My main question was are the only examples in Mercury, and Gold? AI, and Hg are next to each other on the periodic table, just on the metal / non-metal boundar

My main question was are the only examples in Mercury, and Gold? AI, and Hg are next to each other on the periodic table, just on the metal / non-metal boundary, beneath them are the Rg, and Cn. Rg Roentgenium has a short half life, but seems to be tricky to make, it is expected to show some Relativistic properties though: https://en.m.wikipedia.org/wiki/Roentgenium https://en.m.wikipedia.org/wiki/Roentgenium Cn Copernicum, according to Wikipedia seems to show RQM effects it acting like a noble gas, albeit one with a half-life of at most 28s: https://en.m.wikipedia.org/wiki/Copernicium https://en.m.wikipedia.org/wiki/Copernicium If so why only these too? I’d expect there to be several others with mysterious properties too.