(2,2′-Biquinoline-κ2 N,N′)dibromidopalladium(II)

Kwang Ha

doi:10.1107/S1600536812015425

. 2012 Apr 18;68(Pt 5):m618. doi: 10.1107/S1600536812015425

(2,2′-Biquinoline-κ² N,N′)dibromidopalladium(II)

Kwang Ha ^a,^*

PMCID: PMC3344352 PMID: 22590118

Abstract

The Pd^II ion in the title complex, [PdBr₂(C₁₈H₁₂N₂)], is four-coordinated in a distorted square-planar environment by the two N atoms from the chelating 2,2′-biquinoline (Biqu) ligand and two mutually cis Br⁻ anions. The Biqu ligand is not planar, the dihedral angle between the quinoline systems being 17.2 (2)°. In the crystal, the complex molecules are connected by C—H⋯Br hydrogen bonds, forming chains along the c axis. When viewed down the b axis, successive chains are stacked in opposite directions. Intramolecular C—H⋯Br hydrogen bonds are also observed.

Related literature

For the crystal structure of the related chlorido Pd^II complex [PdCl₂(Biqu)], see: Muranishi et al. (2005 ▶).

Experimental

Crystal data

[PdBr₂(C₁₈H₁₂N₂)]
M _r = 522.50
Triclinic,
a = 8.9390 (5) Å
b = 9.2187 (5) Å
c = 11.1486 (6) Å
α = 72.398 (1)°
β = 69.318 (1)°
γ = 87.258 (1)°
V = 817.47 (8) Å³
Z = 2
Mo Kα radiation
μ = 6.02 mm⁻¹
T = 200 K
0.17 × 0.12 × 0.11 mm

Data collection

Bruker SMART 1000 CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.813, T _max = 1.000
5100 measured reflections
3126 independent reflections
2612 reflections with I > 2σ(I)
R _int = 0.018

Refinement

R[F ² > 2σ(F ²)] = 0.028
wR(F ²) = 0.070
S = 1.12
3126 reflections
208 parameters
H-atom parameters constrained
Δρ_max = 0.67 e Å⁻³
Δρ_min = −0.65 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: ORTEP-3 (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812015425/rk2351sup1.cif

e-68-0m618-sup1.cif^{(25.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812015425/rk2351Isup2.hkl

e-68-0m618-Isup2.hkl^{(153.4KB, 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
C2—H2⋯Br1	0.95	2.73	3.252 (5)	116
C14—H14⋯Br1ⁱ	0.95	2.90	3.754 (5)	150
C17—H17⋯Br2	0.95	2.85	3.261 (5)	107

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by the Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0030747).

supplementary crystallographic information

Comment

The title complex, [PdBr₂(C₁₈H₁₂N₂)], crystallized in the triclinic space group P1, whereas the analogous chlorido Pd^II complex [PdCl₂(C₁₈H₁₂N₂)] crystallized in the monoclinic space group P2₁/c (Muranishi et al., 2005).

The central Pd^II ion is four-coordinated in a distorted square-planar environment by the two N atoms from the chelating 2,2'-biquinoline (Biqu) ligand and two mutually cis Br^- anions (Fig. 1). The main contribution to the distortion is the tight N1-Pd1-N2 chelate angle of 78.90 (15)°, which results in non-linear trans axes [angle Br1–Pd1-N2 = 169.85 (10)° and angle Br2–Pd1-N1 = 167.99 (11)°]. The pairs of Pd-N and Pd–Br bond lengths are nearly equivalent [Pd-N = 2.064 (4)Å and 2.073 (4)Å; Pd–Br = 2.4113 (6)Å and 2.4151 (6)Å]. In the crystal structure, the Biqu ligand is not planar. The dihedral angle between the least-squares planes of the quinoline rings is 17.2 (2)°. The quinoline rings are inclined considerably to the least-squares plane of the PdBr₂N₂ unit [maximum deviation = 0.162 (1)Å], making dihedral angles of 41.46 (8)° and 44.33 (8)°. In the crystal, the complex molecules are connected by intermolecular C–H···Br hydrogen bonds, forming chains along the c axis (Fig. 2 and Table 1). When viewed down the b axis, successive chains are stacked in opposite directions. Intramolecular C–H···Br hydrogen bonds are also observed (Table 1). In addition, intermolecular π···π interactions between the six-membered rings are present, the shortest ring centroid-centroid distance being 3.753 (3)Å between pyridine rings.

Experimental

To a solution of K₂PdBr₄ (0.1507 g, 0.299 mmol) in MeOH (20 ml) was added 2,2'-biquinoline (0.0772 g, 0.301 mmol) and stirred for 3 h at room temperature. After addition of H₂O (30 ml) to the reaction mixture, the formed precipitate was separated by filtration and washed with H₂O and acetone, and dried at 323 K, to give a pale red powder (0.1305 g). Crystals suitable for X-ray analysis were obtained by slow evaporation from an acetone solution.