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

Abstract

The synthesis and reaction chemistry of the mono (σ-alkynyl) titanocene chlorides [Ti](Cl)(C⋮CR) {[Ti] = (η5-C5H4SiMe3)2Ti; 2a, R = Ph; 2b, R = SiMe3} is described. Treatment of compounds 2a and 2b with ClMgCH2SiMe3 or LiC⋮CR‘ yields [Ti](CH2SiMe3)(C⋮CSiMe3) (3) or [Ti](C⋮CR)(C⋮CR‘) (5a, R = Ph, R‘ = SiMe3; 5b, R = R‘ = Ph; 5c, R = R‘ = SiMe3), 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 = SiMe3, X = Cl; 7b, R = SiMe3, X = Br) or {[Ti](C⋮CPh)(C⋮CSiMe3)}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⋮CSiMe3)}AgX (10a, X = Cl; 10b, X = Br). Moreover, compound 8a can be synthesized by treatment of 2a or 2b with [CuC⋮CR‘]n (R‘ = SiMe3, Ph). However, when compound 3 is reacted with [CuCl]n under appropriate reaction conditions, the formation of {[Ti](C⋮CSiMe3)2}CuCl (9b), [CuCH2SiMe3]4, [Ti](Cl)(CH2SiMe3) (4), and [Ti]Cl2 (1) is observed; a reaction mechanism for the formation of the latter compounds is discussed. The solid state structures of [Ti](Cl)(CH2SiMe3) (4) and {[Ti](Cl)(C⋮CSiMe3)}CuBr (7b) were determined. Crystals of 4 and 7b are monoclinic, space group P21/n. 4: C20H37ClSi3Ti, 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: C21H35BrClCuSi3Ti, cell constants a = 13.257(7) Å, b = 10.470(5) Å, c = 20.39(1) Å, β = 100.91(3)°, and Z = 4.