Matrix Infrared Spectra and Density Functional Calculations of Ni(CO)x⁻, x = 1−3

Laser-ablated Ni atoms and electrons react with CO in excess argon during condensation to form the Ni(CO) 1 - 4 complexes and Ni(CO) 1 - 3 - anions. Matrix infrared spectra of the neutral complexes with 12 C 16 O, 13 C 16 O, and 12 C 18 O substitution are in agreement with earlier reports with thermal Ni atoms. In addition, new absorptions at 1847.0, 1801.7, and 1858.8 cm - 1 exhibit isotopic spectra in excellent agreement with DFT calculations for the Ni(CO) 1 - 3 - anions. An experiment doped with the CCl 4 electron-trapping molecule gave the same Ni(CO) 1 - 4 spectrum without the corresponding anions, which strongly supports this identification of the molecular anions.