Dichlorido(4,4′-di-tert-butyl-2,2′-bipyridine-κ2 N,N′)palladium(II) dimethyl sulfoxide monosolvate monohydrate

The title compound, [PdCl2(C18H24N2)]·(CH3)2SO·H2O, the PdII ion is in a distorted square-planar geometry. The Pd—N bond distances are 2.022 (2) and 2.027 (2) Å, the Pd—Cl bond distances are 2.2880 (7) and 2.2833 (7) Å, and the ligand bite angle is 80.07 (9)°. The dimethyl sulfoxide and water molecules form linear chains along [100] by O—H⋯O and O—H⋯S hydrogen bonds, generating eight- and 12-membered rings. C—H⋯Cl interactions link the chains, forming a three-dimensional arrangement. In addition, the 4,4-di-tert-butyl-2,2′-bipyridine ligand exhibits π–π stacking interactions [centroid–centroid distances = 3.8741 (15) and 3.8353 (15) Å]. The DMSO solvent is disordered and was refined with an occupancy ratio of 0.866 (3):0.134 (3).


Introduction
The N-N chelate ligands have been studied with a variety of transition metals as building blocks in supramolecular chemistry. 2,2′-Bipyridine and its derivatives have been employed as auxiliary ligands in transition metal complexes usually serving as blocking ligands. Thus, given our continuous interest in the synthesis of metal complexes with potential catalytic activities in cross coupling reactions and the use of N-N quelate ligands (Corona-Rodríguez et al., 2007;Basauri-Molina et al., 2010), we report here the crystal structure of the compound [PdCl 2 ( t Bubpy)]·(CH 3 ) 2 SO)·H 2 O ( t Bubpy = 4,4′-di-tert-butyl-2,2′-bipyridine) as a solvated compound. The crystal structure of the non-solvated complex has been reported previously (Qin et al., 2002;MacLean et al., 2002), and this compound has served as precursor in the formation of metallomacrocycles (Qin et al., 2002;Tzeng et al., 2001) and due to its structure may present π interactions like π-π stacking and C-H···π interactions.

Synthesis and crystallization
To a solution of [Pd(MeCN) 2 Cl 2 ] (0.13 g, 0.501 mmol) in ethanol (10 ml), 4,4′-di-tert-butyl-2,2′-bipyridine (0.1 g, 0.651 mmol) was added under stirring. The resulting orange solution was allowed to react for 4 h under stirring at room temperature. After this time the solution was filtered and the solvent taken off under vacuum to produce a yellow solid.
Crystals suitable for X-ray diffraction experiments were obtained from dimethylsulfoxide as solvent at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. The DMSO solvent is disordered and was refined in two major positions using a free variable of Site Occupational Factor (SOF), the ratio of disordered atoms was 87/13 of SOF.

Results and discussion
The title compound is formed by a molecule of the complex [PdCl 2 ( t Bubpy)], one molecule of dimethylsulfoxide (disordered) and one molecule of water, the structure is presented in Figure 1.

Figure 1
The asymmetric unit of the title compound. All non-hydrogen atoms are shown as ellipsoids with probability level of 50%.  Packing of the molecular entities in the structure of the title compound. Hydrogen bonds interaction as shown by dashed lines.