4,4′-[(2,7-Dibromofluorene-9,9-diyl)dimethylene]dipyridinium bis(perchlorate)

In the crystal of the title compound, C25H20Br2N2 2+·2ClO4 −, intermolecular N—H⋯O and C—H⋯O hydrogen bonds, along with C—H⋯π interactions, stabilize the crystal structure.


Related literature
A variety of ligands of different molecular dimensions and functional properties have been utilized in the preparation of numerous supramolecular assemblies with exotic architectures, see: Applegarth et al., (2005). For related structures, see: Meerssche et al. (1979Meerssche et al. ( , 1980.

scheme I
The structure of the title compound contains a protonated 2,7-dibromo-9,9-bis(4-pyridinium-methyl) fluorene dications DBPMFH 2 2+ and two perchlorate anions ClO 4 -. All the bond lengths and bond angles in the phenyl ring and five-membered ring are corresponding with those observed in 2-acetylaminofluorene (Meerssche et al., 1980) and 4-acetylamino-fluorene (Meerssche et al., 1979). Two bromine atoms along with the thirteen atoms of fluorenyl ring are coplanar (P1) and the biggest deviation is 0.038Å for C6 atom. The dihedral angle between the plane P1 and the pyridyl ring containing N1 atom is 72.11 (2)°.
In the crystal lattice, there are four types of supramolecular interactions (Table 1), including N-H···O hydrogen bonds, C-H···O potential hydrogen bonds, C-H···π supramolecular interaction and π-π stacking interactions. Among these supramolecular interactions, the two types N-H···O hydrogen bonds link two DBPMFH 2 2+ cations with two ClO 4 anions to construct one-dimensional chains, then the other supramolecular interactions help the 1D chains to form three-dimensional net-works, which stabilize the crystal structure.

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 > σ(F 2 ) is used only for calculating Rfactors(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