Formation and characterization of the AsCO and AsCO− molecules. A matrix isolation FTIR and theoretical study

Infrared spectra of arsenic carbonyls trapped in an argon matrix by co-condensation of laser-ablated arsenic atoms and electrons with carbon monoxide are reported. Based on isotopic substitution experiments and theoretical calculations, an IR band at 1919.3 cm−1 has been assigned to the C–O stretching vibration of the neutral AsCO, and a 1756.4 cm−1 band to the C–O stretching mode of the AsCO− anion. The ground states of AsCO and AsCO− were predicted to be 2Π and 1Σ+, respectively. The formation mechanism and the nature of bonding are discussed.