1,2-Bis(2-furylmethylene)hydrazine

Crystals of the title compound, C10H8N2O2, were obtained from a condensation reaction of hydrazine hydrate with furfural. In the crystal structure, the molecule is centrosymmetric and almost planar and the furan rings are parallel by symmetry.

Crystals of the title compound, C 10 H 8 N 2 O 2 , were obtained from a condensation reaction of hydrazine hydrate with furfural. In the crystal structure, the molecule is centrosymmetric and almost planar and the furan rings are parallel by symmetry.

S1. Comment
Schiff bases have been studied for decades (Casellato & Vigato 1977) and they are still one of the most prevalent mixeddonor ligands in coordination chemistry, with numerous applications including single-molecule magnetism, materials science and catalysis. Here, the synthsis and crystal structure of the title compound (I) are reported.
The molecule of (I) is centrosymmetric, with the midpoint of the N-N bond located on the inversion center. The C5-N1 double bond distance of 1.272 (2) Å is shorter than the C═N bond distance found in related hydrazone structures, i.e.

S2. Experimental
Hydrazine hydrate (35% solution in water, 0.71 g, 5 mmol) and furfural (0.96 g, 10 mmol) were mixed, at the same time adding 2 or 3 drops of formic acid, and stirred at room temperature in 30 ml of ethanol solution for 2 days, and then the filtrate was kept open to slowly evaporate for a few days, depositing yellow blocks of (I).

S3. Refinement
The H atoms attached were placed in geometrically idealized positions (C-H = 0.93 Å) and refined as riding with U iso (H) = 1.2U eq (C).

Figure 1
A view of the molecular structure of (I) with displacement ellipsoids for the non-hydrogen atoms drawn at the 30% probability level (arbitrary spheres for the H atoms). The unlabelled atoms are generated by the symmetry operation (1-x, 2-y, -z). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.16 e Å −3 Δρ min = −0.25 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.  (7) 0.0085 (8)  C3 0.0722 (11) 0.0589 (10) 0.0616 (9) 0.0093 (7) 0.0038 (7) 0.0082 (7)  C4 0.0639 (9) 0.0452 (8) 0.0496 (7) −0.0049 (6) −0.0044 (6) 0.0007 (6)  C5 0.0690 (10) 0.0485 (8) 0.0522 (8) −0.0055 (7) 0.0007 (7) 0.0013 (6)