Year: 2026
Type: preprint
Abstract: Sterically demanding ligands are widely used to control coordination geometry and stabilize otherwise inaccessible metal complexes, yet how steric repulsion influences metal–ligand coordination and periodic molecular assembly under surface confinement remains underexplored. Here, we show that a tert -butyl-substituted bis(N-heterocyclic carbene) (bisNHC) assembles into a one-dimensional metal-organic lattice. Steric constraints give rise to an asymmetric NHC–adatom–NHC arrangement, generating dipolar bisNHC–adatom units whose dipole-dipole interactions contribute to their organization into periodic chains. The lattice decomposes upon mild annealing, showing that direct deposition of the free bisNHC is essential for preserving this coordination motif. Despite chemisorption through metal adatoms, the lattice exhibits reduced electronic coupling to the substrate. It also defines sterically protected cavities for individual metal atoms. Lanthanide atoms accommodated within these cavities show higher-energy spin-flip excitations and enhanced positive-bias stability compared with graphene-supported atoms. These findings demonstrate that steric congestion under surface confinement can prevent conventional covalent chain formation without precluding periodic metal–organic assembly. This approach offers a strategy for constructing ordered molecular architectures with tailored coordination sites for individual metal atoms.
Source: ChemRxiv
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7222532364