title: The catena-arsenite chain anion, [AsO2](n)(n-): (H3NCH2CH2NH3)0.5[AsO2] and NaAsO2 (revisited).
abstract: The title compounds contain the catena-arsenite [AsO(2)](n)(n-) unit, in which the As(III) atom is pyramidally coordinated to one terminal and two bridging O atoms, resulting in an infinite anionic chain. Ethylenediammonium catena-arsenite, (C(2)H(10)N(2))(0.5)[AsO(2)], is the first example of this anion in the company of an organic cation. The ethylenediammonium species interact with the [AsO(2)](-) chains by way of N-H.O hydrogen bonds. The structure of sodium catena-arsenite, Na[AsO(2)] [Menary (1958). Acta Cryst. 11, 742-743], has been redetermined to yield more reliable geometrical parameters. The As-O distances are normal and the Na(+) cation is seven-coordinate [Na-O = 2.285 (4)-3.063 (4) A] in a distorted capped trigonal prismatic geometry.
authors.affiliation: Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland.
authors.forename: Clare
authors.initials: C
authors.lastname: Lee
authors.forename: William T A
authors.initials: WT
authors.lastname: Harrison