SYNTHESIS AND MOLECULAR-STRUCTURES OF 2 CYCLOBUTADIENECOBALT COMPLEXES FORMED BY REACTION BETWEEN "PI-CYCLOPENTADIENYLDICARBONYLCOBALT AND PHENYL-2-THIENYLACETYLENE
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abstract
The reaction between h5-cyclopentadienyldicarbonylcobalt and phenyl-2-thienylacetylene in refluxing xylene has been found to produce 78% yield of (h5-cyclopentadienyl)(h4-diphenyldi-2-thienylcyclobutadiene) cobalt, as well as lesser amounts of a cyclotrimerization product, triphenyltri-2-thienylbenzene, and three isomeric cyclopentadienonecobalt complexes. A single crystal X-ray structural study intended to confirm the disposition of the phenyl and thienyl substituents of the cyclobutadiene ring in the first compound was carried out. The results are inconclusive since there is disorder of these groups in the crystalline lattice. The most likely model involves a mixture of cis and trans isomers plus phenylthienyl disorder. The atoms of the (h5-C5H5)Co(C4) moiety are well behaved crystallographically and have molecular parameters which are within accepted values of recent determinations not plagued by disorder or uncertainty of isomeric purity. A minor biproduct, resulting from the apparent coreaction of phenyl-2-thienyl-acetylene and diphenyldiacetylene with h5-cyclopentadienyldicarbonylcobalt, has also been identified by spectral and X-ray diffraction techniques as the novel complex bis [(h5-cyclopentadienyl)(h4-trans-diphenyl-2-thienylcyclobutadienyl)-cobalt]. The crystallographic study of this compound also revealed disorder in the thienyl groups but it is not as severe as that found for the major product. 1977.
