A ladder polysilane as a template for folding palladium nanosheets.

Although discrete nano-sized compounds consisting of a monolayer sheet of multiple atoms have attracted much attention, monolayer transition metal nanosheets are difficult to access. Here we report a template synthesis of the folding metal nanosheet (2) consisting of 11 palladium atoms by treatment of a ladder polysilane, decaisopropylbicyclo[2.2.0]hexasilane (1), with Pd(CN(t)Bu)2. Crystallographic analysis reveals that the compound is composed of two monolayer Pd7 sheets sharing three palladium atoms at the junction. Each Pd atom is stabilized by Pd-Si σ-bonds, Pd-Pd bonds and coordination of isocyanides. Ligand exchange of 2 from CN(t)Bu to CN(2,4,6-Me3-C6H2) is accompanied by structural rearrangement, leading to the formation of another folding Pd11 nanosheet (3) consisting of two edge-sharing Pd7 sheets. The shapes of the Pd7 sheets as well as the dihedral angle between the two Pd7 sheets are dependent on the substituent of the isocyanide ligand.