Synthesis,spectroscopic studies and crystal structures of Re<Superscript>I</Superscript>(CO)<Subscript>3</Subscript>(NN)Cl complexes with <Emphasis Type="Italic">N,N</Emphasis>′-bis(substituted benzylidene)ethane-1,2-diamine Schiff base ligands

Four new Re(I) tricarbonyl-diimine complexes were prepared by reaction of Re(CO)₅Cl with N,N′-bis(substituted benzylidene)ethane-1,2-diamine Schiff base ligands. These compounds were characterized by physico-chemical methods, and their crystal structures were established by X-ray diffraction. The coordination geometry at the Re atom is that of a distorted octahedron, with three carbonyl ligands in the facial geometry.     

Preparation and crystal structure of bis(triethylene glycol-<Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">O</Emphasis>′,<Emphasis Type="Italic">O</Emphasis>′’,<Emphasis Type="Italic">O</Emphasis>‴)manganese(II) dibromide

A new complex, bis(triethylene glycol-O,O′,O′’,O?)manganese(II) dibromide [Mn(TEG)₂]²⁺·2Br^?, was prepared. Its structure was studied by single crystal X-ray diffraction. The complex cation [Mn(TEG)₂]²⁺ is of the host-guest type with two TEG ligands (podands) as hosts. Both TEG ligands are disordered and tetradentate, with all the four oxygen atoms of each ligand participating in the coordination. The Mn²⁺ cation has coordination number 8, and its coordination polyhedron is a distorted bisdisphenoid (trigonal dodecahedron). The geometric parameters (bond lengths, bond and torsion angles) of the complex were determined relatively accurately. In the crystal structure, the ions form infinite thick layers by interionic hydrogen bonds O-H···Br^?.     

Synthesis,structure and DNA-binding studies of tetranuclear copper(II) complexes bridged by asymmetrical<Emphasis Type="Italic"> N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-bis(substituted)oxamides

Two tetranuclear copper(II) complexes bridged by asymmetrical N,N′-bis(substituted)oxamides have been synthesized and characterized as [Cu₄(dmapob)₂(Me₂bpy)₂](pic)₂·6H₂O (1) and [Cu₄(oxbe)₂(dabt)₂](pic)₂ (2), where H₃dmapob and H₃oxbe denote N-benzoato-N′-[3-(dimethylamino)propyl]oxamido and N-benzoato-N′-(2-aminoethyl)oxamide, respectively; and Me₂bpy, dabt, and pic represent 4,4′-dimethyl-2,2′-bipyridine 2,2′-diamino-4,4′-bithiazole, and 2,4,6-trinitrophenol, respectively. Complex 1 was characterized by elemental analyses, IR and electronic spectra, and single-crystal X-ray diffraction. Its structure consists of two asymmetrical binuclear copper(II) units linked by carboxyl bridges into a circular tetranuclear copper(II) complex with an embedded center of inversion. The copper(II) centers are in square-planar and distorted square-pyramidal environments. Hydrogen bonds and aromatic stacking interactions link the tetranuclear copper(II) fragments into a 3D supramolecular structure. The interactions of complexes 1 and 2 with herring sperm DNA (HS-DNA) were investigated by electronic and fluorescence spectra and viscosity measurements. Both complexes bind to HS-DNA via the intercalative mode, and complex 2 displays a significant binding propensity to HS-DNA.     

X-ray and computational structural study of neutral <Emphasis Type="Italic">bis</Emphasis>(<Emphasis Type="Italic">N,N,N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-tetramethylthiophosphoramidoyl)-methylamine

The structure of bis(N,N,N′,N′-tetramethylthiophosphoramidoyl)-methylamine 1 has been determined by single-crystal X-ray diffraction. The compound 1 crystallizes in the monoclinic system, with a space group P2₁/c, a = 11.836(2) Å, b = 11.659(2) Å, c = 12.796(5) Å and β = 95.28(3)°, V = 1758.3(5) Å³ and Z = 4. The X-ray crystallographic data have been assessed by semi-empirical and ab-initio density functional theory and by Hartree–Fock molecular orbital methods. A comparative study of the results of the different methods is given.     

<Emphasis Type="Italic">N</Emphasis>′-tetrazolylmethoxyl derivatives of <Emphasis Type="Italic">N</Emphasis>-methyldiazene <Emphasis Type="Italic">N</Emphasis>-oxides

A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups.     

First example of the synthesis of <Emphasis Type="Italic">S</Emphasis>,<Emphasis Type="Italic">O</Emphasis>-macroheterocycle based on 2(5<Emphasis Type="Italic">H</Emphasis>)-furanone and 2,2´-oxydiethanethiol

A base-catalyzed reaction of 3,4-dichloro-5-methoxy- and 3,4-dichloro-5-ethoxy-2(5H)-furanones with 2,2´-oxydiethanethiol gave thiols and bis-thioethers of 2(5H)-furanone series. A new S,O-macroheterocyclic compound containing a 18-membered oxathiamacrocycle and two 2(5H)-furanone fragments was synthesized based on the thiols in an aqueous solution of potassium hydroxide, which was characterized by X-ray diffraction.     

New heteroscorpionate lanthanide complexes for ring-opening polymerisation of <Emphasis Type="Italic">ε</Emphasis>-caprolactone and <Emphasis Type="Italic">rac</Emphasis>-lactide

Yttrium and lanthanum amido-complexes with bis(pyrazol-1-yl)acetates in their coordination spheres were studied as the catalysts in ε-caprolactone and lactide ring-opening polymerisation. A high molecular mass poly(ε-caprolactone) (PCL) was obtained in almost quantitative yield under mild conditions. rac-Lactide polymerisations were less efficient and required quite harsh experimental conditions to obtain atactic PLA samples with moderate yields. The average chain-length of PCL was dependent upon the choice of the metal centre and the presence of substituents on the pyrazole rings of the ancillary ligand. The ground-state geometries of the complexes and the first stages of ε-caprolactone polymerisation were computationally modelled by means of DFT calculations.     

Directed Aminomethylation of Pyrrole,Indole, and Carbazole with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-Tetramethylmethanediamine

Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl₂·8H₂O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K₂CO₃ occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani.     

Synthesis and characterization of some <Emphasis Type="Italic">o</Emphasis>,<Emphasis Type="Italic">o</Emphasis>′-dihydroxyazo dyes and their metal complexes

The synthesis and characterization of azo dyes containing o,o′-dihydroxy groups and their azo-metal(II) [Cu, Co, Ni, Zn] chelates by ¹H N.M.R., IR, AAS, UV–VIS, magnetic susceptibility and thin-layer chromatography techniques are reported. The stochiometry of the azo-metal chelates was determined by the spectroscopic titration method to be 1:2 (ML₂). The synthesized azo dyes and azo-metal chelate dyes were applied on wool fabric. Fastness to light and washing were measured.     

Synthesis and crystal and molecular structures of <Emphasis Type="Italic">N,N</Emphasis>′-methylenedipyridinium tetrachlorozincate(II) and <Emphasis Type="Italic">N,N</Emphasis>′-methylenedipyridinium tetrachlorocadmate(II)

Treatment of N,N′-methylenedipyridinium dichloride [C₅H₅N-CH₂-NC₅H₅]Cl₂ with MCl₂ (M = Zn or Cd) in aqueous solution gives the organic-inorganic hybrid ionic compounds [C₅H₅N-CH₂-NC₅H₅] · [MCl₄]. Both complex salts were fully characterised by multinuclear NMR spectroscopy, elemental analysis, and their molecular structures confirmed by powder X-ray diffraction studies. The most striking feature in both solid state structures was the presence of the C…Cl-M short contacts between the organic [C₅H₅N-CH₂-NC₅H₅] dication and inorganic [MCl₄] anion, which led to different crystal packing. For [C₅H₅N-CH₂-NC₅H₅]·[ZnCl₄], the C…Cl-Zn interactions led to the alternating arrangement of [C₅H₅N-CH₂-NC₅H₅]²⁺[ZnCl₄]²⁻ to form 1-D chains in the direction [010], and each individual chain had a two-fold rotational axis along the b axis, while for [C₅H₅N-CH₂-NC₅H₅] · [CdCl₄] the C…Cl-Cd associations gave 2-D network. In both solid state structures, the presence of Cl-ring centroid distances gave a strong indication of some form of Cl-π interactions.     

Synthesis,characterization, and biological activities of oxovanadium(IV) and cadmium(II) complexes with reduced Schiff bases derived from <Emphasis Type="Italic">N,N′</Emphasis>-<Emphasis Type="Italic">o</Emphasis>-phenylenebis(salicylideneimine)

New oxovanadium(IV) and cadmium(II) complexes with reduced Schiff bases derived from N,N′-o-phenylenebis(salicylideneimine) have been synthesized and characterized using infrared and UV-visible spectra, ESR, and thermogravimetry. The complexes were identified as [ML] · (H₂O) species, where deprotonated ligands are coordinated to metal through N₂O₂ donor atoms. Antioxidant activity of the ligands and complexes was evaluated, revealing that the complexes exhibit a higher scavenging activity than the corresponding ligands. The prepared cadmium complexes showed slightly higher activity than the vanadium ones. Antifungal activity was tested against different human fungi including yeasts of the Candida genus (C. albicans and C. glabrata) and an opportunistic mould Aspergillus fumigatus. The oxovanadium complexes exhibited a very low activity toward C. albicans while the cadmium ones showed a significant growth inhibition of all the fungi tested; mainly of A. fumigatus though this mould is poorly susceptible to current antifungal agents like Itraconazole.     

<Emphasis Type="Italic">N</Emphasis>-arylsulfanyl-<Emphasis Type="Italic">N</Emphasis>-arylsulfonyl(acyl)-<Emphasis Type="Italic">N</Emphasis>′-phenylthiourea sodium salts

Reactions of N-arylsulfonyl(acyl)arenesulfenamide sodium salts with phenyl isothiocyanate afforded N-arylsulfanyl-N-arylsulfonyl(acyl)-N-phenylthioura sodium salts which were found to increase thermal stability of finely dispersed poly(vinyl chloride).Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1532–1535.Original Russian Text Copyright © 2004 by Koval, Oleinik.     

<Emphasis Type="Italic">N,N</Emphasis>′-bis(<Emphasis Type="Italic">ortho</Emphasis>-acylaryl)diaza-18-crown-6 ethers: Synthesis,complexation in solution,and crystal structure of the complex with lead perchlorate

Two new lariat ethers were obtained from N,N′-diaryldiaza-18-crown-6 (Ar = 2-formyl-4-methylphenyl (II) and 2-benzoyl-4-methylphenyl (III)). In the ethers obtained, the carbonyl O atoms act as additional electron-donating sites. Complexation of lariat ethers II and III with metal cations in solution was studied by ¹H NMR spectroscopy (acetone-d₆, methanol-d₄). The stability constants of the resulting complexes were determined. For lariat ether III and its complexes, the magnetic anisotropy of the benzoyl groups substantially influences the chemical shifts of the protons of the macrocycle. The stability of the complexes increases from ether II to III and in the order K⁺ < Ba²⁺ < Pb²⁺. Complexes with La³⁺ were not obtained. The complex of lariat ether II(L) with Pb(ClO₄)₂, [PbL(H₂O)](ClO₄)₂ · H₂O, was characterized by X-ray diffraction. The Pb²⁺ cation is in the cavity of the lariat ether and is coordinated by the formyl O atoms on one side of the macrocycle plane and by the water molecule on the other side (C.N. 9).     

Synthesis,structure, and magnetic properties of magnesium bis-3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-<Emphasis Type="Italic">о</Emphasis>-benzosemiquinonate complexes with N-donor ligands

A series of six-coordinate magnesium bis-3,6-di-tert-butyl-о-benzosemiquinonate complexes with different N-donor ligands (2,2´-dipyridyl, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, pyridine, N-phenyl-1-(4-pyridinyl)methanimine) were synthesized. The molecular and crystal structures of these complexes were determined by X-ray diffraction. In the complexes with bidentate N-donor ligands, the O,O-diolate o-semiquinone ligands are cis to each other, whereas the compounds with monodentate ligands contain organic radical anions in trans positions. The specific features of magnetic exchange coupling between organic radical ligands were studied by temperature-dependent magnetic susceptibility measurements.     

The synthesis and characterization of copper(II)–<Emphasis Type="Italic">p</Emphasis>-aminosalicylate complexes with diamine ligands

The complexes were synthesized by the reaction between sodium salt of p-aminosalicylic acid (PAS) and Cu(II) for 1 and corresponding ethylenediamine (en) or its derivatives for 2–6. The complexes were characterized by using elemental analyses, FT-IR, UV–Vis, magnetic moment measurements, and thermal analyses techniques. In complex 1[Cu₂(PA)₄(H₂O)₂], two Cu(II) ions were found as bridged by four μ-O:O′ p-aminosalicylato (PA) ligands, forming a cage structure, and two aqua ligands to form dinuclear square-pyramidal geometry around Cu(II) ions. In the complexes 2–6, the PA (anionic form of p-aminosalicylic acid) coordinated to Cu(II) ions as monodentate manner by using its oxygen atom of deprotonated carboxylic acid and ethylenediamine derivatives coordinated to the Cu(II) ions in bidentate manner to form mononuclear octahedral complexes [Cu(PA)₂(L)₂] (L = ethylendiamine, N,N-dimethylethylendiamine, N,N′-dimethylethylendiamine, N,N,N′,N′-tetramethylethylendiamine, and 1,3-propanediamine, for complexes 2, 3, 4, 5, and 6, respectively). In all the complexes OH and NH₂ groups of PA ligands were not coordinated to metals.     

Synthesis of <Emphasis Type="Italic">α</Emphasis>-chloropyridine derivatives of <Emphasis Type="Italic">γ</Emphasis>-aminobutyric acid

The sodium salt of N-(6-chloronicotinoyl)-γ-aminobutyric acid, a structural analog of the known nootropic and vasidilating drug picamilon, was synthesized via Schotten–Baumann acylation of γ-aminobutyric acid with 6-chloronicotinoyl chloride and subsequent neutralization of the N-(6-chloronicotinoyl)-γ-aminobutyric acid that was obtained in >60% yield.     

Determination of the <Emphasis Type="Italic">R</Emphasis> ⇄ <Emphasis Type="Italic">S</Emphasis> enantiomerization barrier in 5,6-dihydrobenzoimidazo[1,2-<Emphasis Type="Italic">c</Emphasis>]quinazolines

Chiral imidazoquinazolines undergoing thermally induced reversible R ⇄ S enantiomerization have been synthesized by the interaction of 2-(o-aminophenyl)benzimidazoles with aldehydes and ketones. The benzimidazole fragment has been used for the first time as an indicator group in temperature-dependent ¹H NMR spectra for determining the energy barrier of this rearrangement. The effects of nearby substituents on the kinetic and activation parameters, and on the recyclization mechanism have been investigated.     

Synthesis and structure of the cobalt(II) coordination compounds with <Emphasis Type="Italic">N,N</Emphasis>-dimethyl-<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-dimethylthiocarbamoylsulfenamide

The CoLX₂ complexes were obtained by the reaction of N,N-dimethyl-N′,N′-dimethylthio-carbamoylsulfenamide (L) with CoX₂ (X = Cl, Br, I, NCS). The complexes were investigated by elemental and X-ray analysis, IR, ¹H NMR, and electron spectroscopy, conductometry, magnetochemistry, thermogravimetry. It is found that these compounds are high-spin complexes of pseudotetraedral structure with bidentate coordination of L through the thione sulfur atom and sulfenamide nitrogen atom.