Cyclic Boron Clusters Enclosing Planar Hypercoordinate Cobalt, Iron, and Nickel
journal contributionposted on 01.12.2008, 00:00 by Keigo Ito, Zhifeng Pu, Qian-Shu Li, Paul von Ragué Schleyer
Planar cyclic boron clusters with cobalt, iron, and nickel atoms at their centerssinglet D8h CoB8−, D9h FeB9−, CoB9, and NiB9+are computed to be stable minima at the BP86/TZVPP DFT level. Stochastic searches of the singlet and triplet potential energy surfaces show the planar hypercoordinate D8h CoB8− (1) and D9h FeB9− (2) singlet isomers to be the global minima. Their double aromatic character with 6 π and 10 radial electrons is documented by detailed NICSzz grid and CMO-NICSzz analyses at PW91/TZVPP. These results encourage gas phase investigations of these two exotic anions. Although isoelectronic with D9h FeB9− (2), CoB9 and NiB9+ prefer nonplanar structures, triplet 3-aT for the former and singlet 4-a for the latter.