Li2PtF6 revisited

In comparison with previous stucture determinations of Li2PtF6, dilithium hexafluoridoplatinate(IV) [Graudejus et al. (2000 ▶). Inorg. Chem. 39, 2794–2800; Henkel & Hoppe (1968 ▶). Z. Anorg. Allg. Chem. 359, 160–177], the current study revealed the Li atom to be refined with anisotropic displacement parameters, thus allowing for a higher overall precision of the model. Li2PtF6 adopts the trirutile structure type with site symmetries of 2.mm, m.mm, ..m and m.2m for the Li, Pt and the two F sites. The Pt—F distances in the slightly distorted PtF6 octahedron are essentially similar with 1.936 (4) and 1.942 (6) Å, and the equatorial F—Pt—F angles range from 82.2 (2) to 97.8 (2)°. The Li—F distances in the somewhat more distorted LiF6 octahedron are 1.997 (15) and 2.062 (15) Å, with equatorial F—Li—F angles ranging from 76.3 (7) to 99.71 (17)°.


Related literature
reported on the synthesis of Li 2 PtF 6 by direct fluorination of (NH 4 ) 2 PtCl 6 and Li 2 CO 3 . The obtained yellow Li 2 PtF 6 was characterized by powder X-ray diffraction and reported to crystallize in the monoclinic crystal system. Graudejus et al. (2000) obtained Li 2 PtF 6 in the form of yellow and air-stable crystals from the reaction of LiF with Pt in anhydrous HF under UV-photolysis of F 2 . The reported space group and unit cell parameters are in accordance with the current redetermination. However, a low precision of the Pt-F bond lengths of only AE0.01 Å was obtained due to many unobserved reflections even at the 2 level. For synthetic details for the preparation of PtF 4 , see: Mü ller & Serafin (1992). Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2007); software used to prepare material for publication: SHELXL97.

Crystal data
The author would like to thank the Deutsche Forschungsgemeinschaft for his Heisenberg fellowship, Professors R. Hoppe and B. Mü ller (Giessen, Germany) for the generous donation of Pt tubes and Pt used in this work, and Solvay Fluor for the donation of F 2 .
Supporting information for this paper is available from the IUCr electronic archives (Reference: WM5032).

Figure 1
View of the coordination polyhedra around Pt and Li. Displacement ellipsoids are shown at the 70% 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.