The Influence of the Ligands Cp*(η 5 ‐C 5 Me 5 ) and Cp(η 5 ‐C 5 H 5 ) on the Stability and Reactivity of Titanocene and Zirconocene Complexes: Reactions of the Bis(trimethylsilyl)acetylene Permethyl metallocene Complexes (η 5 ‐C 5 Me 5 ) 2 M(η 2 ‐Me 3 SiC 2 SiMe 3 ), M = Ti, Zr, with H 2 O and CO 2

The reactions of the bis(trimethylsilyl)acetylene permethyl metallocene complexes Cp   2 * M(η 2 ‐Me 3 SiC 2 SiMe 3 ) (M = Ti ( 1 ), M = Zr ( 2 )) with H 2 O and CO 2 were studied and compared to those of the corresponding metallocene complexes Cp 2 M(L)(η 2 ‐Me 3 SiC 2 SiMe 3 ) (M = Ti ( 3 ), L = – ; M = Zr, L = THF ( 4 )) to understand the influence of the ligands Cp(η 5 ‐C 5 H 5 ) and Cp*(η 5 ‐C 5 Me 5 ) as well as the metals titanium and zirconium on the reaction pathways and the obtained products. In the reaction of the permethyl titanocene complex  1 with water the dihydroxy complex Cp   2 * Ti(OH) 2 ( 5 ) was formed. This product differs from the well‐known titanoxane Cp 2 TiOTiCp 2 which was obtained by the reaction of the corresponding titanocene complex  3 with water . The reaction of the permethyl zirconocene complex  2 with water gives the mononuclear alkenyl zirconocene hydroxide 6 . An analogous product was assumed as the first step in the reaction of the corresponding zirconocene complex 4 with water which ends up in a dinuclear zirconoxane. In the conversion of the permethyl zirconocene complex 2 with carbon dioxide the mononuclear insertion product 7 was formed by coupling of carbon dioxide and the acetylene. In contrast, the corresponding zirconocene complex 4 affords, by an analogous reaction, a dinuclear complex. In additional experiments the known complex Cp   2 * Zr(η 2 ‐PhC 2 SiMe 3 ) ( 8 ) was prepared, starting from Cp   2 * ZrCl 2 and Mg in the presence of PhC≡CSiMe 3 . This complex reacts with carbon dioxide resulting in a mixture of the regioisomeric zirconafuranones 9 a and 9 b . From these in the complex 9 a , having the SiMe 3 group in β‐position to the metal, the Zr–C bond was quickly hydrolyzed by water to give the complex Cp   2 * Zr(OH)OC(=O)–C(SiMe 3 )=CHPh ( 10 a ) compared to complex ( 9 b ) which gives slowly the complex Cp   2 * Zr(OH)OC(=O)–CPh=CH(SiMe 3 ) ( 10 b ).