cis-Dichlorido[4,4,5,5-tetra­methyl-2-(2-pyrid­yl)-2-imidazoline-1-ox­yl]­palladium(II) tetra­hydro­furan hemi­solvate

Sihem Badeche; Djamil Azzedine Rouag; Sabrina Benmebarek; Salah-Eddine Bouaoud; Stéphane Golhen

doi:10.1107/S1600536808004406

. 2008 Feb 20;64(Pt 3):m487–m488. doi: 10.1107/S1600536808004406

cis-Dichlorido[4,4,5,5-tetramethyl-2-(2-pyridyl)-2-imidazoline-1-oxyl]palladium(II) tetrahydrofuran hemisolvate

Sihem Badeche ^a,^*, Djamil Azzedine Rouag ^a, Sabrina Benmebarek ^a, Salah-Eddine Bouaoud ^a, Stéphane Golhen ^b

PMCID: PMC2960750 PMID: 21201871

Abstract

The asymmetric unit of the title complex, [PdCl₂(C₁₂H₁₆N₃O)]·0.5C₄H₈O, consists of one palladium complex in a general position and one half tetrahydrofuran (THF) solvent molecule, with the O atom lying on a twofold rotation axis. The Pd^II atom is bound to one chelating imino nitroxide radical through two N atoms, one from the pyridyl ring and the other from the imidazoline ring. The coordination of the metal centre is completed by two Cl atoms in a cis configuration, leading to a quasi-square-planar coordination of the metal centre. The four atoms that define the Pd^II coordination environment and the eight atoms that belong to the pyridylimine fragment are coplanar, with no deviation larger than 0.087 (5) Å. In the crystal structure, intermolecular interactions shorter than the corresponding van der Waals radii sum are observed only between Pd^II complexes, and no short contact is observed around the THF molecule. Weak C—H⋯O and C—H⋯Cl interactions yield a two-dimensional network of complexes in the (101) plane.

Related literature

For related literature, see: Caneschi et al. (1991 ▶); Davis et al. (1972 ▶); Evans et al. (1968 ▶); Fettouhi et al. (2003 ▶); Li et al. (2004 ▶); Ma et al. (2006 ▶, 2007 ▶); Oshio et al. (1996 ▶); Ueda et al. (2003 ▶, 2005 ▶); Ullman & Holm (1970 ▶); Xu et al. (2007 ▶). graphic file with name e-64-0m487-scheme1.jpg

Experimental

Crystal data

[PdCl₂(C₁₂H₁₆N₃O)]·0.5C₄H₈O
M _r = 431.65
Monoclinic,
a = 19.1398 (10) Å
b = 15.2061 (12) Å
c = 13.8291 (10) Å
β = 123.415 (3)°
V = 3359.6 (4) Å³
Z = 8
Mo Kα radiation
μ = 1.43 mm⁻¹
T = 293 (2) K
0.7 × 0.3 × 0.3 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: none
5707 measured reflections
3065 independent reflections
2049 reflections with I > 2σ(I)
R _int = 0.059

Refinement

R[F ² > 2σ(F ²)] = 0.057
wR(F ²) = 0.152
S = 1.03
3065 reflections
199 parameters
H-atom parameters constrained
Δρ_max = 0.61 e Å⁻³
Δρ_min = −0.95 e Å⁻³

Data collection: COLLECT (Nonius, 2000 ▶); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: HKL DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808004406/dn2318sup1.cif

e-64-0m487-sup1.cif^{(18.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808004406/dn2318Isup2.hkl

e-64-0m487-Isup2.hkl^{(147.4KB, 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
C4—H4⋯O1ⁱ	0.93	2.61	3.307 (8)	132
C10—H10B⋯Cl1ⁱⁱ	0.96	2.77	3.691 (7)	160

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

Acknowledgments

The authors thank the Centre de Diffractomtétrie de l’Université de Rennes 1 CDiFX for the data collection.

supplementary crystallographic information

Comment

Organic nitronyl nitroxide radicals have attracted much attention for their magnetic properties in general and ferromagnetism in particular. Then several transition metal complexes with stable nitronyl nitroxide radical ligands have been prepared and extensively investigated (Ma et al., 2007; Xu et al., 2007; Ma et al., 2006; Ueda et al., 2005; Li et al., 2004; Ueda et al., 2003; Oshio et al., 1996; Caneschi et al., 1991). Our contribution in this field is the synthesis (see Scheme 1) and structure characterization of the title compound.

The molecular structure of the complex [Pd(IM₂py)Cl₂] 0.5THF(I) is shown in Fig. 1 while selected geometric parameters are given in Table 1. Focusing the coordination square of Pd^II, one can notice that Cl2 atom deviates significantly from the phane defined with atoms N3/N1/Pd1/Cl1 by 0.0843 (23) Å. The mean bond distance of Pd—Cl 2.277 Å is in agreement with the values observed in a similar complex while the average bond length of Pd—N 2.045 Å is slightly longer than seen previously (Fettouhi et al., 2003). Due to a chelation of the iminonitroxide radical with Pd^II ion, the four atoms which define the Pd^II coordination plane and the eight atoms which belong to both pyridyl ring and imino fragment are coplanar, the larger deviation to the plane is equal to 0.087 (5) and -0.064 (5) Å for O1 and N3 respectively. Only sp³ carbon C7 and C8 from imino and methyl carbon C9, C10, C11 and C12 deviate significantly from the mean plane.

In the packing, one can notice that intermolecular interactions shorter than the corresponding van-der-Waals radii are only observed between Pd^II complexes, no short contact are observed around THF molecule. Centrosymetric contacts take place between imino and pyridyl ring (O1—H4) of one neighbouring complex as well as contacts between chlorine Cl1 and H10B atom of methylene group (Table 1). These contacts yield a two-dimensional network of interacting complexes along the (101) plane (Fig. 2). Another short contact is observed between two adjacent 2-D networks thanks to a van-der-Waals interaction between two C1 atoms of pyridyl rings of two neighbouring molecules with C1—C1 3.393 (16) Å. The shortest distance between two palladium take place between ions from two adjacent planes (Pd1—Pd1 = 3.648 (2) Å), onto a plane, the shorter Pd1—Pd1 distance is 8.7834 (7) Å. THF solvent molecules are lying between two planes. A contact O1s—H1 of 2.7445 Å is observed with pyridyl ring.

Experimental

Dichlorobis benzonitrile palladium(II) PdCl₂(PhCN)₂ and 2-(ortho- pyridyl)-4,4,5,5-tetramethyl imidazoline-1-oxyl-3-oxyde (NIT2Py) were synthesized according to literature method (Evans et al., 1968; Ullman & Holm, 1970; Davis et al., 1972). The complex Pd(IM₂py)Cl₂ was synthesized as follows: The reaction was performed under a dry nitrogen atmosphere using standard schlenk technique. All solvents used were distilled under nitrogen. To a solution of PdCl₂(PhCN)₂ (0.1 g;0.26 mmol) in 30 ml of toluene was added with stirring a solution of the radical NIT2Py (0.12 g;0.52 mmol) in 20 ml of toluene. After 2 h of stirring at room temperature, the mixture was filtered and the solvent removed under reduced pressure. Parallelepipedic brown crystals of complex (I) suitable for x-ray crystallographic analysis were obtained by slow diffusion of hexane in THF solution of complex (I).