Abstract
A series of ferrocenyl-functionalized β-diketonato manganese(III) complexes, [Mn(FcCOCHCOR)3] with R = CF3, CH3, Ph (phenyl) and Fc (ferrocenyl) was subjected to a systematic XPS study of the Mn 2p3/2 and Fe 2p3/2 core-level photoelectron lines and their satellite structures. A charge-transfer process from the β-diketonato ligand to the Mn(III) metal center is responsible for the prominent shake-up satellite peaks of the Mn 2p photoelectron lines and the shake-down satellite peaks of the Fe 2p photoelectron lines. Multiplet splitting simulations of the photoelectron lines of the Mn(III) center of [Mn(FcCOCHCOR)3] resemble the calculated Mn 2p3/2 envelope of Mn3+ ions well, indicating the Mn(III) centers are in the high spin state. XPS spectra of complexes with unsymmetrical β-diketonato ligands (i.e., R not Fc) were described with two sets of multiplet splitting peaks representing fac and the more stable mer isomers respectively. Stronger electron-donating ligands stabilize fac more than mer isomers. The sum of group electronegativities, ΣχR, of the β-diketonato pendant side groups influences the binding energies of the multiplet splitting and charge transfer peaks in both Mn and Fe 2p3/2 photoelectron lines, the ratio of satellite to main peak intensities, and the degree of covalence of the Mn–O bond.
Highlights
IntroductionThe position and shape of the photoelectron line is further influenced by final-state effects of the metal ions
Properties of metal(III) β-diketonato complexes [M(R1 COCHCOR2 )3 ], M = metal and R = pendant β-diketonato side groups such as CH3, have been studied with a variety of different techniques including crystallography [1], electrochemistry [2], non-linear refractive measurements [3], UV-Vis spectroscopy [4], and high frequency electron paramagnetic resonance (EPR) [5]
2p3/2 envelope could successfully be described with the calculated multiplet splitting from Gupta and
Summary
The position and shape of the photoelectron line is further influenced by final-state effects of the metal ions These final state effects include multiplet splitting, shake-up, and shake-down peaks which are caused by crystal field splitting and charge transfer from the ligand to the metal (back bonding) [6,7]. The main photoelectron lines.between the unpaired core Multiplet p-electrons (2p core and the lines unpaired strong enough, satellite splitting of holes) photoelectron arisesvalence from the3d-electrons coupling of are the angular momenta (spinshake-up peaks which result from valence electrons being transferred to unoccupied states are present orbit coupling) of the unpaired core p-electrons (caused by photoionization) and the unpaired in the XPS spectra at[8,9]. In the XPS of complexes bearing counterparts—e.g., 3d transition metalshigh therespin normally appear shake-up peaks[5] These photoelectron lines can bebinding deconvoluted splitting peaks to as be demonstrated a few complex eV higher than the main peak’s energy.with. Empirically quantify these substructure binding energies as a function of χR and ΣχR of the ligand R-groups
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