Mass spectrometric study on the neutral nanocluster [Cd32Se14(SePh)36L4] (L = THF, OPPh3) upon charged ligand exchange

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) has been applied to the neutral 1.4 nm sized cluster [Cd32Se14(SePh)36(L)4] upon targeted exchange of the neutral ligands L by various anionic ligands in solution. Use of SePh− as a ‘charging ligand’ leads to virtually monodisperse ion beams constituted of the intact cluster as tetra- and tri-anions. An electrostatic model is employed which is consistent with the proposed charge distribution of four excess charges being localized at the corner sites of the tetrahedron. The experimental results suggest a general applicability of charged ligand exchange to obtain monodisperse cluster ion beams.