Infrared spectra and density functional calculations of Cu(CO)1–4+, Cu(CO)1–3, and Cu(CO)1–3− in solid neon

Abstract

Laser-ablated copper atoms, cations, and electrons react with CO molecules to give binary copper carbony neutral complexes as well as cation and anion complexes, which are isolated in solid neon and argon matrices. Based on isotopic substitution as well as density functional calculations of isotopic frequencies, absorptions at 2234.4, 2230.4, 2211.3, and 2202.1 cm−1 in neon are assigned to C–O stretching vibrations of the linear CuCO+ and Cu(CO)2+, trigonal planar Cu(CO)3+, and tetrahedral Cu(CO)4+ cations. The absorptions at 1746.2, 1793.9, and 1838.9 cm−1 in neon and at 1733.4, 1780.8, and 1829.7 cm−1 in argon are assigned to the linear CuCO− and Cu(CO)2−, and trigonal planar Cu(CO)3− anions, respectively. The solid neon observations of Cu(CO)1–3 are 20–9 cm−1 blue shifted from the argon matrix counterparts, which are in agreement with previous thermal copper atom matrix isolation studies. This work provides the first vibrational spectra of Cu(CO)1–4+ and Cu(CO)1–3−.