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

Abstract

(Dimethyl)(phenylethynyl)silyl-substituted cyclopentadiene C5H5SiMe2C2Ph (1) was synthesized by the reaction of in situ generated C5H5SiMe2Cl with LiC2Ph. Metallation of 1 with nBuLi or KN(SiMe3)2 gave the corresponding Li (2) and K (3) salts. Transmetallation of 2 with transition metal halides MCl2 (M = TiCl2, 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)2 generating metallocenophanes 7 and 8 incorporating two metal atoms. Compounds 3, 4Cl2, 6, and [8][OTf] have been characterized by single crystal X-ray structure analysis.