Chlorido(1,2-dimethyl-1H-imidazole-κN 3){2-[(diphenoxyphosphanyl)oxy]phenyl-κ2 C 1,P}palladium(II)

The Pd atom in the title compound, [Pd(C18H14O3P)Cl(C5H8N2)], adopts a slightly distorted square-planar coordination geometry, with the metallated carbon positioned trans to the Cl atom. The crystal structure is stabilized by several weak C—H⋯O and C—H⋯Cl hydrogen-bond interactions. One of the phenyl rings is disordered over two almost equally occupied sites.

The Pd atom in the title compound, [Pd(C 18 H 14 O 3 P)Cl-(C 5 H 8 N 2 )], adopts a slightly distorted square-planar coordination geometry, with the metallated carbon positioned trans to the Cl atom. The crystal structure is stabilized by several weak C-HÁ Á ÁO and C-HÁ Á ÁCl hydrogen-bond interactions. One of the phenyl rings is disordered over two almost equally occupied sites.
Data collection: CrysAlis CCD (Oxford Diffraction, 2010); cell refinement: CrysAlis RED (Oxford Diffraction, 2010); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97. This work was supported by European funds in the frame of the Human Capital Operational Programme through project No. POKL.04.01.01-00-054/10-00 'Development of the potential and educational offer of the University of Wrocławthe chance to enhance the competitiveness of the University'. The financial support is gratefully acknowledged.

I. Blaszczyk, A. M. Trzeciak and A. Gniewek
Comment Carbon-carbon bond-forming catalytic reactions are very important fundamental processes in synthetic chemistry. Among them, the commonly recognized are the Suzuki-Miyaura reaction that leads to formation of biphenyl derivates (Miyaura et al., 1981) and the Sonogashira reaction, which produces phenylated alkines (Sonogashira et al., 1975). In this paper we report the crystallization of a palladacyclic triphenylphosphite complex with a 1,2-dimethylimidazole ligand, the title compound. This complex exhibited high catalytic activity in the Suzuki-Miyaura reaction in ethylene glycol and in the Sonogashira reaction in ionic liquids (Błaszczyk et al., 2011).
The molecular structure of the title compound reveals that the coordination environment of the Pd atom is a slightly distorted square-planar (Fig. 1). The angles between adjacent ligands deviate somewhat from the expected value of 90° (   Table 1). However, the observed bond distances and angles are similar to the already reported for analogous complexes (Błaszczyk et al., 2011). In the title compound the metallated carbon is in the trans orientation to the Cl atom. As a result of the trans influence of the aryl group, the Pd-Cl bond length (Table 1) appears somewhat longer than expected for palladium complexes: 2.298-2.354Å (Orpen et al., 1989). The imidazole ring is oriented at 75.7° with respect to the coordination plane of palladium. The C21-C26 phenyl ring is disordered over two positions with site occupancy factors about 51 and 49%.
The structure is stabilized by a few weak hydrogen bonds of the C-H···O and C-H···Cl types (Desiraju & Steiner, 1999). Consequently, a three-dimensional network of such interactions is formed in the crystal. The shortest C-H···Cl distances observed in the title compound are similar to the values of the N-H···Cl hydrogen bonds identified for Cl bonded to a transition metal (Aullón et al., 1998).

Experimental
The title compound was prepared according to the previously reported procedure (Błaszczyk et al., 2011): 1,2-dimethylimidazole (0.128 g, 1,32 mmol) was added to the solution of [PdCl{P(OC 6 H 4 )(OC 6 H 5 ) 2 }] 2 (0.30 g, 0.33 mmol) in dichloromethane (4 ml). The starting dimeric palladyclic complex [PdCl{P(OC 6 H 4 )(OC 6 H 5 ) 2 }] 2 had been obtained according to published method (Albinati et al., 1990). The solution was stirred at room temperature for 1 h. The solvent was evaporated in vacuo and the white product was precipitated by addition of ethanol and recrystallized from a mixure of dichloromethane and ethanol. Yield: 0.35 g, 97%. All the carbon-bonded H atoms were positioned geometrically and refined using a riding model with aromatic C-H = 0.95Å and U iso (H) = 1.2U eq (C). The methyl groups were refined with C-H = 0.98Å and U iso (H) = 1.5U eq (C). One of the phenyl rings is disordered over two sites with a site occupation factor of 0.512 (8) for the major occupied site. The highest residual peak and the deepest hole in the final difference map are located 0.73 and 0.80Å from the C32 and H26B atom, respectively. Fig. 1. The molecular structure and atom numbering scheme of the title compound. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. Disordered parts with lower occupancy are represented by dashed lines.

Figures
Crystal data [Pd(C 18

Special details
Experimental. The crystal was placed in the cold stream of an open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100 K. Analytical numeric absorption correction was carried out with CrysAlis RED (Oxford Diffraction, 2010) using a multifaceted crystal model (Clark & Reid, 1995