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The electrochemical behavior of the species [Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)I] and [Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)(ACN)](+) in ACN solutions, at 25 degrees C, is described. The kinetic analysis of the cyclic voltammetry curves indicates that the introduction of one electron in the former complex is concerted with the dissociation of the Co-I bond. The ensuing radical undergoes fast solvation to yield the solvato complex [Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)(ACN)](.), which then acts as an efficient electron donor toward the starting material with the formation of[Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)(ACN)](+); finally, the cation is electroreduced at the working potentials to conclude an overall autocatalytic sequence. The solvato complex [Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)(ACN)](.), formed as a product of the above reduction process, can be reversibly reduced to the corresponding anion at more negative potentials. Confirmation of the above mechanism and of the fact that the solvato complex can act as a solution electron donor toward the starting material was obtained by studying the electrochemical behavior of the solvato complex itself and through calculations aimed to better define the dissociative electron-transfer process to [Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)I]. The dissociation of the metal-halide bond in the neutral complex [Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)I], with the formation of[Co(eta(5)-C5H5)(eta(3)-2-MeC3H4)(ACN)](+), was also found to occur spontaneously, in the bulk, through the observation of a progressive change of the cyclic voltammetric pattern. Support for the occurrence of the reaction between the starting complex and the solvent was confirmed by conductivity and spectroscopic measurements, which allowed the rate constant for the homogeneous solvolysis to be determined.

A review with 59 refs. describing the synthesis, structure, and reactivity of monocyclopentadienyl compds. of vanadium. [on SciFinder(R)]

The two new pincer azomethine-thiophene ligands (N,NE',N,NE')-N,N'-(thiophene-2,5-diylbis(methan-1-yl-1-ylidene))bis(naphathalen-2-ylmethanamine) (L1) and (E)-(4,6-dihydropyren-1-yl)-N-((5-((E)-(pyren-1-ylmethylimino)ethyl)thiophen-2-yl)methylene)methanamine (L2), their absorption, fluorescence and MALDI-TOF-MS spectroscopic studies are described. The two systems synthesised combine the emissive probes pyrene and naphthyl with the good chelating properties of a tridentate SN2 donor-set from a thiophene Schiff-base ligand. Both ligands gave analytically pure solid complexes with Ni(II) and Pd(II) salts. The bichromophoric pyrene derivative L2 presents two emission bands in solution, one corresponding to the monomer species and a red-shifted band attributable to the intramolecular excimer. Ni(II) and Pd(II) complexation affects the conformation in solution, increasing the monomer emission at the expense of the excimer band; this effect could be explored in metal ion sensing. System L1 behaves as a non emissive probe. In situ complexation reactions followed by MALDI-TOF-MS spectrometry without matrix support have also been performed; these experiments show that L1 could be a potential chemosensor for Ni(II) and Pd(11). (c) 2007 Elsevier B.V. All rights reserved.

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{{A series of new cationic and neutral (Ar-BIAN) copper(I) complexes {[}in which Ar-BIAN = bis(aryl)acenaphthenequinonediimine] was synthesised and characterised by elemental analysis, 1D and 2D NMR spectroscopy and single-crystal Xray diffraction. The cationic complexes of the general formula {[}Cu(Ar-BIAN)L-2]BF4 {[}L-2 = (PPh3)(2) (1), dppe (2), dppf (3), (AsPh3)(2) (4); Ar = 4-iPrC(6)H(4) (a), 4-MeOC6H4 (b), 4-NO2C6H4 (c), 2-iPrC(6)H(4) (d), Ph2PCH2CH2PPh2 (dppe), (Ph2PC5H4)(2)Fe (dppf)] were synthesised by reaction of {[}Cu(EPh3)(4)]BF4 (E = P or As) and equimolar amounts of Ar-BIAN ligands, or by reaction of equimolar amounts of {[}Cu(NCMe)(4)]BF4, 4-iPrC(6)H(4)-BIAN (a) and diphosphanes dppe or dppf, in dichloromethane, whereas the neutral complexes of the types {[}CuX(Ar-BIAN)(EPh3)] {[}X = Cl