Bis(alkynyl) transition metal complexes, R1C≡C-[M]-C≡CR2, as organometallic chelating ligands;: formation of μ,η1(2)-alkynyl-bridged binuclear and oligonuclear complexes

The reaction chemistry of bis(alkynyl)metal complexes towards different metal centers (electron-rich or electron-poor) to give alkynyl-bridged binuclear and oligonuclear species is described. Different coordination modes of the alkynyl ligands are found in these systems, depending upon the nature of the alkynyl substituents and the metal centers involved. The interconversion of these structures, as well as the factors affecting the preference for one coordination mode over another, is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.