The Distorted Pd9(μ:η5,η2-As2)4(PPh3)8 Architecture

Extended Hückel and density functional calculations were carried out on the title compound 1. Results indicate that the bonding of the interstitial Pdi atom with the D2d distorted (Pds)8(As2)4 cubic host differs from that found in the related metal-centered cubic species M9(μ4-E)6L8. Species 1 can be described as an approximate square-planar 16-electron PdiL4 center bound through Pdi–As rather than Pdi–Pds contacts to a distorted cubic fragment composed of four 30-electron bimetallic Pd2L8 units. Although a substantial gap is computed between the highest occupied molecular orbital and the lowest unoccupied molecular orbital for the observed electron count of 130 MVEs, calculations indicate that such an architecture should be observed for different electron counts close to that count. The incorporation of the central Pd atom does not seem to be essential to ensure the stability of the distorded Pd8(As2)4(PH3)8 cluster. Such empty clusters, with formally four M–M bonds and eight planar 16-electron Pds centers, should exist for electron counts close to 120 MVEs.