Can Electrochemical Measurements Be Used To Predict X-ray Photoelectron Spectroscopic Data? The Case of Ferrocenyl-β-Diketonato Complexes of Manganese(III)

Abstract

In order to better understand intramolecular communication between molecular fragments, a series of ferrocene-functionalized β-diketonato manganese(III) complexes, [Mn(FcCOCHCOR)] with R = CF, 1, CH, 2, Ph = CH, 3, and Fc = Fe(η-CH)(η-CH), 4, the mixed ligand β-diketonato complex [Mn(FcCOCHCOFc)(FcCOCHCOCH)], 5, as well as the acac complex [Mn(CHCOCHCOCH)], 6, were subjected to an electrochemical and X-ray photoelectron spectroscopy (XPS) study. The ferrocenyl (Fe) and Mn redox potentials, E°', and photoelectron lines were sufficiently resolved in each complex to demonstrate a linear correlation between E°' and group electronegativities of ligand R groups, χ, or Σχ, as well as with binding energies of both the Fe 2p and Mn 2p photoelectron lines. These relationships are consistent with effective communication between molecular fragments of 1-5. From these relationships, prediction of Mn and Fe core electron binding energies in [Mn(RCOCHCOR)] complexes from known manganese and/or ferrocenyl redox potentials are, therefore, now possible. Ligand infrared carbonyl stretching frequencies were successfully related to binding energy as a measure of the energy required for inner-sphere reorganization. In particular it became possible to explain why, upon electrochemical oxidation or photoionization, the ferrocenyl Fe inner-shell of 1-5 needs more energy in complexes with ligands bearing electron-withdrawing (CF) groups than in ligands bearing electron-donating groups such as ferrocenyl. The XPS determined entity I (the ratio between the intensities of the satellite and main metal 2p photoelectron lines) is an indication not only of the amount of charge transferred, but also of the degree of inner-sphere reorganization. Just as for binding energy, the quantity I was also found to be related to the energy requirements for the inner-sphere reorganization depicted by the vibrational frequency, v.

A Static Tin–Manganese Battery with 30000-Cycle Lifespan Based on Stabilized Mn3+/Mn2+ Redox Chemistry

“…But some Mn species on the surface of the GrE are observed in XPS spectra (Figure D). It may not be attributed to manganese oxides as there is no lattice oxygen signal in the O 1s spectra (Figure D). − There is a satellite peak around 647.9 eV in the Mn 2p spectra (Figure E), which is caused by charge transfer from ligand to Mn ions and implies the existence of Mn-based complexes. − It should be noted that this shakeup feature cannot be observed in the Mn XPS spectra of manganese oxides. Taking both deconvoluted spectra of O 1s and C 1s into consideration, we speculate that Mn ions should be coordinated by the oxygen-containing groups anchored on GrE.…”

Synthesis, Characterization, and Electrochemistry of Diferrocenyl β-Diketones, -Diketonates, and Pyrazoles

“…200 ppm. For the ferrocenyl groups, in total, four signals are observed between 65–80 ppm, which is typical for the C 5 H 4 and C 5 H 5 perimeters ( Section 4 ) [ 36 , 37 , 38 , 39 , 40 , 41 ].…”

“…For better comparison with our data, we repeated the CV measurements in the presence of the weak coordinating electrolyte [NBu 4 ][B(C 6 F 5 ) 4 ] [ 68 , 125 , 126 ]. As it can be seen from Figure 8 , compound 5 shows its second redox event to be broadened, most likely due to keto-enol tautomerism in the mixed-valent state [ 37 , 38 , 41 ]. This differs from 6 , since this compound only features one β keto-group.…”

“…In addition, they received great interest in the synthesis of (hetero)multimetallic complexes [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ] as catalysts in organic synthesis [ 30 , 31 , 32 ] and as anticancer drugs (especially copper and rhodium β-diketonates) [ 33 , 34 , 35 ]. Recently, they gained topical attention in the study of electron transfer processes, when, for example, redox-active groups such as ferrocenyls are present, i.e., in zirconium, hafnium, copper(I), copper(II), manganese, ruthenium, rhodium(I), and aluminum β-diketonate complexes [ 36 , 37 , 38 , 39 , 40 , 41 ].…”

Synthesis, Electrochemistry, XPS, and DFT Calculations of α-Carbon-Bonded Gold(I) Ferrocenyl- and Ruthenocenyl-Containing β-Diketonato Complexes

“…These included complexes of the type [Rh(FcC κ OCHC κ OR)(CO) 2 ], 67 [PcZr(FcC κ OCHC κ OR) 2 ] (Pc = phthalocyaninato), 68 and [Mn(FcC κ OCHC κ OR) 3 ]. 64 Here, E°′ for Fc and Rc of complexes 2−10 (Table 2) was plotted against Σχ R values of β-diketonato side groups (Figure 3). To illustrate how Σχ R is calculated, consider wave Rc1 of complex 10, [(FcCO)(RcCO)H α C-AuPPh 3 ].…”