Chemical Shift in X-Ray Photoelectron Spectra of Dioxime-Cobalt(III) Complexes

Abstract

The X-ray photoelectron spectra of Co 2p and N is level for [Co(Hdmg)₂L₂]Cl, [CoCl(Hdmg)₂2], H[CoC1₂(Hdmg)2]₂ and [Co(Hbhpn)L₂]C1₂ have been measured, where H2dmg is dimethylglyoxime, H2bhpn is N, N'-bis(2-hydroxyimino-1-methylpropylidene)-1, 3-propanediamine, and L are aniline or its derivatives. The influence of electron donating characteristics or the heat of sublimation of aniline derivative as the axial ligand on the chemical shift of binding energies was studied. The deconvolution of N 1s s pectra indicated the presence of two (for [Co(Hdmg)₂L₂]Cl, [CoCl(Hdmg), L] and [CoCl₂(Hbhpn)]) or three (for [Co(Hbhpn)L₂]C1₂) nitrogen atoms (Fig.2). These nitrogen atoms were found to be due to the amino group of aniline derivative, the hydroxyimino group of Hdmg or Hbhpn, and propanediimine of Hbhpn (Tables 2, 3). The δ Eco-N value (the binding energy difference of Co 2p 1/2 and N is of aniline derivative) was calculated. A linear correlation is observed between the δEco-N/σ, la"and δH(sub)/σ values (Fig.4), where a is Hammett substituent constant of substituted aniline derivative, and δH(sub) is heat of sublimation of aniline derivative. This fact reveals that the bonding strength of cobalt-ligand depends on the electron donating characteristic and the heat of sublimation of aniline delivatives.