Reactions of Hydrogen Sulfide with Singly and Doubly Tucked-in Titanocenes

Hydrogen sulfide reacts with tucked-in titanocene complexes [Ti(III){η5:η1-C5Me4(CH2)}Cp*] (Cp* = η5-C5Me5) (2) and [Ti{η4:η3-C5Me3(CH2)2}Cp*] (3) and their precursors [Cp*2TiMe] (2a) and [Cp*2Ti(η2-Me3SiCCSiMe3)] (3a), respectively, to give the corresponding titanocene hydrosulfides [Cp*2Ti(SH)] (4) and [Cp*2Ti(SH)2] (1), respectively. Hydrogen sulfide also cleaves intramolecular σ- or π-Ti−C bonds in ansa-[TiIII(η1:η5:η5-C5Me4SiMe2CHCH2SiMe2C5Me4)] (5) and ansa-[TiII(η2:η5:η5-C5Me4SiMe2CHCHSiMe2C5Me4)] (6), affording hydrosulfides ansa-[(η5-CH2Me2SiC5Me4)2Ti(SH)] (7) and ansa-[(η5-CH2Me2SiC5Me4)2Ti(SH)2] (8). The S−H bonds of hydrosulfides 4 and 7 were able to react with the Ti−C bonds in 2 and 5, affording titanocene sulfides [(Cp*2TiIII)2S] (11) and ansa-[{(η5-CH2Me2SiC5Me4)2TiIII}2S] (12), respectively. Combination of 7 with 2a gave rise to the mixed titanocene sulfide [ansa-{(η5-CH2SiMe2C5Me4)2Ti}S(TiCp*2)] (13). The titanium(III) d1 electrons in 11−13 form an electronic triplet state well observable by EPR spectra in toluene glass. All the hydrosulfides were decomposed by sunlight. Compound 1 eliminated Cp*H and H2S, while 4 mainly Cp*H. Apparently formed transient [Cp*TiS] species probably gave rise to the serendipitously isolated cluster [{Cp*Ti(S)}4] (14). Crystal structures of the all complexes were determined by X-ray diffraction analysis.