Organometallic Complexes of Graphene

TL;DR

This paper reports the first successful formation of organometallic complexes with graphene and related carbon nanostructures, demonstrating their potential as ligands and opening new avenues in graphene chemistry and catalysis.

Contribution

It introduces novel organometallic complexes of graphene, showing how extended pi-electron systems can form stable hexahapto bonds with chromium, and provides methods for their mild decomplexation.

Findings

Graphene and carbon nanotubes can form stable organometallic complexes with chromium.

Exfoliated graphene shows versatile complexation behavior, forming multiple complex types.

Decomplexation restores pristine graphene, enabling potential catalytic applications.

Abstract

We demonstrate the organometallic hexahapto complexation of chromium with graphene, graphite and carbon nanotubes. All of these extended periodic pi-electron systems exhibit some degree of reactivity toward the reagents CrCO)6 and (eta6-benzene)Cr(CO)3, and we are able to demonstrate the formation of (eta6-rene)Cr(CO)3 or (eta6-arene)2Cr, where arene = single-walled carbon nanotubes (SWNT), exfoliated graphene (XG), epitaxial graphene (EG) and highly-oriented pyrolytic graphite (HOPG). We find that the SWNTs are the least reactive presumably as a result of the effect of curvature on the formation of the hexahapto bond; in the case of HOPG, (eta6-HOPG)Cr(CO)3 was isolated while the exfoliated graphene samples were found to give both (eta6-graphene)2Cr, and (eta6-graphene)Cr(CO)3 structures. We report simple and efficient routes for the mild decomplexation of the graphene-chromium complexes which appears to restore the original pristine graphene state. This study represents the first example of the use of graphene as a ligand and is expected to expand the scope of graphene chemistry in connection with the application of this material in organometallic catalysis.