Cluster transformation of [Cu-3(mu(3)-H)(mu(3)-BH4) ((PPh2)(2)NH)(3)](BF4) to [Cu-3(mu(3)-H)(mu(2), mu(1)-S2CH) ((PPh2)(2)NH)(3)](BF4) via reaction with CS2. X-ray structural characterisation and reactivity of cationic clusters explored by multistage mass spectrometry and computational studies

摘要

The copper nanocluster [Cu-3(mu(3)-H)(mu(3)-BH4)L-3(Ph)](BF4), 1a center dot BF4 (L-Ph = (PPh2)(2)NH = dppa), can potentially react with substrates at either the coordinated hydride or borohydride sites. Reaction of 1a center dot BF4 with CS2 has given rise to [Cu-3(mu(3)-H)(mu(2), mu(1)-S2CH)L-3(Ph)](BF4), (2a center dot 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-3 geometry coordinated on the bottom face by a mu(3)-hydride, on the top face by a mu(2), mu(1)-dithioformate and surrounded by three bridging L-Ph ligands. Reaction of 1a center dot BF4 with elemental sulfur gives the known cluster [Cu-4(L-Ph-H + 2S)(3)](BF4), (3 center dot BF4), which was structurally characterised via X-ray crystallography. ESI-MS of 2a center dot BF4 produces [Cu-3(H)(S2CH)L-3(Ph)](+) and its gas-phase ion chemistry was examined under multistage mass spectrometry conditions using collision-induced dissociation (CID). The primary product, [Cu-3(H)(S2CH)L-2(Ph)](+), formed via ligand loss, undergoes further fragmentation via loss of thioformaldehyde to give [Cu-3(S)L-2(Ph)](+). DFT calculations exploring rearrangement and fragmentation of the model system [Cu-3(H)(S2CH)L-2(Me)](+) (L-Me = (PMe2)(2)NH = dmpa) provide a feasible mechanism. Thus, coupling of the coordinated hydride with the dithioformate ligands gives [Cu-3(S2CH2)L-2(Me)](+), which then undergoes CH2S extrusion via C-S bond cleavage to give [Cu-3(S)L-2(Me)](+).