text: Inorganic atoms form cyclic compounds as well. Examples include sulfur and nitrogen (e.g. heptasulfur imide , trithiazyl trichloride , tetrasulfur tetranitride ), silicon (e.g., cyclopentasilane ), phosphorus and nitrogen (e.g., hexachlorophosphazene ), phosphorus and oxygen (e.g., metaphosphates  and other cyclic phosphoric acid derivatives), boron and oxygen (e.g., sodium metaborate , borax), boron and nitrogen (e.g. borazine ). When carbon in benzene is "replaced" by other elements, e.g., as in borabenzene, silabenzene, germanabenzene, stannabenzene, and phosphorine, aromaticity is retained, and so aromatic inorganic cyclic compounds are also known and well-characterized.