Craig-Type Mobius Aromaticity and Antiaromaticity in Dimetalla[10]annulenes: A Metal-Induced Yin-and-Yang Pair

Aromaticity, one of the most fundamental concepts in chemistry, can be classified as Hiickel- and Mobius-type according to the electron count and topology. In comparison with numerous Hiickel aromatics containing 4n+2 Tc-electrons, Mobius aromatics with 4n pi-electrons, especially the Craig-type species are particularly limited. Herein we demonstrate that the recently synthesized dimetalla[10]annulenes could be Mobius aromatic or antiaromatic although the organic prototype [10]annulene is nonaromatic due to the nonplanarity caused by the steric repulsion of two CH groups, suggesting the first example of yin-and-yang pair with Craig-type Mobius (anti)aromaticity. Further study suggests that the lithium atoms in dimetalla[10]annulenes are not spectator cations but play an important role in the aromaticity switch of these species due to their bonding interaction with the diene moieties. Our findings highlight the magic power of metals in the achievement of Craig-type Mobius aromatics, thus opening an aromatics. avenue to such novel