Reactions of titanocene-bis(trimethylsilyl)ethyne complexes with diethynylsilane derivatives

Titanocene complexes [Ti(η 5 -C 5 H 5− n Me n ) 2 (η 2 -Me 3 SiCCSiMe 3 )] ( n =0, 4 and 5) react uniformly with siladiynes R 2 2 Si(CCR 1 ) 2 , where R 1 =Ph, and R 2 =Ph or Me, at elevated temperature in hydrocarbon solvents to give the corresponding silacyclobutene-annelated titanacyclobutene complexes, 3-bis(η 5 -cyclopentadienyl)titana-6-diorganylsilabicyclo[2.2.0]hexa-1(2),4(5)-dienes, [(η 5 -C 5 H 5− n Me n ) 2 Ti{R 1 2 C 4 (SiR 2 2 )}]. Products arising from [Ti(η 5 -C 5 H 5− n Me n ) 2 (η 2 -Me 3 SiCCSiMe 3 )] ( n =0, 2 (1,3-isomer), 4 and 5) and Me 2 Si(CCCMe 3 ) 2 vary with n : the non-methylated titanocene complex affords a mixture of an analogous silacyclobutene-annelated t…