He-I photoelectron spectra of some d 0 transition metal compounds

Abstract

Photoelectron spectra excited in the gas phase with He-I radiation are reported for the tetroxides, Ru04 and Os04, and for the oxychloride species V0Cl3, CrO2CI2 and Mo0,C12. The X-ray photoelectron spectrum of Os04 has also been measured. The nature of the metal-oxygen bonding in these molecules, as inferred from the spectrometric data, is discussed.We report here the results of a study by He-I photoelectron (PE) spectroscopy of the orbital electronic structures of the tetroxo-species RuO, and OsO,, and the oxychlorides VOC13, CrO,Cl, and MoO,CI, . This investigation represents a natural extension of our previous work on tetrahalide species such as TiC1, and VC14,1' but it was stimulated in part by the widespread interest 3-5 in the electronic structures of oxyanions such as MnO, , quasi-isoelectronic with RuO, and OsO,. He-I PE spectra of OsO, and RuO, have recently been reported by McGlynn and coworkersHowever, the results presented below show that both sets of spectra contain spurious structure due to impurities which, naturally enough, created some confusion with regard to the assignment of the spectra. and by Diemann and Muller.7 EXPERIMENTAL A N D RESULTSWith the exception of RuO, and MoO,Cl,, the compounds studied in the present work were obtained commercially and purified by standard procedures. Ruthenium tetroxide was prepared as a yellow solid of low melting point by the method of Berkowitz and R ~l a n d e r , ~ which involves the oxidation of RuC13 by bromate in aqueous solution. The product suffered slight contamination from bromine which was removed by partial distillation under reduced pressure. The sample was dried by means of a 4 A molecular sieve. Molybdyl chloride (MoO2Cl,) was prepared by chlorination of a commercial sample of MOO,. The pale yellow, microcrystalline product was purified by sublimation and finally obtained as lustrous orange needles, l o somewhat metallic in appearance. $The PE spectra shown in fig. 1 (a)-3 and 6-8 were measured on a medium resolution spectrometer using He-I (21.21 eV) exciting radiation. The spectra were calibrated by reference to lines due to admixed inert gases.

Relativistic electronic structure theory

“…Figures 1 and 2 show the nonrelativistic and relativistic CASPT2 results, respectively. RESC‐CASPT2 gives values for the peak positions and intensities in reasonable agreement with the resolved photoelectron spectrum data 43. The Os valence 6s and 5p orbitals are expected to be stabilized while Os 5d orbitals are destabilized due to the relativistic effect.…”

Excited states of OsO4: A comprehensive time‐dependent relativistic density functional theory study

“…The PE1–5 and UV‐vis6–9 spectra of OsO 4 were well recorded, from which one sees that the primary peaks are energetically well separated from each other such that vibronic couplings can be neglected to a first approximation, unlike MnO 4 − 23. Yet, both relativistic and electron correlation effects have to be accurately accounted for.…”

“…Due to structural simplicity, high symmetry, and volatility, tetrahedral transition metal tetraoxo complexes of a formal d 0 electronic configuration have drawn a great deal of attention to spectroscopic studies. The gas phase UV‐vis excitation and photoelectron (PE) ionization spectra for such systems as OsO 4 1–9 were measured experimentally long ago. Unfortunately, however, it is oftentimes not easy to deduce vertical transition/ionization energies from the experimental bands due to intricate vibronic structure of the spectra.…”

Theoretical study of valence photoelectron spectrum of OsO4: A spin-orbit RESC-CASPT2 study

“…Relativistic effects are important in the study of heavy elements such as OsO 4 . Instead of the Schrödinger equation, one now has to solve the Dirac equation, which involves a four-component Hamiltonian.…”

“…Recently we have proposed a new relativistic scheme by eliminating the small component ͑RESC͒ [4][5][6][7][8][9][10][11][12][13][14][15][16] of the fourcomponent Dirac equation. It is variationally stable and avoids the Coulomb singularity.…”