Bis[(1,1′-biphenyl-2,2′-di­yl)di-tert-butyl­phospho­nium] di-μ-chlorido-bis­[dichlorido­palladate(II)]

Charmaine Arderne; Cedric W Holzapfel

doi:10.1107/S1600536812037786

. 2012 Sep 8;68(Pt 10):m1247. doi: 10.1107/S1600536812037786

Bis[(1,1′-biphenyl-2,2′-diyl)di-tert-butylphosphonium] di-μ-chlorido-bis[dichloridopalladate(II)]

Charmaine Arderne ^a,^*, Cedric W Holzapfel ^a

PMCID: PMC3470136 PMID: 23125580

Abstract

In the title compound, (C₂₀H₂₆P)₂[Pd₂Cl₆], the Pd^II atom within the hexachloridodipalladate(II) dianion has a square-planar geometry. It resides on a centre of inversion with the asymmetric unit containing half of the dianion and one phosphonium cation. Only weak C—H⋯π interactions are present in the crystal structure.

Related literature

For the structures of related Pd_II complexes and background to organopalladium-catalysed reactions, see: Ormondi et al. (2011 ▶); Williams et al. (2008 ▶); Migowski & DuPont (2007 ▶); d′OrLyé & Jutland (2005 ▶); Beletskaya & Cheprakov (2004 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

(C₂₀H₂₆P)₂[Pd₂Cl₆]
M _r = 1020.26
Triclinic,
a = 8.3247 (2) Å
b = 11.2697 (2) Å
c = 11.7004 (3) Å
α = 73.0982 (6)°
β = 85.0900 (6)°
γ = 82.2708 (5)°
V = 1039.49 (4) Å³
Z = 1
Mo Kα radiation
μ = 1.36 mm⁻¹
T = 100 K
0.29 × 0.22 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (AXScale; Bruker, 2010 ▶) T _min = 0.695, T _max = 0.774
39747 measured reflections
5184 independent reflections
5088 reflections with I > 2σ(I)
R _int = 0.017

Refinement

R[F ² > 2σ(F ²)] = 0.015
wR(F ²) = 0.037
S = 1.05
5184 reflections
232 parameters
H-atom parameters constrained
Δρ_max = 0.41 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Data collection: APEX2 (Bruker, 2010 ▶); cell refinement: SAINT (Bruker, 2010 ▶); data reduction: SAINT; 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 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812037786/gg2094sup1.cif

e-68-m1247-sup1.cif^{(21.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812037786/gg2094Isup2.hkl

e-68-m1247-Isup2.hkl^{(253.9KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812037786/gg2094Isup3.mol

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

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

Cg7 is the centroid of the Pd1,Cl3,Pd1′,Cl3′ ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C11—H11⋯Cg7ⁱ	0.95	2.68	3.5952 (13)	138

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors wish to acknowledge the University of Johannesburg for the use of their facilities and for funding for this project.

supplementary crystallographic information

Comment

As part of our continued studies (Williams et al., 2008 and Ormondi et al., 2011) of organopalladium catalysed reactions, we have found that certain palladocycles (Beletskaya & Cheprakov, 2004 and d'OrLyé & Jutland, 2005) are readily converted into highly catalytically active low-ligated Pd⁰ complexes. We now report that treatment of one such palladocycle, namely acetato-(2'-di-t-butylphosphino-1,1'-diphenyl-2yl) palladium(II), with HCl at room temperature results in the formation of the title compound (I) in good yield. Formation of the complex appears to result from the acid-induced reductive elimination of Pd⁰ from the palladocycle followed by oxidation of the palladium in the presence of air and chloride ions (Migowski & DuPont, 2007).

The structure of the title compound (I), [C₂₀H₂₆P. 0.5(Cl₆Pd₂)]₂ shows a square planar geometry for the Pd^II atom within the hexachlorodipalladium(II) anion. The palladium atom sits on a centre of inversion and therefore the asymmetric unit contains half of the trichloropalladium(II) anion and one phosphonium cation. Figure 1 shows a diagram of the molecular structure of the asymmetric unit of (I). Weak interactions were observed in this structure where C—H···Cl and C—H···π are evident only.

Experimental

A solution of hydrogen chloride (142 mg; 4 mmol) in 18 ml of methanol was slowly added to a stirred solution of the palladocycle precursor, namely acetato-(2'-di-t-butylphosphino-1,1'-diphenyl-2yl) palladium(II) (493 mg; 1 mmol) in 17 ml of dichloromethane over a period of 10 minutes. The reaction mixture changed from colourless to dark purple and then to dark brown. After completion of the addition, stirring was discontinued and the reaction mixture left exposed to the air at room temperature. A red crystalline precipitate started to form after 45 minutes. After 24 h, the supernatant solution was removed, the solid material was with ether and dried in vacuo. The solid material (376 mg; 74%) was taken up in 15 ml of 2:1 dichloromethane:methanol and the resulting solution was exposed to the vapours of diethyl ether in a closed system for 24 h. Well formed, dark red prisms of the title compound (I) crystallized from the solution and a suitable single-crystal was selected for the single-crystal X-ray diffraction analysis.