Jadwiga Trocha-Grimshaw

Oxidative nitrogen ⋯ nitrogen coupling of nitriles at a dicopper site and the structure of a pentanuclear copper–triazolyl complex containing two-co-ordinate and three-co-ordinate copper(I)

Reaction of a di-copper(II) complex of a macrocyclic ligand with acetonitrile in the presence of O2 and H2O affords a pentanuclear complex containing two-co-ordinate and three-co-ordinate copper(I) atoms linked via triply bridging 3,5-dimethyl-1,2,4-triazolate groups.

Dicarbonylrhodium(I) complexes of polypyrrole macrocycles. Part 2. Oxidative addition reactions with aldehydes, formates, β-oxo-esters, methyl ketones, and aryl halides

Out-of-plane bisdicarbonylrhodium complexes of etioporphyrin I and a monoazaporphyrin undergo oxidative addition reactions with a variety of substrates RX [R = aryl, acyl, arylcarbonyl, alkoxycarbonyl, ethoxycarbonylmethyl, R′COCH2, or I; X = H or Br (usually) or I or CH2COMe (in certain cases)]. One rhodium atom is detached from the macrocycle. The remaining R–RhIII species is captured by the central porphyrin cavity, retaining R, but with loss of X, to give R–RhIII-etioporphyrin I or -monoazaporphyrin. Several new types of oxidative addition reaction have been observed, including insertion of rhodium into the Cα–H bond of a methyl ketone. The first isolation of stable acylrhodium(III) complexes from the reaction of rhodium(I) complexes with aldehydes is reported, and an improved method for preparing rhodium(III) porphyrins is described.

Activation of an aryl CH bond to oxygen insertion: Model for the phenoloxidase activity of tyrosinase

Abstract The reactions of dioxygen with the binuclear tricoordinate copper(I) complexes, derived from the condensation of benzene- 1,3-dicarboxaldehyde and two molecules of a diamine, give phenoxy-bridged copper(II) complexes by direct hydroxylation of the benzene ring.

Cyclizations. Part 3. Use of a mild-steel cathode in the electrochemical intramolecular cyclization of aryl halides

Abstract One electron reduction of aryl halides is known to generate the aryl radical and halide ion. These aryl radicals will cyclize onto an adjacent benzene ring in a reaction that is potentially useful in organic synthesis and which is well documented at a mercury cathode. 5-(2-Halophenyl)-1-(4-fluorophenyl)tetrazoles are used here as representative substrates and the cyclization reaction to 7-fluorotetrazolo[1,5-f]phenanthridine is developed at cathodes of cadmium, zinc and mild-steel. A high yield of the desired cyclization product is achieved using a mild-steel cathode and a sacrificial magnesium anode in an undivided cell with acetonitrile, 0.1 M tetraethyl ammonium tetrafluoroborate as electrolyte and under an air atmosphere.

Characterisation of 1,6- and 1,8-dibromopyrenes

Treatment of pyrene or 1-bromopyrene with limited amounts of bromine affords 1,6-dibromopyrene and 1,8-di-bromopyrene (not isolated pure by previous workers). Further bromination of either dibromide gives 1,3,6-tri-bromopyrene.

Electrochemical reactions. Part XVIII. Reductive cleavage of aromatic carbon–halogen bonds in the presence of deuterium oxide

Reductive dehalogenation of aromatic compounds at a mercury cathode in dimethylformamide containing 1% deuterium oxide with tetra-n-propylammonium perchlorate as supporting electrolyte may or may not result in deuterium incorporation, depending on the substrate. Compounds giving a radical anion intermediate which is detectable by cyclic voltammetry do not incorporate deuterium. The radical anion decomposes away from the electrode to a σ-radical which abstracts a hydrogen atom from the organic solvent. Compounds which give no detectable radical anion accept one electron in the initial step and fragment to a σ-radical at the electrode surface. This radical is reduced further to a carbanion which reacts with incorporation of deuterium into the product. Evidence for σ-radical intermediates in the latter cases comes from isolation of dimers or products of intramolecular radical cyclisation of appropriate substrates.

Aspects of catalysis. Part IV. Hydrogen transfer from propan-2-ol to αβ-unsaturated ketones catalysed by a soluble hydridoiridium complex. Isolation of a compound containing a carbon–iridium bond and a chelated keto-group

Double bonds in some αβ-unsaturated ketones are reduced by propan-2-ol in the presence of soluble iridium–sulphoxide catalysts. Chalcone gives (2-benzoyl-1-phenylethyl-O)dichlorobis(dimethyl sulphoxide)iridium as a crystalline intermediate, which is converted into dihydrochalcone on treatment with acids.

Identification of α1-acid glycoprotein (orosomucoid) in human synovial fluid by capillary electrophoresis

Capillary electrophoresis of human synovial fluid in a phosphate borate run buffer containing sodium dodecyl sulphate separates a hydrophilic glycoprotein, hyaluronan and a number of low-molecular-mass components. The hydrophilic glycoprotein is identified as alpha 1-acid glycoprotein (AGP), orosomucoid, by co-injection methods with human AGP and by reaction with neuraminidase which released N-acetylneuraminic acid. Finally, a sample of the glycoprotein was isolated by micropreparative capillary electrophoresis, examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis methods and shown to give a positive reaction with AGP antibodies. The peak due to AGP in the capillary electrophoresis is broad and gives evidence for the presence of glycoforms.

N-methylation of etioporphyrin I and octaalkyl-5-azaporphyrins : X-ray structure of trans-Na, Nb-dimethyletioporphyrin I triiodide

Abstract Improved procedures are reported for the preparation of mono-, di- and tri-N-methyl-etioporphyrin I. Demethylation of N a , N b , N c -trimethyletioporphyrin I under acidic, basic or thermal conditions gives N a , N b -dimethyl etioporphyrin I. N-Methylation of octaalkyl-5-azaporphyrins leads, in general, to mixtures of the isomeric mono-, di- and tri-N-alkylated 5-azaporphyrins. An X-ray crystal structure of N a ,N b -dimethyl etioporphyrin I triiodide confirms the trans arrangement of the N-Me groups. The two N-methylated pyrrole rings are twisted 27° to each other.

Dicopper(II) complexes of a binucleating N4 macrocycle containing mono- and di-atomic bridges; magnetic interactions mediated by alkoxo- and diaza-bridging ligands. Crystal structures of [Cu2(L1)(pz)2][ClO4]2, [Cu2(L1)(OEt)2(NCS)2], and [Cu2(L1)(OMe)2(MeCN)2][BPh4]2

Dicopper(II) complexes of 20-membered N4 binucleating macrocycles L1–L3 derived by a cyclic [2 + 2] condensation of diformylthiophene or diformylfuran with the appropriate diamine have been synthesised and characterised by analytical, spectroscopic, magnetic, and X-ray diffraction methods. A pair of bridging ligands, either alkoxo, OR–(R = H, Me, or Et), or diaza (pyrazolate or 1,2,4-triazolate), links the CuII ions. The crystal structure of three compounds [Cu2(L1)(pz)2][ClO4]2(1), [Cu2(L1)(OEt)2(NCS)2](6), and [Cu2(L1)(OMe)2(MeCN)2][BPh4]2(7) have been determined by X-ray diffraction (Hpz = pyrazole). In structures (6) and (7) the copper(II) ions have a trigonal-bipyramidal environment, with ethoxy [(6)] or methoxy [(7)] bridges in a position axial to one CuII and equatorial to the other. Despite the parallel disposition of the dz2 magnetic orbitals, strong antiferromagnetic superexchange is observed for this and the other parallel-planar alkoxobridged dimer described. In structure (1), the copper co-ordination environment is square planar, with cis disposed pyrazolate bridges. Moderate antiferromagnetic exchange is present in (1) and the other diaza compounds, and well defined triplet e.s.r. spectra are observed.