The synthesis of nanographenes (NGs) with open-shell ground states have recently attained increasing attention in view of their interesting physicochemical properties and great prospects in manifold applications as suitable materials within the rising field of carbon-based magnetism. A potential route to induce magnetism in NGs is the introduction of structural defects, for instance non-benzenoid rings, in their honeycomb lattice. Here, we report the on-surface synthesis of three open-shell non-benzenoid NGs (A1, A2 and A3) on the Au(111) surface. A1 and A2 contain two five- and one seven-membered rings within their benzenoid backbone, while A3 incorporates one five-membered ring. Their structures and electronic properties have been investigated by means of scanning tunneling microscopy, noncontact atomic force microscopy and scanning tunneling spectroscopy complemented with theoretical calculations. Our results provide access to open-shell NGs with a combination of non-benzenoid topologies previously precluded by conventional synthetic procedures.

Center for Advancing Electronics Faculty of Chemistry and Food Chemistry Technical University of Dresden 01062 Dresden Germany

Departamento de Física de la Materia Condensada Universidad Autónoma de Madrid 28049 Madrid Spain

IMDEA Nanoscience C Faraday 9 Campus de Cantoblanco 28049 Madrid Spain

Institute of Physics of the Czech Academy of Science CZ 16253 Praha Czech Republic

Instituto de Ciencia de Materiales de Madrid CSIC Cantoblanco 28049 Madrid Spain

Regional Centre of Advanced Technologies and Materials Palacký University Olomouc CZ 77146 Olomouc Czech Republic

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