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

The reaction between [Os-3(CO)(10)(NCMe)(2)] and MeC2C2Me yields the known cluster [Os-3(CO)(9)(mu -CO)(mu (3)-eta (2)-MeC2C2Me)] (1) [Os-3(CO)(9){mu (3)-eta (2):mu (3)-eta (1):eta (3)-MeC2C2MeOC5Me2)Os-3(mu -Co)(CO)(9)] (2), [Os-3(CO)(9){mu (3)-and three previously uncharacterised products [Os-3(CO)(9)(mu -CO){mu (3)-eta (2):mu (3)-eta (1):)(CO)(9)] (2), [Os-3(CO)(9){mu (3)-eta [(MeC2)C-2(Me)]CO[(Me)C-2(C2Me)], MeC2)C-2(Me)]CO[(MeC2)C-2(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 [Os-3(CO)(9)(mu -CO)(mu (3)-eta (2)-PhC2C2Ph)] (5) react with [Co-2(CO)(8)] to form products 6-11 in which one free alkyne function coordinates to a Co-2(CO)(6) unit in each case; the Cluster [{Os-3(CO)(10)}{Co-2(CO)(6)}{mu (3)-eta (2)-parallel to-(MeCC)(mu (2)-eta (2)(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 [Os-3(CO)(9)(mu -OH)(mu (3)-eta (1):eta (2)-eta (2)-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 [Os-3(CO)(8)(L)(mu (3)-eta (1):eta (1):eta (2):eta (2)- {(MeC2)C-2(Me)}(2)CO)] (L = NCMe (17), NMe3 (18)). (C) 2001 Elsevier Science B.V. All rights reserved.