Metallacycles of 1,4-bis(3-thiophenyl)-1,3-butadiyne in mixed metal clusters derived by C-C bond coupling of alkynyls
Yamazaki, S; Taira, Z; Yonemura, T; Deeming, AJ
Reaction of cis-Pt(C equivalent to CTp)(2)(dppe) (Tp = thiophene) with Ru(3)(CO)(11)(CH(3)CN) in refluxing toluene for I It resulted in head-to-head C-C bond coupling of the alkynyl ligands forming 1.4-bis(3-thiophenyl)buta-1,3-diyne, which afforded an extraordinal 1,4-heterodimetalla [5,6-b] thienopentalene. [PtRu(3){mu(4)- eta(1):eta(1):eta(1):eta(4):eta(4):-C(4)H(2)S-C=CC(H)=CTp} (mu-CO)(2)(CO)(6)(dppe)] (1) (Tp = 3-thiophene), in 54% yield. Its crystal structure shows that a hydrogen shift occurs from the thiophene substituent to an end carbon atom of the 1,3-diyne, transforming 1,4-bis(3-thiophenyl)buta-1,3-diene, which results in formations of PtC(4) and RuC(4) rings, both with metallacyclopenta-2,4-diene. The Ru(3)(mu-CO)(2)(CO)(6) moiety conforms to an open cluster, and its central ruthenium atom forms a RuCp ring whose carbon atoms bond to two ruthenium atoms by eight Ru-C pi-bonds. Reactions of the acetylides with single metal media, Fe(CO)5, gave rise to annealation of alkynyls via both cyclic and acyclic dimerization processes, affording extraordinal metallacycles of 1,3-diyne, a platinacyclobutene consisting of a cyclone, [FePt{mu(2)-eta(1):eta(1):eta(4)-(C(4)Tp(2)-CO)-CO}(CO)(3) (dppe)] (2), and a 1,2-heterodimetallacyclo-3-penten-5-one, [FePt(mu 2-eta(1):eta(1):eta(2)-TpCCCCTp-CO(mu-CO)(CO)(2) (dppe)](3), in 15 and 16% yields, respectively.