Transition-Metal Compounds Containing Alkynylsilyl Groups – Cyclopentadienyl Complexes

Abstract

The synthesis of (alkynylsilyl)cyclopentadienyl complexes of titanium and manganese was studied. The titanium compounds PhC≡CMe₂SiC₅H₄CpTiCl₂ (1) and (PhC≡CMe₂SiC₅H₄)₂TiCl₂ (2) were prepared by treating LiC₅H₄SiMe₂C≡CPh with suitable titanium(IV) halides. The manganese compound PhC≡CMe₂SiC₅H₄Mn(CO)₃ (3) could be synthesized by treating Mn(CO)₅Cl with TlC₅H₄SiMe₂C≡CPh or LiC₅H₄SiMe₂C≡CPh. Alternatively, the alkynylation of ClMe₂SiC₅H₄Mn(CO)₃ (6) with PhC≡CMgBr was also successful. In contrast, the direct complexation of (alkynylsilyl)cyclopentadiene or the direct alkynylsilylation of cymantrene were not feasible. Redox reactions and the desilylation of the cyclopentadienyl ring were hampering side reactions in all routes but to varying extent. All three complexes were characterized by NMR spectroscopy. 1 and 3 were also studied by IR and UV/Vis spectroscopy. The molecular and crystal structure of compound 1 was determined by X-ray diffraction analysis.