Synthesis and characterization of poly(siloxane–azomethine) iron(III) coordination compounds

Figures & data

Scheme 1 Synthesis of the macromolecular ligands.

Figure 1 FT-IR spectra of the cross-linked polyazomethine and the corresponding iron(III) complex. Insert shows the Far-IR region for the complex FePAZ.

Scheme 2 The iron(III) complexes of the siloxane polyazomethines.

Table 1. ESI-MS data and assignment of the peaks (negative mode of ionization, methanol) for the complex FePAZ.

Charge, z	M/z found	Assigned structure^∗	M/z calculated
3	416.73	H2-RU^∗∗-AP-H2	418.33
3	460.67	H2-RU-AP-H2 + 5H2O + MeOH	459.73
3	486.65	O-SA-RU-O + H2O + MeOH	487.07
4	719.95	O-(RU)2-SA-AP(FeCl3·2H2O)–H2 + MeOH	720.62
4	790.47	O-(RU)3–H2 + H2O + MeOH	790.7
4	1045.65	O-(RU)4–H2 + 5H2O + MeOH	1045.58
^∗Fragments AP and SA according to Scheme 1.^∗∗{[AP(FeCl3·2H2O)2]–SA} = RU (Scheme 2).

Figure 2 The UV–Vis spectrum of the iron complex, compared with the corresponding polyazomethine ligand PAZ.

Table 2. UV data for the iron complex and the ligand (in ethanol).

	Wavelength (λ max, nm)/ϵ (L/mol cm)
PAZ	270/4.05 × 10^4	288/2.63 × 10^4
FePAZ	274/2.95 × 10^4	282/2.82 × 10^4	330/1.79 × 10^4	374/9.34 × 10^3

Figure 3 XRF spectrum of complex CFePAZ.

Figure 4 The Mössbauer spectrum of the oligomeric iron complex FePAZ.

Figure 5 Comparison of the cyclic voltammetry data for the iron complex FePAZ (solid line) and the ligand PAZ (thin line) dissolved in ethanol and TBAF as electrolyte (dotted line). Scan rate: 50 mV/s.

Figure 6 Cyclic voltammetry in TBAF as supporting electrolyte without (dotted line) and with increasing concentrations of FePAZ in ethanol (solid lines): (1) 0.33 mM; (2) 0.56 mM; (3) 0.74 mM; and (4) 0.88 mM. Scan rate: 50 mV/s. Potential scanned: −1 to + 1.4 V.

Table 3. The catalytic parameters of the polymeric iron complexes for the hydrogen peroxide decomposition in basic conditions.

Complex	TON	TOF (s^−1)
FePAZ	667	7.56 × 10^−2
CFePAZ	129	2.4 × 10^−1