TRICARBONYLBIS( eta 2-CIS-CYCLOOCTENE)IRON: PHOTOCHEMICAL SYNTHESIS OF A VERSATILE Fe(CO)3 SOURCE FOR OLEFIN ISOMERIZATION AND PREPARATIVE APPLICATIONS.

Article abstract of DOI:10.1021/ja00319a021

The photoreaction of pentacarbonyliron and cis-cyclooctene in alkane solvent at minus 40 degree C results in high yield formation of tricarbonylbis( eta **2-cis-cyclooctene)iron (1). Solid 1 can be handled at room temperature. In solution at approximately greater than minus 35 degree C the complex is substitutionally labile and serves as a versatile source of the Fe(CO)//3 unit. The thermal reaction of 1 with 1-pentene results in extensive isomerization of the alkene with turnover numbers up to 2000, thus establishing the role of Fe(CO)//3 as the repeating unit in the catalytic alkene isomerization. Turnover rates are 0. 48 min** minus **1 at minus 20 degree C, 12. 2 min** minus **1 at 0 degree C, and 173 min** minus **1 at 20 degree C. Ligand exchange with 1,3-dienes and vinyl-substituted aromatic compounds provides excellent yields of the corresponding ( eta **4-organic ligand)Fe(CO)//3 complexes. The reaction of 1 with 2-butyne demonstrates that alkyne coupling products are accessible under remarkably mild conditions.