Synthesis and Structures of ansa ‐Titanocene Complexes with Diatomic Bridging Units for Overall Water Splitting

The synthesis of a series of ansa ‐titanocene dichlorides [Cp′ 2 TiCl 2 ] (Cp′=bridged η 5 ‐tetramethylcyclopentadienyl) and the corresponding titanocene bis(trimethylsilyl)acetylene complexes [Cp′ 2 Ti(η 2 ‐Me 3 SiC 2 SiMe 3 )] is described. The ethanediyl‐bridged complexes [C 2 H 4 (C 5 Me 4 ) 2 TiCl 2 ] ( 2 ‐Cl 2 ) and [C 2 H 4 (C 5 Me 4 ) 2 Ti(η 2 ‐Me 3 SiC 2 SiMe 3 )] ( 2‐ btmsa; btmsa=η 2 ‐Me 3 SiC 2 SiMe 3 ) can be obtained from the hitherto unknown calcocenophane complex [C 2 H 4 (C 5 Me 4 ) 2 Ca(THF) 2 ] ( 1 ). Furthermore, a heterodiatomic bridging unit containing both, a dimethylsilyl and a methylene group was introduced to yield the ansa ‐titanocene dichloride [Me 2 SiCH 2 (C 5 Me 4 ) 2 TiCl 2 ] ( 3 ‐Cl 2 ) and the bis(trimethylsilyl)acetylene complex [Me 2 SiCH 2 (C 5 Me 4 ) 2 Ti(η 2 ‐Me 3 SiC 2 SiMe 3 )] ( 3 ‐btmsa). Besides, tetramethyldisilyl‐ and dimethylsilyl‐bridged metallocene complexes (structural motif 4 and 5 , respectively) were prepared. All ansa ‐titanocene alkyne complexes were reacted with stoichiometric amounts of water; the hydrolysis products were isolated as model complexes for the investigation of the elemental steps of overall water splitting. Compounds 1 , 2 ‐btmsa, 2 ‐(OH) 2 , 3 ‐Cl 2 , 3 ‐btmsa, 4 ‐(OH) 2 , 3 ‐alkenyl and 5 ‐alkenyl were characterised by X‐ray diffraction analysis.