Prediction of donor-acceptor-type novel noble gas complexes in the triplet electronic state

Closed-shell noble gas (Ng) compounds in the singlet electronic state have been extensively studied in the past two decades after the revolutionary discovery of 1 HArF molecule. Motivated by the experimental identification of very strong donor-acceptor-type singlet-state Ng complex 1 ArOH + , in the present article, for the first time, we report new donor-acceptor-type noble gas complexes in the triplet electronic state ( 3 NgBeN + (Ng = He-Rn)), where most of the Ng-Be bond lengths are smaller than the corresponding covalent limits. The newly proposed complexes are predicted to be stable by various computational tools, including coupled-cluster and multireference-based methods, with strong Ng-Be bonding (40.4-196.2 kJ mol −1 ). We have also investigated 3 NgBeP + (Ng = He-Rn) complexes for the purpose of comparison. Various computational results, including the structural parameters, bonding energies, vibrational frequencies, and atoms-in-molecule properties suggest that it may be possible to prepare and characterize these triplet state complexes through suitable experimental technique(s). Noble gas donor-acceptor type complexes in triplet electronic state! First ever report of very strong, noble gas-beryllium complexes ( 3 NgBeY + ; Ng = He-Rn; Y = N, P) in the triplet state with a large singlet-triplet energy gap and Ng-Be covalent bonding.