Crystal structure of 1,1-diacetylferrocene dihydrazone

The title compound, [Fe(C 7 H 9 N 2 ) 2 ], crystallizes with two crystallographically independent molecules in the unit cell. These represent the chiral atropoisomers distinguished by the mutual arrangement of the two acetyl–hydrazone groups with a cis conformation of the C=N bonds. The two cyclopentadienyl (Cp) rings are planar and nearly parallel, the tilt between the two rings being 3.16 (16)° [4.40 (18)° for the second independent molecule]. The conformation of the Cp rings is close to eclipsed, the twist angle being 0.1 (2)° [3.3 (2)°]. The two acetyl–hydrazone substituents are also planar and are inclined at 13.99 (15)/9.17 (16)° [6.83 (17)/14.59 (15)°] relative to the Cp rings. The Fe—C bond lengths range from 2.035 (3) to 2.065 (2) Å, with an average of 2.050 (3) Å [2.036 (3) to 2.069 (2), average 2.046 (3) Å], which agrees well with those reported for most ferrocene derivatives. In the crystal, the molecules form dimers via two strong N—H...N hydrogen bonds. The dimers are linked into a three-dimensional framework by weak N—H...N hydrogen bonds.