Dicobalt hexacarbonyl diphenylacetylene

The molecule of diphenylacetylene dicobalt hexacarbonyl has been shown by an x-ray investigation.57 to have the structure shown in Figure 11-19. Each cobalt atom forms six bonds, directed toward the corners... 

Dicyclopentadienyldinickeldiphenylbutadiyne-dicobalt hexacarbonyl has been prepared from diphenyldiacetylene in which one triple bond acts as a bridging group between two nickel atoms and the other between two cobalt atoms (203). Reduction of the diphenylacetylene complex (R = R = Ph) with sodium and alcohol in liquid ammonia yields dibenzyl, showing that the diphenylacetylene grouping is bonded only to the nickel atoms. The corresponding complex of acetylene (R = R = H) has also been prepared from nickeloccne and acetylene (69) ... 

Pig. 11-19.—The structure of dicobalt hexacarbonyl diphenylacetylene, Coa(CO)fCi (C H )j. Large circles represent cobalt atoms, small circles carbon atoms, and circles of intermediate size oxygen atoms. 

The structure of dicobalt hexacarbonyl diphenylacetylene is shown in Figure 17.6. Two 7i-orbitals of the carbon-carbon triple bond bond to two cobalt atoms. The bond length of C-C is slightly longer (1.46 A) than that of an ordinary carbon-carbon double bond. The cobalt atom forms a distorted octahedral configuration [37]. 

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