Abstract
The paramagnetic compounds exo,exo-bis(η(5)-isodicyclopentadienyl)chlorotitanium(III) (3) and its analogue with trimethylsilyl-substituted isodicyclopentadienide (isodiCp) ligand (4), and the similar pair of diamagnetic exo,exo-bis(isodicyclopentadienyl)[η(2)-bis(trimethylsilyl)ethyne]titanium(II) complexes 5 and 6 were obtained by common reduction procedures from exo,exo-bis(isodicyclopentadienyl)titanium(IV) dichloride (1) and exo,exo-bis[η5-2-(trimethylsilyl)isodicyclopentadienyl]titanium(IV) dichloride (2), respectively. As indicated by ESR spectroscopy compound 3 is a dimer in the solid state and in frozen toluene glass but monomeric in toluene solution.
Compound 4 is monomeric in solution as well as in the solid state. As judged from the red shift of the vibration, compound 6 binds bis(trimethylsilyl)ethyne more strongly than compound 5.
A comparison of their wavenumbers with those of the [Ti(C5H5-nMen)(2)(η(2) -Me3SiC-CSiMe3)] (n=2-5) complexes shows that Lewis acidity.