The interaction among E3 (E=Si, Ge, Sn) clusters and different ligands (L) encompassing five carbon-based donors (cyclic (alkyl)(amino)carbene (cAAC), N-heterocyclic carbene (NHC), saturated NHC (SNHC), mesoionic carbenes (MIC1, and MIC2)), two nitrogen-based donors (trimethylamine and pyridine), and two phosphorous-based donors (phosphinine and trimethylphosphine) in E3 (L)3 complexes is explored through DFT computations. Although all carbenes form very strong bonds with E3 clusters, cAAC makes the strongest bond with Si3 and Ge3 clusters, and MIC1 with the Sn3 cluster. Nevertheless, other ligand-bound complexes are also viable at room temperature. This finding indicates that experimentalists may make use of them to synthesize the desired clusters based on precursor availability. The nature of the interaction in E-L bonds is analyzed through natural bond orbital analysis; energy decomposition analysis, in combination with the natural orbital for chemical valence; and adaptive natural density partitioning analysis. The L→E σ-donation and L←E π-back-donation play important roles in making contacts between L and E3 clusters favorable; where the former is significantly more dominant over the latter.
Keywords: ab initio calculations; carbene ligands; cluster compounds; donor-acceptor systems; group 14 elements.
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