trans-Dichloridobis[dicyclo­hex­yl(phen­yl)phosphane-κP]palladium(II)

Andrew R Burgoyne; Reinout Meijboom; Hezron Ogutu

doi:10.1107/S1600536812010100

. 2012 Mar 10;68(Pt 4):m404. doi: 10.1107/S1600536812010100

trans-Dichloridobis[dicyclohexyl(phenyl)phosphane-κP]palladium(II)

Andrew R Burgoyne ^a, Reinout Meijboom ^a,^*, Hezron Ogutu ^a

PMCID: PMC3343813 PMID: 22589787

Abstract

The title compound, [PdCl₂{P(C₆H₁₁)₂(C₆H₅)}₂], forms a monomeric complex with a trans-square-planar geometry. The Pd—P bond lengths are 2.3343 (5) Å, as the Pd atom lies on an inversion centre, while the Pd—Cl bond lengths are 2.3017 (4) Å. The observed structure was found to be closely related to [PdCl₂{P(C₆H₁₁)₃}₂] [Grushin et al. (1994 ▶). Inorg. Chem. 33, 4804–4806], [PdBr₂{P(C₆H₁₁)₃}₂] [Clarke et al. (2003 ▶). Dalton Trans. pp. 4393–4394] and [PdCl₂P(C₆H₁₁)₂(C₇H₇)}₂] [Vuoti et al. (2008 ▶). Eur. J. Inorg. Chem. pp. 397–407] (C₆H₁₁ is cyclohexyl and C₇H₇ is o-tolyl). One of the cyclohexyl rings is disordered with the phenyl ring in a 0.587 (9):413 (9) ratio. Five long-range C—H⋯Cl interactions were observed within the structure.

Related literature

For a review on related compounds, see: Spessard & Miessler (1996 ▶). For the synthesis of the starting materials, see: Drew & Doyle (1990 ▶). For similar R-P₂PdCl₂ compounds, see: Ogutu & Meijboom (2011 ▶); Muller & Meijboom (2010a ▶,b ▶). For their applications, see: Bedford et al. (2004 ▶).

Experimental

Crystal data

[PdCl₂(C₁₈H₂₇P)₂]
M _r = 726.03
Triclinic,
a = 9.439 (4) Å
b = 10.095 (4) Å
c = 10.623 (5) Å
α = 113.115 (2)°
β = 107.321 (2)°
γ = 91.625 (2)°
V = 876.5 (7) Å³
Z = 1
Mo Kα radiation
μ = 0.80 mm⁻¹
T = 100 K
0.27 × 0.13 × 0.11 mm

Data collection

Bruker X8 APEXII 4K KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2007 ▶) T _min = 0.885, T _max = 0.918
12144 measured reflections
2931 independent reflections
2891 reflections with I > 2σ(I)
R _int = 0.024

Refinement

R[F ² > 2σ(F ²)] = 0.021
wR(F ²) = 0.051
S = 1.19
2931 reflections
266 parameters
12 restraints
H-atom parameters constrained
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.38 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT-Plus (Bruker, 2007 ▶); data reduction: SAINT-Plus and XPREP (Bruker, 2007 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812010100/zl2455sup1.cif

e-68-0m404-sup1.cif^{(32.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812010100/zl2455Isup2.hkl

e-68-0m404-Isup2.hkl^{(140.9KB, 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
C8—H8B⋯Cl1	0.97	2.91	3.559 (2)	125
C5—H5⋯Cl1ⁱ	0.93	2.94	3.619 (7)	131
C13—H13⋯Cl1ⁱⁱ	0.98	2.68	3.254 (11)	118
C18—H18B⋯Cl1ⁱⁱ	0.97	2.97	3.542 (13)	119
C15—H15A⋯Cl1ⁱⁱⁱ	0.97	3.02	3.800 (8)	139

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

Acknowledgments

ARB thanks the University of Johannesburg and the South African National Research Foundation for financial support.

supplementary crystallographic information

Comment

Complexes involving palladium metal centres are amongst some of the most popular catalytic precursors in organic synthesis due to their catalytic abilities. They are used in carbon-carbon bond formation reactions like the Heck, Stille and Suzuki reactions (Bedford et al., 2004).

[PdCl₂(L)₂] (L = tertiary phosphine, arsine or stibine) complexes can conveniently be prepared by the substitution of 1,5-cyclooctadiene (COD) from [PdCl₂(COD)]. The title compound, trans-[PdCl₂(C₁₈H₂₇P)₂], crystallizes with the Pd atom on a center of symmetry and each pair of equivalent ligands in a mutually trans orientation. The geometry is, therefore, slightly distorted square planar and the Pd atom is not elevated out of the coordinating atom plane. All angles in the coordination polyhedron are close to the ideal value of 90°, with P—Pd—Cl = 89.296 (16)° and P—Pd—Clⁱ = 90.704 (16)°. As required by the crystallographic symmetry, the P—Pd—Pⁱ and Cl—Pd—Clⁱ angles are 180°. The symmetry code used to define atoms through the inversion point is: (iv) 2 - x, -y, 2 - z.

One of the cyclohexyl rings, C13–C18, in the title compound is disordered with the phenyl ring, C1–C6, over the same positions in a 59:41 (9) occupancy ratio.

The title compound compares well with other closely related Pd^II complexes from the literature containing two chloro and two tertiary phosphine ligands in a trans geometry (Muller & Meijboom, 2010a, b). The title compound, having a Pd—Cl bond length of 2.3017 (4) Å and a Pd—P bond length of 2.3343 (5) Å, fits well into the typical range for complexes of this kind. Notably the title compound did not crystallize as a solvated complex; these type of Pd^II complexes have a tendency to crystallize as solvates (Ogutu & Meijboom, 2011).

Due to the disorder of the cyclohexyl ring and phenyl ring, the crystilline structure for the title compound forms an isostructure with a variety of [PdCl₂(PR₃)₂] compounds (R = any combination of aryl and cylcohexyl rings). Notably, the title compound is quintessentially isostructural with: [PdCl₂{P(C₆H₁₁)₃}₂] (Grushin et al., 1994); [PdBr₂{P(C₆H₁₁)₃}₂] (Clarke et al., 2003); and [PdCl₂{P(C₆H₁₁)₂(C₇H₇)}₂] (Vuoti et al., 2008) ((C₆H₁₁) = cyclohexyl, (C₇H₇) = o-tolyl). The Pd–P and Pd–X (X = Br and Cl) bond lengths were compared and it was observed that they were all within the same range of 2.3–2.4 Å. The angles between the bonds around the Pd atom were all observed to be approximately right angles.

A weak hydrogen bond exists between C13—H13···Cl1ⁱ (Symmetry code: -x + 2, -y, -z + 2) with the distance listed in Table 1. Four other longer range hydrogen interactions exist as shown in Table 1.

Experimental

Dicyclohexylphenylphosphine (0.05 g, 0.35 mmol) was dissolved in acetone (5 cm³). A solution of [Pd(COD)Cl₂] (0.05 g, 0.17 mmol) in acetone (5 cm³) was added to the phosphine solution. The mixture was stirred for 5 minutes, after which the solution was left to crystallize. Yellow crystals of the title compound were obtained. ¹H NMR (CDCl₃, 400 MHz, p.p.m.): 7.6–7.5 (m, 4H), 7.4 (m, 6H), 2.6 (t, 4H), 2.1 (d, 4H), 1.8–1.7 (m, 10H), 1.4–1.2 (m, 20H), 1.1–1.0 (m, 6H). ³¹P{H} NMR (CDCl₃, 162.0 MHz, p.p.m.): 28.05. IR (cm^-1): 2925, 2849, 2161, 2023, 1977, 1446, 1433, 1261, 1109, 1011, 848, 773, 700 and 690.