Crystal structure of diaquabis(4-tert-butylbenzoatoκO)bis(nicotinamide-κN1)cobalt(II) dihydrate

The asymmetric unit of the mononuclear cobalt complex, [Co(C₁₁H₁₃O₂)₂- (C₆H₆N₂O)₂(H₂O)₂].2H₂O, contains one half of the complex molecule, one coordinating and one non-coordinating water molecule, one 4-tert-butylbenzoate (TBB) ligand and one nicotinamide (NA) ligand; the Co atom lies on an inversion centre. All ligands coordinating to the Co atom are monodentate. The four nearest O atoms around the Co atom form a slightly distorted square-planar arrangement, with the distorted octahedral coordination completed by the two pyridine N atoms of the NA ligands at distances of 2.1638 (11) Å . The coordinating water molecules are hydrogen bonded to the carboxyl O atoms [O ⋯ O = 2.6230 (17) Å ], enclosing an S(6) hydrogenbonding motif, while intermolecular O-H⋯O hydrogen bonds link two of the non-coordinating water molecules to the coordinating water molecules and NA anions. The dihedral angle between the planar carboxylate group and the adjacent benzene ring is 29.09 (10)°, while the benzene and pyridine rings are oriented at a dihedral angle of 88.53 (4)°. In the crystal, O-H⋯O and N- H⋯O hydrogen bonds link the molecules, enclosing R²₂(8), R²₂(10) and R⁴₄(12) ring motifs, forming layers parallel to (001). The C and H atoms of the tert-butyl group of the TBB ligand are disordered over two sets of sites with an occupancy ratio of 0.631 (5):0.369 (5).