A STABLE BIMETALLIC COPPER(I) TITANIUM ACETYLIDE

The reaction. of [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C=CSiMe(3))(2)]CuCl (4) with 1 equiv of LiC=CR (R= SiMe(3) (5a), t-Bu (5b), Ph (5c)) affords the monomeric complexes [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C=CSiMe(3))(2)]CuC=CR (R=SiMe(3) (3a), t-Bu (3b), Ph (3c)). Complexes 3 were independently prepared by starting from (eta(5)-C(5)H(4)SiMe(3))(2)Ti(C=CSiMe(3))(2) (2) and 1/n [CuC=CR](n) (R=SiMe(3) (2a), t-Bu (2b), Ph (2c)) and are the first examples of stable monomeric bis(eta(2)-alkyne)(eta(1)-alkynyl)copper compounds. Reaction of 1 with 1/4[CuO-t-Bu](4) (6) results in the formation of the remarkably stable bimetallic acetylide complex [(eta(5)-C(5)H(4)SiMe(3))(2)Ti(C=CSiMe(3))(C=CCu)](2) (7) (mp 157 degrees C dec) by nucleophilic substitution of one of the alkynyl-SiMe(3) groups in 1, whereby t-BuOSiMe(3) is eliminated Other nucleophiles (e.g. F- and EtO(-)) show a similar reactivity, although in this case the substitution is much slower and less selective.