The borosulfates are heteropoly anion compounds which have sulfate groups attached to boron atoms. Other possible terms are sulfatoborates or boron-sulfur oxides. The ratio of

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

borate A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name also re ...

reflects the degree of condensation. With (SO₄)₄sup>5- there is no condensation, each ion stands alone. In (SO₄)₃sup>3- the anions are linked into a chain, a chain of loops, or as ₂(SO₄)₆sup>6− in a cycle. Finally in (SO₄)₂sup>− the sulfate and borate tetrahedra are all linked into a two or three-dimensional network. These arrangements of oxygen around boron and sulfur can have forms resembling

silicates In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name i ...

. The first borosulfate to be discovered was K₅ (SO₄)₄in 2012. Over 75 unique compounds are known. They are distinct from the

borate sulfate Borate sulfates are mixed anion compounds containing separate borate and sulfate anions. They are distinct from the borosulfates where the borate is linked to a sulfate via a common oxygen atom. List References

{{Sulfates Borate sulfates ...

s which have separate, uncondensed sulfate and borate ions. Related compounds include

boroselenates The boroselenates are chemical compounds containing interlinked borate and selenate groups sharing oxygen atoms. Both selenate and borate groups are tetrahedral in shape. They have similar structures to borosulfates and borophosphates The borophosp ...

, borotellurates, and also boroantimonates, borogallates, borogermanates,

borophosphates The borophosphates are mixed anion compounds containing borate and phosphate anions, which may be joined together by a common oxygen atom. Compounds that contain water or hydroxy groups can also be included in the class of compounds. Borophosphates ...

, boroselenites and borosilicates.

Formation

Borosulfates are formed by heating

boric oxide Boron trioxide or diboron trioxide is the oxide of boron with the formula . It is a colorless transparent solid, almost always glassy (amorphous), which can be crystallized only with great difficulty. It is also called boric oxide or boria. It h ...

, oleum, or sulfuric acid, with metal carbonates. The degree of condensation is varied with the ratio of oleum to sulfuric acid. Pure oleum is more likely to yield compounds with disulfate groups.

Reactions

When heated to around 500 °C the borosulfates decompose by emitting SO₃ vapour and form a metal sulfate and boric oxide.

List

References

{{Borates Borates Sulfates