OK. It seems that we need go down in IR (~350cm-1) or to do Raman for the ν-Pd-Cl resonances, but I am still curious about the ν-Pd-P stretchings of these compounds.

Mr. Tóth,

It sould be, however, about 350 cm-1

We have obtained another spectrum at lower wavelength with IR. This clearly shows a double peak (symmetric and asymmetric stretchings) for ν-Pd-Cl at 353 and 358 cm-1. Thus, contrary to that previously thought our PdCl2(PR3)2 complex should be cis. Yet, our complex show a strong double peak at 520 and 506 cm-1 just like trans PdCl2(PPh)3 with 520 and 506 cm-1. Are these no ν-Pd-P stretchings or are they apparently irrelevant for the geometry?

@Imre Tóth:  Those (520 and 506 cm-1) are most likely vibrations related to your PR3 ligands - the two PR3 groups in your Pd-complex are not covalently coupled to each other, so that they would not be sensitive to the difference of cis/trans isomerism.  When I run vibrational calcuations on trans and cis PdCl2(PPh3)2, I get several vibrations in that range corresponding to the PPh3 ligand.

Thank you Kaoru. Good point. Since, for example, cis-PdCl2[P(CH3)2Ph]2 gives a single resonance at 490 cm-1, it seems that ν-Pd-P vibrations are rather characteristic for the ligand than for the geometry. Right?

Regards,

               Imre

I prepared some phosphine complexes of Pd(II).the v(Pd-P) appeared around 420 Cm-1 as a single band for trans complex  and a double band for cis.