N-Heterocyclic germylenes supported by bulky dianionic N, N-chelating ligands

In this contribution, three novel diamine pro-ligands, incorporating sterically bulky aryl and aliphatic N-substituents, have been developed; viz. (NCNTCHP)H-2 (NCNTCHP = {(TCHP)NCH2} 2CH2 , TCHP = 2,4,6-tricyclohexylphenyl), (NONTCHP)H-2 (NONTCHP = {(TCHP)NSiMe2}(2)O), and (NONAd )H-2(NONAd = {(Ad)NSiMe2}(2)O; Ad = 1adamantyl). Through salt metathesis or transamination synthetic approaches, the N-heterocyclic germylenes, [: Ge(NCNTCHP)], [:Ge(NONTCHP)], and [:Ge(NONAd )], have been prepared and crystallographically characterized. The electronic structure of each germylene was studied by DFT calculations. The steric profile of the germaniumbound ligands was also assessed using computational models, and the results compared to those for structurally similar compounds. Significant steric crowding of the germanium centre ( >70 % ligand coverage) was observed for [:Ge(NCNTCHP )] and [:Ge(NONTCHP )], while [:Ge(NONAd )] exhibited substantially less steric saturation at the metal centre (similar to 62 % ligand coverage). Through these studies, we have shown the potential suitably of the developed ligands to stabilise other low-valent main-group species.