Unsaturated SiC4H6Si-bridged ansa-permethyltitanocene(TiIII) acetylide and hydroxide

Paramagnetic complexes ansa-[Ti(CCCMe3){η5:η5-C5Me4SiMe2CHCHCH2CH2SiMe2C5Me4}] (1) and ansa-[Ti(OH){η5:η5-C5Me4SiMe2CH2CHCHCH2SiMe2C5Me4}] (2) were prepared by reactions of ansa-[Ti(III){η3:η5:η5-C5Me4SiMe2CHCHCHCH2SiMe2C5Me4}] (3) with t-butylethyne or water, respectively. The X-ray single crystal diffraction analysis of 1 and 2 showed that the cis-double bond is situated asymmetrically in the ansa-bridge of 1 whereas, in 2, the double bond is trans, and lies in the bridge centre. ESR and UV-near IR spectra indicated a weaker oxygen π-electron donation into the Ti–O bond of 2 compared to analogous methoxide ansa-[Ti(III)(OMe){η5:η5-C5Me4SiMe2CH2CHCHCH2SiMe2C5Me4}] (4) or decamethyltitanocene hydroxide (5).