The crystal structure of KIBr2.H2O

Abstract

Crystals of potassium dibromoiodide monohydrate, KIBr2. H20, are orthorhombic, space group Pnnm, with a= 12.183 (5), b= 13"046 (5), c=4"390 (3)/~, Z=4. All atoms lie on mirror planes. The structure was refined from diffractometer data by least-squares methods to R= 5.8 %. The structure consists of nearly linear chains of halogen atoms extending infinitely along b. The two independent IBr~-anions are linear and symmetrical, both with I-Br bond lengths of 2.71 A. The closest O...Br distance is 3.60/~, indicative of weak hydrogen bonding.

Polyhalogen and Polyinterhalogen Anions from Fluorine to Iodine

“…In the case of three‐atom polyinterhalogen anions, for example, [Cl‐I‐Cl] − or [Br‐I‐Br] − , it is questionable whether the polyinterhalides are classical or non‐classical. As symmetrical anions, they show three‐center four‐electron bond character, and clearly should be classified as classical polyinterhalogen anions, similar to KIBr 2 . Note that if the radius of the cation increases, like for cesium, the anion could become more asymmetric with respect to the bond lengths (278 and 262 pm) .…”

“…As symmetrical anions, they show three-center four-electron bond character,a nd clearly should be classified as classical polyinterhalogen anions,s imilar to KIBr 2 . [149] Note that if the radius of the cation increases,l ike for cesium, the anion could become more asymmetric with respect to the bond lengths (278 and 262 pm). [150] Theq uestion that arises is:I sa ne lectropositive central iodine surrounded by more electronegative bromine atoms or is ab romide coordinated by an IBr molecule?A final decision is hard to make because there are several effects present in the crystal structures.L iterature-known structures of [XYX] À and [XYZ] À will be discussed below.T able 12 summarizes all experimentally known trihalogen anions.…”

K6(IO6H4)(HI2O6)(HIO3)2(IO3)4·2H2O: A Case of Iodate with Coexisting [I5+O3] and [I7+O6] Units

“…The related proportions are found to be 0.35, 1.24, 0.18, 79.29, 17.17, and 1.77% for these six branches, respectively. The I + valence state is only found in two structures . I 3+ valence state is found in seven compounds. − The I 4+ valence state is merely found in one case .…”

Polyhalogen‐ und Polyinterhalogen‐Anionen von Fluor bis Iod

“…Für dreiatomige Polyinterhalogen‐Anionen wie [Cl‐I‐Cl] − oder [Br‐I‐Br] − ist es fraglich, ob ein klassisches oder nichtklassisches Polyinterhalogen‐Anion vorliegt. In den symmetrischen Anionen liegt eine 3‐Zentren‐4‐Elektronen‐Bindung vor, weshalb sie ähnlich wie KIBr 2 als klassische Polyinterhalogen‐Anionen bezeichnet werden sollten. Steigt jedoch der Radius des Kations, wie für Caesium, kann die Asymmetrie des Anions zunehmen (Bindungslängen von 278 und 262 pm) .…”