An electrospray ionization mass spectrometry (ESI-MS) survey of the types of cationic copper clusters formed from an acetonitrile solution containing a 1:1:20 mixture of tetrakis(acetonitrile)copper(I) tetrafluoroborate [Cu(MeCN)(4)(BF4)], bis(diphenylphosphino)amine (dppa = (Ph2P)(2)NH = L), and NaBH4 revealed a major peak, which based on both the accurate masses and isotope distribution was assigned as [Cu-3(BH4)(H)(L)(3)](+). This prompted synthetic efforts resulting in isolation of the dppa ligated trinuclear copper hydride nanoclusters, [Cu-3(mu(2)-Cl)(mu(3)-H)(L)(3)](BF4) and [Cu-3(mu(3)-BH4)(mu(3)-H)(L)(3)](BF4), which were subsequently structurally characterized using high resolution ESI-MS, X-ray crystallography, NMR, and IR spectroscopy. The X-ray structures reveal a common structural feature of the cation, in which the three copper(I) ions adopt a planar trinuclear Cu-3 geometry coordinated on the bottom face by a mu(3)-hydride and surrounded by three dppa ligands. ESI-MS of [Cu-3(mu(2)-Cl)(mu(3)-H)(L)(3)](BF4) and [Cu3(mu(3)-BH4)(mu(3)-H)(L)(3)](BF4) produces [Cu-3(mu(2)-Cl)(mu(3)-H)(L)(3)](+) and [Cu-3(mu(3)-BH4)(mu(3)-H)(L)(3)](+). The unimolecular gas-phase ion chemistry of these cations was examined under multistage tandem mass spectrometry conditions using collision-induced dissociation (CID). CID of both cations proceeds via ligand loss to give [Cu-3(mu(3)-H)(X)(L)(2)](+), which is in competition with BH3 loss in the case of X = BH4. DFT calculations on the fragmentation of [Cu-3(mu(3)-BH4)(mu(3)-H)(L-Me)(3)](+)suggest that BH3 loss produces the hitherto elusive [Cu3(mu(3)-H)(mu(2)-H)(L)(2)](+), which undergoes further fragmentation via H-2 loss. CID of the deuterium labeled cluster [Cu-3(mu(3)-D)(mu(3)-BD4)(L)(3)](+) reveals that the competing losses of ligand and BD3 yield [Cu-3(mu(3)-BD4)(mu(3)-D)(L)(2)](+) and [Cu-3(D)(2)(L)(3)](+) as primary products, which subsequently fragment via further losses of BD3 or a ligand to give [Cu-3(D)(2)(L)(2)](+). The coordinated hydrides in the latter ion are activated toward elimination of D-2 to give [Cu-3(L)(2)](+). Loss of HD and 2HD are minor channels, consistent with higher DFT predicted endothermicities to form [Cu-3(D)(L)(L-H)](++) and [Cu-3(L-H)(2)](+).