Tetra(chlorido/iodido)(1,10-phenanthroline)platinum(IV) hemi[di(chlorine/iodine)]

The asymmetric unit of the title compound, [PtCl3.66I0.34(C12H8N2)]·0.5(Cl0.13I1.87), contains a neutral PtIV complex and one half of a halogen molecule. The PtIV ion is six-coordinated in a distorted octahedral environment by two N atoms of the 1,10-phenanthroline ligand and Cl or I atoms. The refinement of the structure and the EDX analysis indicate that the compound is a solid solution in which there is some substitution of Cl for I and vice versa. The chemical formula of the pure state of the compound would have been [PtCl4(C12H8N2)]·0.5I2. In the analysed crystal, two Cl atoms are partially (ca 25% and 9%) replaced by I atoms, and the I2 molecule has a minor component modelled as ICl. As a result of the disorder, the different trans effects of the N and Cl/I atoms are not distinct. The complex displays intermolecular π–π interactions between the six-membered rings, with a centroid–centroid distance of 3.771 (4) Å. There are also weak intramolecular C—H⋯Cl hydrogen bonds.


S1. Comment
The asymmetric unit of the title compound contains a neutral Pt IV complex and one half-molecule of iodine which includes some Cl atoms (ca 6%). The Pt IV ion is six-coordinated in a distorted octahedral environment by two N atoms of the 1,10-phenanthroline ligand and Cl or I atoms. The chemical formula of the pure state of the title compound would have been [PtCl 4 (C 12 H 8 N 2 )].0.5I 2 . In the particular crystal of the compound used, two Cl atoms (Cl3 and Cl4) are partially (ca 25% and 9%, respectively) displaced by the I atoms (I3 and I4) through the substitution reaction between the Cland Iligand, and the I 2 molecule also appears to have a minor component, that is I-Cl ( Fig. 1 and 2). The chemical formula which resulted from the refinement of the structure was [PtCl 3.66 I 0.34 (C 12 H 8 N 2 )].0.5(Cl 0.13 I 1.87 ), and in this case the ratio of the Cl atom to I atom is 2.91:1. An EDX analysis of the compound, however, gave a ratio of Cl:I = 2.47:1. Accordingly, the exact composition may very well be variable, and likely dependent on the exact conditions present during crystal formation. Even though these data are slightly different, they indicate clearly that the crystals are a solid solution in which there was some substitution of Cl for I and vice versa.
As a result of the different trans effects of the N and Cl atoms, the Pt-Cl bonds trans to the N atom are in general slightly shorter than bond lengths to mutually trans Cl atoms (Kim et al. 2009a and2009b). But the trans effects of the N and Cl/I atoms in the crystal are not distinct owing to the disordered atoms. The Pt-I distance is restrained to the value given in table 9.6.3.3 of the International Tables Vol. C (Orpen et al., 1989) (2.658 Å). The main contributor to the distortion from a true octahedral structure is the tight N1-Pt1-N2 chelate angle (81.3 (2)°), which result in non-linear trans axes (<Cl1-Pt1-N1 = 174.14 (16)° and <Cl2-Pt1-N2 = 175.97 (17)°). The complex displays intermolecular ππ interactions between the six-membered rings, with a shortest centroid-centroid distance of 3.771 (4) Å and with a dihedral angle between the ring planes of 2.1 (3)°. There are also weak intramolecular C-H···Cl hydrogen bonds (Table   1).
The iodine molecule was presumedly formed as a consequence of the oxidation of the iodide ion by the Pt 4+ ion, and crystallized with the partially substituted complex. The bond distance between the I atoms is 2.708 (2) Å.

S2. Experimental
To a solution of [PtCl 4 (C 12

Figure 1
The disordered structure of the title compound, with displacement ellipsoids drawn at the 30% probability level for non-  View of a packing detail of the title compound. For the sake of clarity, only the major disorder component is shown. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 1.29 e Å −3 Δρ min = −0.50 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 > 2σ(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.