Tricarbonyl(η5-formylcyclopentadienyl)manganese(I) and tricarbonyl(η5-formylcyclopentadienyl)rhenium(I) containing short π(CO)···π(CO) and π(CO)···π interactions.

The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C(6)H(5)O)(CO)(3)], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C(6)H(5)O)(CO)(3)], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in a trans position relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographic c axis for (I) and along the [201] direction for (II). Symmetry-related stacks are bound to each other by weak intermolecular C-H...O hydrogen bonds, leading to the formation of the three-dimensional network.