1,1′-Bis[bis(4-tert-butylphenyl)methyl]ferrocene

The molecule of the title compound, [Fe(C26H31)2], is located on an inversion center. The two cyclopentadienyl rings exhibit a staggered conformation, which results from the bulky bis(4-tert-butylphenyl)methyl substituents situated on opposite sides of the molecule.

The molecule of the title compound, [Fe(C 26 H 31 ) 2 ], is located on an inversion center. The two cyclopentadienyl rings exhibit a staggered conformation, which results from the bulky bis(4tert-butylphenyl)methyl substituents situated on opposite sides of the molecule.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: MW2088).
generation of ferrocenyl derivatives of the Gomberg radical (Gomberg, 1900;Gomberg, 1901;Gomberg, 1902). The triphenylmethyl radical exists in solution in an equilibrium with its unsymmetrical dimer, where one para phenyl carbon atom forms a bond to the central methyl carbon of the second molecule (Lankamp et al., 1968;McBride, 1974). In order to prepare starting compounds for the synthesis of ferrocenyl diaryl radicals, diphenylfulvene was equipped with tertbutyl substituents in the para position to prevent such side reactions. Treatment with lithium aluminium hydride and metalation with n-butyllithium, followed by complexation with iron(II) chloride, gave the corresponding ferrocene with two bis(4-tert-butylphenyl)methyl substituents.
The iron center is bound to the cyclopentadienyl ring in the typical η 5 manner. The distance between the two cyclopentadienyl ring planes is 3.315 Å, implying a Cp cent -Fe distance of 1.658 Å. The two Cp rings are arranged in a staggered conformation which results from the large di(4-tert-butylphenyl)methyl substituents arranging on opposite sides of the molecule.

Figure 1
View of the title compound showing thermal ellipsoids at 50% probability.  View of the packing of the title compound.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. All hydrogen atoms were placed in calculated positions (C-H 0.96, 0.98 or 1.00 Å) and refined by using a riding model. 0.0308 (9) 0.0257 (9) 0.0245 (9) −0.0020 (7) 0.0082 (7) −0.0023 (7) C9 0.0291 (9) 0.0254 (9) 0.0332 (9) −0.0050 (7) 0.0079 (7) 0.0009 (7)