(Carbonato-κ2 O,O′)bis(di-2-pyridylamine-κ2 N,N′)cobalt(III) bromide

In the title compound, [Co(CO3)(C10H9N3)2]Br, a distorted octahedral coordination of the CoIII atom is completed by four N atoms of the two chelating di-2-pyridylamine ligands and two O atoms of the chelating carbonate anion. The di-2-pyridylamine ligands are nonplanar and the dihedral angles between the 2-pyridyl groups are 29.11 (9) and 37.15 (12)°. The coordination cation, which has approximate C 2 symmetry, is connected to the bromide ion via an N—H⋯Br− hydrogen bond. The ionic pair thus formed is further assembled into a dimer via N—H⋯O interactions about an inversion centre. A set of weaker C—H⋯O and C—H⋯Br− interactions connect the dimers into a three-dimensional network.

In the title compound, [Co(CO 3 )(C 10 H 9 N 3 ) 2 ]Br, a distorted octahedral coordination of the Co III atom is completed by four N atoms of the two chelating di-2-pyridylamine ligands and two O atoms of the chelating carbonate anion. The di-2pyridylamine ligands are nonplanar and the dihedral angles between the 2-pyridyl groups are 29.11 (9) and 37.15 (12) . The coordination cation, which has approximate C 2 symmetry, is connected to the bromide ion via an N-HÁ Á ÁBr À hydrogen bond. The ionic pair thus formed is further assembled into a dimer via N-HÁ Á ÁO interactions about an inversion centre. A set of weaker C-HÁ Á ÁO and C-HÁ Á ÁBr À interactions connect the dimers into a three-dimensional network.
(Carbonato-2 O,O')bis (di-2-pyridylamine-2   The title compound ( Fig. 1) was obtained as a byproduct in the preparation of [Co(Hdpa) 2 (apo)]Br from CoBr 2 , where apo is 2-acetylphenolate ion and Hdpa is di-2-pyridylamine. The chelating carbonate ligand in the coordination cation was identified from its geometrical parameters, namely the two bonds of 1.325 (4) and 1.341 (4) Å indicated single C-O bonds and the bond length of 1.183 (4) Å pointed to a C=O bond. The presence of the carbonate anion in the studied compound concurred with the +3 oxidation state of the cobalt atom. The Co III atom shows a distorted octahedral coordination that is completed by four N atoms of the two chelating di-2-pyridylamine ligands and two O atoms of the chelating carbonate anion ( Table 1). The bidentate Hdpa ligands chelate the Co III atom to form two six-membered rings with the N1-Co1-N9 bite angles of 90.42 (10) and 88.48 (10)°, in ligand A and B respectively. The diimine ligands are non-planar with the N(py)-C-N(H)-C torsion angles of 28.1 (4) and -27.6 (4)° in the A ligand and 28.0 (4) and -33.5 (4)° in the B Hdpa ligand.
The coordination cation has approximate C 2 symmetry with a pseudo-twofold axis passing through atoms O3, C1 and Co1. It binds one Branion via a N-H···Brhydrogen bond and the ionic pair thus formed assembles into a dimer, via N-H···O hydrogen bonds (Fig. 2, Table 2), centered about an inversion center. These dimers are further connected via a C10B-H10B···O3(x, y -1, z) interaction into chains extended along [010] and the chains are joined via a set of C-H···O and C-H···Brinteractions into a three-dimensional network (Table 2).
Interesingly, similar interactions between the coordination cation and the anion, and the formation of dimers of the ionic pairs, was also observed in the nitrate and perchlorate salts of the same cation (Castillo et al., 2011;Williams et al., 1987).
Moreover, the crystals of the nitrate salt and the title bromide salt are to a large extent isostructural.
Experimental 2 mmol (0.342 g) of di-2-pyridylamine (Hdpam), dissolved in a small amount of EtOH, was added to a solution of 1 mmol (0.238 g) of CoBr 2 .H 2 O in 5 ml of EtOH and the mixture was stirred for 30 min. Then, to this mixture was added dropwise an ethanolic solution containing 1 mmol (0.136 g) of 2-hydroxyacetophenone (Hapo) and 1 mmol of CH 3 ONa. The solution was stirred at room temperature under an argon atmosphere for 2 h or refluxed with continuous stirring. Two types of crystals precipitated from the solution. The main product, in the form of small crystals of light orange color, was identified as the mixed-ligand Co II complex [Co(dpamH) 2 (apo)]Br (mean yield 62%). The side-product, in the form of large dark-red crystals, was identified as the Co III complex, [Co(dpamH) 2 (CO 3 )]Br. When the reaction between CoBr 2 and Hdpam was repeated in air the title compound, [Co(dpamH) 2 (CO 3 )]Br, was obtained as the main product.

Refinement
The H-atoms of the NH groups were located in difference electron-density maps. In the final cycles of lease-squares refinement the N-H bond lengths were constrained to 0.86 Å with U iso (H) = 1.2U eq (N). All the other H-atoms were initially identified in difference electron-density maps but were placed at calculated positions, with C-H = 0.95 Å, and were refined as riding on their carrier atoms, with U iso (H) = 1.2U eq (C). Fig. 1. Asymmetric unit of the title compound with the displacement ellipsoids shown at the 50% probability level.    120.1 (2) C12B-C13B-H13B 120.5 C10A-N9A-Co1 120.9 (2) C8B-C13B-H13B 120.5