M^IV chemistry

Several binary Sn^IV compounds are known. SnO₂ comprise the rutile structure and SnX₂ along with X=S, Se, Te the CdI₂ layer structure. SnF₄ comprise a layer structure constructed from corner-sharing octahedra, but another tetrahalides form tetrahedral molecules. The halides are good Lewis acids, particularly SnF₄, that forms complexes like [SnF₆]^2-.

The Pb^IV state is very strongly oxidizing and only fluorides and oxides form stable binary compounds. PbO₂ and PbF₄ have similar structures like with tin, and mixed-valency oxides like Pb₃O₄ (consisting of Pb^IV and Pb^II) are known. Another Pb^IV compounds involve salts consisting the [PbCl₆]^2- ion as well as a number of molecular covalent compounds, such type of the tetraacetate Pb(CH₃CO₂)₄ and organometallic compounds.

Neither element depicts any simple aqueous chemistry in the M^IV state, like the oxides MO₂ are insoluble in water at all pH values. In molten KOH reaction of SnO₂ provides the octahedral hydroxoanion [Sn(OH)₆]^2-, in difference to the normal tetrahedral silicates and germanates, but in parallel along with isoelectronic compounds like Te(OH)₆ also found in period 5. Another 'stannates' are mixed oxides with no discrete oxoanions (example CaSnO₃ with the perovskite structure).