Recent developments in the chemistry of mono- and dinuclear complexes of the macrocyclic dianion, 5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11] tetraazac

Mixed-valence compounds of the early transition metals

Neutral and Cationic Group 4 Metal Compounds Containing Octamethyldibenzotetraazaannulene (Me8taa2-) Ligands. Synthesis and Reactivity of (Me8taa)MX2 and (Me8taa)MX+ Complexes (M = Zr, Hf; X = Cl, Hydrocarbyl, NR2, OR)

The voltammetric behavior in alkaline solution of a nickel-based chemically modified electrode (Ni-CME) prepared by oxidative electropolymerization of a nickel–tetraazaannulene complex (NiIIL) was investigated. After electrochemical deposition of the (NiIIL)n film in dichloromethane on a conducting substrate, the modified electrode was continuously cycled in alkaline solution until a steady voltammetric profile was obtained. Although upon electrochemical treatment in basic solutions the nickel–nitrogen tetracoordination of the (NiIIL)n film is probably lost, the nickel species remain entrapped inside the polymeric skeleton and exhibit stable redox behavior resembling that of the nickel hydroxide electrode. This makes it possible to prepare very thin films of nickel-based modified electrodes. In cyclic voltammetry experiments the Ni-CME exhibits a pH dependence of the peak potentials typical of the α-Ni(OH)2/γ-NiOOH redox process, and a separation between anodic and cathodic peak potentials of 64mV at pH 13.2 and 10 mVs−1. The redox catalysis at Ni-CMEs of representative compounds that are not easily electrooxidized, such as choline, cadaverine, γ-amino butyric acid (GABA), benzyl alcohol, and glycine, is demonstrated. The good stability of these nickel-based modified electrodes makes them attractive in analytical applications.

Electrode modification with a poly(NiII-tetramethyldibenzotetraaza[14]annulene) film. Electrochemical behavior and redox catalysis in alkaline solutions. I

Kinetics of methanol oxidation on poly(NiII-tetramethyldibenzotetraaza[14] annulene)-modified electrodes

[Mo(C 22 H 22 N 4 )] 2 PF 6 •CH 2 Cl 2 cristallise dans le systeme monoclinique avec le groupe d'espace C2/c. Affinement de la structure jusqu'a 0,054

New dimeric quadruply metal-metal bonded molybdenum(II) derivative with a dibenzotetraaza[14]annulene ligand: access to new mixed valence complexes and structural characterization of the MoII/MoIII dimer

The quadruply metal–metal bonded molybdenum(II) complex [Mo2L2](1)(L = C22H22N42–) reacts with tetracyanoethylene (TCNE) to afford first the biradical compound [(1)+·(TCNE)–·] and then, presumably via reaction with traces of water, the oxo-molybdenum(v) derivative [MoOL][C3(CN)5](2), the structure of which has been determined by X-ray diffraction [Mo–O 1.670(3)A]; reduction of (2) with Na/Hg gives the dinuclear multiply metal–metal bonded radical anion (1)–·.

Jean Marc Giraudon

Papers

New dimeric quadruply metal-metal bonded molybdenum(II) derivative with a dibenzotetraaza[14]annulene ligand: access to new mixed valence complexes and structural characterization of the MoII/MoIII dimer

Ready, reversible conversion of a quadruply metal–metal bonded dinuclear complex into a mononuclear complex