Nickel(II), palladium(II) and platinum(II) complexes of <Emphasis Type="Italic">N</Emphasis>-allyl-<Emphasis Type="Italic">N</Emphasis>′-pyrimidin-2-ylthiourea

Platinum(II), palladium(II) and nickel(II) complexes with N-allyl-N′-pyrimidin-2-ylthiourea were synthesized in 1:1 and 1:2 [metal:ligand] stoichiometric ratios and characterized by elemental analyses, molar conductivities, magnetic susceptibilities and by i.r., u.v.-vis., ¹H- and ¹³C-n.m.r. and mass spectra. The ¹H- and ¹³C- n.m.r. chemical shifts reveal coordination of one pyrimidine-N and sulphur atoms to Pt^II and Pd^II. The i.r. spectra indicate that the ligand behaves as a neutral monodentate towards Ni^II; coordinates via a pyrimidine-N and as a bidendate towards Pd^II and Pt^II coordinates via thione-S and a pyrimidine-N. The magnetic moments and electronic spectral data suggest a square-planar geometry for Pt^II and Pd^II complexes, a mixture of square-planar and tetrahedral geometries for the tetracoordinate Ni^II complex and octahedral for the six-coordinate one. The E.I. mass spectra of the complexes showed some isotope ion peaks of [M]⁺ and fragments containing metals; assignments of fragments containing metal ions were supported by the appearance of their peaks among isotope clusters.     

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.     

Synthesis and characterization of novel (<Emphasis Type="Italic">E</Emphasis>,<Emphasis Type="Italic">E</Emphasis>)-dioxime and its mono- and polynuclear metal complexes containing azacrown moieties

The novel (E,E)-dioxime,7,8-bis(hydroxyimino)-1,14-bis(monoaza[8]crown-6)-benzo[f]-4,11-dioxa-1,14-diazadecane[7,8-g]quinoxaline (H₂L), has been synthesized by the reaction of 6,7-diamino-1,12-bis(monoaza[18]crown-6)benzo[f]-4,9-dioxa-1,12-diazadecane (4) which has been prepared by the reduction of 6,7-dinitro-1,12-bis(mono-aza[18]crown-6)benzo[f]-4,9-dioxa-1,12-diazdecane (3) and cyanogendi-N-oxide. Mononuclear Ni^II and Cu^II complexes of H₂L have a metal:ligand ratio of 1:2 and the ligand coordinates through two hydroxyimino nitrogen atoms, as do most of the (E,E)-dioximes. The hydrogen-bridged Ni^II complex was converted into its BF ₂ ⁺ capped anologue by the reaction with BF₃ · Et₂O. The reaction of the Cu^II complex with 2,2′-dipyridyl as an end-cap ligand gave the homotrinuclear complex. Structures for the ligand and its complexes are proposed in accordance with elemental analysis, magnetic susceptibility measurements, ¹H, ¹³C-n.m.r, IR and MS spectral data.     

Solubilities and Transfer Chemical Potentials for Cobalt(III) Complexes in <Emphasis Type="BoldItalic">t</Emphasis>-butanol– <Emphasis Type="BoldItalic">i</Emphasis>-propanol–, and ethanol–water Mixtures

Solubilities in t-BuOH–, i-PrOH–, and EtOH–H₂O mixtures at 298.2 K are reported for a number of salts of mono- and bi-nuclear cobalt(III) complexes. From these solubilities and published single ion transfer chemical potentials, on the TATB (Ph₄As ⁺≡ BPh₄^-) assumption, transfer chemical potentials have been derived for most of these cobalt(III) complexes. The results and trends are discussed in relation to those for other ions and complexes. Effects of ligand nature for transfer to t-BuOH–H₂O mixtures are detailed and, for a selection of complexes, trends for transfer of a given complex to t-BuOH–, i-PrOH–, EtOH– , and MeOH– H₂O mixtures are compared.     

<Emphasis Type="Italic">o</Emphasis>-Semiquinone metal complexes as derivatives of sterically hindered di-<Emphasis Type="Italic">o</Emphasis>-quinone

ESR spectroscopy was used to study a series of mono- and binuclear o-semiquinone metal complexes, viz., derivatives of sterically hindered di-o-quinone 1,2-bis(2,5-di-tert-butylcyclohexadiene-1,5-dion-3,4-yl)ethane (1). Hindered rotation was found in the o-semiquinone moiety of the generated complexes. Magnetochemical measurements for polymeric bis(o-semiquinolate)copper(II) based on di-o-quinone 1 showed two antiferromagnetic channels of interaction between the paramagnetic centers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1580–1584, July, 2005.     

Synthesis,characterization and X-ray crystal structures of the bis–ligand zinc(II) and cadmium(II) complexes of the methylpyruvate Schiff base of <Emphasis Type="Italic">S</Emphasis>-methyldithiocarbazate

New bis-chelated Zn^II and Cd^II complexes of empirical formula, [M(mpsme)₂] (mpsme=the anionic form of the tridentate ONS donor ligand formed from methylpyruvate and S-methyldithiocarbazate) have been prepared and characterized by conductance, i.r., electronic and n.m.r. spectroscopic techniques. Spectral evidence supports a six-coordinate distorted octahedral structure for these complexes. X-ray crystallographic structural analysis also confirms that, in both the [Zn(mpsme)₂] and [Cd(mpsme)₂] complexes, the methylpyruvate Schiff base of S-methyldithiocarbazate is coordinated to the metal ions as a uninegatively charged tridentate ONS chelating agent via the carbonyl oxygen atom, the azomethine nitrogen atom and the thiolate sulfur atom. Both complexes are assigned a distorted octahedral geometry in which the ligands are arranged meridionally around the metal ions. The distortion from regular octahedral geometry is attributable to the restricted bite angles of the ligand.     

3,3,3-Trifluoro-<Emphasis Type="Italic">N</Emphasis>′-(3-trifluoromethylphenyl)-1,2-propanediamine and its <Emphasis Type="Italic">N</Emphasis>-mono-and <Emphasis Type="Italic">N,N</Emphasis>-dicarboxyethyl derivatives: synthesis,protolytic and complexation properties

3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu²⁺, Ni²⁺, Zn²⁺) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu²⁺ ions increase with an increase in the number of N-carboxyethyl groups. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2465–2469, November, 2005.     

Studies on Mononuclear Chelates Derived from Substituted Schiff Bases Ligands (Part 3). Synthesis and Characterization of a New 5-Nitrosalicylidene-<Emphasis Type="Italic">p</Emphasis>-aminoacetophenoneoxime and Its Complexes with Co(II), Ni(II), Cu(II), and Zn(II)

A new ligand, 5-nitrosalicylidene-p-aminoacetophenoneoxime (HL), was synthesized from p-aminoacetophenoneoxime and 5-nitrosalicylaldehyde under reflux in absolute EtOH at 60°C for 3 h. Mononuclear complexes with a metal : ligand ratio of 1 : 2 were prepared with Co^II, Ni^II,Cu^II, and Zn^II salts. Their structures were determined on the basis of elemental analyses, IR, ¹H and ¹³C NMR, electronic spectra, magnetic susceptibility measurements, molar conductivity, and thermogravimetric analyses. According to the results, two ligands were suggested to be coordinated to each metal atom by phenolic oxygen and imino nitrogen to form high-spin tetrahedral complexes with cobalt(II), nickel(II), and copper(II) while forming a diamagnetic complex with zinc(II).__________From Koordinatsionnaya Khimiya, Vol. 31, No. 6, 2005, pp. 441–445.Original English Text Copyright © 2005 by Canpolat, Kaya.This article was submitted by the authors in English.     

Synthesis,characterization and antimicrobial activity of macrocylic phenoxo-bridged di- and tetra-nuclear complexes from <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]succinoyl/sebacoyldicarboxamides

Macrocyclic ligands N,N-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]succinoyl dicarboxamide (H₂L¹) and N,N-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]sebacoyl dicarboxamide (H₂L²) were synthesized and characterized by various spectral techniques. Macrocyclic di- and tetra-homonuclear phenoxo bridged Cu^II, Co^II, Ni^II, Zn^II, Cd^II and Hg^II complexes have been synthesized through the template method by using the precursors 2,6-diformyl-4-methylphenol, succinoyldihydrazide/ sebacoyldihydrazide and respective metal chlorides in 2:2:2/2:2:4 ratio respectively. The synthesized complexes were characterized by i.r., n.m.r., u.v.-vis., FAB-mass, e.s.r., magnetic susceptibility and elemental analyses data. The elemental analyses and FAB-mass spectral data have justified the dinuclear and tetra nuclear structure for the complexes of the ligands H₂L¹ and H₂L² respectively. The observed low magnetic moment values revealed the existence of antiferromagnetic spin exchange interaction operating between the two metal centers. Electronic data suggested the octahedral geometry for Ni^II complexes and square pyramidal geometry for Cu^II, Co^II, Zn^II, Cd^II and Hg^II complexes of both the ligands. The Cu^II, Co^II and Zn^II complexes of both the ligands have shown good antifungal activity against Aspergillus niger and Fusarium oxysporum and medium to weak antibacterial activity against Escherichia coli and Staphylococcus aureus when compared to the standard drugs Grisefulvin and Ciprofloxacin respectively.     

Synthesis and studies of spectroscopic and electrochemical properties of dinuclear ruthenium(<Emphasis Type="SmallCaps">II</Emphasis>) and manganese(<Emphasis Type="SmallCaps">II</Emphasis>) complexes

New dinuclear ruthenium manganese complexes of general composition (bpy)₂Ru(L)MnCl_x(H₂O)₂ (L is 1,10-phenanthroline-5,6-dione, 3,3′-dicarboxy-2,2′-bipyridyl, or bis(pyrazolyl); x = 2 or 4) were synthesized by the reaction of (bpy)₂Ru(L) with MnCl₂ · 4H₂O. These compounds and the starting mononuclear ruthenium complexes were studied by spectrophotometric and electrochemical methods in MeCN. The position of the charge-transfer band Ru^II → L in the spectra depends on the donor-acceptor characteristics of the ligand L. For the dinuclear complex under study, the formal potentials of reversible one-electron oxidation of Ru^II are in the range of 0.9–1.2 V (vs. the standard hydrogen electrode), whereas oxidation of Mn^II occurs at more positive (by 0.1–0.2 V) potentials. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2281–2285, October, 2005.     

Ambidentate behavior of pentadentate <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-bis(2-hydroxyphenyl)-pyridine-2,6-dicarboxamide towards transition metal(II) salts

Complexes of Co(II), Ni(II), Cu(II), Mn(II), Zn(II) and Cd(II) with N,N′-bis(2-hydroxyphenyl)pyridine-2,6-dicarboxamide have been synthesized and characterized by elemental analysis, conductivity measurements, spectral (electronic, i.r., n.m.r. and e.p.r.), electrochemical and thermal studies. I.r. studies show that the ligand behaves in an ambidentate way. It coordinates through the pyridine nitrogen, two amide oxygens and two phenolic oxygens in the Co(II), Ni(II), and Cu(II) complexes, whereas in the Mn(II), Zn(II) and Cd(II) complexes it coordinates through the pyridine nitrogen, two uncharged amide nitrogens and two-phenolic oxygens under similar experimental conditions.     

Metastable complexes of some <Emphasis Type="Italic">d</Emphasis>- and <Emphasis Type="Italic">f</Emphasis>-block metals with mesogenic cyanobiphenyls

Formation of metastable complexes with different metal to mesogenic ligand ratio (M/L = 1/2 and 1/1) has been shown by IR–, UV–Vis, ESR-spectroscopic techniques for low temperature co-condensation of some d- and f-block transition metals (Ag, Cu, Eu, Sm) and mesogenic derivatives of cyanobiphenyls. The Quantum chemistry calculations have been carried out to study equilibrium structures of complexes. Biligand complex models with one and two metal atoms and antiparallel disposition of two ligand molecules are considered. Relative spectral shifts and relative thermal stability of complexes are discussed.     

Synthesis and Stereochemistry of 1<Emphasis Type="Italic">H</Emphasis>,5<Emphasis Type="Italic">H</Emphasis>-Naphtho[1,8-<Emphasis Type="Italic">ef</Emphasis>][1,3]dithiocine 2-Oxides

3-Substituted 1H,5H-naphtho[1,8-ef][1,3]dithiocines (R = H, Me, Ph, t-Bu) were oxidized with m-chloroperoxybenzoic acid to the corresponding 2-oxides having trans configuration (R ≠ H). According to the ¹H and ¹³C NMR data (including NOESY experiments), the disubstituted compounds at room temperature exist in a boat conformation with equatorial orientation of the substituent on C³ and oxygen atom on S². The compound with no substituent on C³ gives rise to a mixture of boat conformers with axial and equatorial sulfoxide oxygen atoms at a ratio of 83:17.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 7, 2005, pp. 1109–1112.Original Russian Text Copyright © 2005 by Kikilo, Khairutdinov, Shtyrlin, Klochkov, Klimovitskii.     

Synthesis and Complexing Properties of <Emphasis Type="Italic">N,N</Emphasis>′-Bis(2-hydroxyethyl) Diaza Crown Ethers

The stability constants of complexes of 12-, 15-, and 18-membered diaza crown ethers, N,N′-dimethyl diaza crown ethers, and N,N′-bis(2-hydroxyethyl) diaza crown ethers with alkali and alkaline-earth metal ions in 95% aqueous methanol at 25°C were determined. The stability of the complexes of unsubstituted diaza crown ethers with alkali metal cations is low, probably because of stabilization of the exo,exo conformation of the ligands due to interaction of the nitrogen lone electron pairs with the solvent. The complexes with the double-charged cations are appreciably more stable. N,N′-Dimethyl diaza crown ethers form stable complexes with all the ions studied. As compared to the dimethyl derivatives, N,N′-bis(2-hydroxyethyl) diaza crown ethers form more stable complexes with the Na⁺, K⁺, Ca²⁺, Sr²⁺, and Ba²⁺ ions, which is due to participation of the side hydroxyethyl groups in the coordination.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 665–669.Original Russian Text Copyright © 2005 by Kulygina, Vetrogon, Basok, Luk’yanenko.     

<Emphasis Type="Italic">Ab initio</Emphasis> study of aniline and <Emphasis Type="Italic">n</Emphasis>-propylamine associates with nitrobenzene and <Emphasis Type="Italic">m</Emphasis>-cresol

An ab initio (6-31G**) study of binary associates of aniline and n-propylamine with nitrobenzene and m-cresol has been carried out. The structures corresponding to the total energy minimum of the system have been found for the associates, and their geometrical and energy characteristics have been determined. Basic types of intermolecular interactions have been established, and their effects on the reactivity of the amino group have been investigated.Original Russian Text Copyright © 2004 by I. A. Novakov, V. V. Korolkov, A. I. Pavlyuchko, B. S. Orlinson, and L. A. GribovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 595–601, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Regioselectivity of reductive debromination of substituted pentabromobenzenes with sodium <Emphasis Type="Italic">tert</Emphasis>-butoxide in DMSO

The regioselectivity of reductive debromination of substituted pentabromobenzenes C₆Br₅X (X = NH₂, OMe, Me, H, Cl, F, and NO₂) under the action of Bu^tONa in DMSO containing Bu^tOH has been studied. The reaction followed the halophilic mechanism via carbanions. Deceased. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2305–2308, October, 2005.     

Synthesis of magnesium catecholate and <Emphasis Type="Italic">o</Emphasis>-semiquinone complexes by oxidation of the metal with 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">o</Emphasis>-benzoquinone

Oxidation of amalgamated magnesium metal with 3,6-di-tert-butyl-o-benzoquinone (1) in different aprotic organic solvents afforded magnesium catecholate and bis-o-semiquinolate complexes. The catecholate derivatives of magnesium CatMgL₂ (Cat is the 3,6-di-tert-butyl-o-benzoquinone dianion, L = THF or Py) were synthesized in high yields in pyridine and tetrahydrofuran, respectively. The reactions in diethyl ether or dimethoxyethane produced hexacoordinated metal bis-o-semiquinolates SQ₂MgL_n (SQ is the 3,6-di-tert-butyl-o-benzoquinone radical anion, L = Et₂O, n = 2; L = DME, n = 1). The reaction with the use of toluene as the solvent gave a magnesium bis-o-semiquinolate complex containing the coordinated unreduced o-quinone molecule. The molecular structures of the [CatMgPy₂]₂ and SQ₂Mg·DME complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–98, January, 2007.     

Syntheses of <Emphasis Type="Italic">tetrakis</Emphasis>(benzylisocyanide)<Emphasis Type="Italic">bis</Emphasis>(tri-<Emphasis Type="Italic">i</Emphasis>-propylphosphite) cobalt(III) tetrafluoroborate: comparison with trialkylphosphine–alkylisocyanide complexes of cobalt(III)

Tetrakis(benzylisocyanide)bis(tri-i-propylphosphite)cobalt(III) tetrafluoroborate, [Co(CNCH₂Ph)₄{P(OCHMe₂)₃}₂] (BF₄)₃, has been synthesized by ligand substitution of both [Co(CNCH₂Ph)₄{OAs(C₆H₄Me-p)₃}₂](BF₄)₃ and [Co(CNCH₂Ph)₄(OSbPh₃)₂](BF₄)₃. IR and electronic spectra, magnetic susceptibility, and cyclic voltammetric measurements are reported. The data are consistent with low-spin tetragonal coordination; i.e., trans-[Co(CNCH₂Ph)₄{P(OCHMe₂)₃}₂](BF₄)₃. Comparison is made with tetrakis(alkylisocyanide)bis(trialkylphosphine) cobalt(III) complexes.     

Functionalization of sterically hindered <Emphasis Type="Italic">o</Emphasis>-benzoquinones: amino-substituted 3,6-di(<Emphasis Type="Italic">tert</Emphasis>-butyl)-<Emphasis Type="Italic">o</Emphasis>-benzoquinones

New sterically hindered functionalized o-quinones were synthesized by the 1,4-nucleophilic addition of secondary cyclic amines to 3,6-di(tert-butyl)-o-benzoquinone. The ability of these o-quinones to form o-semiquinone complexes with transition and main-group metals was studied by ESR spectroscopy in solution. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1786–1793, September, 2007.     

Synthesis and reactivity of <Emphasis Type="Italic">N,N-bis</Emphasis>(diphenylphosphino)dimethylaniline compounds

New chalcogenides and complexes of N,N-bis(diphenylphosphino)dimethylanilines were prepared by the reaction of N,N-bis(diphenylphosphino)dimethylaniline ligands with aqueous H₂O₂, elemental S and Se and transition metal complexes based on Cu, Pd and Pt. All the new compounds have been characterised by spectroscopy and the molecular structures of the three complexes of N,N-bis(diphenylphosphino)dimethylanilines have been determined by X-ray crystallography.