Some lead compounds exist in formal oxidation states other than +4 or +2.
Lead(III) may be obtained, as an intermediate between lead(II) and lead(IV), in larger organolead complexes; this oxidation state is not stable, as both the lead(III) ion and the larger complexes containing it are radicals.
The same applies for lead(I), which can be found in such radical species.

Numerous mixed lead(II,IV) oxides are known.
When PbO₂ is heated in air, it becomes Pb₁₂O₁₉ at 293 °C, Pb₁₂O₁₇ at 351 °C, Pb₃O₄ at 374 °C, and finally PbO at 605 °C.
A further sesquioxide, Pb₂O₃, can be obtained at high pressure, along with several non-stoichiometric phases.
Many of them show defective fluorite structures in which some oxygen atoms are replaced by vacancies: PbO can be considered as having such a structure, with every alternate layer of oxygen atoms absent.

Negative oxidation states can occur as Zintl phases, as either free lead anions, as in Ba₂Pb, with lead formally being lead(−IV), or in oxygen-sensitive ring-shaped or polyhedral cluster ions such as the trigonal bipyramidal Pb₅²⁻ ion, where two lead atoms are lead(−I) and three are lead(0).
In such anions, each atom is at a polyhedral vertex and contributes two electrons to each covalent bond along an edge from their sp³ hybrid orbitals, the other two being an external lone pair.
They may be made in liquid ammonia via the reduction of lead by sodium.
Some lead compounds exist in formal oxidation states other than +4 or +2. Lead(III) may be obtained, as an intermediate between lead(II) and lead(IV), in larger organolead complexes; this oxidation state is not stable, as both the lead(III) ion and the larger complexes containing it are radicals. The same applies for lead(I), which can be found in such radical species.
Numerous mixed lead(II,IV) oxides are known. When PbO₂ is heated in air, it becomes Pb₁₂O₁₉ at 293 °C, Pb₁₂O₁₇ at 351 °C, Pb₃O₄ at 374 °C, and finally PbO at 605 °C. A further sesquioxide, Pb₂O₃, can be obtained at high pressure, along with several non-stoichiometric phases. Many of them show defective fluorite structures in which some oxygen atoms are replaced by vacancies: PbO can be considered as having such a structure, with every alternate layer of oxygen atoms absent.
Negative oxidation states can occur as Zintl phases, as either free lead anions, as in Ba₂Pb, with lead formally being lead(−IV), or in oxygen-sensitive ring-shaped or polyhedral cluster ions such as the trigonal bipyramidal Pb₅²⁻ ion, where two lead atoms are lead(−I) and three are lead(0). In such anions, each atom is at a polyhedral vertex and contributes two electrons to each covalent bond along an edge from their sp³ hybrid orbitals, the other two being an external lone pair. They may be made in liquid ammonia via the reduction of lead by sodium.
Lead