However, in moving from left to right across the periodic table, transition-metal d orbitals fill up with electrons, reducing the ability of the metal to accept electrons donated by an oxo ligand.

All agreed that vibranium would likely be located in the middle section of the periodic table, where the majority of metals are located.

Bismuth, element 83 on the periodic table of elements, is a post-transition metal, according to Los Alamos National Laboratory.

But the existence of these complexes was born in controversy. Terminal metal-oxo complexes are common for early- and middle-transition metals—those in periodic table groups 3 to 8.