)₄] (II), and [DA18C6H₂]·(HCOO)₂·(H₂O)₂ (III). The complexes are characterized using IR spectroscopy, chemical analysis, and powder X-ray diffraction. From the comparison of the structural and spectral characteristics of [DA18C6H₂]·An₂·(H₂O)_2n (where An = Cl^?,NO ₃ ^? ,HCOO^?,HSO ₄ ^? ; n = 0.1), correlations are derived between the conformation of the [DA18C6H₂]²⁺ units and the conformation-sensitive frequencies. On the basis of these correlations, the conformations of the N⁺CCO and OCCO units were determined in the diazonia cations of compounds I and II and in [DA18C6H₂]·[UO₂(NO₃)₄]; the latter was prepared previously by reacting [UO₂(NO₃)₂(H₂O)₂]·(H₂O)₄ with DA18C6 in ethanol in the presence of nitric acid.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Synthesis and characterization of a new pyrrolidine containing sulfur ligand and the transition metal complexes of Co(II), Ni(II) and Cu(I)

Potassium 1,3-dipyrrolidinopropan-2-O-xanthate (LK), and its complexes with Co(II), Ni(II) and Cu(I) have been prepared and characterized as [CoL₂(H₂O)₂]?·?2H₂O, [NiL₂(H₂O)₂] and CuL?·?2H₂O by FT-IR, ¹H and ¹³C NMR spectroscopies, elemental analyses, magnetic susceptibility and TGA techniques.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.