A novel triplet germylene F3CGe¨GeGeH at theoretical levels

F3CGe¨GeGeH, with two unpaired electrons, is the only triplet (t) ground state germylene found among 30 divalent species, with XHGe3 formula, at six reasonably high ab initio and DFT levels (X = H, NH2, SiH3, and CF3). Its corresponding singlet (s) appears at a higher energy while showing a negative force constant. The crossing angle (Ф) between the above s and t states is 90°. Replacement of CF3 with H and NH2 increases Ф to 120° and 160°, respectively. No crossing of the s and t states occurs for H3SiGeGeGeH, whose s state is its global minimum. Having X directly attached to the divalent germylene in XGeGeGeH, increases the X effects on ΔEs-t,X compared to the isomeric species: 3-X-1,2,3-trigermapropargylene, 3-X-1,2,3-trigermavinylidene and 2-X-1,2,3-trigermacyclopropenylidene, respectively. Nonetheless, the latter cyclic divalent species appear relatively more stable with the highest LUMO-HOMO energy gaps, while their NICS calculations show their aromatic character change as a function of X (SiH3 > H > CF3 > NH2). Finally, the global minimum among the 30 isomeric XHGe3 is found to be SiH3 substituted singlet trigermacyclopropenylidene.