Transition-Metal Compounds Containing Alkynylsilyl Groups - Cyclopentadienyl Complexes

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.