Reactions of Group 4 Metallocene Alkyne Complexes with Carbodiimides: Experimental and Theoretical Studies of the Structure and Bonding of Five-Mem bered Hetero-Metallacycloallenes

摘要

The reaction of the low-valent metallocene(Ⅱ) sources Cp_2Ti(η~2-Me_3SiC_2SiMe_3) (7) and Cp_2Zr(py)(η~2-Me_3SiC_2SiMe_3) (11, Cp = η~5-cyclopentadienyl, py = pyridine) with carbodiimides RN=C—NR (R = Cy, i-Pr, p-Tol) leads to the formation of five membered hetero-metalla-cycloallenes Cp_2M{Me_3SiC=C=C[N(SiMe_3)(R)]-N(R)} C9M-R) CM = Ti, R = i-Pr: M = Zr, R = Cy, i-Pr,p-Tol). Elimination of the alkyne (as the hitherto known reactivity of titanocene and zirconocene alkyne complexes would suggest) was not observed. The molecular structures of the obtained complexes were confirmed by X-ray studies. Moreover, the structure and bonding of the complexes 9Zr-Cy and 9Zr-p-Tol was investigated by DFT calculations.