Synthesis, structure, and electrochemical properties of 4,5-diaryl-1,2,3-triphosphaferrocenes and the first example of multi(phosphaferrocene)
Andrey V. Petrov, Almaz A. Zagidullin, Ilya A. Bezkishko, Mikhail Khrizanforov, Kirill V. Kholin, Tatiana P. Gerasimova, Kamil Ivshin, Ruslan P. Shekurov, Sergey A. Katsyuba, Olga Kataeva, Yulia H. Budnikova, Vasili A. Miluykov
Abstract
The reaction between aryl substituted sodium 1,2,3-triphospholides or disodium bis(1,2,3-triphospholide) and [Fe(η6-(C6H5CH3)Cp]+[PF6]- in boiling diglyme results in pure 1,2,3-triphosphaferrocenes 1-3 or bis(1,2,3-triphosphaferrocene) 4, respectively, in good yields. The structure of all obtained 1,2,3-triphosphaferrocenes 1-4 has been extensively studied experimentally (NMR, UV-Vis spectroscopy, and X-ray analysis for 1 and 4) and quantum chemically. The electrochemical properties of 1,2,3-triphosphaferrocenes 1-4 in the solid state were studied for the first time and a reversible one-electron oxidation (E1/2 = 0.52-0.92 V vs. Fc+/Fc) was demonstrated for 1, 3, and 4. In the case of 1,4-bis(5-phenyl-4-(1,2,3-triphospaferrocenyl))benzene 4, consecutive oxidation in the solid state is observed in contrast to other 1,2,3-triphosphaferrocenes 1-3. According to the ESR data, the g-factor of the oxidized bis(1,2,3-triphosphaferrocene), 4 (g = 2.12) is different from the g-factors of oxidized 1,2,3-triphosphaferrocenes 1-3 (g = 2.01). This is the first example of multi(ferrocenyl) systems based on the phosphaferrocene motif, which in turn opens up a new fundamental platform for the preparation of compounds with stimuli-responsive properties.