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Issue 11, 2012
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The electronic structure and chemical bonding in gold dihydride: AuH2 and AuH2

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Abstract

We report an investigation of the electronic structure and chemical bonding of AuH2 using photoelectron spectroscopy and ab initio calculations. We obtained vibrationally resolved photoelectron spectra of AuH2 at several photon energies. Six electronic states of AuH2 were observed and assigned according to the theoretical calculations. The ground state of AuH2 is known to be linear, while that of neutral AuH2 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 AuH2 is measured to be 3.030 ± 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 AuH2. The linear geometry is a saddle point for the ground and first excited states of AuH2, resulting in double-well potentials for these states along the bending coordinate. Spectroscopic evidence is observed for the detachment transitions to the double-well potentials of the ground and first excited states of AuH2. Higher excited states of AuH2 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 5dπ to H 2pπ back donation. The simplicity of the linear AuH2 anion and its novel spectroscopic features make it a textbook example for understanding the covalent bonding properties and relativistic effects of Au.

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

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Article information


Submitted
17 Jul 2012
Accepted
14 Aug 2012
First published
15 Aug 2012

Chem. Sci., 2012,3, 3286-3295
Article type
Edge Article

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

H. Liu, Y. Wang, X. Xiong, P. D. Dau, Z. A. Piazza, D. Huang, C. Xu, J. Li and L. Wang, Chem. Sci., 2012, 3, 3286
DOI: 10.1039/C2SC20984E

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