{2,6-Bis[(2,6-diphenyl­phosphan­yl)­oxy]-4-fluoro­phenyl-κ3 P,C 1,P′}(6-methyl-2,2,4-trioxo-3,4-dihydro-1,2,3-oxathia­zin-3-ido-κN)palladium(II)

Benjamin F Wicker; Rachel Seaman; Norris W Hoffman; James H Davis, Jr; Richard E Sykora

doi:10.1107/S1600536811002911

. 2011 Jan 29;67(Pt 2):m286–m287. doi: 10.1107/S1600536811002911

{2,6-Bis[(2,6-diphenylphosphanyl)oxy]-4-fluorophenyl-κ³ P,C ¹,P′}(6-methyl-2,2,4-trioxo-3,4-dihydro-1,2,3-oxathiazin-3-ido-κN)palladium(II)

Benjamin F Wicker ^a, Rachel Seaman ^a, Norris W Hoffman ^a, James H Davis Jr ^a, Richard E Sykora ^a,^*

PMCID: PMC3051636 PMID: 21522930

Abstract

The title acesulfamate complex, [Pd(C₃₀H₂₂FO₂P₂)(C₄H₄NO₄S)], contains a four-coordinate Pd(II) ion with the expected, although relatively distorted, square-planar geometry where the four L—Pd—L angles range from 79.58 (8) to 102.47 (7)°. The acesulfamate ligand is N-bound to Pd [Pd—N = 2.127 (2) Å] with a dihedral angle of 76.35 (6)° relative to the square plane. Relatively long phenyl–acesulfamate C—H⋯O and phenyl–fluorine C—H⋯F interactions consolidate the crystal packing.

Related literature

For the low toxicity of acesulfamate, see: Lipinski (2003) ▶. For examples of different modes of acesulfamate bonding to transition metals, see: Bulut et al. (2005 ▶); Cavicchioli et al. (2010 ▶); Şahin et al. (2009 ▶, 2010 ▶); Dege et al. (2006 ▶, 2007 ▶); Beck et al. (1985 ▶); İçbudak et al. (2005 ▶). For applications of ¹⁹F-NMR reporter moieties in monitoring ligand-substitution equilibria, see: Hoffman et al. (2009 ▶); Kwan et al. (2007 ▶); Carter et al. (2004 ▶); Wicker et al. (2007 ▶).

Experimental

Crystal data

[Pd(C₃₀H₂₂FO₂P₂)(C₄H₄NO₄S)]
M _r = 763.96
Triclinic,
a = 10.6088 (12) Å
b = 11.0069 (7) Å
c = 14.066 (2) Å
α = 89.175 (9)°
β = 88.524 (12)°
γ = 82.021 (7)°
V = 1625.9 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.79 mm⁻¹
T = 290 K
0.67 × 0.55 × 0.25 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.620, T _max = 0.828
6311 measured reflections
5963 independent reflections
5091 reflections with I > 2σ(I)
R _int = 0.020
3 standard reflections every 120 min intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.028
wR(F ²) = 0.078
S = 1.05
5963 reflections
416 parameters
H-atom parameters constrained
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.41 e Å⁻³

Data collection: CAD-4-PC (Enraf–Nonius, 1993 ▶); cell refinement: CAD-4-PC; data reduction: XCAD4-PC (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: OLEX2 (Dolomanov et al., 2009 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811002911/gw2097sup1.cif

e-67-0m286-sup1.cif^{(24.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811002911/gw2097Isup2.hkl

e-67-0m286-Isup2.hkl^{(291.9KB, 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
C23—H23⋯O3ⁱ	0.93	2.42	3.284 (4)	155
C16—H16⋯O6ⁱⁱ	0.93	2.47	3.284 (4)	146
C10—H10⋯O4ⁱⁱⁱ	0.93	2.50	3.305 (5)	145
C8—H8⋯F1^iv	0.93	2.48	3.406 (5)	173

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

The chlorido analogue used to prepare Ph{Pd_F}Ace was provided by Dr Man-Lung Kwan of John Carroll University, University Heights, Ohio, USA. The authors gratefully acknowledge the Department of Chemistry and the Univeristy Committee for Undergraduate Research at the University of South Alabama for their generous support and the Department of Energy and Oak Ridge National Laboratory for the Nonius CAD-4 X-ray diffractometer used in these studies. They also acknowledge support from the National Science Foundation–grant #CHE-99–09502, REU Supplement with Professor Alan Marshall of Florida State University/National High Magnetic Field Laboratory, Tallahassee, Florida USA.

supplementary crystallographic information

Comment

As thoroughly tested, apparently innocuous foodstuff additives (Lipinsky, 2003), the attraction of the acesulfamate and saccharinate anions as weakly binding ligands for organotransition-metal complexes and components of ionic liquids is obvious. The title complex, abbreviated as Ph{Pd_F}Ace hereafter, is readily prepared in high yield by a benchtop procedure from its chlorido analogue (Kwan et al., 2007; Hoffman et al., 2009) in an extension of Rh(I) Vaska chemistry (Carter et al., 2004). The presence of the pincer-ligand fluorine atom on the central aryl ring affords a convenient ¹⁹F-NMR reporter moiety (whose accuracy may also be corroborated by the two equivalent pendant-arm phosphinite donors by ³¹P-NMR) for monitoring ligand-substitution chemistry of the acesulfamate anion. A previous study of anion-metathesis equilibria using neutral Ph{Pd_F}X and N(PPh₃)₂⁺ salts has shown anion affinity for Ph{Pd_F}⁺ to follow X^- = chloride > saccharinate > trifluoroacetate > acesulfamate > nitrate (Wicker et al., 2007). The acesulfamate complex displays a fascinating combination of ¹⁹F and ³¹P couplings to ¹³C nuclei in the pincer central fluoro-aryl ring, in which J_F—C and J_P—C correspond visually to their respective doublet and triplet coupling patterns.

A survey of crystal structures of transition-metal acesulfamate complexes shows three principal forms of metal–acesulfamate bonding: (i) monodentate metal to N bond, (ii) monodentate metal to carbonyl O bond (Şahin et al., 2010; Dege et al., 2007), and (iii) metal bonds to both N and carbonyl O in κ²-manner (Şahin et al., 2009; Dege et al., 2006; Bulut et al., 2005). When water is present in the crystal, extensive hydrogen bonding occurs. The title compound, a four-coordinate d⁸ complex, has the expected distorted square-planar geometry in which the acesulfamate is N-bound to Pd. The Pd—N distance is 2.127 (2) Å, significantly longer than the Pt—N distance (2.036 (3) Å) in another square-planar d⁸ complex, K₂[trans-Pt(Ace)₂Cl₂] (Cavicchioli et al., 2010; Beck et al., 1985), but much shorter than those in divalent late-metal N-acesulfamates with octahedral Jahn-Teller distortion: 2.7175 (16) Å in trans-Cu(c—C₆H₁₀-1,2-(NH₂)₂)(Ace)₂ (Şahin et al., 2010) and 2.3180 (19) Å in trans-Co(H₂O)₄(Ace)₂ (İçbudak, 2005). The only directly comparable structure above, K₂[trans-Pt(Ace)₂Cl₂], probably has a shorter Pt—N distance than that in Ph{Pd_F}Ace because the trans-effect of the fluoroaryl-Pd moiety is stronger than that of N-bound acesulfamate. The almost-planar acesulfamate ring (with the sulfur the only significantly nonplanar atom) in Ph{Pd_F}Ace is tilted 76.35 (6)° from the Pd(II) coordination plane, whereas the similarly nearly-planar acesulfamate ring in K₂[trans-Pt(Ace)₂Cl₂] is nearly perpendicular to the Pt(II) coordination plane.

Experimental

Pd(C₄H₄NO₄S)(C₁₈H₂₂FO₂P₂), abbreviated by Ph{Pd_F}Ace hereafter, was prepared by stirring Ph{Pd_F}Cl (25 mg, 0.040 mmol) with silver(I) acesulfamate (1.5 mol equiv.) in benzene (25 mL) at ambient temperature for 24 h. The AgCl precipitate was then removed by filtration, and the solvent was removed on a rotary evapaorator to afford a white microcrystalline solid (88% yield). Suitable single crystals were prepared by slow evaporation of solvent from a solution in fluorobenzene at 24 °C. The complex was characterized by NMR in CDCl₃.

¹H: (relative to internal TMS) δ 1.999 and δ 2.015 (3H, apparent doublet); δ 5.476 and δ 5.480 (1H, apparent doublet); δ 6.443 (2H, doublet, ³J_H—F=9.7 Hz); δ 7.51 (8H, overlapping multiplets); δ 7.807 (12H, overlapping multiplets)

¹⁹F: (relative to internal C₆F₆ at δ -161.59) δ -111.29 (triplet of triplets,³J_H—F=9.7 Hz, ⁵J_P—F=1.9 Hz)

³¹P: (relative to external 85% aq. phosphoric acid) δ 148.79 (doublet, ⁵J_P—F=1.9 Hz)

¹³C: (relative to internal TMS) Ace: δ 19.47(s), δ 103.34(s), carbonyl not observed with 6 K scans Ph₂P: δ 128.69(t; ³J_P—C=5.8 Hz), ? 132.35(s), δ 132.43(t; ¹J_P—C=53 Hz), δ 132.54(t; ²J_P—C=8.2 Hz) Pincer Aryl: δ 95.69(d of t; ²J_F—C=26 Hz), ³J_P—C=8.6 Hz), δ 123.68(d of t; ³J_F—C~²J_P—C\sim 32 Hz, ³J_P—C=8.6 Hz), δ 164.07(d of t; ³J_F—C=15 Hz, ²J_P—C=7.7 Hz), δ 163.93(d; ¹J_F—C=244 Hz)