Effect of para-substituents on NC bonding of aryl isocyanide molecules adsorbed on metal surfaces studied by sum frequency generation (SFG) spectroscopy

Mikio Ito; Hidenori Noguchi; Kohei Uosaki

doi:10.1063/5.0236548

Effect of para-substituents on NC bonding of aryl isocyanide molecules adsorbed on metal surfaces studied by sum frequency generation (SFG) spectroscopy

J Chem Phys. 2024 Nov 28;161(20):204703. doi: 10.1063/5.0236548.

Authors

Mikio Ito^{1

2

3}, Hidenori Noguchi^{1

2}, Kohei Uosaki¹

Affiliations

¹ National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Japan.
² Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo 060-8623, Japan.
³ Department of Chemical Science and Engineering, National Institute of Technology, Tokyo College, Hachioji, Tokyo 193-0997, Japan.

PMID: 39575744
DOI: 10.1063/5.0236548

Abstract

The effect of para-substituents on the NC bond of aryl isocyanide molecules adsorbed on Au, Ag, Pt, and Pd surfaces was examined by vibrational sum frequency generation (VSFG) spectroscopy. The frequency of NC stretching vibration, υNC, depended on the electronic property of the substituents. When the substituents were more electron-withdrawing and more electron-donating, υNC shifted to lower and higher frequencies, respectively. However, υNC shifted to lower frequency again when the substituents were too electron-donating. The strong dependence of υNC on metal substrates was also observed, reflecting the difference in metal d-band energies, which leads to the difference in the contributions of σ-donation and π back-donation of the NC-metal coupling.