### Atomic and Electronic Structure of [M(Salen)] Complexes and Their Polymers
#### 3.2.1 Xps
Based on a comparative analysis of the binding energies of the inner 1\(s\) electrons of functional nitrogen and oxygen atoms, it was found that the binding energies of these electrons do not change significantly in going from monomer to polymer, thus indicating the stability of the coordination center in the monomer during the process of electrochemical polymerization (see Table 2). It was also established that the formation of the [M(Salen)] complexes is accompanied by the appearance of an excess electron density on oxygen ions, which, \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Compound** & **C 1s** & **N 1s** & **E\({}_{\text{blir}}\), eV** & & & \\  & & & **O 1s** & **M 2\(p\), 3\(d\), 4\(f\)** & **Calibration** & **Ref.** \\ \hline H\({}_{2}\)(Salen) & 284.8 & 398.65 & 532.5 & - & & \\
[Ni(Salen)] & 285.75 & 400.55 & 532.1 & no information & & Pt 4\(f_{7/2}\) 71.1 eV & [46] \\ \hline
[Ni(Salen)] & 285.5 & 400.3 & 532.0 & Ni 2\(p_{3/2}\) 856.3 & Pt 4\(f_{7/2}\) 71.1 eV & [45] \\ \hline
[Ni(Salen)] & not specified & 398.4 & 530.2 & \begin{tabular}{c} Ni 2\(p_{3/2}\) \\ 854.3 \\ \end{tabular} & C 1s 284.8 eV & [44] \\ \hline poly-[Ni(Salen)] & not specified & 399.1 & 530.2 & \begin{tabular}{c} Ni 2\(p_{3/2}\) \\ 854.9 \\ \end{tabular} & C 1s 284.8 eV & [44] \\ \hline poly-[Ni(CH\({}_{3}\)O-Salen)] ox & not specified & 399.8 & 531.5, 533.3, 534.6 & \
\begin{tabular}{c} Ni 2\(p_{3/2}\) \\ 854.9 \\ \end{tabular} & \multirow{4}{*}{C 1s 284.8 eV} & \multirow{4}{*}{[48]} \\ poly-[Ni(CH\({}_{3}\)O-Salen)] red & not specified & 399.8 & 531.5, 533.3, 534.6 &
\begin{tabular}{c} Ni 2\(p_{3/2}\) \\ 854.9 \\ \end{tabular} & & \\ poly-[Cu(Salen)] ox & 399.5 \(\pm\) 0.1 & 531.2 \(\pm\) 0.1 & & & \\ poly-[Cu(Salen)] red & 399.4 \(\pm\) 0.1 & 531.2 \(\pm\) 0.1 & & & \\ poly-[Ni(Salen)] ox & 399.7 \(\pm\) 0.1 & 531.3 \(\pm\) 0.1 & & & \\ poly-[Ni(Salen)] red & not specified & 399.6 \(\pm\) 0.1 & 531.2 \(\pm\) 0.1 & not specified & C 1s 285.0 eV & [39] \\ poly-[Pd(Salen)] ox & 399.8 \(\pm\) 0.1 & 531.3 \(\pm\) 0.1 & & & \\ poly-[Pd(Salen)] red & 399.8 \(\pm\) 0.1 & 531.2 \(\pm\) 0.1 & & & \\ poly-[Pt(Salen)] ox & 400.4 \(\pm\) 0.1 & 532.4 \(\pm\) 0.1 & & & \\ poly-[Pt(Salen)] red & 400.3 \(\pm\) 0.1 & 531.9 \(\pm\) 0.1 & & & \\ \hline
[Pd(3\)-CH\({}_{3}\)Salen] & 285.0 & 400.0 & 531.6 & Pd 3\(d_{5/2}\) & & \\  & 286.4 & 291.1 & & & 338.7 & \\  & 284.2 & 399.2 & & & \\ poly-[Pd(3-CH\({}_{3}\)Salen)] ox & 287.2 & 401.3 & 531.7 & Pd 3\(d_{5/2}\) & & \\  & 289.1 & 403.1 & & 337.9 & C 1s 285.0 eV & [40] \\  & 284.6 & & & & \\ poly-[Pd(3-CH\({}_{3}\)Salen)] red & 285.9 & 399.6 & & & Pd 3\(d_{5/2}\) & & \\  & 287.1 & 402.9 & 531.3 & 338.2 & & \\  & 289.6 & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._apparently, is then used in the electrically stimulated oxidation of the monomeric complex. In this regard, it was suggested that the electronic state of oxygen in the salen ligand plays a key role in the formation of the polymer structure. In other words, during the oxidation of the monomer at the anode, the oxygen ions of the coordination center perform the function of an electronic \"depot\", being a source of electrons during the electrochemical oxidation of each structural unit. Among the important results obtained in these works, one should also include the observation that after XPS measurements, polymer samples retained their electrically conductive and optical properties, i.e., they were not destroyed or transformed in a noticeable way during their irradiation with intense beams of ionizing X-rays. All this additionally indicates the promise of using X-ray spectroscopy methods to study the properties of electrically conductive polymers. To summarize, it is important to say that the XPS method is effective for studying the change in the binding energy of core electrons of ligand atoms (C, N, O) and complexing metal atoms in going from monomer fragments to polymers.