Synthese und Reaktionsverhalten von (#eta#~2-BrC ident to CR)Co_2(CO)_6. Die Festkorperstruktur von Pentacarbonyl-[#mu#-(1,2,3,4-#eta#:1,4-#eta#)-1,4-diphenyl-1,3-butadien-1,4-diyl]dicobalt

摘要

The reaction of BrC ident to CR (1a, R = ~nPr; 1b, R = ~nBu; 1c, R = SiMe_3; 1d, R = Ph) with Co(CO)_8 (2) in a 1:1 molar ratio produces the hexacarbonyldicobalt complexes (#eta#~2-BrC ident to CR)Co_2(CO)_6 (3a, R = ~nPr; 3b, R = ~nBu; 3c, R = SiMe_3; 3d, R = Ph) in moderate yields. Apart from these complexes, pentametallic cobalt clusters of the general composition Co_5(CO)_12(C ident to CR) (4a, R = ~nPr; 4b, R = ~nBu; 4c, R = SiMe_3; 4d, R = Ph) are formed. Treatment of 1d with Na[Co(CO)_4] (5) yields the butadi-1,3-yne complex [(#eta#~2-C ident to CPh)Co_2(CO)_6]_2 (6). A possible reaction mechanism for the formation of complexes 4 and 6 is described. The reactin of 4d with P(O~iPr)_3 (7) leads to a cluster degradation and the formation of Co_2(CO)_6[P(O`iPr)_3]_2 (8). In contrast, on addition of HC ident to CPh (9) to 4d the dicarbonyl(#eta#~2-HC ident to CPh)Co_2(CO)_6 (11). Complex 10 was characterized by single crystal X-ray crystallography. Homobimetallic 10 features a 5-membered PhC=CH-CH=CPh-Co(CO)_3 ring, which is #eta#~5-coordinated to a Co(CO)_2 fragment.