Electronic structure of 1 ML NTCDA/Ag(1 1 1) studied by photoemission spectroscopy

We performed high-resolution photoemission experiments at different photon energies to investigate the valence band structure of 1 ML of 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA) on Ag(1 1 1). Besides the known occupied molecular orbitals HOMO and HOMO − 1 we observe a new state close to the Fermi level, which results from the interaction between NTCDA and the substrate, partially filling the lowest unoccupied orbital of the free molecule (LUMO) in the monolayer system. By tuning the photon energy through the carbon K-edge, a resonance like change of the spectral intensity at the HOMO and HOMO − 1 energies is clearly revealed, which we use for an assignment of the individual spectral features to a predominant localization either at the naphthalene core or the anhydride group.     

Chelating or bridging? Halide-controlled binding mode of diamido donor ligands in iron(III) complexes

In a series of iron(III) halide complexes of the form {FeX[MesN(SiMe(2))]2O}2 (Mes = mesityl; X = Cl, Br, I), the ancillary diamidosilylether ligand can either chelate to one metal or instead bridge two metal centers, as a function of the halide coligand. The complexes are prepared from diamidosilyletheriron(II) precursors, which are oxidized with iodine, benzyl bromide, or PhICl2 to yield the appropriate iron(III) halide. The bromide analogue can also be synthesized by reacting the iron(II) precursor with a bromonium transfer agent (stabilized by adamantylideneadamantane). The latter reaction may proceed via an iron(IV) intermediate, which can oxidize the normally noncoordinating, inert [B(ArF)4]- counteranion [ArF = 3,5-(CF3)2Ph].