Crystal structure of Cr (III) complex containing nitrilotriacetic acid and 4, 4-bipyridine

The title compound (C10H9N2)[Cr(C6H7NO6)2](C10H8N2)∙2H2O or (4,4´-bipyH)[Cr(ntaH)2](4,4´-bipy)∙2H2O (ntaH3 is nitrilotriacetic acid) was synthesized by reaction of Cr(NO3)3∙9H2O with 4,4´-bipyridine, and nitrilotriacetic acid with 4:2:1 molar ratio in aqueous solution. The crystal structure of this complex was identified using X-ray crystallography. The unit cell parameters are as follows:a = 9.8501(3) Å, b = 13.157(2) Å, c = 26.842(4) Å, β = 104.807(7)°.
The final R value is 0.041 for 7747 independent reflections. The title compound crystallized in monoclinic system and belongs to P21/c space group.  The central CrIII atom is coordinated by two tridentaid (ntaH2) ligands and the resulted CrO4N2 set can be described as distorted octahedral geometry. The asymmetric unit contains two half of anionic complex, one 4, 4´-bipyridiniom ion, (4, 4´-bipyH)+, one neutral 4, 4´-bipyridine molecule and two non-coordinated water molecules. Intramolecular hydrogen bonds, π-π [centroid –centroid distances of 3.674 Ǻ], C-H…π, O-H…π and N-H…π stacking interactions [with distance of 3.714, 3.736 and 3.270 Å respectively], connect the various components into a supramolecular structures.