Portugaliae Electrochimica Acta 21 (2003) 85-90 PORTUGALIAE ELECTROCHIMICA ACTA Electrochemical Study of Alkynyl Fe(II) Complexes Ana I.F. Venâncio, a Luísa M.D.R.S. Martins a,b Armando J.L. Pombeiro a * a) Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. b) Secção de Química Inorgânica, DEQ, ISEL, R. Conselheiro Emídio Navarro, 1949-014 Lisboa, Portugal Received 10 September 2002; accepted in revised form 14 January 2003 Abstract The behaviour of the neutral alkynyl complexes trans-[FeBr(L)(depe) 2 ] (L = −C≡C− C(=CH 2 )Ph 1a, −C≡C−CPh 2 (H) 1b; depe = Et 2 PCH 2 CH 2 PEt 2 ) is studied by cyclic voltammetry and the electrochemical P L and E L ligand parameters for the alkynyl ligands are estimated showing that they behave as very strong net electron-donors. Keywords: alkynyl, anodic behaviour, electrochemical ligand parameters, cyclic voltammetry. Introduction The tertiary propargylic alcohols, HC≡CC(OH)R 1 R 2 (R 1 , R 2 = alkyl or aryl), are very versatile species and by reaction with a metallic fragment they can be converted into vinylidene, allenylidene and alkynyl ligands. In particular the allenylidene complexes (M=C=C=C ) present an extended unsaturated carbon chain and are expected to be highly reactive species (chemically [1-3] and * Corresponding author. E-mail address: pombeiro@ist.utl.pt