(2E,6E)-2,6-Bis(ferrocenylmethylidene)cyclohexanone dichloromethane monosolvate

In the title compound, [Fe2(C5H5)2(C18H16O)]·CH2Cl2, the C=C bonds both adopt E conformations. In one ferrocenyl group, the five-membered rings are in a near-eclipsed conformation, whereas in the other they are mutually rotated by ca 21.5°. The central cyclohexanone ring adopts a sofa conformation. In the crystal, the dichloromethane solvent moleucle forms C—H⋯O hydrogen bonds to the organometallic molecules to generate [010] chains of alternating solvent and organometallic species.

In the title compound, [Fe 2 (C 5 H 5 ) 2 (C 18 H 16 O)]ÁCH 2 Cl 2 , the C C bonds both adopt E conformations. In one ferrocenyl group, the five-membered rings are in a near-eclipsed conformation, whereas in the other they are mutually rotated by ca 21.5 . The central cyclohexanone ring adopts a sofa conformation. In the crystal, the dichloromethane solvent moleucle forms C-HÁ Á ÁO hydrogen bonds to the organometallic molecules to generate [010] chains of alternating solvent and organometallic species.
The molecule of the title compound (I) exists as the most stable configuration of (E,E)-isomer ( Fig.1). In the two ferrocenyl moieties Fe1 atom is further to the plane of Cps1 (the substituted cyclopentadienyl ring) (Table 1) and nearer to the plane of Cp1 (the unsubstituted cyclopentadienyl ring) but Fe2 atom is nearer to the plane of Cps2 and further to the plane of Cp2, just in reverse manner, with distances of Fe1 to Cg1 and Cgs1 (Cg and Cgs are respectively the centers of Cp and Cps in the every ferroceneyl group) 1.649 (5) Å and 1.641 (4) Å, respectively, and these of Fe2 to Cgs2 and Cg2 1.635 (4) Å and 1.651 (4) Å, respectively. The two planes of Cp and Cps in the every ferrocenyl group are almost parallel because the dihedral angles of Cp1 to Cps1 and Cp2 to Cps2 are 1.1 (5)° and 1.2 (6)° (Table 2), respectively.
In the crystal, the molecules are linked by two C-H···O hydrogen-bonds.

Experimental
Under the protection of argon gas a total of powder potassium hydroxide (1.68 g, 0.03 mol), ferrocenecarboxaldehyde (4.28 g, 0.02 mol) and cyclohexanone (0.98 g, 0.01 mol) were dissolved in 50 ml ethanol and the mixture solution was reacted in a microwave (700 W, generating 2450 MHz frequency) refluxing system for 3 min. Then the red mixture solid was poured into 40 ml water, filtered off, washed with water and and a water/ethanol (1:1) mixture three times. After drying and recrystallization from 95% ethanol, the title compound (4.20 g) was obtained, yield 85. 5% and m.p. 436.5-437.8 K (lit. 435.5-436.5;Bai et al., 2004). Orange needles were obtained by slow evaporation of a solution of the solid in dichloromethane/ether (9:1 volume ratio) at room temperature over a period of 8 d.

Refinement
After their location in a difference map, all H atoms were fixed geometrically at ideal positions and allowed to ride on the parent C atoms, with C-H distances of 0.93 Å (aryl) and 0.97 Å (CH 2 ), and with U iso (H) values of 1.2U eq (C).

Special details
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.