title: Reactions of alkynes with cis-RuCl2(dppm)2: exploring the interplay of vinylidene, alkynyl and η(3)-butenynyl complexes.
abstract: Reactions of cis-RuCl2(dppm)2 with various terminal alkynes, of the type HC≡CC6H4-4-R (1 equiv.), in the presence of TlBF4 have resulted in the formation of cationic vinylidene complexes trans-[RuCl(=C=CHC6H4-4-R)(dppm)2]BF4 ([1]BF4). These complexes can be isolated, or treated in situ with a suitable base (Proton Sponge, 1,8-bis(dimethylamino)naphthalene) to yield the mono-alkynyl complexes trans-RuCl(C≡CC6H4-4-R)(dppm)2 (2). Through similar reactions between cis-RuCl2(dppm)2 with 2 equiv. of alkyne, TlBF4 and base, trans-bis(alkynyl) complexes, trans-Ru(C≡CC6H4-4-R)2(dppm)2 (3), can be isolated when R is an electron withdrawing substituent (R = NO2, COOMe, C≡CSiMe3), whereas reactions with alkynes bearing electron donating substituents (R = OMe and Me) form cationic η(3)-butenynyl complexes [Ru(η(3)-{HC(C6H4-4-R)=CC≡CC6H4-4-R})(dppm)2](+) ([4](+)). This work highlights the importance of the electronic character of the alkyne in influencing product outcome.
authors.affiliation: Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK.
authors.forename: Samantha G
authors.initials: SG
authors.lastname: Eaves
authors.forename: Dmitry S
authors.initials: DS
authors.lastname: Yufit
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
authors.forename: Jason M
authors.initials: JM
authors.lastname: Lynam
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Low