{N,N-Bis[2-(diphenylphosphanyl)ethyl]aniline}(η2-dibenzylideneacetone)palladium(0)

In the title complex, [Pd(C34H33NP2)(C17H14O)], the Pd0 atom is coordinated in a trigonal planar geometry formed by two P atoms of a bis[(diphenylphosphino)ethyl]aniline ligand and a C=C (η2) bond involving the C atoms that are in the α,β positions relative to the central ketone of the dibenzylideneacetone ligand.

In the title complex, [Pd(C 34 H 33 NP 2 )(C 17 H 14 O)], the Pd 0 atom is coordinated in a trigonal planar geometry formed by two P atoms of a bis[(diphenylphosphino)ethyl]aniline ligand and a C C ( 2 ) bond involving the C atoms that are in the , positions relative to the central ketone of the dibenzylideneacetone ligand.

Experimental
Crystal data [Pd(C 34  tidentate ligands may contain donor atoms of the same type or be comprised of mixed donor atoms such as oxygen, carbon, phosphorous, sulfur and nitrogen (i.e., NNN, PNP, SPS). Advantages of mixed donor systems include flexible coordination modes and complex stability, both of which have the potential to increase performance in catalytic applications (Hii et al., 1999), including coupling, hydrogenation and dehydrogenation reactions. Many examples of PNP-type (phosphorous/nitrogen/phosphorous) ligands have been studied because the hemilabile property of the nitrogen atom gives different coordination geometries, including tridentate monomeric (PNP), bidentate monomeric (PP) and bidentate dimeric (PP) modes, which can be controlled by substitution of the nitrogen atom, thereby affecting the nitrogen donor strength.
The molecular structure of the title compound is shown in Fig. 1. The geometry around the palladium atom is trigonal planar with the angle between the Pd-P1-P2 and Pd-C41-C42 planes being 1.40 °. The N, N-bis[(diphenylphosphino)ethyl]aniline ligand is in a monomeric (PP) binding mode in which the nitrogen atom of the ligand is not bound to the metal center (distance between N1 and Pd1 is 3.405 Å). The average Pd1-P bond length is 2.326 Å, which is consistent with similar structures reported in the literature (Retbøll et al., 2002;Goddard et al., 1995). Dibenzylideneacetone (dba) is bound to Pd1 via one of the carbon-carbon double bonds in an η 2 fashion, with the C41=C42 bond (1.411 (3)Å) slightly elongated due to complexation when compared to C44=C45 (1.327 (3) Å) and the C41=C42 centroid-Pd1 distance is 2.044 Å.
Similar Pd(0) coordination environments have been previously reported with chelating diphosphine and dba ligands which also display the elongated carbon-carbon double bond (1.417 (3) Å) (Retbøll et al., 2002). This coordination mode is not surprising since Pd 2 dba 3 is the metal precursor used in the synthesis of the title complex and includes two palladium atoms with each metal bound η 2 to the three dba ligands.
The reaction mixture was stirred at room temperature for 15 h, followed by filtration and removal of the solvent. Pure product was obtained by recrystallization from methylene chloride and hexanes yielding orange crystals suitable for diffraction.
Purity and composition were confirmed by comparing 1 H and 31 P{ 1 H} NMR spectroscopy and mass spectrometry data to literature values (Hii et al., 1999). Yield = 54%.