Synthesis, structural characterization, and gas-phase unimolecular reactivity of the silver hydride nanocluster [Ag3((PPh 2)2CH2)3(μ3-H)] (BF4)2

A bis(diphenylphosphino)methane-ligated trinuclear silver hydride nanocluster, [Ag-3((Ph2P)(2)CH2)(3)(mu(3)-H)](BF4)(3), featuring three silver(I) ions coordinated to a mu(3)-hydride, and its deuteride analogue, [Ag-3((Ph2P)(2)(CH2)(3)(mu(3)-D)](BF4)(2), have been isolated and structurally characterized using electrospray ionization mass spectrometry (ESI-MS), X-ray crystallography, NMR and IR spectroscopy. The position of the deuteride in [Ag-3((Ph2P)(2)(CH2)(3)(mu(3)-D)](BF4)(2) was determined by neutron diffraction. ESI-MS of [Ag3L3(mu(3)-H/D)](BF4)(2) [L = ((Ph2P)(2)CH2)(2)] produces [Ag3L3(mu(3)-H/D)](2+) and [Ag3L3(mu(3)-H/D)(BF4)](+). A rich gas-phase ion chemistry of [Ag3L3(mu(3)-H/D)](2+) is observed under conditions of collision-induced dissociation (CID) and electron-capture dissociation (ECD). CID gives rise to the following complementary ion pairs: [Ag3L2](+) and [L+(H/D)](+); [Ag-2(H/D)L-2](+) and [AgL](+); [Ag-2(H/D)L](+) and [AgL2](+). ECD gives rise to a number of dissociation channels including loss of the bis(phosphine) ligand, fragmentation of a coordinated bis(phosphine) ligand via C-P bond activation, and loss of a hydrogen (deuterium) atom with concomitant formation of [Ag3L3](+). Under CID conditions, [Ag3L3(mu(3)-H/D)(BF4)](+) fragments via ligand loss, the combined loss of a ligand and [H,B,F-4], and cluster fragmentation to give [Ag-2(BF4)L-2](+) and [Ag-2(L-H)L](+) [where (L-H) = (Ph2P)(2)CH-].