Crystal structure of [2,6-difluoro-3-(pyridin-2-yl-κN)pyridin-4-yl-κC 4](pentane-2,4-dionato-κ2 O,O′)platinum(II)

The PtII atom adopts a distorted square-planar coordination geometry, being C,N-chelated by a 2′,6′-difluoro-2,3′-bipyridine ligand and O,O′-chelated by a pentane-2,4-dionato anionic ligand.


Chemical context
Cyclometalated platinum(II) compounds with C,N-chelating ligands have been considered as an attractive research area due to their wide applications, such as biological imaging, nonlinear optics, oxygen sensing and organic light-emitting diodes (OLEDs) (Hudson et al., 2012). In particular, phenylpyridine (ppy) based platinum(II) -diketonate compounds have been widely studied because of their excellent stability and high quantum efficiency in OLEDs (Rao et al., 2012). However, examples of platinum(II) compounds with C,N-chelating bipyridine ligands are scarce. Herein, we report the result of our investigation on the crystal structure of a novel platinum(II) compound with fluorinated bipyridine and acetylacetonate (acac, O,O) ligands.

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. The asymmetric unit consists of one Pt II atom, one 2,6difluoro-2,3-bipyridine ligand and one acetylacetonate anion. The Pt II atom is four-coordinated by the C,N-chelating 2 0 ,6 0difluoro-2,3 0 -bipyridinato ligand and by the O,O 0 -chelating ISSN 2056-9890 pentane-2,4-dionato ligand, forming a distorted square-planar coordination sphere due to narrow ligand bite angles, which range from 81.28 (17) to 93.25 (13) . The Pt-C bond length of 1.951 (4) Å is shorter than the Pt-N bond length of 1.995 (4) Å due to the more electronegative fluorine substituent on the C-bound pyridine ring. The Pt-C, Pt-N and Pt-O bond lengths (Table 1) are in normal ranges as reported for similar Pt II compounds, e.g. [Pt(Bppy)(acac)] (Bppy is a boron-functionalized phenylpyridine; Rao et al., 2012). Within the C,N-bidentate ligand of the title compound, the two pyridine rings are approximately co-planar, making a dihedral angle of 1.2 (2) , indicating that an effective conjugation of the two pyridine rings occurs in the title compound. The molecular structure is stabilized by weak intramolecular C-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds (Table 2).

Figure 2
The two-dimensional supramolecular network formed through C-HÁ Á ÁF interactions (yellow dashed lines). H atoms not involved in intermolecular interactions have been omitted for clarity.

Figure 3
The three-dimensional supramolecular network formed throughstacking interactions (black dashed lines). Yellow dashed lines indicate the C-HÁ Á ÁF interactions. H atoms not involved in intermolecular interactions have been omitted for clarity.

Synthesis and crystallization
The title compound was synthesized according to a previous report (Rao et al., 2012). Slow evaporation from a dichloro-methane/hexane solution afforded yellow crystals suitable for X-ray crystallography analysis.

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.