271 J. Electroanal. Chem., 274 (1989) 271-279 Elsevier Sequoia S.A., Lausanne - printed in The Netherlands zyxwvutsrqponmlkjihgfedcbaZYXWV Pre Iim lna ry note zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA New stable modified electrodes coated by electroactive films of ~l~~ole nickel( II)-biplane complex Eric Labbe, Fetid Bedioui and Jacques Devynck * Laboratoire ~Electr~himie (URA 216 da CNRS), Ecole N&male Sup&ewe de Chimie de Paris, II rue P&M Curie, 7.5231Paris Cedex OS (France) (Received 6 October 1989) INTRODUCTION Transition metals, and especially nickel, when in a low valent state and stabilized by various organic or mineral ligands, are well known catalysts for homogeneous organic reactions [l]. Catalytic agents made up with monovalent or zerovalent nickel are usually obtained by chemical or electrochemical reduction of Ni(II) complexes. For the most part, the work reported in the field of organic electrosynthesis concerns complexes in which nickel is ‘associated with phosphorous ligands [2], such as tertiary phosphine, and with 2,2’-bipyridine [2-81. In the latter case, electroas- sisted catalysis is essentially applied to dimerisation or codimerisation of dienes and alkenes, home- and heter~up~ng of organic halides and car~xylation of organic compounds. In order to improve or to promote a desired electrochemical sequence in a whole electroassisted catalytic process, the attachment of transition-metal complexes to electrodes, in relation to confining and ~n~tra~g them in the vicinity of the electron source, has been researched intensively over the past several years [9]. Thus, pyrrole-based polymers containing catalytic sites have been prepared by electropoly- merisation of adequately designed transition-metal complexes with pyrrole-sub- stituted ligands [lo]. Recently, our efforts have concentrated on the preparation of polypyrrole-polypyridyl complex- Ill-141 and polypyrrole-metalloporphyrin- [15-171 modified electrodes aimed at catalyzing organic reactions. The electrochemical preparation and behaviour of polymer-supported Ni cata- lysts obtained by el~tropol~~sation of p~ol~substituted ligands have been reported [13,18-201. The modified electrodes obtained do not offer a good and sufficient stability and electroactivity, and in some cases, the Ni(II)-polypyrrole * To whom wrrespondence should be addressed. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED 0022-0728/89/‘$03.50 8 1989 EClsevk Sequoia S.A.