Novel rhodium <Emphasis Type="Italic">N</Emphasis>-heterocyclic carbene catalysed arylation of aldehydes with phenylboronic acid

Reaction of 1,3-dialkylperhydrobenzimidazolinylidene, 1,3-dialkyl-4-methylimidazolinylidene and 1,3-dialkylimidazolinylidene with [RhCl(COD)]₂ yields {1,3-dialkylperhydrobenzimidazolin-2-ylidene}-, {1,3-dialkyl-4-methylimidazolin-2-ylidene}- {1,3-dialkylimidazolin-2-ylidene}chloro(η⁴-1,5-cyclooctadiene)rhodium(I) complexes (2a–c) and (4a, b). All compounds synthesised were characterised by elemental analysis, n.m.r. spectroscopy. Phenylboronic acid reacts with aldehydes in the presence of a catalytic amount of the new rhodium(I)–carbene complexes (2a–c) and (4a, b), to give the corresponding aryl secondary alcohols in good yield (73–99%).     

Synthesis,Spectra and Electrochemistry of Dinitro-bis-{1-alkyl-2-(arylazo) imidazole} Ruthenium(II). Nitro-nitroso Derivatives and Reactivity of the Electrophilic {Ru-NO}<Superscript>6</Superscript>System

Ag⁺ assisted aquation of blue cis-trans-cis-RuCl₂(RaaiR′)₂ (4–6) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH₂)₂(RaaiR′)₂](ClO₄)₂ [Raai R′=p-R-C₆H₄ N=N–C₃H₂–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO₂ (c) and R′ = Me (1/4/7/10), CH₂CH₃ (2/5/8/11), CH₂Ph (3/6/9/12)] that have been reacted with NO₂⁻in warm EtOH resulting in violet dinitro complexes of the type, Ru(NO₂)₂(RaaiR′)₂ (7–9). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the compounds, (7b–9b) with conc. HClO₄ nitro-nitrosyl derivatives, [Ru(NO₂)(NO)(OMeaaiR′)₂](ClO₄)₂ (10b–12b) are isolated. The solution structure and stereoretentive transformation in each step have been established from ¹H n.m.r. results. All the complexes exhibit strong MLCT transitions in the visible region. They are redox active and display one metal-centred oxidation and successive ligand-based reductions. The redox potentials of Ru(III)/Ru(II) (E_1/2^M) of (10b–12b) are anodically shifted by ∼ ∼0.2 V as compared to those of dinitro precursors, (7b–9b). The ν(NO) >1900 cm⁻¹ strongly suggests the presence of linear Ru–NO bonding. The electrophilic behaviour of metal bound nitrosyl has been proved in one case (12b) by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine group, and the heteroleptic tris chelates thus formed have been characterised.     

Gold(I)-diphenylphosphinomethane–arylazoimidazole: synthesis and multinuclear NMR investigation

Reaction of [Au₂(dppm)Cl₂] with AgOTf in CH₂Cl₂ medium followed ligand addition and leads to [Au₂(dppm)(RaaiR′)](OTf) [RaaiR′ = p-R–C₆H₄–N = N–C₃H₂–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), OSO₂CF₃ is the triflate anion, and dppm is the diphenylphosphinomethane-ring]. The ¹H-n.m.r. spectral measurements suggest methylene, –CH₂–, in RaaiEt gives a complex AB type multiplet while in RaaiCH₂Ph it shows AB type quartets with coupling constant of avg. 6 Hz. Considering all the moities there are a lot of different carbon atoms in the molecule which gives a lot of different peaks in the ¹³C-n.m.r spectrum. In the ¹H–¹H-COSY spectrum of the present complexes and contour peaks in the ¹H–¹³C-HMQC spectrum in the present complexes, assign the solution structure and stereoretentive transformation in each step.     

Coumarin-derivatized fluorescent <Emphasis Type="Italic">vic</Emphasis>-dioxime-type ligand and its complexes; the preparation,spectroscopy, and electrochemistry

A new vic-dioxime bearing coumarin functionality, N′¹,N′²-Dihydroxy-N ¹,N ²-bis(4-methyl-2-oxo-2H-chromen-7-yl)oxalimidamid (LH₂), N,N-bis-[4-methylcoumarinyl]-diamino glyoxime (LH₂), and its mono- and dinuclear complexes {copper^II, cobalt^II, nickel^II and uranyl^II} have been reported. The fluorescence excitation and emission spectra of LH₂ and its complexes with metal ions were examined. It was observed that fluorescence and excitation emission intensity of LH₂ was quenched depending on complex formation with metal ions. The characterizations of all newly synthesized compounds were made by elemental analysis, ¹H-n.m.r, i.r., u.v.–vis., and l.c-m.s./m.s. data. Electrochemical behaviour of the ligand involving oxime and coumarine moieties, and its complexes with Ni^II, Cu^II, Co^II and UO ₂ ^II were investigated by cyclic voltammetry. The comparison of the electrochemical behaviour of the ligand with its complexes enabled us to identify metal-, oxime- and coumarine-based signals.     

Dioxovanadium(V) Complexes Incorporating Tridentate ONO Donor Hydrazone Ligands Derived from Acetylhydrazide and 2-hydroxybenzaldehyde/2-hydroxyacetophenone. Synthesis, Characterization and Reactivity

Reaction of VOSO₄ with the tridentate ONO donor ligand derived from the condensation of acetylhydrazide with either 2-hydroxybenzaldehyde (H₂L¹) or 2-hydroxyacetophenone (H₂L²) (general abbreviation H₂L) in an equimolar ratio in the presence of two equivalents of sodium acetate in aqueous-methanolic medium in air produces yellow dioxovanadium(V) complexes of the type, [V^vO₂(H⁺-L)], (1) and (2) in good yield. Aerial oxygen is most likely the oxidant (for the oxidation of V^IV→V^V) assisted by the ligand basicity. Complexes are characterized by elemental analyses and by i.r., n.m.r. and u.v.–vis. spectroscopies. I.r. spectra of the complexes indicate the tridentate dinegative forms of the ligands. The ¹H-n.m.r. spectrum of (2) in CD₃CN solvent indicates the presence of a strongly deshielded N–H proton. Conductivity measurements in DMF solution indicate that the complexes are non-electrolytic and so the H⁺ ion is strongly bonded probably with the uncoordinated imine-N nitrogen of the coordinated Schiff base moiety. Both complexes exhibit only the LMCT band in the u.v. region in MeOH and they are electroactive, displaying an irreversible reduction peak near −0.35 V versus s.c.e. in methanol solution. Methanol solutions of the complexes are reversibly reduced by ascorbic acid to the corresponding V^IV analogue as is evident from their u.v.–vis. spectra. The CH₂Cl₂ suspension of these complexes (1) and (2) reacts separately with 8-hydroxyquinoline (Hhq) in air to produce the mixed-ligand complexes of the type [V^vO(L)(hq)].     

Organometallic gold(I)-pentafluorophenyl-P,O, As,S, TPA,dppm, dppe,dppa-coordinating-phosphines: synthesis and detailed spectroscopic characterisation

[Au(C₆F₅)(tht)], which on reaction with P, O, S-coordinating phosphines in CH₂Cl₂ medium leads to [Au(C₆F₅)(X)] [X = PPh₃ H, (1a), oMe, (1b), pMe, (1c), mMe, (1d), AsPh₃ (2), OPPh₃ (3), SPPh₃ (4), dppm, dppe, dppa = diphenylphosphino-methane,-ethane,-ammine(5, 6, 7), TPA = 135-tetraaza-7-phosphino adamentane(8), Py4H (9a), 4Bu (9b), 4Ac (9c), tht = tetrahydrothiophen, C₆F₅ is the pentafluorophenyl ring]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. I.r. spectra of the complexes show –C = C– and C₆F₅ stretching near at 1610 and 1510, 955, 800 cm⁻¹. The ¹H-n.m.r. spectra as well as ³¹P- (¹H)n.m.r. suggest solution stereochemistry, proton movement, phosphorus proton interaction. ¹³C-n.m.r. spectrum reflect the carbon skeleton in the molecule. In the ¹H–¹H COSY spectrum of the present complexes and contour peaks in the ¹H–¹³C-HMQC spectrum, assign the solution structure and stereoretentive conformation in each step.     

Mononuclear and heterobimetallic palladium(II) and platinum(II) complexes containing the mixed ligands <Emphasis Type="Italic">N</Emphasis>-(2-pyridyl or 2-pyrimidyl) acetamide and tertiary diphosphine

Palladium(II) and platinum(II) complexes containing mixed ligands N-(2-pyridyl)acetamide (AH) or N-(2-pyrimidyl)acetamide (BH) and the diphosphines Ph₂P(CH₂) _n PPh₂, (n = 1, 2 or 3) have been prepared. The prepared complexes [Pd(A)₂(diphos)] or [Pd(B)₂(diphos)] have been used effectively to prepare bimetallic complexes of the type [(diphos)Pd(μ-L)₂M′Cl₂] where M′ = Co, Cu, Mn, Ni, Pd, Pt or SnCl₂; L = A or B. The prepared complexes were characterized by elemental analysis magnetic susceptibility, i.r. and UV–Vis spectral data. ³¹P–{¹H}-n.m.r. data have been applied to characterize the produced linkage isomers.     

A study on the electronic effect of <Emphasis Type="Italic">para</Emphasis> substituents in the aryloxy ring of the hydrazone ligands on the vanadium centre in a family of mixed-ligand [V<Superscript>V</Superscript>O(ONO)(OO)] complexes

[V^IVO(acac)₂] reacts with the methanolic solutions of tridentate dibasic ONO donor hydrazone ligands derived from the condensation of benzoyl hydrazine with either 2-hydroxyacetophenone (H₂L¹) or its para-substituted derivatives (H₂L^2–4) (general abbreviation H₂L), in the presence of vanillin (Hvan) in equimolar ratio under aerobic conditions generating the mixed-ligand oxovanadium(V) complexes of the type [V^VO(L)(van)], (1)–(4) in good yield. All the complexes are diamagnetic and exhibit only ligand-to-metal charge transfer (l.m.c.t.) band near 510 nm in addition to intra-ligand (π → π*) transition band near 330 nm in CH₂Cl₂ solution. ¹H-n.m.r. spectra of the complexes in CDCl₃ solution indicate the presence of two isomeric forms [(1A), (1B); (2A), (2B); (3A), (3B) and (4A), (4B)] in different ratios, which is explained by the interchange of the two binding sites of van⁻ motif between its coordinated equatorial and axial positions. Complexes display two quasi-reversible one electron reduction peaks near +0.10 V and near +0.30 V versus s.c.e. in CH₂Cl₂ solution which are attributed to the successive reduction of V^V→ V^IV and the V^IV→ V^III motifs, respectively. λ_max (for l.m.c.t. transition), and the two reduction potential values (E _1/2)^I (average of the first step anodic and first step cathodic peak potentials) and (E _1/2)^II (average of the second step anodic and second step cathodic peak potentials) of the complexes, are found to be linearly related to the Hammett constants (σ) of the substituents in the aryloxy ring of the hydrazone ligands. λ_max, (E _1/2)^I and (E _1/2)^II values show large dependence: dλ_max/dσ = 37.29 nm, d(E _1/2)^I/dσ = 0.21 V and d(E _1/2)^II/dσ = 0.21 V, respectively, on σ.     

Novel Bimetallic Complexes of Copper,Nickel and Manganese Derived from the Cobalt(III) Complex and their Interaction Studies with Calf Thymus DNA

Synthesis of new bimetallic water-soluble complexes [C₁₂H₂₃N₄O₇CoCu]5H₂O · Cl₂ (2), [C₁₂H₂₃N₄O₇CoNi]5H₂O · Cl₂ (3) and [C₁₂H₂₃N₄O₇CoMn]5H₂O · Cl₂ (4) has been achieved by reaction of the Co^III complex [C₁₂H₂₁N₄O₆Co]5H₂O (1), with transition metal ions. Various physico-chemical techniques: elemental analysis, i.r., u.v.–vis., e.p.r,¹H-, ¹³C- and 2D-n.m.r, spectroscopy, electrochemistry and molar conductance measurements were employed to characterize the complexes. The interaction of the monometallic complex (1) and bimetallic complexes (2–4) with calf thymus DNA have been carried out by u.v.–vis. titration, cyclic voltammetry (c.v.) and viscosity measurements. The intrinsic binding constant K_b of the complexes has been calculated. The absorption spectra of complexes exhibit a red shift with an overall ‘hyperchromic effect’ in the presence of CT-DNA. The binding affinity of the bimetallic complexes to calf thymus DNA is twofold in comparison with complex (1). The intrinsic binding constant value K_b of complex (1) was found to be 1.2 × 10³ M⁻¹, while the K_bvalue of complexes (2–4) were of the order of 1.4 × 10³, 2.2 × 10³ and 2.1 × 10³ M⁻¹, respectively. The K_b values are close to the border between classical and non-classical intercalation that indicates that the binding mode may be electrostatic, probably with covalent preference in bimetallic complexes. The electrochemical behavior of complexes (1–4) was studied in H₂O and displays quasireversible Co^II/Co^I, Cu^II/Cu^I, Ni^II/Ni^I and Mn^II/Mn^Iredox couples. The voltammetric studies of the complexes in the absence and in the presence of DNA exhibit a shift in the formal potential E⁰ and ratio of cathodic to anodic peak currents i_pa/i_pc, indicating binding of the complexes to calf thymus DNA. The viscosity of DNA decreases with increasing concentration of the complex, suggesting that complexes (2–4) bind to calf thymus DNA by electrostatic association with covalent preference.     

Organometallic gold(I)–nickel(II)–aryldiethynyl (–C≡C(Ar)C≡C–) phosphine complexes: synthesis and multinuclear n.m.r. study

Silver triflate [AgOTf] assisted de-bromination gives [Ni(dppm/dppe/(PPh₃)₂)(OTf)₂], which on reaction with aryldiethynyls and gold(I) phosphines in CH₂Cl₂ medium, by the self assembly technique, leads to [{Ni(dppm/dppe/(PPh₃)₂}{(1,4-AB)Au(PPh₃)}₂] [{Ni₄(dppm/dppe/(PPh₃)₂)₄(1,4AB)₄}] [dppm/dppe = diphenyl phosphino-methane (1), -ethane (2), where OSO₂CF₃ is the triflate anion]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. I.r. spectra of the complexes show –C=C– and –C=N–, as well as phosphine stretching. The ¹H-n.m.r. spectra as well as ³¹P(¹H)-n.m.r. suggest solution stereochemistry, proton movement, phosphorus proton interaction. Considering all the moities there are a lot of carbon atoms in the molecule reflected by the ¹³C-n.m.r. spectrum. In the ¹H–¹H-COSY spectrum of the present complexes and contour peaks in the ¹H–¹³C-HMQC spectrum, assign the solution structure and stereo-retentive transformation in each step.     

Synthesis, spectral and electrochemical behaviour of cytosinato bridged complexes of ruthenium(II) and platinum(II) with 1-alkyl-2-(arylazo)imidazoles

Dechlorination of M(RaaiR′) _n Cl₂ by AgNO₃ produced [M(RaaiR′) _n (MeCN)₂]⁺² [M = Ru(II), n = 2; Pt(II), n = 1; RaaiR′ = 1-alkyl-2-(arylazo)imidazole)] which upon reaction with the nucleobase cytosine (C) in MeCN solution gave cytosinato bridged dimeric compounds which were isolated as perchlorate salts [M₂(RaaiR′) _n (C)₂](ClO₄)₂ · H₂O. The products were characterized by IR, u.v.–vis., ¹H-n.m.r. spectroscopy and cyclic voltammetry. In MeCN solution the ruthenium complexes exhibit a strong MLCT band at 550–555 nm and two redox couples positive to SCE due to two metal-center oxidation along with ligand reduction, negative to SCE. The platinum complexes show a weak transition at 500–520 nm in MeCN and exhibit only ligand reduction in cyclic voltammetry. The coordination of the ligand was supported by ¹H-n.m.r. spectral data.     

Steric distortion of planar NiP<Subscript>2</Subscript>N<Subscript>2</Subscript> chromophores: a spectral,cyclic voltammetric and single crystal X-ray structural study

The complexes trans-[Ni(4-MP)₂(NCS)₂]·MeCN (1) and trans-[Ni(3-MP)₂(NCS)₂] (2) (4-MP = tri(4-methylphenyl)phosphine, 3-MP = tri(3-methylphenyl)phosphine) were prepared and characterized by IR, UV–visible, NMR spectra, CV, TGA and single crystal X-ray crystallography. Both the complexes have planar geometry and are diamagnetic. The Ni–P distances in both complexes are relatively short as a result of strong back donation from nickel to phosphorus. The phenyl rings in the 3-MP analogue (2) show increased pitching with reference to the plane formed by the ipso carbons due to increased steric effects. For complex (2), the N–Ni–N and P–Ni–P angles are significantly lower than the almost linear N–Ni–N and N–Ni–P angles observed for both complex (1) and trans-[Ni(PPh₃)₂(NCS)₂]. This observation indicates that the 3-methylphosphine ligand forces complex (2) to distort towards a tetrahedral geometry. IR spectra of both complexes show strong bands around 2,090 cm⁻¹ due to N-coordinated thiocyanate, while the electronic spectra contain d–d transitions around 452 nm. Cyclic voltammograms show that the irreversible one-electron reduction potentials increase in the following order: trans- [Ni(PPh₃)₂(NCS)₂] < trans- [Ni(3-MP)₂(NCS)₂] < trans-[Ni(4-MP)₂(NCS)₂], revealing the electron releasing effect of the methyl groups. The planar complexes exhibit interallogony in coordinating solvents.     

Kinetic studies on H<Superscript>+</Superscript>-catalysed aquation of chromium(III)-oxalato-asparaginato and chromium(III)-oxalato-histidinato complexes

Three chromium(III) complexes with asparagine (Asn) and histidine (His) of the [Cr(ox)₂(Aa)]²⁻ type, where Aa = N,O–Asn, N,O–His or N,N′–His, were obtained and characterized in solution. The complexes with N,O–Aa undergo acid-catalysed aquation to give a free amino acid and cis-[Cr(ox)₂(H₂O)₂]⁻, whereas the complex with N,N′–His undergoes parallel reaction paths: (1) isomerization to the N,O–His complex and (2) liberation of an oxalate ligand. Kinetics of the N,O–Aa complexes in HClO₄ media were studied spectrophotometrically under pseudo-first-order conditions. The absorbance changes were attributed to the chelate ring opening at the Cr–N bond. The linear dependence of rate constants on [H⁺] was established, and a mechanism for the chelate ring cleavage was postulated. The existence of a metastable intermediate with O-monodentate Aa ligand was proved experimentally. Effect of [Cr(ox)₂(Aa)]²⁻ on 3T3 fibroblasts proliferation was studied. The tests revealed low cytotoxicity of the complexes. Complexes with Ala, His and Cys are good candidates for biochromium sources.     

Synthesis of O,O Ethane Bridged Bis-copper(II) Macrocycles. Selective Enzyme Model for Catecholase Activity

New mononuclear and dinuclear complexes [3-hydroxyethyl-1,3,5,8,11pentaazacyclotridecane]copper(II) (1)/nickel(II) (2) perchlorate and O,O ethane bridged bis-copper(II) (3)/nickel(II) (4) macrocycles have been synthesized and characterized by various spectroscopic techniques, viz. i.r., n.m.r., e.p.r., u.v.–vis. and conductance measurements. Spectral data and conductance measurements reveal that all the complexes are consistent with square-planar geometry and are ionic in nature. The catalytic activity of the dinuclear Cu(II) complex (3) in the presence of pyrocatechol was determined spectrometrically by monitoring the increase of the o-benzoquinone characteristic absorption band at 25,000 cm⁻¹ with respect to time in DMF saturated with molecular oxygen. The kinetic parameters V_max (2.8×10⁻³ M s⁻¹) and K_M (1.4×10⁻³ mm) have been determined by Michaelis–Menten method. Electrochemistry of the dinuclear Cu(II) complex has been studied in the presence of molecular oxygen with pyrocatechol and without pyrocatechol at a scan rate of 0.1 V s⁻¹ by cyclic voltammetry. On addition of pyrocatechol, complex shows a shift in E_pc, E_pa and E_1/2 values indicating the oxidation of substrate (pyrocatechol).     

The synthesis and characterization of a new (<Emphasis Type="Italic">E,E</Emphasis>)-dioxime containing 13-membered dithiadiazamacrocyclic moieties and its mononuclear complexes

A new (E,E)-dioxime, (6Z,7Z)-15,16-dihydro-14H-dibenzo[b,h][1,10,4, 7]dithiadiazacyclotride-cine-6,7(5H,8H)-dionedioxime (H ₂ L) has been synthesized by reacting cyanogen-di-N-oxide (2) with 2,2′-[propane-1,3-diylbis(thio)]dianiline (1). Mononuclear complexes (4) and (5) of this ligand have been synthesized by reacting the vic-dioxime (H₂L) with NiCl₂ · 6H₂O and CoCl₂ · 6H₂O, respectively. The BF ₂ ⁺ capped Ni(II) and Co(III) complexes (6) and (7) of the dioxime have been synthesized from (4) and (5). The new compounds were characterized by a combination of elemental analysis, ¹H- and ¹³C-n.m.r, i.r. and m.s. spectral data.     

Indenyl complexes of ruthenium containing thiolate ligands. Structure of IndRu(dppe)SPh

The indenyl ruthenium thiolate complexes IndRu(PPh₃)₂SR, (1) [Ind = η⁵-C₉H₇; R = Pr ⁿ (a), Ph (b), CH₂Ph(c)] were prepared directly by reacting the thiolate anions (RS⁻) with IndRu(PPh₃)₂Cl. The one-pot reaction of IndRu(PPh₃)₂Cl, thiolate anions and dppa ligands gave IndRu(dppa)SR [dppa= bis(diphenylphosphino)ethane: dppe (2); bis(diphenylphosphino)methane: dppm (3)]. Complexes (1) readily react with NOBF₄ in THF at room temperature to give [IndRu(PPh₃)(NO)SR]BF₄, (4). Complexes (1)–(4) have been characterized by spectroscopic techniques (i.r.,¹H-n.m.r., ³¹P-n.m.r.) and by elemental analysis. The crystal structure of IndRu(dppe)SC₆H₅, (2b) has been determined by X-ray analysis.     

Synthesis, Characterization and the Antioxidative Activity of Copper(II), Zinc(II) and Nickel(II) Complexes with Naringenin

New complexes of Cu^(II), Zn^(II) and Ni^(II) with naringenin have been synthesized and characterized on the basis of elemental analyses, molar conductivities, ¹H-n.m.r., i.r. spectra, u.v. spectra, thermal analyses, and fluorescence spectra. In addition, the suppression ratio for O₂⁻· (a) and OH· (b) of the complexes were studied by spectrophotometric methods. The results show that the effect of the Cu^(II)-complex IC₅₀ (a) = 0.003 μm, IC₅₀ (b) = 0.06 μm is the most remarkable, and the average scavenger ability of the complexes (IC₅₀=0.06–2.67μm) against OH· is higher than that of the ligand (IC₅₀ = 28.5 μm). Taken together, these results indicate that the scavenger effect can be enhanced by the formation of metal-ligand coordination complexes, and the transition-metal ions may have differential and selective roles.     

Complexes of iron(III) salen and saloph Schiff bases with bridging 2,4,6-<Emphasis Type="BoldItalic">tris</Emphasis>(2,5-dicarboxyphenylimino-4-formylphenoxy)-1,3,5-triazine and 2,4,6-<Emphasis Type="BoldItalic">tris</Emphasis>(4-carboxyphenylimino-4′-formylphenoxy)-1,3,5-triazine

Four new trinuclear Fe(III) complexes involving tetradenta Schiff bases N,N ¹ -bis(salicylidene) ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(salophH₂) with 2,4,6-tris(2,5-dicarboxyphenylimino-4-formylphenoxy)-1,3,5-triazine (DCPI-TRIPOD) or 2,4,6-tris(4-carboxyphenylimino-4′-formylphenoxy)-1,3,5-triazine (CPI-TRIPOD) have been synthesized and characterized by means of elemental analysis carrying out ¹H-n.m.r., i.r. spectroscopy, thermal analyses and magnetic susceptibility measurements. The complexes can also be characterized as high-spin distorted octahedral Fe^III bridged by carboxylic acids. The tricarboxylic acids play a role as bridges for weak antiferromagnetic intramolecular exchange.     

Effect of the Counter Anion and Solvate on the Structure,Stability and Spectral Properties of a Ruthenium(II) Complex Containing Group 15 Donors and 2,2′ :6′,2′′-terpyridine

Ruthenium complexes [Ru(κ³−tpy)(AsPh₃)₂C1]PF₆ · 0.42H₂O (tpy =2,2′:6′,2′′-terpyridine) (1) and a new crystal form of [Ru(κ³−tpy)(AsPh₃)₂Cl]BF₄ (2), which crystallized without water solvate, and their comparative studies on spectral, structure and stability aspects are reported. The complexes have been characterized by elemental analyses, FAB-MS, i.r., ¹H n.m.r. and electronic spectral studies. In these complexes weak C—H···Fπ and face-to-face π–π interactions lead to a single helical motif while, C—H···FX (X=F, Cl) interactions result in linear chains. Various studies on the stability of the complexes suggested that the compound containing the counter anion PF₆^- is more stable than the other containing BF₄^- as the counterpart.     

Synthesis and Biological Activity of Novel (E,E)-vic-dioximes

A novel vic-dioxime ligand containing the thiourea group, (4E,5E)-1,3-bis{4-[(4-methylphenylamino)methyl] phenyl}- 2-thiooxaimidazoline-4,5-dione dioxime, (4) mmdH₂ has been prepared from N,N′-bis{4-[(4-methylphenylamino)methyl]phenyl}thiourea, (3) mft and cyanogen di-N-oxide. Mononuclear [M(mmdH)₂], where M = Ni^II, Co^II and Cu^II complexes of the (4) mmdH₂ bidentate ligand have been obtained with a 1:2 metal:ligand ratio, as do most the vic-dioximes. The complexes are formed by coordination of N, N atoms of the ligand. The vic-dioxime ligand and its some transition metal complexes have been characterized by elemental analyses, molar conductance data, magnetic susceptibility, i.r., ¹H-n.m.r and u.v.–vis. spectroscopy. Conductivity measurements have shown that mononuclear complexes are non-electrolytes. In addition, the ligands and metal complexes were screened for antibacterial and antifungal activities by agar well diffusion techniques using DMF as solvent.