Metal-substituted Ti8C12 metallocarbohedrynes: toward less reactive clusters as building blocks of cluster-assembled materials

• Published in: Physical chemistry chemical physics : PCCP Vol. 14; no. 27; pp. 9642 - 9653
• Main Authors: Berkdemir, Cüneyt, Castleman, A. W, Sofo, Jorge O
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 21.07.2012
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Molecular orbital; Stoichiometry; Theoretical study; Density functional method; Spin density; Dimer; Chemical reactivity; Isomer
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c2cp40509a

To form cluster-assembled materials, the clusters should have low reactivity and be characterized by a closed-shell electronic configuration with a large gap between the highest occupied and the lowest unoccupied molecular orbitals (HOMO-LUMO). Using spin-polarized density functional theory calculations, we investigate the M-substituted Ti 8 C 12 metallocarbohedrynes to search for less reactive clusters as building blocks for cluster-assembled materials (M = Be, Mg, Ca, Sr, Ba and Sc, Y). The selected atoms in the correct stoichiometry would produce a metallocarbohedryne that is isoelectronic with the Ti 8 C 12 2+ , which has a closed-shell electronic configuration and an enhanced HOMO-LUMO gap of 1.735 eV. According to our results, the HOMO-LUMO gaps of the M-substituted Ti 8 C 12 metallocarbohedrynes are in the range of 0.715-0.979 eV for the case of Be, Mg, Ca, Sr and Ba and in the range of 0.865-1.294 eV for the case of Sc and Y. Among all the M-substituted metallocarbohedrynes we consider here, one of the isomers of Ti 6 Sc 2 C 12 is not only energetically more favorable but also exhibits a larger HOMO-LUMO gap of 1.294 eV. This result indicates that the Ti 6 Sc 2 C 12 (4) metallocarbohedryne should be less reactive than the Ti 8 C 12 metallocarbohedryne which has a narrow HOMO-LUMO gap of 0.146 eV. Moreover, we show that the intercluster interaction between two individual Ti 6 Sc 2 C 12 (4) metallocarbohedrynes is relatively weak compared to the Ti 8 C 12 dimer. The substantial attraction between individual clusters is purely of ionic origin and will help maintain the solid formed.