An international team involving the University of Valencia has succeeded in stabilising a negatively charged nickel atom, without ligands, inside a molecular carbon cage, thus challenging traditional laws of chemistry. This finding opens new avenues for designing and developing smaller, more efficient nanomaterials with unique properties for use in electronics, magnetic devices and catalyst industries.
The study, recently published in Nature Chemistry, describes the isolation and stabilisation of a nickel atom — carrying a very unusual -2 negative charge — within a small carbon cage. This represents an unprecedented advancement in transition metal chemistry.
Although metallic elements typically oxidise by donating electrons to non-metallic elements — resulting in a positive charge in their compounds — under rare conditions, when surrounded by appropriate ligands, they can exist in negatively charged states. The work, led by Peking University (China) and the University of Valencia (UV), has managed to get an electropositive metal like nickel to accept electrons and behave as an electronegative species, stabilised by encapsulation inside a fullerene nanostructure.
“This achievement challenges classical paradigms in chemistry and opens up new possibilities for the design of nanometre-scale materials with unique properties, which could be applied in the development of novel electronic and magnetic devices, or even catalysts for industrial processes”, explains Eugenio Coronado, professor of Inorganic Chemistry at the UV, head of the Spanish contribution to the study and researcher and director of the Institute of Molecular Science (ICMol) at the academic institution. “It is a fascinating discovery that challenges some of the most established principles of coordination chemistry and transition metal reactivity”, Coronado adds. “Traditionally, it was believed that certain behaviours of transition metals could not be achieved without the assistance of specific ligands. However, by stabilising these compounds without ligands, inside a molecular carbon cage, we are unlocking possibilities that seemed unthinkable before”, he affirms.
The participation in this project reinforces ICMol’s leadership in the study of advanced molecular nanomaterials, as well as its commitment to frontier science which, although complex, holds great potential for impact on future technologies.
Reference:
Lanthanide–nickel molecular intermetallic complexes featuring a ligand-free Ni2− anion in endohedral fullerenes. Panfeng Chuai, Ziqi Hu, Yang-Rong Yao, Zhanxin Jiang, Aman Ullah, Ya Zhao, Weiren Cheng, Muqing Chen, Eugenio Coronado, Shangfeng Yang & Zujin Shi. Nature Chemistry (2025).
