Synthesis and reactivity of bis-alkynyl appended metallocenes of Ti, Fe, and Co

Dimethyl)(phenylethynyl)silyl-substituted cyclopentadiene [C.sub.5][H.sub.5]Si[Me.sub.2][C.sub.2]Ph (1) was synthesized by the reaction of in situ generated [C.sub.5][H.sub.5]Si[Me.sub.2]Cl with Li[C.sub.2]Ph. Metallation of 1 with [sup.n]BuLi or KN[(Si[Me.sub.3]).sub.2] gave the corresponding Li (2) and K (3) salts. Transmetallation of 2 with transition metal halides MCl2 (M = Ti[Cl.sub.2], Fe, and Co) generated the corresponding early and late transition metal metallocenes (4, 5, and 6) with pendant alkynyl substituents. Compounds 4 and 6 are the first examples of bis alkyne appended Ti and Co metallocenes. Complexes 5 and 6 undergo alkyne dimerization in the presence of CpCo[(CO).sub.2] generating metallocenophanes 7 and 8 incorporating two metal atoms. Compounds 3, 4[Cl.sub.2], 6, and [8][OTf] have been characterized by single crystal X-ray structure analysis. Key words: cyclopentadiene, alkyne, titanium, cobalt, heterometallic, metallocenophane. Resume : On a realise la synthase du (dimethyl)(phenylethynyl)silylcyclopentadie;ne, [C.sub.5][H.sub.5]Si[Me.sub.2][C.sub.2]Ph (1) par reaction du chlorure de (dime;thyl)(phe;nyle;thynyl)silyle, [C.sub.5][H.sub.5]Si[Me.sub.2]Cl avec le Li[C.sub.2]Ph. La metallation du produit 1 avec [sup.n]BuLi ou le KN[(Si[Me.sub.3]).sub.3] conduit aux sels correspondants du lithium (2) ou du potassium (3). La transmetallation du produit 2 avec des halogeenures de metaux de transitions, M[Cl.sub.2] (M = Ti[Cl.sub.2], Fe et Co) conduit aux metallocenes correspondants (4, 5 et 6)de metaux de transition du debut et de la fin de cette serie portant des substituants alcynyles. Les composes 4 et 6 sont les premiers exemples de metallocenes du titane et du cobalt portant deux appendices bisalcyne. Les complexes 5 et 6, mis en presence de CpCo[(CO).sub.3], donnent lieu a une dimeerisation de l'alcyne qui conduit aux metallocenophanes 7 et 8 incorporant deux atomes metalliques. On a caracterise les composes 3, 4[Cl.sub.2,] 6 et [8][OTf] par diffraction des rayons-X par un cristal unique. Mots-cles: cyclopentadiene, alcyne, titane, cobalt, heteeromeetallique, metallocenophane. [Traduit par la Redaction]
Introduction Cyclopentadienyl (Cp) ligands are one of the most common ligands used in organometallic chemistry as they form complexes with most of the transition metals. Various functional groups have been [...]