Other compounds

The sulfides of As and Sb are locate in nature. As₂S₃ and Sb₂S₃ with the stoichiometries supposed for As^III and Sb^III have polymeric structures. Compounds like As₄S₄ (6) and P₄Sn (n=3^-10) are molecules based on P₄ or As₄ tetrahedra with bridging -S- groups inserted; some of the phosphorus compounds also have terminal P=S groups identical to P=O in 5.

Phosphazines are compounds consisting of repeated -PX₂N- units. For instance, the reaction

gives chains and rings with a distribution of n values. The (PX₂N) unit has similar number of valence electrons like (Me₂SiO), which forms silicone polymers. In the valence structure like drawn in 7 P and N carry formal charges, but there is possibly some P=N double bonding.

Binary compounds with metals are usually of low ionic character. Several of those with transition metals comprise the NiAs and related structures and depict metallic properties. A  number of compounds appear to consists of polyanionic species (example P₂^4- isoelectronic with S₂ ^2- in Sr₂P₂, and P₇^3- in Na₃P₇), even though the bonding is surely not fully ionic.