Theoretical Study of Pd₁₁Si₆ Nanosheet Compounds Including Seven‐Coordinated Si Species and Its Ge Analogues

Abstract

Nanosheet compounds Pd11 (SiiPr)2 (SiiPr2 )4 (CNtBu)10 (1) and Pd11 (SiiPr)2 (SiiPr2 )4 (CNMes)10 (2), containing two Pd7 (SiiPr)(SiiPr2 )2 (CNR)4 plates (R=tBu or Mes) connected with three common Pd atoms, were investigated with DFT method. All Pd atoms are somewhat positively charged and the electron density is accumulated between the Pd and Si atoms, indicating that a charge transfer (CT) occurs from the Pd to the Si atoms of the SiMe2 and SiMe groups. Negative regions of the Laplacian of the electron density were found between the Pd and Si atoms. A model of a seven-coordinated Si species, that is, Pd5 (Pd-SiMe), is predicted to be a stable pentagonal bipyramidal molecule. Five Pd atoms in the equatorial plane form bonding overlaps with two 3p orbitals of the Si atom. This is a new type of hypervalency. The Ge analogues have geometry and an electronic structure similar to those of the Si compounds. But their formation energies are smaller than those of the Si analogues. The use of the element Si is crucial to synthesize these nanoplate compounds.

Construction of a Planar Tetrapalladium Cluster by the Reaction of Palladium(0) Bis(isocyanide) with Cyclic Tetrasilane

“…This indicates that the structure of the cluster can be tuned by changing the auxiliary ligand on the metal. Theoretical calculations were also used to elucidate the electronic structure and bonding nature of these clusters [34]. Along the same line, in this study we intend to use octaisopropylcyclotetrasilane (3) (Chart 1) having four Si-Si bonds as a template for the clustering of palladium species.…”

A Ketimide-Stabilized Palladium Nanocluster with a Hexagonal Aromatic Pd7 Core

“…More recently, several low-valent Pd nanoclusters that do not contain CO or phosphine co-ligands have also been reported, such as [Pd 3 (μ 3 -C 7 H 7 ) 2 ] 2+ , [Pd 13 (μ 4 -C 7 H 7 ) 6 ] 2+ , , and [Pd 6 (μ-GePh 2 ) 2 (CN-2,6-Me 2 C 6 H 3 ) 8 (μ-CN-2,6-Me 2 C 6 H 3 ) 2 ] . Other noteworthy Pd nanoclusters include the Pd 11 nanosheet, [Pd 11 (Si i Pr) 2 (Si i Pr 2 ) 4 (CN t Bu) 10 ], , the Pd 5 nanosheet, [Pd 5 (C 18 H 12 ) 2 ] 2– , and the Pd 6 “bow-tie” cluster, [Pd 6 Cl 2 (SiPh 2 ) 2 (CN t Bu) 8 ] . While these complexes do not contain CO or PR 3 , in many cases they still contain π-accepting ligands, such as isocyanides, tropylium cation (C 7 H 7 + ), and silylenes. , That said, Pd nanoclusters are still relatively rare, and only handful of ligands are known to stabilize this class of materials.…”