(η5-Cyclopentadienyl)(η6-1,2-dipyrrolidin-1-ylbenzene)iron(II) hexafluoridophosphate

Both complexed rings in the iron(II) complex cation of the title salt, [Fe(C5H5)(C14H20N2)]PF6, are almost parallel [dihedral angle between planes = 5.34 (13)°]. Among the C atoms of the complexed arene ring, the quaternary C atoms are located at the longest, albeit unequal, distances from the Fe atom [2.252 (2) and 2.168 (2) Å].

Both complexed rings in the iron(II) complex cation of the title salt, [Fe(C 5 H 5 )(C 14 H 20 N 2 )]PF 6 , are almost parallel [dihedral angle between planes = 5.34 (13) ]. Among the C atoms of the complexed arene ring, the quaternary C atoms are located at the longest, albeit unequal, distances from the Fe atom [2.252 (2) and 2.168 (2) Å ].

Comment
The title compound, along with similar mono-and/or di-N-butylamino-and cyano-arenes complexed with a cyclopentadienyliron(II) moiety, were reported in the study of nucleophilic aromatic mono-and di-substitution reactions using 1,2-, 1,3-, and 1,4-dichlorobenzene FeCp complexes (Lee et al., 1989). The ORTEP of the title compound is shown in Figure 1. The two aromatic rings are not planar, with an angle of 5.34 (13)° between the planes formed by C1···C6 and C21···C25. This is the largest value among those reported previously by our group, although lower than the values 7° reported for 1,1'-trimethylenebenzene-CpFe cation (Nesmeyanov et al., 1977), and 5.4° reported for hexaethylbenzene-CpFe complex (Dubois et al., 1989). No standard uncertainties were given by these authors.
The Fe ion is located at the distances 1.6601 (12) Å from the Cp and 1.5680 (11) Å from the phenyl ring, and these values are close to those reported in the literature for similar complexes (see for example Piórko et al., 1995;Fuentealba et al., 2007;Manzur et al., 2009; and literature cited therein). The Fe -C1 distance at 2.252 (2) Å (where C1 is one of the quaternary carbon atoms in the phenyl ring bonding N1 of pyrrolidinyl substituent), is the longest among the distances Fe to C atoms of this ring. The distance Fe -C2 (where C2 is another quaternary carbon atom of the complexed phenyl ring) is significantly shorter at 2.168 (2) Å. While this second value is typical for an aromatic C atom (in a FeCp or Fe-pentamethylCp complexed phenyl ring) to Fe distance (see for example Piórko et al., 1995;Manzur et al., 2000;Fuentealba et al., 2007;Manzur et al., 2009, and literature cited therein), the Fe -C1 distance is the longest one reported, to the best of our knowledge, for similar iron complexes. In a complexed arene ring, the longest bond between carbon atoms of this ring is found for C1 -C2  (3) Å]. One of the pyrrolidinyl rings (N2 -C11···C14) appears to be quite symmetrical and located in and below the plane of the metal-complexed phenyl ring, while another one (N1 -C7···C10) shows distorted both interatomic distances and angles, and is located above the plane of the complexed phenyl ring. The planes defined by the carbon atoms of both pyrrolidinyl rings are tilted with respect to the phenyl ring plane by 32.12(0.17)° for a plane C11···C14 and 29.40(0.13)° for the plane C7···C10.

Experimental
The title compound was prepared following the method of Lee et al. (1989). A crystal used for data collection was grown by slow evaporation of solvents from a solution of the complex in acetone-diethyl ether-dichloromethane mixture at 280 K.

Refinement
The H atoms were placed in geometrically idealized positions with C-H distances of 0.99Å (aromatic) and 0.98Å (methylene) and constrained to ride on the parent C atom with Uiso(H) = 1.2Ueq(C) for aromatic and methylene protons.