A second orthorhombic polymorph of 3-ferrocenylacrylaldehyde

The title compound (systematic name: 3-ferrocenylprop-2-en-1-one), [Fe(C₅H₅)(C₈H₇O)] (I), crystallizing in the space group P2₁2₁2₁, with a = 5.77599 (11) Å, b = 7.38297 (13) Å and c = 24.4180 (4) Å consists of fused ferrocene and acrylaldehyde moieties. In the crystal, C—H⋯O hydrogen bonds link the molecules into infinite chains propagating along the a-axis direction and C—H⋯π interactions help to consolidate the packing. Compound (I) is a polymorph of the previously reported form of ferrocenylacrylaldehyde [Imhof (2004). Acta Cryst. E60, m1234–m1236], which also crystallizes in space group P2₁2₁2₁ with cell parameters a = 7.9192 (2) Å, b = 11.1648 (3) Å and c = 12.4204 (4) Å. The Hirshfeld surface analysis of (I) indicates that the most important contributions to the crystal packing are from H⋯ (58.9%), H⋯C/C⋯H (22.6%) and H⋯O/O⋯H (17.5%) contacts. Computational methods revealed a C—H⋯O hydrogen-bonding energy of −10.9 kJ mol⁻¹.