Iron-based trinuclear metal-organic nanostructures on a surface with local charge accumulation

TL;DR

This paper reports the synthesis and characterization of iron-based trinuclear metal-organic nanostructures on a surface, revealing a unique electron accumulation that could enable new catalytic and magnetic functionalities.

Contribution

It introduces a novel on-surface synthesis method for trinuclear iron-based nanostructures with a unique charge accumulation mechanism.

Findings

Successful synthesis of trinuclear iron clusters on a surface.

Identification of a coplanar tpy linkage with a mixed valence state.

Evidence of local charge accumulation at the interface.

Abstract

Coordination chemistry relies on harnessing active metal sites within organic matrices. Polynuclear complexes - consisting of organic ligands binding to clusters of several metal atoms are of particular interest, owing to their electronic/magnetic properties and potential for functional reactivity pathways. However, their synthesis remains challenging; only a limited number of geometries and configurations have been achieved. Here, we synthesise - via supramolecular chemistry on a noble metal surface - one-dimensional metal-organic nanostructures composed of terpyridine (tpy)-based molecules coordinated with well-defined polynuclear iron clusters. By a combination of low-temperature scanning probe microscopy techniques and density functional theory, we demonstrate that the coordination motif consists of coplanar tpy's linked via a linear tri-iron node in a mixed (positive) valence, metal-metal bond configuration. This unusual linkage is stabilized by a local accumulation of electrons at the interface between cations, ligand and surface. The latter, enabled by the bottom-up on-surface synthesis, hints at a chemically active metal centre, and opens the door to the engineering of nanomaterials with novel catalytic and magnetic functionalities.