Fig. 2: Tandem mass spectra of [{Cr_xCu₂} + Na]⁺ (x = 10, 12) at different collision energies.

a,b, MS² spectra of [{Cr₁₀Cu₂} + Na]⁺ (m/z = 3,365) at collision energies of 0 eV, 100 eV and 140 eV (a) and [{Cr₁₂Cu₂} + Na]⁺ (m/z = 3,910) at collision energies of 0 eV, 120 eV and 150 eV (b). Occurring fragmentation pathways are labelled: (i) – [NH₂^n/iPr₂]⁺, – Piv⁻; (ii) –Cu^II, – 2 Piv⁻; (iii) – [NH₂^n/iPr₂]⁺, – F⁻ and (iv) – Cu^II, – Piv⁻, – F⁻. Satellite peaks (labelled with ‘s’) correspond to the labelled main peak via the exchange of one anionic ligand for another one (Piv⁻ for F⁻ or F⁻ for Piv⁻; mass difference 82 Da). The spectra of both ions present two regions, one at lower m/z and one at higher m/z. Insets: schematics of {Cr₁₀Cu₂} and {Cr₁₂Cu₂} (Cr, green; Cu, brown).

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