We report on the utilization of the ethylene-bridged bis[(dialkylamino)cyclopropenimine] (bisCPI) ligand, LCPI, to give access to new main-group E(II) halide complexes (E = Ge, Sn, Pb; 1, 2, 3). Subsequent reduction with Collman's reagent (Na2Fe(CO)4 • dioxane) enables the isolation of a series of zero-valent tetrylone-tetracarbonyl iron complexes, (LCPI)E(Fe(CO)4 (E = Ge (4), Sn (5), Pb (6)). Compounds 4 – 6 were reacted further with iron pentacarbonyl to yield the bis-tetracarbonyl iron complexes (LCPI)E[(Fe(CO)4]2 (E = Ge (7), Sn (8), Pb (9)). The electronic structure of these complexes was studied by 57Fe Mössbauer spectroscopy and computationally by density functional theory calculations.

https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202501324