title: Peculiar antiaromatic inorganic molecules of tetrapnictogen in Na+Pn4- (Pn = P, As, Sb) and important consequences for hydrocarbons.
abstract: Although aromaticity has been observed in inorganic and all-metal species, the concept of antiaromaticity has not been extended beyond organic molecules. Here, we present theoretical and experimental evidence that the 6 -electron tetrapnictogen dianions in Na+Pn42- (Pn = P, As, Sb) undergo a transition from being aromatic to antiaromatic upon electron detachment, yielding the first inorganic antiaromatic Na+Pn4- molecules. Two types of antiaromatic structures were characterized, the conventional rectangular species and a new peculiar quasiplanar rhombus species. Aromaticity and antiaromaticity in the tetrapnictogen molecules were derived from molecular orbital analyses and verified by experimental photodetachment spectra of Na+Pn42-. On the basis of our findings for the tetrapnictogen clusters, we predicted computationally that the organic C4H4- anion also possesses two antiaromatic structures: rectangular and rhombus. Moreover, only the rhombus antiaromatic minimum was found for the radical NC3H4, thus extending the peculiar rhombus antiaromatic structure first uncovered in inorganic clusters into organic chemistry.
authors.affiliation: Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA.
authors.forename: Aleksey E
authors.initials: AE
authors.lastname: Kuznetsov
authors.forename: Hua-Jin
authors.initials: HJ
authors.lastname: Zhai
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Boldyrev