Crystal Structure of Bis{cis-bis(diphenylphosphino)ethylene}palladium(0) Acetone Solvate

cis-Bis(diphenylphosphino)ethylene (dppen) is a quite interesting bidentate phosphorous ligand. In particular, the [M(dppen)2] (M=Cu(I), Ag(I) and Au(I)) complexes have been of interest in the cyclotoxic and antitumour activity in several murine tumour models.l A large number of the Cr(III), Fe(II), Co(II), Ni(II), Pt(II) and Pd(II) complexes with dppen have been characterized crystallographically and spectroscopically. On the other hand, the chances to investigate the lowvalence dppen complexes such as Ni(0) and Pd(0) have been few, owing to difficulties of their isolation and crystallization. In this study we have prepared Pd(0) dppen complex [Pd(dppen)2] • CH3000H3 and characterized it crystallographically. The yellow single crystals were obtained from the reaction solution of [Pd(dibenzylidenacetone)2] (115.0 mg, 2.0X102 mol) and dppen (180 mg, 2.0X102 mol) in acetone (10 ml) after one week. Data collection was performed on a Rigaku AFC-5R diffractometer with graphite monochromated Mo Ka radiation (20.71069 A). The linear absorption coefficient for Mo Ka is 5.46 cm 1. The structure was solved by a direct method (MITHRIL)2 and an empirical, spherical, absorption correction was applied using a program called DIFABS3 after an isotropic refinement for all non-hydrogen atoms. The scattering factors and anomalous factors corrections for non-hydrogen atoms were taken from ref. 4. Positional and anisotropic thermal parameters of nonhydrogen atoms were refined by a full-matrix leastsquares calculation. The positions of the hydrogen atoms were obtained from a difference Fourier synthesis. All calculations were performed using a TEXSANS crystallographic software package. The crystal and experimental data are given in Table 1. The selected atomic positional parameters around Pd coordination sphere are given in Table 2. The molecular structure is shown in Fig. 2, together with the atomic labeling scheme. Selected bond distances and angles are listed in Table 3. The Pd atom is Table 1 Crystal and experimental data