Theoretical study on [3]- and [4]radialene complexes CpM(C2nH2n) (n = 3, 4; M = Sc∼Ni): Special metal-aromatic interaction along with metal-alkene bonds
[3]radialene might be Y-aromatic instead of traditionally cyclic aromatic. The LUMO of radialene reshapes to be cyclic aromatic when forming a dative bond. The metal-aromatic interaction may exist between metal and radialene in CpM(C2nH2n).