and 2d with 1. A single crystal X-ray structure determination of 3b (Z=2, triclinic, space group P-1) highlighted a weak axial elongating Jahn-Teller effect and a high degree of bond conjugation.An X-ray photoelectron spectroscopic study, by virtue of linear relationships between group electronegativities of ligand R groups, χ R , or χ R , and binding energies of both the Fe 2p 3/2 and Mn 2p 3/2 photoelectron lines, confirmed communication between molecular fragments of 2a-2d as well as 3a-3d. This unprecedented observation allows prediction of binding energies from known β-diketonato side group χ R values.Keywords: Manganese, ferrocene, betadiketonato complexes, substituent effects, electronic spectra, X-ray photoelectron spectroscopy, binding energy predictions.
IntroductionThe first row transition metal, manganese, exhibits a wide variety of oxidation states in compounds ranging from Mn(I), e. we then highlight intramolecular communication between molecular fragments of 3a-3d from results of an X-ray photoelectron spectroscopic (XPS) study.
Results and discussion
Synthesis and characterizationThe ferrocene-containing manganese ( IR spectra of 3a-3d and 4 displayed the characteristic strong ν CO vibrations found between 1498-1572 cm -1 (Experimental Part) which is typical for chelate-bonded β-diketonato ligands in transition metal chemistry. 22 A shift to lower wave numbers is observed for 3a-3d and 4 compared to the free β-diketones 2a-2d (1620 -1710 cm -1 ) 23 which allows the monitoring of the reaction progress. Prominent CH-stretching bands are also observed at ca. 3100 cm -1 .Peak maxima of the UV-Vis spectra of complexes 3a-3d and 4 ( Figure 1) are summarized in Table 1. Dichloromethane solutions of the highly soluble complexes 3a-3c and 4 all showed relatively high extinction coefficients. All complexes followed the Beer-Lambert law, A = εCl, which implies a linear relationship between absorbance and concentration. Van der Zeiden 24 reported a similar lower energy band in tungsten(0) -diketonato complexes and assigned it to a MLCT band with destabilized t 2g level after appropriate calculations.
Single Crystal X-ray structure of 3bTo understand the trends observed in XPS-obtained binding energies for Fe(II) (and also Mn(III)) of complexes 3a -3d described in the next section, an evaluation of the structural characteristics of 3b is useful. The fac isomer of complex 3b crystallized from toluene in the triclinic space group P-1 having ca. 1 disordered solvent molecule for every two molecules of 3b. The refinement parameters and crystal data are summarized in Table 2 and the molecular structure of 3b, highlighting atom labeling, are shown in Figure 2. Selected bond distances and bond angles are summarized in the caption of Figure 2, but the full set of bond lengths and angles is available in Supplementary Information.
