Cluster transformation of [Cu(μ-H)(μ-BH)((PPh)NH)](BF) to [Cu(μ-H)(μ,μ-SCH)((PPh)NH)](BF) via reaction with CS. X-ray structural characterisation and reactivity of cationic clusters explored by multistage mass spectrometry and computational studies.

The copper nanocluster Cu(μ-H)(μ-BH)L, 1a·BF4 (L = (PPh)NH = dppa), can potentially react with substrates at either the coordinated hydride or borohydride sites. Reaction of 1a·BF4 with CS has given rise to Cu(μ-H)(μ,μ-SCH)L, (2a·BF4), which was structurally characterised using electrospray ionisation (ESI) with high-resolution mass spectrometry (HRMS), X-ray crystallography, NMR, IR and UV-Vis spectroscopy. The copper(i) atoms adopt a planar trinuclear Cu geometry coordinated on the bottom face by a μ-hydride, on the top face by a μ,μ-dithioformate and surrounded by three bridging L ligands. Reaction of 1a·BF4 with elemental sulfur gives the known cluster Cu(L-H + 2S), (3·BF4), which was structurally characterised via X-ray crystallography. ESI-MS of 2a·BF4 produces [Cu(H)(SCH)L] and its gas-phase ion chemistry was examined under multistage mass spectrometry conditions using collision-induced dissociation (CID). The primary product, [Cu(H)(SCH)L], formed via ligand loss, undergoes further fragmentation via loss of thioformaldehyde to give [Cu(S)L]. DFT calculations exploring rearrangement and fragmentation of the model system [Cu(H)(SCH)L] (L = (PMe)NH = dmpa) provide a feasible mechanism. Thus, coupling of the coordinated hydride with the dithioformate ligands gives [Cu(SCH)L], which then undergoes CHS extrusion via C-S bond cleavage to give [Cu(S)L].