Tetrabromido(di-2-pyridylamine-κ2 N 2,N 2′)platinum(IV)

The PtIV ion in the title complex, [PtBr4(C10H9N3)], is six-coordinated in a slightly distorted octahedral environment by two pyridine N atoms from a chelating di-2-pyridylamine (dpa) ligand and four Br− anions. The complex molecule has mirror symmetry, with the PtIV atom, two Br atoms and the central N atom of the dpa ligand lying on the mirror plane. The dpa ligand is not planar, showing a dihedral angle of 34.7 (2)° between the pyridine rings. The complex molecules are connected by intermolecular N—H⋯Br hydrogen bonds, forming chains along [001]. Intermolecular C—H⋯Br hydrogen bonds and π–π interactions between the pyridine rings [centroid–centroid distance = 3.667 (4) Å] are also observed.

The Pt IV ion in the title complex, [PtBr 4 (C 10 H 9 N 3 )], is sixcoordinated in a slightly distorted octahedral environment by two pyridine N atoms from a chelating di-2-pyridylamine (dpa) ligand and four Br À anions. The complex molecule has mirror symmetry, with the Pt IV atom, two Br atoms and the central N atom of the dpa ligand lying on the mirror plane. The dpa ligand is not planar, showing a dihedral angle of 34.7 (2) between the pyridine rings. The complex molecules are connected by intermolecular N-HÁ Á ÁBr hydrogen bonds, forming chains along [001]. Intermolecular C-HÁ Á ÁBr hydrogen bonds andinteractions between the pyridine rings [centroid-centroid distance = 3.667 (4) Å ] are also observed.
The Pt IV ion is six-coordinated in a slightly distorted octahedral environment defined by two pyridine N atoms from a chelating dpa ligand and four Branions ( Fig. 1). The complex is disposed about a mirror plane, passing through the Pt1, Br1, Br2 and N2 atoms. The Pt-N and Pt-Br bond distances are comparable to those observed in the related Pt II complex [PtBr 2 (dpa)] (Ha, 2012). In the crystal, the dpa ligand is not planar. The dihedral angle between the least-squares planes of the pyridine rings is 34.7 (2)°. The complex molecules are stacked in columns along the a axis and connected by intermolecular N-H···Br hydrogen bonds, forming chains along the c axis ( Fig. 2, Table 1). Intermolecular π-π interactions between the pyridine rings are present, with a centroid-centroid distance of 3.667 (4) Å. Intermolecular C-H···Br hydrogen bonds are also observed (Table 1).

Experimental
To a solution of K 2 PtCl 6 (0.240 g, 0.49 mmol) and KBr (0.745 g, 6.26 mmol) in H 2 O (50 ml) was added di-2-pyridylamine (0.086 g, 0.50 mmol), and the mixture was stirred for 24 h at room temperature. The formed precipitate was separated by filtration, washed with H 2 O and acetone, and recrystallized from a mixture of N,N-dimethylformamide and ether to give a red powder (0.144 g). Crystals suitable for X-ray analysis were obtained by slow evaporation from a CH 3 CN solution at room temperature.

Refinement
C-bound H atoms were positioned geometrically and allowed to ride on their respective parent atoms, with C-H = 0.95 Å and with U iso (H) = 1.2U eq (C). N-bound H atom was located from a difference Fourier map and then allowed to ride on its parent atom in the final cycles of refinement, with N-H = 0.92 Å and U iso (H) = 1.2U eq (N). The highest peak (1.89 e Å -3 ) and the deepest hole (-1.62 e Å -3 ) in the difference Fourier map are located 0.85 Å and 0.67 Å from atoms Pt1 and Br1, respectively.

Computing details
Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.89 e Å −3 Δρ min = −1.61 e Å −3 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 Pt1 0.02241 (