Chloridotris(penta­fluoro­benzene­thiol­ato-κS)[tris­(4-fluoro­phen­yl)phosphine-κP]osmium(IV)

Asdrúbal Arias; Lidia Meléndez; Sylvain Bernès; Maribel Arroyo

doi:10.1107/S1600536810011281

. 2010 Mar 31;66(Pt 4):m477–m478. doi: 10.1107/S1600536810011281

Chloridotris(pentafluorobenzenethiolato-κS)[tris(4-fluorophenyl)phosphine-κP]osmium(IV)

Asdrúbal Arias ^a, Lidia Meléndez ^a, Sylvain Bernès ^b,^*, Maribel Arroyo ^a

PMCID: PMC2983803 PMID: 21580558

Abstract

The title complex, [Os(C₆F₅S)₃Cl(C₁₈H₁₂F₃P)], displays a trigonal-bipyramidal Os^IV coordination geometry with the S atoms of three thiolate ligands occupying the equatorial positions. The thiolate pentafluorophenyl substituents are all placed above the equatorial plane, forming a claw-like cavity which accommodates the chloride ligand with a normal Os—Cl bond length. The phosphine ligand trans to the chloride ligand reveals a short Os—P bond length compared to other chloride–phosphine Os^IV complexes (average = 2.40 Å). This strong bonding indicates that the inductive effect of the F atoms in the phosphine does not affect significantly its basicity, compared to triphenylphosphine. This feature is also consistent with the known poor trans influence of Cl⁻. The crystal packing involves π–π contacts between inversion-related thiolate C₆F₅ rings, with a centroid–centroid separation of 3.659 (8) Å.

Related literature

For the structures of related five-coordinated Os^IV complexes, see: Hills et al. (1991 ▶); Arroyo et al. (1994 ▶, 2007 ▶, 2009 ▶); Cerón et al. (2006 ▶); Mendoza et al. (2006 ▶). For the structure and basicity of free tris(4-fluorophenyl)phosphine, see: bin Shawkataly et al. (1996 ▶) and Allman & Goel (1982 ▶), respectively. For geometrical analysis using the Cambridge Structural Database, see: Bruno et al. (2002 ▶).

Experimental

Crystal data

[Os(C₆F₅S)₃Cl(C₁₈H₁₂F₃P)]
M _r = 1139.26
Monoclinic,
a = 17.983 (7) Å
b = 10.446 (5) Å
c = 21.521 (8) Å
β = 107.62 (2)°
V = 3853 (3) Å³
Z = 4
Mo Kα radiation
μ = 3.70 mm⁻¹
T = 298 K
0.5 × 0.4 × 0.3 mm

Data collection

Siemens P4 diffractometer
Absorption correction: ψ scan (XSCANS; Siemens, 1996 ▶) T _min = 0.215, T _max = 0.330
13694 measured reflections
6749 independent reflections
5120 reflections with I > 2σ(I)
R _int = 0.052
3 standard reflections every 97 reflections intensity decay: 0.5%

Refinement

R[F ² > 2σ(F ²)] = 0.048
wR(F ²) = 0.135
S = 1.33
6749 reflections
542 parameters
H-atom parameters constrained
Δρ_max = 1.96 e Å⁻³
Δρ_min = −2.11 e Å⁻³

Data collection: XSCANS (Siemens, 1996 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL-Plus; molecular graphics: Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXTL-Plus.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810011281/kp2255sup1.cif

e-66-0m477-sup1.cif^{(29.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810011281/kp2255Isup2.hkl

e-66-0m477-Isup2.hkl^{(330.3KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Os1—S1	2.205 (3)
Os1—S2	2.199 (3)
Os1—S3	2.206 (3)
Os1—Cl1	2.414 (2)
Os1—P1	2.334 (2)

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Acknowledgments

We gratefully acknowledge CONACYT (27915E), VIEP (ARCS-NAT-09-G) and PROMEP for financial support.

supplementary crystallographic information

Comment

We have been interested for a long time in Os^IV complexes bearing fluorinated thiolate ligands, as these systems are involved in the study of the C—F bond activation (Arroyo et al., 2007, and references therein). For the five-coordinated complexes with general formula [Os^IV(thiolate)₄(phosphine)], the metal centre is invariably found to be in a trigonal-bipyramidal geometry (e.g. Mendoza et al., 2006; Cerón et al., 2006; Arroyo et al., 2009), with the phosphine and one thiolate groups placed in axial positions. Of interest are the complexes [OsX(thiolate)₃(phosphine)], where X is an halogen trans to the phosphine in a bipyramidal geometry (Hills et al., 1991; Arroyo et al., 1994)and halides are known to have little trans influence, allowing the estimation of the basicity of the coordinated phosphine.

The title complex was obtained by reaction of [Os(SC₆F₅)₄(P(C₆H₄F-4)₃)] (space group P1, Arroyo et al., 2009) and HCl(aq) in acetone (see Experimental). The complex approximates 3-fold symmetry (Fig. 1), with atoms P1 and Cl1 placed in axial positions. The coordinated Cl^- ion is placed in a cavity approximating point symmetry C₃, formed by the C₆F₅ groups of the thiolate ligands, all 'up' towards and around the smaller chloride ligand. The trigonal-bipyramidal coordination geometry of the Os^IV centre is completed by three S atoms in the equatorial plane.

The chloride ligand is found at the expected distance from the metal center, Os—Cl = 2.414 (2) Å, which compares well with the average Os—Cl bond length retrieved from 804 hits in the CSD, 2.401 Å (CSD, version 5.31 with all updates; Bruno et al., 2002). A quite different situation is observed for the phosphine: the Os—P bond is short, 2.334 (2) Å, compared to other Os^IV complexes including the P—Os—Cl fragment (ca. 2.40 Å). For all the 340 hits retrieved in the CSD with a P—Os—Cl fragment, the average Os—P bond length is 2.383 (2) Å. The phosphine is thus strongly bonded to the metal centre in the title compound. In spite of the inductive effect of the F atoms in the phosphine, a significant amount of electron density should be donated back to the rings and the P atom, favoring the ligand bonding. This behaviour is consistent with the pK_a of that phosphine, 1.97, which is close to the pK_a of triphenylphosphine, 2.73 (Allman & Goel, 1982). Finally, the strong coordination of tris(4-fluorophenyl)phosphine in the title compound also affects the geometry of this ligand: short P—C bond lengths are observed, in the range 1.787 (10)–1.797 (10) Å, while the mean P—C distance reported in the free tris(4-fluorophenyl)phosphine is 1.825 (5) Å (bin Shawkataly et al., 1996).

The crystal structure is stabilized by intermolecular π–π interactions involving C₆F₅ rings of thiolate ligands related by an inversion centre (Fig. 2). The separation between the centroids of stacked rings is 3.659 (8) Å.

Experimental

The previously prepared complex [Os(SC₆F₅)₄(P(C₆H₄F-4)₃)] (Arroyo et al., 2009) (0.200 g, 0.154 mmol) was dissolved in acetone (50 ml), and HCl 1.5 M (5 ml) was added. The mixture was stirred at room temperature for ca. 48 h, monitoring the progress of the reaction by TLC. The solvent was distilled off under vacuum and the solid product was purified through a silica gel chromatographic column eluted with hexane-dichloromethane (4:1), affording [OsCl(SC₆F₅)₃(P(C₆H₄F)₃)] (75% yield). Complex decomposes at 423 K, with colour changing from dark-brown to black, and does not show defined melting point. FAB-MS {m/z (%) [fragment]}: 1139 (2) [M⁺], 1121 (4) [M⁺—F], 1105 (65) [M⁺—Cl], 1045 (4) [M⁺—C₆H₄F], 941 (100) [M⁺—SC₆F₅], 923 (9) [M⁺—SC₆F₅—F], 391 (34) [M⁺—P(C₆H₄F)₃-2SC₆F₅—Cl]. Single crystals were obtained by slow evaporation of the eluent at room temperature.