There are examples of a new class of compounds that, on the basis of their chemical formulae, would appear to be Zintl phases,  e.g., KIn, which is metallic and paramagnetic. Molecular orbital calculations have shown that the anion is  (In) and that the extra electron is distributed over the cations and, possibly, the anion antibonding orbitals. Another exception is the metallic InBi. InBi fulfills the Zintl phase requisite of element-element bonds but not the requisite of the polyanionic structure fitting a normal valence compound, i.e., the Bi–Bi polyanionic structure does not correspond to a normal valence structure such as the diamond Tl in NaTl.