Synthesis of Bimetallic Copper-Rich Nanoclusters Encapsulating a Linear Palladium Dihydride Unit

The structurally precise Cu-rich hydride nanoclusters [PdCu14H2(dtc/dtp)(6)(C equivalent to CPh)(6)] (dtc: di-butyldithiocarbamate (1); dtp: di-isopropyl dithiophosphate (2)) were synthesized from the reaction of polyhydrido copper clusters [Cu28H15((S2CNBu2)-Bu-n)(12)](+) or [Cu20H11{S2P((OPr)-Pr-i)(2)}(9)] with phenyl acetylene in the presence of Pd(PPh3)(2)Cl-2. Their structures and compositions were determined by single-crystal X-ray diffraction and the results supported by ESI-mass spectrometry. Hydride positions in 1 were confirmed by single-crystal neutron diffraction. Each hydride is connected to one Pd-0 and four Cu-I atoms in slightly distorted trigonalbipyramidal geometry. The anatomies of clusters 1 and 2 are very similar and DFT calculations allow rationalizing the interactions between the encapsulated [PdH2](2-) unit and its Cu-14 bicapped icosahedral cage. As a result, Pd has the highest coordination number (14) so far recorded.