Bis(3-carboxy-5-nitrobenzoato)bis[2-(pyridin-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline]manganese(II)

In the title compound, [Mn(C8H4NO6)2(C18H11N5)2], the MnII atom is six-coordinated by two N,N′-bidentate 6-(pyridin-4-yl)-5H-cyclopenta[f][1,10]phenanthroline (pcp) ligands and two carboxylate O atoms from two monodentate 3-carboxy-5-nitrobenzoate anions in a distorted cis-MnO2N4 octahedral arrangement. Within the pcp ligands, the dihedral angles between the polycyclic skeletons and pendant pyridine rings are 6.2 (2) and 8.3 (2)°. In the crystal, molecules are linked by O—H⋯N and N—H⋯O hydrogen bonds. Several aromatic π–π stacking interactions [shortest centroid–centroid separation = 3.516 (3) Å] are also observed.

carboxylic acid) as a secondary ligand and L as a N-donor chelating ligand, generating a new molecular Mn II complex, The central Mn II atom is six-coordinated by four N atoms from two different L ligands, and two carboxylate O atoms from two different 1,3-Hbdc ligands in a distorted octahedral sphere. The O-H···N and N-H···O H-bonding interactions further stabilize the structure of (I).

Experimental
A mixture of MnCl 2 . 4H 2 O (0.5 mmol), 1,3-H 2 bdc (0.5 mmol) and L (0.5 mmol) in 1 ml distilled water was heated at 460 K in a Teflon-lined stainless steel autoclave for seven days. The reaction system was then slowly cooled to room temperature.
Pale yellow blocks of (I) were collected from the final reaction system by filtration, washed several times with distilled water and dried in air at ambient temperature. Yield: 31% based on Mn(II).

Refinement
All H atoms were positioned geometrically (C-H = 0.93 Å) and refined as riding, with U iso (H) = 1.2U eq (carrier). Fig. 1. The asymmetric unit in (I) with isplacement ellipsoids drawn at the 30% probability level.

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.