Reactions of [Os3(CO)10(NCMe)2] with symmetric diynes and their reactivity towards [Co2(CO)8]

The reaction between [Os3(CO)10(NCMe)2] and MeC2C2Me yields the known cluster [Os3(CO)9(μ-CO)(μ3-η2-MeC2C2Me)] (1) and three previously uncharacterised products [Os3(CO)9(μ-CO){μ3-η2:μ3-η1:η1:η3-MeC2C2MeOC5Me2)Os3(μ-CO)(CO)9] (2), [Os3(CO)9{μ3-η4-[(MeC2)C2(Me)]CO[(Me)C2(C2Me)]}] (3) and [Os3(CO)9{μ3-η4-[(MeC2)C2(Me)]CO[(MeC2)C2(Me)]}] (4). The structures of 2 and 3 have been determined by X-ray crystallography. Cluster 2 incorporates two linked triosmium clusters joined by an unsaturated five-membered metallacycloether ring and 3 exhibits an alkyne-functionalised metallacyclohexadieneone ring. 1–4 and [Os3(CO)9(μ-CO)(μ3-η2-PhC2C2Ph)] (5) react with [Co2(CO)8] to form products 6–11 in which one free alkyne function coordinates to a Co2(CO)6 unit in each case; the cluster [{Os3(CO)10}{Co2(CO)6}{μ3-η2-‖-(MeCC)(μ2-η2(CCMe)}] (6) has been structurally characterised. The reaction of 1 and 5 with Me3NO–MeCN leads to the replacement of one CO ligand with MeCN, the products 12 and 13 reacting with H2O to form [Os3(CO)9(μ-OH)(μ3-η1:η2:η2-RC3CHR)] (R=Me (two isomers 14, 15), Ph (16)); the X-ray structure of 16 is reported. Reaction of 3 with Me3NO–MeCN results in the substitution of a CO ligand with either a MeCN or NMe3 ligand at the metallocyclic Os atom to afford the clusters [Os3(CO)8(L)(μ3-η1:η1:η2:η2-{(MeC2)C2(Me)}2CO)] (L=NCMe (17), NMe3 (18)).