Oxime Oxygen Atoms Research Articles

Interaction of Cefdinir with Iron in Aqueous Solution.

Cefdinir (CFDN) is an orally active, semisynthetic cephalosporin antibiotic and its structure is characterized by an oxyimino side chain which is able to form complexes with various metal ions. We observed that bioavailability of CFDN in dogs was reduced when it was co-administered with iron(II) salts. To assess possible effects of extraneous iron such as iron supplements on the bioavailability of CFDN, stability constants of the complexes formed between CFDN and iron(II) and iron(III) have been determined in aqueous solution by potentiometric and spectrophotometric titration methods. The stability constants were as follows : log β110=7.53, log β120=14.44, log β130=18.33 for the iron(II) complexes and log β110=10.43, log β120=20.40 and log β130=27.54 for the iron(III) complexes. Theoretical species distribution diagrams as a function of pH for solutions of metal (M) (0.1 mM) and ligand (L) (0.3 mM) showed that M1L1H0 and M1L2H0 existed as major species for the iron(II) system and M1L2H0 and M1L3H0 were main species for the iron(III) system under neutral conditions. From these results it is believed that complex formation in the digestive tract is involved in the reduction of the bioavailability of CFDN in dogs. In addition, spectrophotometric studies indicated that iron(II) coordinated to CFDN via the thiazole-ring and deprotonated oxime nitrogen atoms and iron(III) coordinated via the amide and deprotonated oxime oxygen atoms.

Synthesis and X-Ray Structures of Ni(II) Complexes of 1-(2-Pyridinyl)Ethanone Oxime

Abstract A study of the complexation of Ni(II) with 1-(2-pyridinyl)ethanone oxime as a function of pH was carried out. A green complex, dibromobis(1-(2-pyridinyl)ethanone oxime)nickel(II), was isolated at pH 3. This octahedral complex (1) crystallizes in space group P21/n (a = 8.754(2), b = 11.136(3), c = 18.210(4) A, β = 92.18(2)[ddot], Z = 4) and has cis bromide ions (av. Ni-Br = 2.57(2) A), cis pyridine nitrogens (av. Ni-N = 2.091(9) A), and trans oxime nitrogens (av. Ni-N = 2.043(7) A). An orange octahedral complex, diaquo(1-(2-pyridinyl)ethanone oxime)(1-(2-pyridinyl)ethanone oximato)nickel(II) nitrate, (2) crystallized at pH 6 in space group P21/c (a = 12.497(3), b = 7.501(2), c = 20.940(5) A, β = 95.59(2)[ddot], Z = 4) and has trans water molecules (av. Ni-O = 2.069(5) A), cis pyridine nitrogens (av. Ni-N = 2.109(5) A, and cis oxime nitrogens (av. Ni-N = 2.037(6) A). Complex (2) has a short intramolecular hydrogen bond between oxime oxygen atoms (O…O = 2.524(3) A). A dark reddish-brown complex form...

Synthesis of an ether oxime ligand and its rhodium(III) complex, and X-ray structure of the rhodium(III) complex: Unique rhodium(III) bonding to a simple ether

The ligand 3-methoxy-3-methyl-2-butanone oxime and its rhodium(III) complex have been synthesized, and the complex has been structurally characterized. The octahedron around the rhodium atom involves two trans-chlorine atoms [RhCl = 2.3236(8) Å], two cis-oxime nitrogen atoms [av. RhN = 1.958(3) Å] and two cis-ether oxygen atoms [av. RhO = 2.117(3) Å]. The oxime oxygen atoms are involved in a short intramolecular hydrogen bond (OO = 2.391 Å). Synthesis and characterization of the ligand and the rhodium(III) complex are described, and the 1H NMR results are given and discussed. To our knowledge this is the first characterized ether oxime metal complex.

Syntheses and Structures of μ-Oxo-Bis[dichloroiron(III)]-Bis-[2,6-Diacetylpyridinedioximate(-1)]Iron(II) and Related Compounds

The syntheses and structures of four new compounds are described. Two of these compounds are the anhydrous and dihydrate chloride salts of the diamagnetic bis(2,6-diacetylpyridinedioxime)iron(II) cation, [Fe(DAPDH2)2]2+. In this complex cation the DAPDH2 ligand binds to the iron, as expected, through its three nitrogen atoms leaving the four oxime oxygen atoms protonated and uncoordinated. The third compound is (AsPh4)2[Fe2OCl6], a new salt of the well-known oxo-bridged diiron complex, [Fe2OCl6]2−. The synthesis of (AsPh4)2[Fe2OCl6] is a high yield, straightforward, one-step preparation starting with AsPh4Cl and ferrous chloride in methanol. In this synthesis Fe(II) is oxidized to Fe(III) by atmospheric O2. The fourth new compound is the novel and unexpected triiron complex [Fe(DAPDH)2Fe2OCl4]. This complex is derived from [Fe(DAPDH2)2)]2+ and [Fe2OCl6]2− by removing the H+ from each of two adjacent oxime oxygen atoms of the former and one Cl− from each of the Fe(III) ions of the latter. The resulting neu...

Acid induced reactions of a sydnone ketoxime

Abstract3‐(2‐Acetylphenyl)sydnone oxime 1a reacts with acids (methanesulfonic‐, p‐toluenesulfonic, trifluoroacetic‐acid or Amberlite IR 118) to give products apparently derived from protonation of the oxime oxygen or nitrogen atom followed by cyclization to the sydnone ring or interception by water.

PREPARATION, CHARACTERIZATION AND CRYSTAL STRUCTURES OF TWO AMINE-OXIME RHODIUM COMPLEXES

Abstract Two amine-oxime complexes of rhodium(III) have been synthesized and structurally characterized as model compounds for a study of potential rhodium radiopharmaceuticals. Dichlorobis (2-acetylpyridineoxime)-rhodium(III) crystallizes in space group Pnma with a=13.462(4), b=12.496(2), c=9.661(2)Å, Z=4, Dx =1.819(2)g/cm3. The chloro ligands are trans (av Rh[sbnd]Cl=2.337(2)Å) in the octahedral Rh(III) complex. The oxime oxygens are involved in a short intramolecular hydrogen bond (O[sbnd]O=2.446(4)Å) with the hydrogen atom as well as the rhodium and two chlorine atoms on the mirror. Dichloro-[4,4′-(1,2-ethanediyldiimino)bis(4-methyl-2-pentanone-dioxime)]rhodium (III) crystallizes in space group P212121 with a=14.435(3), b=7.638(9), c=16.596(3)Å, Z=4, Dx =1.667(2)g/cm3. The trans dichoro octahedral complex (av Rh[sbnd]↓ =2.341(11)Å) has cis amine nitrogens (av Rh[sbnd]N=2.079(3)Å) and cis oxime nitrogens (av Rh[sbnd]N=2.030(3)Å). The oxime oxygen atoms are involved in a short intramolecular hydrogen bond (O[sbnd]O=2.423(3)Å). Synthesis and proton magnetic resonance results are included, along with a comparison with other rhodium(III) amine-oxime complex structures.

Intramolecular hydrogen bonding: synthesis and crystal structure of nickel(II) and copper(II) complexes of a tetradentate amine oxime

In the reaction of the tetradentate ligand 3,3′-(1,4- butanediyldiamino) bis (3-methyl-2-butanone)-dioxime (BnAO) with nickel(II) and copper(II), the monomeric [Ni(BnAO-H)]I·H 2O and a mixed monomer/dimer salt [Cu(BnAO-H)H 2O] 2[(Cu(BnAO-H)) 2](ClO 4) 4, respectively, are formed, and all complexes have an intramolecular hydrogen bond between cis oxime groups. The OHO bonds give the characteristic infrared absorptions as well as the downfield proton-NMR signal (Ni complex). [Ni(BnAO-H)]I·H 2O crystallizes in space group P2 1/ a with a=13.511(2), b=10.599(2), c=14.096(2) Å, β=97.52°, Z=4 and D c=1.623 g/cm 3. The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to a final R of 0.021 for 2124 reflections with I 2σ( I). The nickel(II) atom in the complex has slightly distorted square planar geometry with an intramolecular O···O contact of 2.417(7) Å. The copper(II) complex crystallizes in space group P2 1/ c with a =13.425(2), b=21.446(3), c=14.349(4) Å, β= 104.4(5)°, Z=8 (monomers) and D c=1.485 g/cm 3. The final R value for this complex was 0.053 for 3033 reflections with I 2σ( I). This structure contains a monomeric [Cu(BnAO-H)H 2O] + ion and a dimeric [(Cu(BnAO-H)) 2] 2+ ion, having intramolecular O···O hydrogen bonds of 2.421(5) and 2.531(5) Å, respectively. The copper(II) ions have square-pyramidal coordination with the axial positions occupied by an oxygen of the water of hydration in the monomer and by an oxime oxygen atom in the dimer. A center of symmetry relates the two halves of the dimer. The copper atom in each case is out of the plane of the four nitrogen atoms toward the axial site. The copper(II) complex is unusual in that the crystal contains both a monomer and a dimer.

A SHORT HYDROGEN BONDED COLUMNAR STRUCTURE: SYNTHESIS, SPECTROSCOPIC STUDIES AND X-RAY STRUCTURE OF A PALLADIUM(II) COMPLEX OF ALFA-FURIL DIOXIME

Abstract Synthesis, spectroscopic studies and single crystal X-ray structure of [Pd(Hafdo)2], where H2afdo is α-furilglyoxime, were carried out because of its potential columnar stack structure and the existence of a short intramolecular hydrogen bond. The compound crystallizes in the orthorhombic space group Pnab with a=6.930(3), b=14.286(2) and c=19.837(4) A. The intensity data were collected on a CAD-4 diffractometer and the structure was refined to a final R value of 6.1%. The central metal atom in this inner complex has planar geometry and the oxime oxygen atoms are involved in a short intramolecular hydrogen bond with O[sbnd]O distance of 2.583(4) A. The complex molecules are stacked above one another along the crystallographic a axis with adjacent molecules rotated 90° with respect to each other. The Pd-Pd distance is 3.465(4) A. The two oxygen atoms of the planar furane groups are separated by 2.686(4) A and the furane rings are oriented at an angle of 46.7° with respect to each other. The columna...

SYNTHESIS AND CHARACTERIZATION OF ANTI-2-FURAN CARBOXALDOXIME COMPLEXES WITH COBALT(II), COPPER(II & I) AND SILVER(I)

Abstract The ligand, 2-furan carboxaldoxime exists in two geometrical isomeric forms: anti-(β-form) and syn-(α-form). Six different complexes of Co(II), Cu(II), Cu(I) and Ag(I) with anti-2-furan carboxaldoxime (FDH) have been prepared and characterized by elemental analysis, molecular weights, conductance studies, magnetic moments and infra-red spectral studies. These are [Co(FDH)4Cl2], [Co(FD)2], [Cu(CH3COO)2 (FDH)]2, [Cu(FD)(OH)]2, Cu(FDH)2 Cl and AgNO3·2FDH. Under the similar conditions, syn- form does not form any complex with these metal ions. The complexes [Co(FDH)4Cl2] and [Co(FD)2] are neutral, monomeric and para-magnetic (μ=4.88 and 4.52 BM respectively); the former may be considered as octahedral with FDH acting as monodentate, and the latter as tetrahedral with FD− as a bidentate ligand. Both the Cu(II) complexes are neutral, dimeric, weakly para-magnetic (μ=0.44 and 0.28 BM respectively) with the bridging acetato groups in [Cu(CH3 COO)2 (FDH)]2 and with bridging hydroxo groups in [Cu(FD)(OH)]2. The Cu(I) complex may be polymeric, being insoluble in most solvents. The Ag(I) compound is cationic 1:1 electrolyte in nitrobenzene. In all these complexes the ligand functions as monodentate and/or bidentate, coordinating with furan oxygen and oxime oxygen in the latter case. The C[sbnd]O[sbnd]C stretching frequency of furan may be taken as the criterion for the denticity of this ligand which is observed at 1240 cm−1 (in the free ligand). A shift to lower frequency is observed in the complex if the ligand acts as bidentate. However this frequency is not affected if the ligand acts as monodentate coordinating through the oxime oxygen atom. The ligand has been shown to be present in the ionized and/or unionized form in these complexes.