This talk, which honors the academic career of Professor John Fackler over the last half-century, will mainly focus upon our recent/current research on the preparation and crystallographic/spectroscopic characterization of CO/PR3-ligated nanosized heterometallic Pd-Au and Pd-Tl clusters combined with highly insightful theoretical calculations (by SAI). This presentation will include: (1) Compelling experimental/theoretical evidence that the observed much greater stabilities toward carbon monoxide in well-defined non-isovalent Pd2-by-Au2-substituted Au2Pdn-2 nanosized clusters (n = 23, 30), relative to nanosized homopalladium Pdn clusters with n > 10 being generally unstable under CO, are a consequence of electron delocalization of each Au 6s valence electron toward a Au+ configuration; this finding has direct relevance with a recent report on highly active Pd-Au nanoparticle catalysts that the presence of Au prevents CO poisoning. (2) Experimental evidence suggesting that the so-called �inert� 6s2 electron-pair of 6s25d10 Tl(I) can exert either a positive or negative stabilizing influence relative to that of 6s05d10 Au(I) in different bimetallic closed-shell Tl(I)-M(0) clusters versus corresponding Au(I)-M(0) ones (M = Pd, Pt). (3) The first homopalladium carbide cluster possessing an oversized tetra-coordinated carbide atom within a new type of completely encapsulated tetrahedral-deformed metal-connected Pd4 cavity of pseudo-D2 symmetry with three pairs of opposite twofold equivalent Pd-Pd tetrahedral-like edges being 2.71, 2.98, and 3.60 �. An astonishing molecular feature is that this {Pd4(�4-C)}Pd32 cluster is an isostructural and electronically equivalent analogue of the known nanosized Au4Pd32 cluster. Comparative analysis of the geometrically analogous and electronically equivalent interior Pd4(�4-C) and Au4 fragments in these two clusters is particularly relevant to the observed improved performances of commercial palladium catalysts by gold-atom incorporation to suppress carbonization.

Synthesis and crystallographic/spectroscopic/theoretical characterization of CO/PR<sub>3</sub>-ligated nanosized Pd(0)-Au(I) and Pd(0)-Tl(I) clusters: Their unexpected chemical reactivities with catalytic implications

244th National Meeting (2012)

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Synthesis and crystallographic/spectroscopic/theoretical characterization of CO/PR3-ligated nanosized Pd(0)-Au(I) and Pd(0)-Tl(I) clusters: Their unexpected chemical reactivities with catalytic implications

Synthesis and crystallographic/spectroscopic/theoretical characterization of CO/PR₃-ligated nanosized Pd(0)-Au(I) and Pd(0)-Tl(I) clusters: Their unexpected chemical reactivities with catalytic implications