Electron Spin Resonance of Pd(I). I. γ-Irradiated Bis(acetylacetonato)palladium(II)

Abstract
A paramagnetic complex produced in γ‐irradiated bis(acetylacetonato)palladium(II) [Pd(II) (acac)2] has been studied by means of the electron spin resonance technique. It is found that the same complex is produced by the uv irradiation of the frozen solution of Pd(II) (acac)2 and N,N,N′,N′‐tetramethyl‐paraphenylenediamine(TMPD) in ethanol. In this case, it is most probable that Pd(II) (acac)2 has been reduced by the electrons photoejected from TMPD. The g tensor for the paramagnetic complex produced in the γ‐irradiated single crystals exhibits axial symmetry with the g‖ direction coincident with that for Cu(II) (acac)2 which is diluted in Pd(II) (acac)2. In view of these results it is concluded that [Pd(I) (acac)2] has been produced by the above procedures. The ESR parameters for this complex are interpreted in terms of the molecular‐orbital theory developed by Maki and McGarvey, and the covalent character of the metal–ligand bond is compared with that for Cu(II) (acac)2.