Crystal structure of 1-ferrocenyl-2-(4-nitro­phen­yl)ethyne

The title ferrocene derivative, [Fe(C5H5)2(C8NO2)], including an alkyne bonded to a para-nitro­phenyl substituent, which was synthesized from a copper-free Sonogashira cross-coupling reaction between ethynylferrocene and 4-bromo-1-nitro­benzene, crystallizes in the P21/n space group. In the ferrocene unit, the penta­dienyl (Cps) rings are in an eclipsed conformation. The angle of rotation between the substituted cyclo­penta­dienyl ring and the p-nitro­phenyl group is 6.19 (10)°, yielding a quasi-linear extension of the ferrocenyl substitution. Important inter­molecular inter­actions arise from π–π stacking between the Cp rings and the p-nitro­phenyl, from corners of the Cp rings that are perpendicularly aligned, and between the O atoms from the nitro substituent and carbons at the corners of the Cp rings, propagating along all three crystallographic axes.