(R)-2-[(Dimethylamino)methyl]-1,1′-bis(diphenylphosphinothioyl)ferrocene dichloromethane monsolvate

In the title compound, [Fe(C20H21NPS)(C17H14PS)]·CH2Cl2, both cyclopentadienyl (Cp) rings constituting the ferrocene unit are substituted by a sulfur-protected diphenylphosphine. One of the Cp ligands is additionally substituted by a dimethylaminomethyl group causing the chirality of the molecule. Surprisingly, although the synthetic procedure yielded the title compound as a racemic mixture, the reported crystal is enantiomerically pure with the R absolute configuration. The dimethylamino group is exo with respect to the Cp ring. Both diphenylthiophosphine groups are trans with respect to the centroid–Fe–centroid direction. Weak intramolecular C—H⋯S and C—H⋯π interactions between symmetry-related molecules are observed. The contribution of the disordered solvent was removed from the refinement using SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155].

In the title compound, [Fe(C 20 H 21 NPS)(C 17 H 14 PS)]ÁCH 2 Cl 2 , both cyclopentadienyl (Cp) rings constituting the ferrocene unit are substituted by a sulfur-protected diphenylphosphine. One of the Cp ligands is additionally substituted by a dimethylaminomethyl group causing the chirality of the molecule. Surprisingly, although the synthetic procedure yielded the title compound as a racemic mixture, the reported crystal is enantiomerically pure with the R absolute configuration. The dimethylamino group is exo with respect to the Cp ring. Both diphenylthiophosphine groups are trans with respect to the centroid-Fe-centroid direction. Weak intramolecular C-HÁ Á ÁS and C-HÁ Á Á interactions between symmetry-related molecules are observed. The contribution of the disordered solvent was removed from the refinement using SQUEEZE in PLATON [Spek (2009). Acta Cryst. D65,[148][149][150][151][152][153][154][155].  Routaboul et al. (2005Routaboul et al. ( , 2007.

Experimental
Crystal data [Fe(C 20 Table 1 Hydrogen-bond geometry (Å , ). diffraction analysis could be grown from a dichloromethane solution by slow diffusion of hexane.
In the title compound, both Cp rings constituting the ferrocene unit are substituted by a sulfur protected diphenylphosphine. One of the Cp ligands is additionally substituted by a dimethylaminomethyl group causing the chirality of the molecule. Surprisingly, although the synthetic procedure yielded the title compound as a racemic mixture, the reported crystal is enantiomerically pure with the R absolute configuration (Fig. 1). The dimethylamino moiety is exo with respect to the Cp ring as already observed for the related 2-(diphenylthiophophino)-dimethylaminomethylferrocene (Mateus et al., 2006). The C2-C21-N2 group is bent with respect to the Cp ring making a dihedral angle of 73.8 (3)° and the two methyl groups have rotated around the C21-N2 bond from the idealized bisecting position to minimize the interactions with the corresponding C111-C116 phenyl ring. The two diphenylthiophosphine moieties are trans with respect to the Ct1-Fe-Ct2 centroid direction (Ct1 and Ct2 being the centroids of the C1-C5 and C6-C10 Cp rings, respectively) as it was also observed in the molecular structure of related 1,1-(bisdiphenylthiophosphino)ferrocene (Fang et al.,1995;Pilloni et al., 1997). The P1-Ct1-Ct2-P6 torsion angle is 146.75 (2)°.
The two Cp rings are eclipsed with a twist angle of 0.8 (2)°. There is a weak intramolecular C-H···S interaction (Table   1). Weak intramolecular C-H···S and C-H···π interactions between symmetry related molecules are observed (Table 1).

Experimental
In a Schlenk tube, were dissolved, under argon, 13.5 g (55.6 mmol) of N,N-dimethylaminomethylferrocene in 80 ml of dry diethylether. The solution was cooled down to -78°C and 42 ml (67.1 mmol) of a 1.65M n-BuLi solution in hexane were added dropwise. The solution was then stirred 3 h at RT. After cooling back to -78°C again, 27 ml (150 mmol) of freshly distilled chlorodiphenylphosphine were added dropwise. After stirring overnight at RT, water was added slowly under argon. The aqueous phase was then extracted by three fractions of dichloromethane under argon. The organic solutions were dried with sodium sulfate. After evaporation of the solvents, the crude material was dissolved, under argon, in 400 ml of dry dichloromethane in a Schlenk tube. 10.2 g of sulfur (318 mmol) was then added and the solution supplementary materials sup-2 . E68, m799-m800 was kept at reflux for 2 h. The crude material was purified by flash chromatography on silica with pentane then ether as eluent to yield two yellow fractions (first fraction: 0.45 g of 1,1′-bis(diphenylthiophosphino) 2-dimethylaminomethylferrocene (1.2%); second fraction: 23.2 g of 2-(diphenylthiophosphino)dimethylaminomethylferrocene (91%)).
Some residual electron densities were difficult to modelize and therefore the SQUEEZE function of PLATON (Spek, 2009) was used to eliminate the contribution of the electron density in the solvent region from the intensity data, and the solvent-free model was employed for the final refinement. There are two cavities of 246 Å 3 per unit cell. PLATON estimated that each cavity contains 82 electrons which may correspond to two solvent molecules of dichloromethane as suggested by chemical analyses.
The dimethylamino moiety displays rather large ellipsoids however attempts to modelize a disordered model failed and thus these large ellipsoids reflect rather thermal motion than disorder.  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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (