Jean-Michel Kerbaol

Cobalt(II)-dibenzotetraaza[14]annulene complex electropolymerization for electrode modification

Abstract Cobalt complexes of dibenzotetraaza[14]annulene (CoTAA), 5,7,12,14-tetramethyldibenzotetraaza[14]annulene (CoTMTAA), and dichlorodibenzotetraaza[14]annulene (CoTAACl 2 ) have been studied by voltammetry in benzonitrile (BN). Their electropolymerization from solutions in BN was performed by oxidation at carbon and platinum electrodes. The Co(II)/Co(I) and Co(III)/Co(II) redox systems are clearly apparent on the voltammograms, as well as the electroactivity of the conducting polymer, when the electrode is in contact with the non-aqueous solvent. More surprising is the fact that the modification of electrode surfaces is also possible from the oxidation of aqueous acidic solutions of CoTAA and CoTAACl 2 (2.25 M H 2 SO 4 ). In contact with an acidic aqueous medium (0.5 M H 2 SO 4 ), the Co(III)/Co(II) system of poly(CoTAA) is fully reversible. The polymer thus obtained can grow as a remarkably thick, dense and conducting phase.

Syntheses, structural characterisation and magnetic properties of Fe(II) and Mn(II) compounds with the pentacyanopropenido ligand; structural characterisation of a substituted pyrazolo[1,5-a]pyrimidine

Reactions between the metal(II) salts [M(CH3CN)n](BF4)2 (M = Fe, n = 6; M = Mn, n = 4) and some organic anionic polynitriles were studied. With the pentacyanopropenide anion pcp− [pcp− = (NC)2CC(CN)C(CN)2−], were obtained, according to the experimental conditions, the new complexes [M(pcp)2(H2O)4] (1, M = Fe; 2, M = Mn) and [M(pcp)2] (3, M = Fe; 4 = Mn). Use of the hexacyano-3,4-diazahexadienediide anion [(NC)2CC(CN)NNC(CN)C(CN)22−] instead of pcp− did not afford polynitrile metal complexes but led to a new organic derivative 5, of formula C10N8H2. Crystallographic studies indicated that the isostructural compounds 1 and 2 involve discrete monomeric units with pcp ligands acting with a monodentate coordination mode and having the metal in a pseudooctahedral trans-MN2O4 environment; however, a rich hydrogen bond system gives rise to a 3D array. Complex 3, which presents metal in a pseudooctahedral MN6 environment, has a 3D structure arising from pcp ligands having an unprecedented μ3-coordination mode. Compound 5 is a bicyclic derivative with a pyrazolo[1,5-a]pyrimidine skeleton. In all derivatives, the organic part is essentially planar and involves a strongly delocalized π system. The magnetic properties of the inorganic complexes have been studied in the 2–300 K range. Fit of the magnetic data indicates high spin complexes with weak antiferromagnetic interactions in 2, 3 and 4 and the presence of a significant zero field splitting of the Fe(II) ion in 1.

Unprecedented reactivity of a Schiff base ligand in the co-ordination sphere of copper(I) complex towards β-diketones. Synthesis and X-ray characterisation of a new copper(I) complex

The reactions of the copper(I) derivative [CuL(THF)(CH 3 CN)]PF 6 ( 1 ), in which L is the di-imine/pyridine ligand 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine, with different β-diketones (2,4-pentanedione (acacH), 1,3-diphenyl-1,3-propanedione (dbm)) yielded the new Cu(I) salt [CuL′ 2 ]PF 6 ( 2 ) (L′: 2-[acetyl]-6-[1-(2,6-diisopropylphenylimino)ethyl]pyridine). These reactions of β-diketones with a di-imine/pyridine ligand co-ordinated to a Cu(I) centre constitute the first example of a partial hydrolysis of such a Schiff base within the inner sphere of a Cu centre. Compound 2 ·acaH has been characterised by X-ray crystallography.