Formation of negative ions from cobalt tricarbonyl nitrosyl Co(CO)3NO clusters

Abstract

Electron attachment and corresponding dissociative electron attachment (DEA) to cobalt tricarbonyl nitrosyl (Co(CO)₃NO) clusters have been studied by co-expansion with Ar gas into a high vacuum. A monochromatic electron beam was utilized to generate negative ions and the resulting reaction products were identified using mass spectrometry. The ion fragments corresponding to Co(CO)₃NO monomers closely resemble results from earlier gas phase experiments and studies conducted on Co(CO)₃NO in He nanodroplets. However, contrary to the gas phase or He nanodroplet ion yields, a resonance structure comprising several peaks at energies above ∼4 eV was observed both in the case of molecular clusters [Co(CO)₃NO]_n⁻ (with n = 1, 2, 3) and clusters comprising DEA fragments. Additionally, the ion yields of numerous other clusters such as ions without nitrosyl ([Co(CO)₄]⁻, [Co₂(CO)₅]⁻), clusters consisting of two fragments such as ([Co₂(CO)NO]⁻, [Co₂(CO)(NO)₂]⁻, [Co₂(CO)₂NO]⁻, [Co₂(CO)₂(NO)₂]⁻, [Co₃(CO)(NO)₃]⁻, [Co₃(CO)₈(NO)₃]⁻, [Co₃(CO)(NO)₂]⁻, [Co₃(CO)₃(NO)₂]⁻, and [Co₃(CO)₅(NO)₂]⁻) were recorded. Moreover, NO bond dissociation was confirmed with the [Co(CO)₂N]⁻ion and with N- or O-retaining cluster ions, such as [Co₂(CO)(NO)N]⁻, [Co₂(CO)₂(NO)N]⁻, [Co₃(CO)₂(NO)N]⁻, [Co₃(CO)₃(NO)N]⁻ and [Co₃(CO)(NO)₂N]⁻, or [Co₂(CO)₂O]⁻, [Co₂(CO)₃O]⁻, [Co₃(CO)₃O]⁻, [Co₃(CO)₄O]⁻and [Co₃(CO)₂(NO)O]⁻ respectively.