Synthesis and characterization of 1,12-bis(ferrocenyl)-1,3,5,7,9,11-dodecahexayne and its coordination to triosmium and dicobalt carbonyls

1,12-Bis(ferrocenyl)-1,3,5,7,9,11-dodecahexayne (1) was synthesized by in situ oxidative coupling of the terminal triyne FcC=CC=CC=CH (5). The reaction of hexayne 1 with Os-3-(CO)(11)(NCMe) (2) yielded the new hexaosmium compound Os-6(CO)(22)(mu(6)-eta(8)-FCC(4)CdropCCdropCC(4)-Fc) (6) in 15% yield. Compound 6 contains two open triosmium clusters coordinated parallel to opposite sides of the hexayne chain. Compound 1 also reacted with CO2(CO)(8) to afford Co8(CO)24(mu(8)-eta(2):eta(2):eta(2):eta(2)-FcC(2)CdropCC(4)CdropCC(2)Fc) (7) in 35% yield. In compound 7, four dicobalt hexacarbonyl groups have been added to the hexayne chain. Compounds 1, 6, and 7 were characterized by IR, H-1 NMR, and single-crystal X-ray diffraction analyses. Differential pulse voltammograms show only one two-electron oxidation peak for compounds 1, 6, and 7, indicating that there is no detectable electronic communication between the two terminal ferrocenyl groups by this method.