title: Isolation and Structural Characterization of a Mackay 55-Metal-Atom Two-Shell Icosahedron of Pseudo-Ih Symmetry, Pd55L12(μ3-CO)20 (L = PR3, R = Isopropyl): Comparative Analysis with Interior Two-Shell Icosahedral Geometries in Capped Three-Shell Pd145, Pt-Centered Four-Shell Pd-Pt M165, and Four-Shell Au133 Nanoclusters.
abstract: We present the first successful isolation and crystallographic characterization of a Mackay 55-metal-atom two-shell icosahedron, Pd55L12(μ3-CO)20 (L = PPr(i)3) (1). Its two-shell icosahedron of pseudo-Ih symmetry (without isopropyl substituents) enables a structural/bonding comparison with interior 55-metal-atom two-shell icosahedral geometries observed within the multi-shell capped 145-metal-atom three-shell Pd145(CO)72(PEt3)30 and 165-metal-atom four-shell Pt-centered (μ12-Pt)Pd164-xPtx(CO)72(PPh3)20 (x ≈ 7) nanoclusters, and within the recently reported four-shell Au133(SC6H4-p-Bu(t))52 nanocluster. DFT calculations carried out on a Pd55(CO)20(PH3)12 model analogue, with triisopropyl phosphine substituents replaced by H atoms, revealed a positive +0.84 e charge for the entire Pd55 core, with a highly positive second-shell Pd42 surface of +1.93 e.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Jeremiah D
authors.initials: JD
authors.lastname: Erickson
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Evgueni G
authors.initials: EG
authors.lastname: Mednikov
authors.affiliation: Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Ivanov
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Lawrence F
authors.initials: LF
authors.lastname: Dahl