Formation of aminomethylidyne from hydrogen cyanide on Pt(111)

Abstract

The thermal chemistry of HCN has been investigated from 85 to 450 K by Fourier transform-infrared absorption spectroscopy (FT-IRAS) and thermal desorption spectroscopy (TDS). The adsorption of HCN at 85 K yields an infrared spectrum consisting of an intense band at 3298 cm −1 due to the CH stretch and a weak band at 1311 cm −1 that is assigned to the overtone of the HCN bend. The close resemblance between the IR spectrum of HCN absorbed on Pt(111) at 85 K and the IR spectrum of HCN in the gas phase and trapped in an argon matrix suggests that HCN is adsorbed molecularly at 85 K and is only weakly perturbed by the surface. Upon warming to 300 K, the H 12C 14N is transformed to a new molecular species with bands at 3363, 1567, and 1323 cm −1. From the shifts of these bands following initial adsorption of the H 13C 14N and H 12C 15N isotopes, they are assigned to an NH stretch (3363 cm −1), NH 2 bend (1567 cm −1), and CN stretch (1323 cm −1). Comparison with the IR spectrum of an Os 3H(μ-CNH 2)CO 10 complex indicates that the 300 K species is aminomethylidyne, CNH 2.