Tricarbon­yl([eta]⁵-formyl­cyclo­pentadien­yl)manganese(I) and tricarbon­yl([eta]⁵-formyl­cyclo­penta­dien­yl)rhenium(I) containing short [pi](CO)...[pi](CO) and [pi](CO)...[pi] 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 [pi](CO)...[pi](CO) and [pi](CO)...[pi] 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.