Conformational energy of the (eta(5)-cyclopentadienyl) Iron(II) dicarbonylgroup

The conformational energy of the (eta(5)-cyclopentadienyl) iron(II) dicarbo nyl group was determined by variable-temperature H-1 NMR spectroscopic stud ies on cis-4-phenyl-1-(eta(5)-cyclopentadienyl) iron-(II) dicarbonyl cycloh exane. This is the first determination of the A-value of a group with a tra nsition metal directly attached to a cyclohexane ring. The stereospecific s ynthesis of cis- and trans-4-phenyl-1-(eta(5)-cyclopentadienyl) iron(II) di carbonyl cyclohexane and cis- and trans-4-tert-butyl-1-(eta(5)-cyclopentadi enyl) iron(II) dicarbonyl cyclohexane and the X-ray crystal structure of ci s-4-tert-butyl-1-(eta(5)-cyclopentadienyl) iron(II) dicarbonyl cyclohexane are reported.