The electronic structure and chemical bonding in gold dihydride: AuH2− and AuH2

Abstract

We report an investigation of the electronic structure and chemical bonding of AuH 2 À using photoelectron spectroscopy and ab initio calculations. We obtained vibrationally resolved photoelectron spectra of AuH 2 À at several photon energies. Six electronic states of AuH 2 were observed and assigned according to the theoretical calculations. The ground state of AuH 2 À is known to be linear, while that of neutral AuH 2 is bent with a :H-Au-H equilibrium bond angle of 129 . This large geometry change results in a very broad bending vibrational progression in the photoelectron spectra for the ground-state transition. The electron affinity of AuH 2 is measured to be 3.030 AE 0.020 eV. A short bending vibrational progression is also observed in the second photodetachment band, suggesting a slightly bent structure for the first excited state of AuH 2 . The linear geometry is a saddle point for the ground and first excited states of AuH 2 , resulting in double-well potentials for these states along the bending coordinate. Spectroscopic evidence is observed for the detachment transitions to the doublewell potentials of the ground and first excited states of AuH 2 . Higher excited states of AuH 2 due to detachment from the nonbonding Au 5d electrons are all linear, similar to the anion ground state. Kohn-Sham molecular orbital analyses reveal surprising participation of H 2p orbitals in the Au-H chemical bonding and an unprecedented weak Au 5dp to H 2pp back donation. The simplicity of the linear AuH 2 À anion and its novel spectroscopic features make it a textbook example for understanding the covalent bonding properties and relativistic effects of Au.

Probing the Electronic Structure and Chemical Bonding in Tricoordinate Uranyl Complexes UO2X3– (X = F, Cl, Br, I): Competition between Coulomb Repulsion and U–X Bonding

“…37,38 The electron kinetic energy resolution of the current magnetic-bottle photoelectron analyzer with the shortened electron flight tube was about 3%, i.e., 30 meV for 1 eV electrons. 42b, 44 2.2. Theoretical Methods.…”

Photoelectron spectroscopy and the electronic structure of the uranyl tetrachloride dianion: UO2Cl42−

“…34 The only modification was the shortening of the electron flight tube from 4.0 m to 2.5 m, resulting in a slight decrease of electron energy resolution. 35 Briefly, the UO 2 Cl 4 2− anion was produced by electrospray of a 1 mM solution of UCl 4 in acetonitrile with a trace amount of water. A radio frequency-only quadrupole device guided the anions from the ESI source into a Paul trap operated at room temperature, where anions were accumulated for 0.1 s before being pulsed into the extraction zone of a time-of-flight mass spectrometer.…”

Photoelectron spectroscopy and theoretical studies of gaseous uranium hexachlorides in different oxidation states: UCl6q− (q = 0–2)

“…It was modified by shortening the electron flight tube from 4.0 m to 2.5 m, only resulting in a slight decrease of the electron energy resolution. 33 The [UCl 6 ] − and [UCl 6 ] 2− anions were produced by ESI, using a 1 mM solution of UCl 4 in acetonitrile. A radio frequency quadrupole device guided the anions from the ESI source into a cryogenically controlled ion trap, 23,29 where the anions were accumulated and cooled for 0.1 s before being pulsed into the extraction zone of a time-of-flight mass spectrometer.…”