Two coordination modes of CuII in a binuclear complex with N-(pyridin-2-ylcarbonyl)pyridine-2-carboxamidate ligands

In the title dinuclear complex, (acetonitrile-1κN)[μ-N-(pyridin-2-ylcarbonyl)pyridine-2-carboxamidato-1:2κ5 N,N′,N′′:O,O′][N-(pyridin-2-ylcarbonyl)pyridine-2-carboxamidato-2κ3 N,N′,N′′]bis(trifluoromethanesulfonato-1κO)dicopper(II), [Cu2(C12H8N3O2)2(CF3O3S)2(CH3CN)], one of the CuII ions is five-coordinated in a distorted square-pyramidal N3O2 environment provided by two N-(pyridin-2-ylcarbonyl)pyridine-2-carboxamidate (bpca) ligands, while the second CuII ion is six-coordinated in a distorted octahedral N4O2 environment provided by one bpca ligand, two trifluoromethansulfonate ligands and one acetonitrile molecule. Weak intermolecular C—H⋯O and C—H⋯F hydrogen bonds and π–π stacking interactions with centroid–centroid distances of 3.6799 (15) and 3.8520 (16) Å stabilize the crystal packing and lead to a three-dimensional network.

The above mentioned complex presents the copper(II) ion Cu1 in a five-coordinate environment in a somewhat distorted square pyramidal geometry. The coordination includes two bpca ligands. One ligand acts as a tridentate N,N′N′′chelate through two pyridine nitrogen atoms (Cu-N1 = 1.978 (2) and Cu-N3 = 1.988 (2) Å) and one amide nitrogen In the crystal lattice, the dinuclear units are packed through intermolecular C-H···A (A = O, F) hydrogen bonds (Table   1) between the pyridine ring hydrogen atoms and the carbonyl oxygen atoms (O1, O2) of the bpca ligand, the sulfonyl oxygen (O9, O10) and the fluor atom (F5) of the trifluoromethansulfonate ligands. The pyridine rings interact also via ππ stacking interactions, with Cg-Cg distances of 3.6799 (15) Å for the interaction between the tridentate bpca ligands, and of 3.8520 (16) Å for the interactions between the bridging bpca ligands (Fig. 2).

Refinement
H atoms were included in calculated positions (C-H = 0.95 Å for aromatic H, C-H=0.98 Å for methyl H), and refined using a riding model, with U iso (H) = 1.2U eq and U iso (H) = 1.5U eq for methyl H atoms.

Figure 1
The molecular structure of the title compound with displacement ellipsoids at the 40% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq  (4)