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(C6H5O)(CO)3], (I), and tricarbon­yl(formyl­cyclo­penta­dien­yl)rhenium(I), [Re(C6H5O)(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.