The crystal and molecular structure of acetylcyclopentadienyl-manganese and -rhenium tricarbonyls

The X-ray investigation of the title compounds has shown that in CH₃COC₅H₄Mn(CO)₃ the orientation of CO groups with respect to the cyclopentadienyl ring is almost the same as in the unsubstituted manganese compound whereas in CH₃COC₅H₄Re(CO)₃ the orientation is different to that in C₅H₅Re(CO)₃, so that the molecule as a whole becomes less symmetrical. Unsubstituted cyclopentadienyl-manganese and -rhenium tricarbonyls are isostructural and entirely analogous; that the two acetyl derivatives are not isostructural is possibly caused by conformational differences. Both molecules have the “piano stool” configuration with the CH₃CO group almost coplanar with the cyclopentadienyl ring plane. Interatomic distances and bond angles in these molecules are typical for this type of compound.