Bonding and stability of dinitrogen-bonded donor base-stabilized Si(0)/Ge(0) species [(cAAC Me -Si/Ge) 2 (N 2 )]: EDA-NOCV analysis.

Recently, dinitrogen (N 2 ) binding and its activation have been achieved by non-metal compounds like intermediate cAAC-borylene as (cAAC) 2 (B-Dur) 2 (N 2 ) [cAAC = cyclic alkyl(amino) carbene; Dur = aryl group, 2,3,5,6-tetramethylphenyl; B-Dur = borylene]. It has attracted a lot of scientific attention from different research areas because of its future prospects as a potent species towards the metal free reduction of N 2 into ammonia (NH 3 ) under mild conditions. Two (cAAC)(B-Dur) units, each of which possesses six valence electrons around the B-centre, are shown to accept σ-donations from the N 2 ligand (B ← N 2 ). Two B-Dur further provide π-backdonations (B → N 2 ) to a central N 2 ligand to strengthen the B-N 2 -B bond, providing maximum stability to the compound (cAAC) 2 (B-Dur) 2 (N 2 ) since the summation of each pair wise interaction accounted for the total stabilization energy of the molecule. (cAAC)(B-Dur) unit is isolobal to cAAC-E (E = Si, Ge) fragment. Herein, we report on the stability and bonding of cAAC-E bonded N 2 -complex (cAAC-E) 2 (N 2 ) (1-2; Si, Ge) by NBO, QTAIM and EDA-NOCV analyses (EDA-NOCV = energy decomposition analysis coupled with natural orbital for chemical valence; QTAIM = quantum theory of atoms in molecule). Our calculation suggested that syntheses of elusive (cAAC-E) 2 (N 2 ) (1-2; Si, Ge) species may be possible with cAAC ligands having bulky substitutions adjacent to the C cAAC atom by preventing the homo-dimerization of two (cAAC)(E) units which can lead to the formation of (cAAC-E) 2 . The formation of E[double bond, length as m-dash]E bond is thermodynamically more favourable (E = Si, Ge) over binding energy of N 2 inbetween two cAAC-E units.