Abstract: A systematic investigation of the Ge(CH₃)₂, CH₃GeSiH₃, CH₃GeGeH₃, XGeCY₃ (X; Y = H, F, Cl, Br) species was carried out using the DFT functionals BLYP, B3LYP and BHHLYP. Predicted are the singlet-triplet energy gaps and four types of neutral-anion separations: adiabatic electron affinity (EA_ad), zero-point vibrational energy corrected EA_ad(ZPVE), vertical electron affinity (EA_vert), and vertical detachment energy (VDE). The basis sets used for all atoms are of double-ζ plus polarization quality with additional s- and p-type diffuse functions denoted DZP++. The geometries are fully optimized with each functional independently. Vibrational frequency analyses are performed to compute zero-point energy corrections and to determine the nature of the stationary points. The EA_ad(ZPVE) values (eV) obtained with the BHLYP functional is Ge(CH₃)₂ = 0.46 eV, CH₃GeSiH₃ = 1.22 eV and CH₃GeGeH₃ = 1.26 eV, and FGeCCl₃ = 1.66 eV. The singlet-triplet splittings range from 1.28 eV (HGeCF₃) to 2.22 eV (FGeCCl₃). The XGeCY₃ (Y = Br) species are most often characterized by three-membered cyclic systems involving the divalent germanium atom, the carbon atom and a halogen atom. The predicted results are helpful for the synthesis, characterizations, and applications of these germylene derivatives.