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

Nam-Ho Kim; Kwang Ha

doi:10.1107/S1600536809007703

. 2009 Mar 11;65(Pt 4):m379. doi: 10.1107/S1600536809007703

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

Nam-Ho Kim ^a, Kwang Ha ^a,^*

PMCID: PMC2969087 PMID: 21582331

Abstract

The asymmetric unit of the title compound, [PtCl_3.66I_0.34(C₁₂H₈N₂)]·0.5(Cl_0.13I_1.87), contains a neutral Pt^IV complex and one half of a halogen molecule. 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 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.

Related literature

For details of some other Pt–phenanthroline complexes, see: Buse et al. (1977 ▶); Fanizzi et al. (1996 ▶); Kim et al. (2009a ▶,b ▶). For related Pt–bipyridine complexes, see: Hambley (1986 ▶); Hojjat Kashani et al. (2008 ▶). For bond-length data, see: Orpen et al. (1989 ▶).

Experimental

Crystal data

[PtCl_3.66I_0.34(C₁₂H₈N₂)]·0.5(Cl_0.13I_1.87)
M _r = 669.26
Orthorhombic,
a = 14.215 (5) Å
b = 12.733 (5) Å
c = 17.575 (6) Å
V = 3180.8 (19) Å³
Z = 8
Mo Kα radiation
μ = 11.92 mm⁻¹
T = 293 K
0.25 × 0.17 × 0.15 mm

Data collection

Bruker SMART 1000 CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.111, T _max = 0.168
17485 measured reflections
3246 independent reflections
2169 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.062
S = 0.86
3246 reflections
194 parameters
8 restraints
H-atom parameters constrained
Δρ_max = 1.29 e Å⁻³
Δρ_min = −0.50 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809007703/pk2156sup1.cif

e-65-0m379-sup1.cif^{(19.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809007703/pk2156Isup2.hkl

e-65-0m379-Isup2.hkl^{(159.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯Cl2	0.93	2.73	3.320 (8)	122
C10—H10⋯Cl1	0.93	2.66	3.240 (7)	121

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Acknowledgments

This work was supported by a Korea Research Foundation grant funded by the Korean Government (MOEHRD) (KRF-2007-412-J02001).

supplementary crystallographic information

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 [PtCl₄(C₁₂H₈N₂)].0.5I₂. 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 Cl^- and I^- ligand, and the I₂ 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_3.66I_0.34(C₁₂H₈N₂)].0.5(Cl_0.13I_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 and 2009b). 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 π-π 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 Pt⁴⁺ ion, and crystallized with the partially substituted complex. The bond distance between the I atoms is 2.708 (2) Å.

Experimental

To a solution of [PtCl₄(C₁₂H₈N₂)].H₂O (0.0821 g, 0.153 mmol) in H₂O (20 ml) was added KI (0.1318 g, 0.794 mmol), and stirred for 2 h at room temperature. The precipitate was separated by filtration and washed with water (20 ml) and MeOH (20 ml) and dried under vacuum, to give a dark brown powder (0.0846 g). Black crystals suitable for X-ray analysis were isolated from an acetone solution of the reaction products. EDX analysis (%atom): Cl 62.30%, I 25.18%, Pt 12.52%.