Reaction Chemistry of Alkynyl-Functionalized Titanocenes. X-ray Structure Analyses of (η5-C5H4SiMe3)2Ti(Cl)(CH2SiMe3) and [(η5-C5H4SiMe3)2Ti(Cl)(C⋮CSiMe3)]CuBr

The synthesis and reaction chemistry of the mono (σ-alkynyl) titanocene chlorides [Ti](Cl)(C⋮CR) {[Ti] = (η 5 -C 5 H 4 SiMe 3 ) 2 Ti; 2a, R = Ph; 2b, R = SiMe 3 } is described. Treatment of compounds 2a and 2b with ClMgCH 2 SiMe 3 or LiC⋮CR‘ yields [Ti](CH 2 SiMe 3 )(C⋮CSiMe 3 ) ( 3 ) or [Ti](C⋮CR)(C⋮CR‘) ( 5a, R = Ph, R‘ = SiMe 3; 5b, R = R‘ = Ph; 5c, R = R‘ = SiMe 3 ), respectively. The reaction of compounds 2a, 2b, or 5a with polymeric [CuX] n (X = Cl, Br, I) produces the heterobimetallic titanium−copper complexes {[Ti](Cl)(C⋮CR)}CuX ( 6a, R = Ph, X = Cl; 6b, R = Ph, X = Br; 6c, R = Ph, X = I; 7a, R = SiMe 3, X = Cl; 7b, R = SiMe 3, X = Br) or {[Ti](C⋮CPh)(C⋮CSiMe 3 )}CuX ( 8a, X = Cl; 8b, X = Br). While compounds 2a and 2b do not react with [AgX] n (X = Cl, Br), it is found that the bis(σ-alkynyl)titanocene 5a is able to break down the polymeric structure of [AgX] n to produce the heterobimetallic compounds {[Ti](C⋮CPh)(C⋮CSiMe 3 )}AgX ( 10a, X = Cl; 10b, X = Br). Moreover, compound 8a can be synthesized by treatment of 2a or 2b with [CuC⋮CR‘] n (R‘ = SiMe 3, Ph). However, when compound 3 is reacted with [CuCl] n under appropriate reaction conditions, the formation of {[Ti](C⋮CSiMe 3 ) 2 }CuCl ( 9b ), [CuCH 2 SiMe 3 ] 4, [Ti](Cl)(CH 2 SiMe 3 ) ( 4 ), and [Ti]Cl 2 ( 1 ) is observed; a reaction mechanism for the formation of the latter compounds is discussed. The solid state structures of [Ti](Cl)(CH 2 SiMe 3 ) ( 4 ) and {[Ti](Cl)(C⋮CSiMe 3 )}CuBr ( 7b ) were determined. Crystals of 4 and 7b are monoclinic, space group P 2 1 / n . 4: C 20 H 37 ClSi 3 Ti, cell constants a = 6.812(2) Å, b = 11.298(6) Å, c = 33.16(1) Å, β = 92.25(3)°, and Z = 4. 7b: C 21 H 35 BrClCuSi 3 Ti, cell constants a = 13.257(7) Å, b = 10.470(5) Å, c = 20.39(1) Å, β = 100.91(3)°, and Z = 4.