Study of the metal-oxygen bond in simple tris-chelate complexes by He(I) photoelectron spectroscopy

Ionization energies of metal chelates. Acetylacetonates, trifluoroacetylacetonates, and hexafluoroacetylacetonates of trivalent metals of the first transition series

“…Even though comparison PE spectra are not available for these complexes the extracted values are reasonable when compared with observed changes in energies of metal and ligand orbitals as CH, is replaced by CF,. The energies of metal dominated orbitals are shifted by slightly less than those of ligand dominated x orbitals (as illustrated very well by the PE spectra of the Cr(II1) complexes) and also band Y moves closer to band A as the number of d electrons increases (24). The weak processes should influence the values of the ionization energies extracted from the "best fit" curves for T i ( a c a~)~ and V ( a c a~)~.…”

“…The results for the Mn(II1) and Fe(II1) chelates show no obvious evidence, in either electron or photon impact, for ionization by electron removal from an eb orbital (correlating with eg* in octahedral symmetry) of mainly metal 3d character. Although the barely discernible shoulder Z in the PE spectrum of Mn(hfa), was suggested to arise in this way (24) we believe other assignments are possible and regard the energies of the eg* orbitals as a currently unsolved problem.…”

“…1 and 3-9 are available photoelectron spectra for the complexes. These spectra were redrawn and positioned to the same energy scale as the ionization efficiency curves from photographic enlargements of the published PE spectra (24). Assignments of bands K, L, and M, observed in some spectra, were more tentative.…”

Electronic structure and photoelectron spectra of nickel (II) acetylacetonate and its thio- and amino-substituted analogues

“…The UPS studies of the electronic effects substituting the OeH group in the Н-асас enol with HNH [40] and SeH [45] indicated theIE for the p-and norbitals depended on the substituent. Calculations for the model compounds Ia e IIIa, which substitute the metal atom for hydrogen, exhibited changes in the ligand levels.…”

Photoelectron Spectroscopy (PES) of Organometallic Compounds withCM(MGe,Sn,Pb) Bonds

“…Cauletti and coworkers 53 Fragalà and coworkers 137 analysed the He I and He II spectra of β-diketonato complexes of formula Me 2 Sn(pd) 2 (36) and Cl 2 Sn(pd) 2 (37) (pd = pentane-2,4-dionate), having a pseudo-octahedral trans or cis configuration, with the aim both of elucidating the stereochemistry of such complexes and of gaining more direct insight into the bonding of the alkyl-or halo-tin moiety with the bidentate ligand. The interaction between the orbitals of the ligands (π 3 , n − and n + for each chelate ring, following the notation of Evans and coworkers 138 ) and the Sn orbitals depends critically on the molecular conformation. The molecule of 36 is known to have in both solution and the solid state a trans-'pseudooctahedral' geometry, whilst that of 37 has a cis structure, as shown in Figure 24.…”