Novel acetylene-linked di-cobalt and tetra-cobalt carbonyl clusters

{Co-2(CO)(6)} groups were attached to p-diethynylbenzene-based acetylenes g iving complexes of general formula [{Co-2(CO)(6){(mu(2)-eta(2:2)-RC2C6H4C2R ')] ((4): R = R' = H; (4a): R = SiMe3, R' = H; (4b): R = R' = SiMe3); [{Co- 2(CO)(6)}(2)(mu(4)-eta(2:2:2:2)-RC2C6H4C2R')] ((3): R = R' = H; (3a): R = S iMe3, R' = H; (3b): R = R' = SiMe3); [{Co-2(CO)(6)}(4)(mu(8)-eta(2:2:2:2:2: 2:2:2)-R2C6H4C2C2C6H4C2R)]((5): R = H; (5b):R = SiMe3). The addition of Co- 4(CO)(12) to p-diethynylbenzene and to 4 was also investigated, producing [ {Co-4(CO)(8)(mu-CO)(2)}(mu(4)-HC2C6H4C2H)] (6) and [{Co-2(CO)(6)} {(Co-4(CO )(8)(mu-CO)(2)}(mu(8)-HC2C6H4C2H)] (7). The syntheses of the acetylenic der ivatives of C-60 [(trimethylsilyl)ethynyl] hydrofullerene [60] (8a) and (ph enylethynyl) hydrofullerene[60] (9) and the new ligand [(trimethylsilyl)die thynylbenzene]hydrofullerene[60] (10a) were performed and the resulting ace tylenes were reacted with dicobaltoctacarbonyl giving the corresponding com plexes [(trimethylsilyl)(dicobalthexacarbonyl)ethynyl]hydrofullerene[60] (1 1a), (phenylethynyl)(dicobalthexacarbonyl)hydrofullerene[60] (12) and [(tri methylsilyl)bis(dicobalthexacarbonyl)diethynylbenzene] (13a). The reaction of 1-bromo-3,5-diethynylbenzene and 1,3,5-triethynylbenzene with dicobaltoc tacarbonyl resulted in the formation of [HC2{Co-2(CO)(6)}](2)C6H2Br (16) an d [HC2{Co-2(CO)(6)}](2)C6H3 (15) as expected. Crystals of 3a, 3b, 4, 4b, 15 and 16 suitable for single-crystal X-ray diffraction were grown and the mo lecular structures of these compounds an discussed. (C) 1999 Elsevier Scien ce S.A. All rights reserved.