Ferrocene-1-carbaldehyde thiosemicarbazone

The asymmetric unit of the title compound, [Fe(C5H5)(C7H8N3S)], consists of two crystallographically independent molecules, A and B. The cyclopentadienyl (Cp) rings in both molecules adopt an eclipsed conformation and are parallel to each other, forming dihedral angles of 2.5 (3) and 1.1 (3)°, respectively. The mean plane of the semicarbazone group is coplanar with the attached Cp ring in molecule A, whereas it is twisted away in molecule B. In the crystal structure, intermolecular N—H⋯S hydrogen bonds link the molecules into two-dimensional planes parallel to the ab plane. The structure is further consolidated by C—H⋯π interactions.

In the crystal structure, intermolecular N-H···S hydrogen bonds (Table 1) link the molecules into two-dimensional layers parallel to ab plane (Fig. 2). The crystal structure is further consolidated by C7A-H7AA···Cg1 interactions.

Experimental
Formylferrocene thiosemicarbazone was prepared as described by Mariño et al. (2006). The single crystals were grown from an aqueous ethanol solution at room temperature in the dark.

Refinement
All H-atoms were placed in calculated positions, with C-H = 0.93-0.98 Å and N-H = 0.86 Å and refined using a riding model, with U iso (H) = 1.2 U eq (C, N). The highest residual density peak is located 1.06 Å from atom Fe1B and the deepest hole is located 0.75 Å from atom Fe1A. Fig. 1

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.