Theoretical descriptions of novel triplet germylenes M₁-Ge-M₂-M₃ (M₁ = H, Li, Na, K; M₂ = Be, Mg, Ca; M₃ = H, F, Cl,...

In a quest to identify new ground-state triplet germylenes, the stabilities (singlet-triplet energy differences, ΔE_S-T) of 96 singlet (s) and triplet (t) M₁-Ge-M₂-M₃ species were compared and contrasted at the B3LYP/6-311++G**, QCISD(T)/6-311++G**, and CCSD(T)/6-311++G** levels of theory (M₁ = H, Li, Na, K; M₂ = Be, Mg, Ca; M₃ = H, F, Cl, Br). Interestingly, F-substituent triplet germylenes (M₃ = F) appear to be more stable and linear than the corresponding Cl- or Br-substituent triplet germylenes (M₃ = Cl or Br). Triplets with M₁ = K (i.e., the K-Ge-M₂-M₃ series) seem to be more stable than the corresponding triplets with M₁ = H, Li, or Na. This can be attributed to the higher electropositivity of potassium. Triplet species with M₃ = Cl behave similarly to those with M₃ = Br. Conversely, triplets with M₃ = H show similar stabilities and linearities to those with M₃ = F. Singlet species of formulae K-Ge-Ca-Cl and K-Ge-Ca-Br form unexpected cyclic structures. Finally, the triplet germylenes M₁-Ge-M₂-M₃ become more stable as the electropositivities of the α-substituents (M₁ and M₂) and the electronegativity of the β-substituent (M₃) increase.