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Origin of Extraordinary Stability of Square‐Planar Carbon Atoms in Surface Carbides of Cobalt and Nickel
Author(s) -
Nandula Anjan,
Trinh Quang Thang,
Saeys Mark,
Alexandrova Anastassia N.
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201501049
Subject(s) - tetracoordinate , carbide , materials science , cobalt , nickel , surface reconstruction , chemical physics , crystallography , planar , aromaticity , chemical stability , electron counting , metal , chemistry , computational chemistry , surface (topology) , electron , geometry , molecule , metallurgy , physics , organic chemistry , computer graphics (images) , mathematics , quantum mechanics , computer science
Abstract Surface carbides of cobalt and nickel are exceptionally stable, having stabilities competitive with those of graphitic C on these surfaces. The unusual structure of these carbides has attracted much attention: C assumes a tetracoordinate square‐planar arrangement, in‐plane with the metal surface, and its binding favors a spontaneous p4g clock surface reconstruction. A chemical bonding model for these systems is presented and explains the unusual structure, special stability, and the reconstruction. C promotes local two‐dimensional aromaticity on the surface and the aromatic arrangement is so powerful that the required number of electrons is taken from the void M 4 squares, thus leading to Peierls instability. Moreover, this model predicts a series of new transition‐metal and main‐group‐element surface alloys: carbides, borides, and nitrides, which feature high stability, square‐planar coordination, aromaticity, and a predictable degree of surface reconstruction.