Octahedral SeO66− and Square-Pyramidal SeO54−, Two New Oxoselenate Anions

Abstract

High-pressure techniques were applied to obtain the new oxoselenate Na4SeO5, whereas a further oxoselenate, Na6Se2O9, is also accessible under standard pressure. Both enrich the known oxoselenate(VI) ions SeO42− (tetrahedron) and SeO54− (trigonal bipyramid) by two additional anionic polyhedra, namely by a square-pyramidal pentaoxoselenate and by octahedral SeO66− ions (see picture).