Ammonium bis(salicylaldehyde thiosemicarbazonato)ferrate(III), a supramolecular material containing low‐spin FeIII

The synthesis and crystal structure (100 K) of the title compound, ammonium bis[salicylaldehyde thiosemicarbazonato(2?)‐κ³O,N¹,S]iron(III), NH₄[Fe(C₈H₇N₃OS)₂], is reported. The asymmetric unit consists of an octahedral [Fe^III(thsa)₂]^? fragment, where thsa^2? is salicylaldehyde thiosemicarbazonate(2?), and an NH₄⁺ cation. Each thsa^2? ligand binds via the thiolate S, the imine N and the phenolate O donor atoms, resulting in an Fe^IIIS₂N₂O₂ chromophore. The ligands are orientated in two perpendicular planes, with the O and S atoms in cis and the N atoms in trans positions. The Fe^III ion is in the low‐spin state at 100 K. The crystal structure belongs to a category I order–disorder (OD) family. It is a polytype of a maximum degree of order (MDO). Fragments of the second MDO polytype lead to systematic twinning by pseudomerohedry.     

Synthesis,characterization, thermogravimetry,and structural study of uranium complexes derived from dibasic S-alkylated thiosemicarbazone ligands

Two pentagonal bipyramidal complexes, ethanol-(S-ethyl-N¹,N⁴-bis(3-methoxy-2-hydroxybenzaldehyde)-isothiosemicarbazide-N,N′,O,O′)-dioxidouranium(VI) (1) and ethanol-(S-ethyl-N¹-(2-hydroxyacetophenone)-N⁴-(5-bromo-2-hydroxybenzaldehyde)-isothiosemicarbazide-N,N′,O,O′)-dioxidouranium(VI) (2), have been prepared and characterized. Their structures have been determined by X-ray crystallography, and the structural parameters are discussed with those observed in related complexes. Electronic absorption, proton magnetic resonance, and FT-IR spectra have been recorded and analyzed. In both complexes, the U(VI) centers are surrounded by N₂O₂ donor ligands, two oxido groups, and one ethanol in a distorted pentagonal bipyramid. The thermal stability of the new complexes has also been determined.     

Synthesis,crystal structures,and catalytic properties of phenoxo-bridged dinuclear manganese(III) complexes with bis-Schiff bases

Two structurally similar centrosymmetric phenoxo-bridged dinuclear manganese(III) complexes, [Mn₂(L¹)₂(N₃)₂] (1) and [Mn₂(L²)₂(NCS)₂] (2), were prepared from the tetradentate bis-Schiff base ligands, N,N’-bis(salicylidene)propane-1,2-diamine (H₂L¹) and N,N’-bis(salicylidene)ethane-1,2-diamine (H₂L²), respectively, in the presence of pseudohalides. The complexes have been characterized by FTIR, elemental analyses, and molar conductivity. Structures of the complexes have been confirmed by single-crystal X-ray determination. The bis-Schiff base ligands coordinate with Mn through their phenolate oxygen and imino nitrogen. Each Mn is an octahedral. The complexes showed that they exhibit high activity in catalytic olefin oxidation.     

Metal Derivatives of Thiosemicarbazones: Crystal and Mole­cular Structures of Mono‐ and Dinuclear Copper(II) Complexes with N1‐Subsitituted Salicylaldehyde Thiosemicarbazones

Reactions of copper(II) acetate with N¹‐subsitituted salicylaldehyde thiosemicarbazones [R¹R²C²=N³–N²H–C¹(=S)–N¹HR³;R¹ = 2‐HO–C₆H₄–, R² = H : R³ = Me (H₂L¹), Et (H₂L²)] are described. Copper(II) acetate was reacted with H₂L¹ and H₂L² ligands in the presence of polypyridyl co‐ligands, and this led to the formation ofmononuclear complexes, [Cu(κ³‐O, N, S‐L¹)(κ²‐N, N‐bipy)] ( 1 ),[Cu(κ³‐O, N, S‐L)(κ²‐N, N‐phen)] [L = L¹ ( 3 ), L² ( 4 )], [Cu(κ³‐O, N, S‐L)(κ²‐N, N‐tmphen)] [L =L¹ ( 5 ), L² ( 6 )] and a dinuclear complex, [Cu₂L²₂(bipy)] ( 2 ) (bipy = 2, 2′‐bipyridine, phen = 1, 10‐phenanthroline, tmphen = 3, 4, 7, 8‐tetramethyl‐1, 10‐phenanthroline). In dinuclear complex 2 , one ligand is O, N³,S‐chelating, while second is O, N³,S‐chelation‐cum‐N²‐bridging; and in all others thio‐ligands are O, N³,S‐chelating. The μ_eff values for the complexes lie in the range of 1.79–1.83 BM. Complexes 1 , 3 – 6 have square pyramidal arrangement, whereas complex 2 has two independent molecules in the crystal lattice, and each molecule has trigonal bipyramidal square planar (5:4) coordination pair. Complexes 2 , 4 , and 6 showed fluorescence properties.     

Synthesis and characterization of nickel(II) complexes with three potentially hexadentate Schiff-base ligands and polyamines: X-ray crystal structure determination of one nickel(II) complex

Three new potentially hexadentate N₄O₂ Schiff-base ligands (H₂L¹, H₂L² and H₂L³) were prepared from the reaction of the polyamines N,N′-bis(2-aminophenyl)-1,2-ethanediamine (L¹), N,N′-bis(2-aminophenyl)-1,3-propanediamine (L²) and N,N′-bis(2-aminophenyl)-1,4-butanediamine (L³), respectively with salicylaldehyde. Reaction of the Schiff bases with Ni(II) salts in the presence of N(Et)₃ gave the neutral complexes [NiL⁴], [NiL⁵] and [NiL⁶]. Ni(II) complexes of the polyamines were also prepared. One of complexes [Ni(L¹)(MeCN)₂](ClO₄)₂·MeCN has been characterized through X-ray diffraction methods.     

Hydroxy and methoxy substituted N 1,N 4-diarylidene-S-methylthiosemicarbazone iron(III) and nickel(II) complexes

Template reactions of 2,4-dihydroxy-, 2,5-dihydroxy-, 2-hydroxy-3-methoxy- and 2-hydroxy-4-methoxy-benzaldehyde with methoxy- and hydroxy-substituted salicylaldehyde S-methylthiosemicarbazones in the presence of NiCl₂ and FeCl₃ resulted in the corresponding hydroxy- and methoxy-substituted N¹,N⁴-diarylidene-S-methylthiosemi-carbazone complexes. Characterization of the compounds, [Fe(L)Cl] and [Ni(L)], was accomplished by means of elemental analysis, conductivity and magnetic measurements, i.r. and ¹H-n.m.r. spectra. A systematic trend has been observed for the chemical shift values of the aromatic protons in the spectra of complexes.     

Lanthanum(III) Complexes with N-alk(en)yl-1,10-phenanthroline-2-methyleneamine and their DNA-binding Mode

Five new tridentate ligands and their corresponding La(III) complexes, [La(III)(L)₂(H₂O)_n](ClO₄)₃ where n = 2,3 and 4; L is N-methyl-1,10-phenanthroline-2-methyleneamine (L₁), N-ethyl-1,10-phenanthroline-2-methyleneamine (L₂), N-propyl-1,10-phenanthroline-2-methyleneamine (L₃), N-n-butyl-1,10-Phenanthroline-2-methyleneamine (L₄), and N-benzyl-1,10-phenanthroline-2-methyleneamine (L₅), have been synthesized, and characterized by elemental analysis, IR, far-IR, ¹H-NMR, thermal gravity analysis and conductance measurement. The interaction of the lanthanum(III) complexes with calf thymus DNA was studied by means of UV, fluorescence, CD and viscosity measurements. Using ethidium bromide as a fluorescence probe, the binding mode of the complexes with calf thymus DNA was studied spectroscopically. All the results suggest that the complexes perhaps interact with calf thymus DNA by intercalative and coordination binding mode.     

Structural,spectroscopic, and biological aspects of S∩N donor Schiff-base ligands and their chromium(III) complexes

New chromium(III) complexes are synthesized by classical thermal and microwave (MW)-irradiated techniques. The Schiff bases 2-acetylfuran-S-benzyldithiocarbazate (L¹H), 2-acetylthiophene-S-benzyldithiocarbazate (L²H), 2-acetylpyridine-S-benzyldithiocarbazate (L³H), and 2-acetylnaphthalene-S-benzyldithiocarbazate (L⁴H) were prepared by condensation of -S-benzyldithiocarbazate in ethanol with the respective ketones by using MW as well as conventional methods. The chromium(III) complexes have been prepared by mixing CrCl₃ · 6H₂O in 1 : 1 and 1 : 2 molar ratios with monofunctional bidentate ketimines. The structure of the ligands and their transition metal complexes were confirmed by elemental analysis, melting point determinations, molecular weight determinations, infrared (IR), electronic and electron paramagnetic resonance (EPR) spectral, and X-ray powder diffraction studies. On the basis of these studies it is clear that the ligands coordinated to the metal atom in a monobasic bidentate mode by S∩N donors. Thus, an octahedral environment around the chromium(III) has been proposed. The growth inhibiting potential of the ligands and complexes has been assessed against a variety of fungal and bacterial strains.     

Mononuclear manganese(II) and manganese(III) complexes of N<Subscript>2</Subscript>O donors involving amine and phenolate ligands: absorption spectra,electrochemistry and crystal structure of [Mn(L<Subscript>3</Subscript>)<Subscript>2</Subscript>](ClO<Subscript>4</Subscript>)

A number of mononuclear manganese(II) and manganese(III) complexes have been synthesized from tridentate N₂O aminophenol ligands (HL₁–HL₅) formed by reduction of corresponding Schiff bases with NaBH₄. Three types of tridentate N₂O aminophenols have been prepared by reducing with NaBH₄which are (a) Schiff bases obtained by bromo salicylaldehyde reaction with N,N-dimethyl/N,N-diethyl ethylene diamine (HL₁, HL₂), (b) Schiff bases obtained by condensing salicylaldehyde/bromo salicylaldehyde and picolyl amine (HL₃, HL₄), (c) pyridine-2-aldehyde and 2-aminophenol (HL₅). All the manganese complexes have been prepared by direct addition of manganese perchlorate to the corresponding ligands and were characterized by the combination of i.r., u.v.–vis spectroscopy, magnetic moments and electrochemical studies. The u.v.–vis spectra of all of the manganese(III) complexes show two weak d–d transitions in the 630–520 nm region, which support a distorted octahedral geometry. The electron transfer properties of all of the manganese(III) complexes (1–4 and 6) exhibit mostly similar characteristics consisting two redox couples corresponding to the Mn^III → Mn^II reductions and Mn^III → Mn^IV oxidations. The electronic effect on the potential has also been studied by changing different substituents in the ligands. In all cases, an electron-donating group stabilizes the higher oxidation state and electron withdrawing group prefers the lower oxidation state. The cyclic voltammogram of [Mn^II(L₅)₂] shows an irreversible oxidation Mn^II → Mn^III at −0.88 V, followed by another quasi-reversible oxidation Mn^III → Mn^IV at +0.48 V. The manganese(III) complex (3) [Mn(L₃)₂]ClO₄has been characterized by X-ray crystallography.     

Assemblies of 1D and 2D Copper(II) Chiral Coordination Polymers by Salicylaldehyde Schiff Bases: Synthesis,Crystal Structures,and Magnetic Properties

Reaction of CuCl₂ · 2H₂O with chiral Schiff bases and sodium dicyanamide led to the formation of two chiral copper(II) coordination polymers, namely [Cu₄(L¹)₂(dca)₄]_n ( 1 ) and [Cu₂(L²)(μ‐Cl)(dca)(H₂O)]_n · nH₂O ( 2 ) {H₂L¹ = (1R, 3S)‐N′,N′′‐bis[salicylidene]‐1,3‐diamino‐ 1,2,2‐trimethylcyclopentane, H₂L² = (1R, 3S)‐N′,N′′‐bis[3‐ethoxysalicylidene]‐1,3‐diamino‐ 1,2,2‐trimethylcyclopentane, dca = dicyanamide}. Both complexes were structurally characterized by elemental analyses, IR spectroscopy and single‐crystal X‐ray diffraction. Complex 1 exhibits a two‐dimensional polymeric structure formed by single dca bridging tetranuclear Cu₄ units. Complex 2 displays a left‐handed helical chain structure constructed from Cu₂ dimers with single dca bridges. The chirality of 1 and 2 was confirmed by circular dichroism (CD) measurements in solution. Both complexes exhibit strong antiferromagnetic couplings with J = –308(4) cm^–1 for 1 and J = –123(1) cm^–1 for 2 in 2–300 K.     

High potential isomeric dihalobis[2-(arylazo)pyridine] osmium(III) perchlorate monohydrate

Summary The preparation of isomeric complexes [Os^IIIX₂L₂]ClO₄· H₂O [{(4)} and (5): X = Cl or Br, L(1) = 2-(phenylazo)-pyridine (L¹) or 2-(m-tolylazo)pyridine(L²)] via stereo-retentive oxidation of the corresponding osmium(II) precursors [(2) and (3), respectively] is described. The complexes were characterized using spectroscopic and electrochemical methods. The low-spin (idealized t _2g ⁵ ; S = 1/2) paramagnetic complex ions display characteristic osmium(III) e.p.r. spectra in frozen (-196° C) MeCNPhMe. In dry MeCN solution, the OsX₂N₄ unit exhibits irreversible [OsX₂L₂]²⁺/[OsX₂L₂]⁺ and reversible [OsX₂L₂]⁺/[OsX₂L₂] couples at ca. 1.8 and 1.0 V versus saturated calomel electrode (s.c.e.), respectively. The use of (4)/(5) as an oxidant is noted.     

Heterovalent trinuclear Co(III)-Co(II)-Co(III) complexes with N-(2-Carboxyethyl)salicylaldimines

The heterovalent trinuclear cobalt complexes [Co₂^IIIL₄ ⁱ · Co^II(H₂O)₄] · nXmY (L ⁱ are deprotonated Schiff bases derived from substituted salicylaldehydes and β-alanine; i = 1–3) were obtained and characterized. An X-ray diffraction study of the trinuclear cobalt complex with N-(2-carboxyethyl)salicylaldimine showed that the central Co(II) ion and the terminal Co(III) ions are linked by bridging carboxylate groups. Either terminal Co(III) atom is coordinated to two ligand molecules. They form an octahedral environment consisting of two azomethine N atoms, two phenolate O atoms, and two O atoms of two carboxylate groups. The central Co(II) atom is coordinated to four water molecules and to two O atoms of two bridging carboxylate ligands involved in the coordination sphere of the terminal Co(III) atoms.     

Die Chelatbildung von N-Tris(2-aminoethyl)amin-N′,N′,N″,N″,N‴,N‴-hexaessigsäure (H6TTAHA) und N-(Pyrid-2-yl-methyl)ethylendiamin-N,N′,N′-triessigsäure (H3PEDTA) mit Gadolinium(III) – Synthesen,Komplexstabilität und NMR-Relaxivität

Chelate Formation of N-Tris(2-aminoethyl)amine-N′,N′,N″,N″,N?,N?-hexaacetic Acid (H₆TTAHA) and N-(Pyrid-2-yl-methyl)ethylenediamine-N,N′,N′-triacetic Acid (H₃PEDTA) with Gadolinium(III) – Syntheses, Stability Constants, and NMR-Relaxivities The chelate formation of N-tris(2-aminoethyl)amine-N′,N′,N″,N″,N?,N?-hexaacetic acid (H₆TTAHA) and N-(pyrid-2-yl-methyl)ethylenediamine-N,N′,N′-triacetic acid (H₃PEDTA) with gadolinium(III) has been studied potentiometrically in aqueous solution at 25°C and μ = 0.1 (KCl). [Gd(TTAHA)]^3?: 1gβ_M/ML = 19.0; {H[Gd(TTAHA)]}^2?: 1gK_H/MHL = 8.30; [Gd(PEDTA)]: 1gβ_M/ML = 15.56. Both 1 : 1 gadolinium(III) complexes were isolated as Na₂H[Gd(C₁₈H₂₄N₄O₁₂)] · 3.5 H₂O and [Gd(C₁₄H₁₆N₃O₆)] · 3 H₂O, respectively. Their ¹H-NMR relaxivities [1 · mmol^?1 · s^?1] ({H[Gd(TTAHA)]}^2?: 9.5; [Gd(PEDTA)]: 8.8) offer promising applications for ¹H-NMR imaging.     

Ruthenium(III) complexes with modified nucleobases: N-Substituted adenines

New chlorido-dimethylsulfoxide-ruthenium(III) complexes with different N⁶-substituted adenines have been prepared and characterized. Three ruthenium complexes have been structurally characterized by X-ray diffraction crystallography: [Ru^IIICl₄(DMSO)[H-(N⁶-pentyladenine)]] (1), [Ru^IIICl₄(DMSO)[H-(N⁶-hexyladenine)]] (2) and [Ru^IIICl₄(DMSO)[H-(N⁶,N⁶-dibutyladenine)]] (3). In all cases ruthenium ion show octahedral geometry coordinated to four chlorido ligands and one S coordinated sulfoxide (DMSO). The coordination sphere is completed by an adenine moiety coordinated to Ru(III) via N(9) and protonated at N(3). Other similar complexes have been obtained with N⁶-propyladenine, [Ru^IIICl₄(DMSO)[H-(N⁶-propyladenine)]] · 0.5EtOH (4) and N⁶-benzylaminopurine (BAP) [Ru^IIICl₄(DMSO)[H-(BAP)]] · 0.5H₂O (5) which have been spectroscopically characterized. Otherwise, in different reaction conditions, we have obtained an out sphere complex of Ru(II), [H-(BAP)][Ru^IICl₃(DMSO)₃] (6), with identical complex unit than the structurally solved [H-(creat)][Ru^IICl₃(DMSO)₃] (7) which was included for comparison purposes. Preliminary electrophoretic mobility and atomic force microscopy (AFM) studies of the interaction between Ru(III) compounds and plasmidic DNA pBR322 have been performed. These results show different morphological changes in plasmidic DNA forms.     

A Novel Pentadentate Redox‐Active Ligand and Its Iron(III) Complexes: Electronic Structures and O2 Reactivity

A novel redox‐active ligand, H₄^Ph2SL^AP ( 1 ) which was designed to be potentially pentadentate with an O,N,S,N,O donor set is described. Treatment of 1 with two equivalents of potassium hydride gave access to octametallic precursor complex [H₂^Ph2SL^APK₂(thf)]₄ ( 2 ), which reacted with FeCl₃ to yield iron(III) complex [H₂^Ph2SL^APFeCl] ( 3 ). Employing Fe[N(SiMe₃)₂]₃ for a direct reaction with 1 led to ligand rearrangement through C?S bond cleavage and thiolate formation, finally yielding [HL^APFe] ( 5 ). Upon exposure to O₂, 3 and 5 are oxidized through formal hydrogen‐atom abstraction from the ligand NH units to form [^Ph2SL^SQFeCl] ( 4 ) and [L^SQFe] ( 6 ) featuring two or one coordinated iminosemiquinone moieties, respectively. Mössbauer measurements demonstrated that the iron centers remain in their +III oxidation states. Compounds 3 and 5 were tested with respect to their potential as models for the catechol dioxygenase. Thus, they were treated with 3,5‐di‐tert‐butyl‐catechol, triethylamine and O₂. It turned out that the iron–catecholate complexes react with O₂ in dichloromethane at ambient conditions through C?C bond cleavage mainly forming extradiol cleavage products. Intradiol products are only side products and quinone formation becomes negligible. This observation has been rationalized by a dissociation of two donor functions upon coordination of the catecholate.     

Tetradentate asymmetric Schiff bases and their Ni(II) and Fe(III) complexes

Three asymmetric Schiff-base tetradentate diimines H₂L¹, H₂L², and H₂L³ [(2-OH)C₆H₄N=CHC₆H₄2-N=CHC₆H₃(2-OH)(5-X), X?=?H, CH₃, Cl respectively] have been synthesized by a two step process. The reaction of 2-hydroxy aniline with 2-nitro-benzaldehyde in EtOH gave the starting Schiff base, 2-hydroxy-N-(2-nitrobenzylidene)aniline (SB-NO₂), which was reduced into the amino derivative (SB-NH₂) in solution. Reacting SB-NH₂ with 2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-5-chlorobenzaldehyde gave the three new ligands H₂L¹, H₂L², and H₂L³ respectively. Their dimeric, binuclear metal complexes with Ni(II) and Fe(III) have also been synthesized. The ligands and their complexes were characterized by elemental analyses, LC–MS, IR, electronic, ¹H and ¹³C-NMR spectra, TGA, conductivity and magnetic measurements. All of the spectroscopic, analytical and other data indicate octahedral geometry M₂L₂(H₂O)X₂ (M: Ni,Co;X: Cl or H₂O), except for NiL² which is monomeric. Antimicrobial activities of the ligands and the complexes were evaluated against five bacteria. While the ligands and the Ni complexes are inactive towards Pseudomonas aeruginosa and Staphylococcus aureus, Fe complexes are active; only Fe complexes are inactive against Escherichia coli. All of the compounds have antimicrobial activities against Bacillus subtilis, and Yersinia enterecolitica.     

Synthesis,crystal structure and antibacterial activity of manganese(III) and cobalt(III) complexes containing pentadentate Schiff bases of a common amine and thiocyanate

Abstract

Four new mononuclear Schiff base manganese(III) and cobalt(III) complexes viz. [Mn(L¹)(NCS)] (1), [Mn(L²)(NCS)] (2), [Co(L³)(NCS)] (3), and [Co(L⁴)(NCS)]·0.5CH₃OH·0.5H₂O (4), containing thiocyanate as a common pseudohalide ion are reported. The pentadentate Schiff base ligands H₂L¹, H₂L², H₂L³, and H₂L⁴ were obtained by the condensation of substituted salicylaldehydes with N-(3-aminopropyl)-N-methylpropane-1,3-diamine. The syntheses of the complexes have been achieved by the reaction of manganese(II) perchlorate or cobalt(II) perchlorate with the respective Schiff bases in the presence of thiocyanate in methanol medium. Complexes 1–4 have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 adopt nearly similar structures containing the MN₄O₂ (M?=?Mn, Co) chromophore in which each central M(III) ion adopts a distorted octahedral geometry. Weak intermolecular H-bonding interactions are operative in these complexes to bind the molecular units. The antibacterial activity of 1–4 and their constituent Schiff bases has been tested against some common bacteria.     

NS and NSO-Donor ligands and their metal complexes. Synthesis and characterisation of a new low-spin iron(III) complex with 1,2-di(o-aminophenylthio)ethane and iron(III), cobalt(III) and manganese(III) complexes of 1,2-di(o-salicylaldiminophenylthio)ethane

Summary Iron(III) complexes of a quadridentate N₂S₂ donor ligand, 1,2-di(o-aminophenylthio)ethane (DAPTE) and its Schiff Base with salicylaldehyde, a hexadentate N₂S₂O₂ donor ligand,viz. 1,2-di(o-salicylaldiminophenylthio)ethane (H₂DSALPTE) have been synthesised and characterised.The Schiff base ligand (1 mol) gave a dark green tri-iron(III) [Fe₃(DSALPTE)(HDSALPTE)Cl₃]Cl₂ complex when reacted with anhydrous iron(III) chloride (1 mol). The Mössbauer data of this complex suggest the presence of three iron sites, one of which is octahedral and the other two tetrahedral. On the other hand, Fe(ClO₄)₃ reacted smoothly with H₂DSALPTE in ethanol to give a mononuclear pseudo-octahedral complex in which the ligand functions in a dibasic hexadentate fashion. Mössbauer data suggest the presence of a low-spin-high-spin equilibrium in the solid state. The manganese(III) and cobalt(III) complexes of the Schiff base, H₂DSALPTE, are also studied for the sake of comparison with the corresponding iron(III) complex. The N₂S₂ ligand, however, formed a low-spin pseudo-octahedral iron(III) complex. The complexes have been characterised by elemental analysis, molar conductance values, cryomagnetic data and i.r., electronic and Mössbauer spectral data.     

Synthesis,characterization, electrochemistry,catalytic, and antimicrobial studies of ruthenium(III) complexes containing ONO donor ligands

A series of ruthenium(III) complexes [RuX(EPh₃)₂L] (where X = Cl or Br; E = P or As; L = deprotonated dibasic tridentate ligand) were prepared by the reaction of [RuX₃(EPh₃)₃] with Schiff bases (H₂L¹–H₂L⁴). The ligands were prepared by the condensation of N-4 phenyl/methyl semicarbazide with o-vanillin/o-hydroxy acetophenone. The complexes were characterized by elemental, physico-chemical, and electrochemical methods. Catalytic studies of these complexes for the oxidation of alcohols and aryl–aryl coupling were carried out. Antimicrobial experiments were also carried out.     

Iridium (III) and rhodium (III) triazoles by 1,3-dipolar cycloadditons to a coordinated azide in iridium (III) and rhodium (III) compounds

The reaction of [(η⁵-C₅Me₅)M(μCl)Cl]₂ with the ligand (L^∩L) in the presence of sodium methoxide yielded compounds of general formula [(η⁵-C₅Me₅)M(L^∩L)Cl] (1–10) (where M = Ir or Rh and L^∩L = N^∩O or O^∩O chelate ligands). Azido complexes of formulation [(η⁵-C₅Me₅)M(L^∩L)N₃] (11–20) have been prepared by the reaction of [(η⁵-C₅Me₅)M(μN₃)(X)]₂ (X = Cl or N₃) with the corresponding ligands or by the direct reaction of [(η⁵-C₅Me₅)M(L^∩L)Cl] with NaN₃. These azido complexes [(η⁵-C₅Me₅)M(L^∩L)N₃] undergo 1,3-dipolar cycloaddition reaction with substituted alkynes in CH₂Cl₂ and for the first time in ethanol at room temperature to yield iridium (III) and rhodium (III) triazoles (21–28). The compounds were characterized on the basis of spectroscopic data, and the molecular structures of 2 and 26 have been established by single crystal X-ray diffraction.