Ferrocenylbutadiyne.

The title compound, [Fe(C(5)H(5))(C(9)H(5))], crystallizes in a form of a π-π-stacked assembly formed as a result of strong inter-molecular π-π inter-actions between (a) the triple bonds of two neighboring butadiyne substituents overlapping in a 'head-to-tail' fashion [characterized by C⋯C short contacts of 3.622 (5), 3.567 (6) and 3.556 (6) Å] and (b) the triple bonds of the butadiyne substituent and substituted cyclo-pendadiene ring of neighboring mol-ecules [C⋯C = 3.474 (5) and 3.492 (6) Å]. The linear butadiyne substituent has alternating C-C triple and single bonds, while the unsubstituted cyclo-penta-diene ring is slightly positionally disordered (although the structure reported here was solved as non-disordered) and retains a close to eclipsed conformation.