Side‐On Bonded Beryllium Dinitrogen Complexes

The preparation and spectroscopic identification of the complexes NNBe(η 2 ‐N 2 ) and (NN) 2 Be(η 2 ‐N 2 ) and the energetically higher lying isomers Be(NN) 2 and Be(NN) 3 are reported. NNBe(η 2 ‐N 2 ) and (NN) 2 Be(η 2 ‐N 2 ) are the first examples of covalently side‐on bonded N 2 adducts of a main‐group element. The analysis of the electronic structure using modern methods of quantum chemistry suggests that NNBe(η 2 ‐N 2 ) and (NN) 2 Be(η 2 ‐N 2 ) should be classified as π complexes rather than metalladiazirines.