The impact of optical excitation on the binding in complexes of the cationic gold dimer: Au2+N2${\rm{Au}_{2}^{+}} {\rm{N}_{2}} $ and Au2+N2O${\rm{Au}_{2}^{+}} {\rm{N}_{2}{\rm{O}}} $

Abstract

The vibrationally resolved Ã2Σ+ ← trueX∼2${\tilde{\rm{X}}}^{2} $Σ+ transitions of Au2+N2${\rm{Au}_{2}^{+}} {\rm{N}_{2}} $ and Au2+normalN2O${\rm{Au}_{2}^{+}} {\rm{N}_{2}{\rm{O}}} $ are reported together with a detailed characterization of important geometric and electronic properties, enabling a deep understanding of the bonding mechanism at the molecular level. Comparison with time‐dependent density functional theory calculations reveals that the ligand stabilizes the Au2+${\mathrm{Au}}_{2}^{+}$ entity in the trueX∼2${\tilde{\rm{X}}}^{2} $Σ+ state by donating electron density into the half‐filled bonding orbital leading to the strengthening of the Au-Au$\text{Au-Au}$, N-N$\text{N-N}$, and N-O$\text{N-O}$ bonds. This effect is reversed in the Ã2Σ+ state, where the Au-Au$\text{Au-Au}$ bonding orbital is already filled and the ligand destabilizes the Au-Au$\text{Au-Au}$ bond by donating into the antibonding orbitals of Au2+${\mathrm{Au}}_{2}^{+}$. The spectral detail obtained provides a deep understanding of the interplay of multiple electronic states in gas‐phase metal‐complex cations, opening the door for a systematic approach in the study of excited state reactivity in organometallic chemistry. Key points High‐resolution spectroscopic characterization of Au2+normalL${\mathrm{Au}}_{2}^{+}\text{L}$ complexes by photodissociation of mass‐selected ions in the optical range and determination of fundamental molecular constants and ligand binding energies Detailed insight into geometric and electronic structure of ground and excited state of catalytically relevant gold cluster cations Effect of ligands on chemical bonding and reactivity of Au2+${\mathrm{Au}}_{2}^{+}$ in ground and excited electronic state

Photochemical properties of a potential interstellar dust precursor: the electronic spectrum of Si3O2+

“…This approach was initially tested and optimized by recording high-resolution vibronic spectra of gold cluster cations. [62][63][64][65] First applications of EPD spectroscopy to Si-containing cluster ions include the first spectrum of a Si n C m + cation (namely Si 4 C 2 + ) 66 and the first spectrum of diatomic Si 2 + . 67 Herein, we extend these efforts to Si 3 O 2 + and report the first optical spectrum of any polyatomic…”