Stoichiometric Transformations of Alkynes

We have already found that the reactions of the coordinatively unsaturated diruthenium(ii) complex 1 with alkynes result in unique coupling of the alkynes to afford a variety of ruthenacycles, depending significantly upon the substituent on the alkynes. On the other hand, the corresponding reactions of the 

Ru /Ru complex [Cp Ru(/ -SPr%RuCp ] 6 give the bisalkynyl complexes [Cp Ru(CsCR)( /-SPr )2Ru(CsCR)Cp ] (R = aryl), which are further converted into diruthenacyclopentadienoindan complexes upon protonation. Here we focus on the transformations of alkynes by the Ru /Ru complexes 4 and [Cp RuCl(/i-SR)2RuClCp ] 7 (R = Me or Et). 

The vinylidene complexes 8 also react with nucleophiles such as water and methanol. Hydration of the unsubstituted vinylidene complex 8a leads to the formation of the rj -acetyl complex 13, whereas the corresponding reactions of 8b and 8c result in the C-C bond cleavage, giving the cationic carbonyl complex 14 and organocarbonyl products R COMe(R = OMe or Me). On the other hand, the reactions of 8 with methanol afford the methoxycarbene complex 15 and the vinyl complex 16, depending upon the substituent of the vinylidene complexes 8. Intramolecular nucleophilic attack takes place in the reaction of 4 with 3-butyn-l-ol, giving the cyclic alkoxycarbene complex [Cp RuCl(p-SPr%Ru =C(CH2)30 Cp ](OTf).  

---