Novel triplet germylenes in focus: normal vs. abnormal triplet exocyclic tetrazol-5-vinylidene germylenes at DFT

A theoretical investigation into novel germylenes: effects of nitrogen substitution on stability and multiplicity

The effects of substituting nitrogen atoms on the stability of novel singlet (s) and triplet (t) forms of germylenes (1-20) are compared and contrasted, at B3LYP/AUG-cc-pVTZ level of theory. Every one of the 40 new divalents scrutinized appears as a minimum on its energy surface, for showing no negative force constant. Also, every singlet (1_s-20_s) appears more stable than its corresponding triplet (1_t-20_t). The highest stability (ΔE_s-t) is achieved by germylene (11) where all the three nitrogens are bonded to the central boron atom. The E_HOMO slightly decreases when the number of electronegative, σ-acceptor nitrogen atoms increases, and also causes it to be less electron-rich. Germylene 16_s with low stability (ΔE_s-t = 17.19 kcal/mol), bond gap (ΔE_HOMO-LUMO = 57.46 kcal/mol^-1), and atomic charge on -G̈e- (+ 0.9012), has high electrophilicity (ω = 3.78 eV) and nucleophilicity (N = 3.87 eV). Germylenes 8_s, 14_s, and 19_s with coordinate covalent bond between nitrogen (N(Y)) and germylene center have low ω and high ΔE_HOMO-LUMO. The purpose of the present work was, therefore, to assess the influence of nitrogen substituents on the stability (ΔΕ_s-t), band gaps (ΔΕ_HOMO-LUMO), N, ω, and heat of hydrogenation (ΔE_H). This investigation is aimed to introduce novel germylenes that can be applied as cumulated multi-dentate NHG̈e ligands.