NH₄IO₂F₂ and (NH₄)₃(IO₂F₂)₃·H₂O: A Series of Ammonium-Containing Fluoroiodates with Wide Band Gaps

Abstract

A series of ammonium-containing fluoroiodates, NH4IO2F2 and (NH4)3(IO2F2)3·H2O, with isolated [IO2F2] units have been fabricated by a fluorine-oxygen substitution strategy from NH4IO3. The two compounds crystallize in the orthorhombic system, but in different space groups, noncentrosymmetric Pca21 for NH4IO2F2 and centrosymmetric Pnma for (NH4)3(IO2F2)3·H2O, and show wide band gaps of 4.53 eV for (NH4IO2F2) and 4.55 eV for ((NH4)3(IO2F2)3·H2O). In addition, NH4IO2F2 exhibits a 1.2 × KDP second harmonic generation response, a short ultraviolet cutoff edge in iodates, and a good crystal growth habit. The crystal of NH4IO2F2 with a size of 11 × 5 × 2 mm3 was obtained by the aqueous solution method. The results enrich the structural diversity of iodate and supply a greater understanding of the design of new functional materials based on the fluoroiodates.

Definition of the Halogen Bond (IUPAC Recommendations 2013): A Revisit

“…To confirm the view developed above, we performed DFT calculations for the ammonium dioxo­(difluoro)­iodane, [F 2 IO 2 ] − ]­[NH 4 ] + , ion-pair, the crystal structure of which has been reported (CSD ref JELFOZ) . Our calculations suggest that the electrophilic σ-hole develops ( V S,max = 28.1 kcal mol –1 with ωB97X-D/aug-cc-pVTZ (for all atoms) and aug-cc-pVTZ-PP (for I)) along the outer extensions of the two O–I covalent bonds in [F 2 IO 2 ] − , and the nucleophilic region ( V S,min = −35.3 kcal mol –1 ) is mainly concentrated around the O atom upon the formation of the [F 2 IO 2 ] − ]­[NH 4 ] + ion-pair.…”

“…323 Nonlinear intramolecular halogen bonds are found in the crystals shown in Figure 15d− To confirm the view developed above, we performed DFT calculations for the ammonium dioxo(difluoro)iodane, [F 2 IO 2 ] − ][NH 4 ] + , ion-pair, the crystal structure of which has been reported (CSD ref JELFOZ). 327 Our calculations suggest that the electrophilic σ-hole develops (V S,max = 28.1 kcal mol −1 with ωB97X-D/aug-cc-pVTZ (for all atoms) and aug-cc-pVTZ-PP (for I)) along the outer extensions of the two O−I covalent bonds in [F 2 IO 2 ] − , and the nucleophilic region (V S,min = −35.3 kcal mol −1 ) is mainly concentrated around the O atom upon the formation of the [F 2 IO 2 ] − ][NH 4 ] + ion-pair. These sites of opposite polarity on the O and I atoms on neighboring ion pairs attract each other, thus forming halogen bonds that are responsible for the stability of the inorganic layer in the crystal.…”

Halogen Bonding Assembles Anion⋅⋅⋅Anion Architectures in Non‐centrosymmetric Iodate and Bromate Crystals

“…Halogen bonded anions are typically involved in a tight network of HBs. Iodine frequently acts as tridentate HaB donor and affords supramolecular polyanionic adducts with different topologies, for instance ribbons, [27] and two‐ [28] or three‐dimensional [29] architectures.…”

(C(NH2)3)2(I2O5F)(IO3)(H2O) and C(NH2)3IO2F2: Two Guanidine Fluorooxoiodates with Wide Band Gap and Large Birefringence

“…Meanwhile, more abundant and diverse structures can be obtained. Iodate fluorides (with only the M–F chemical bonds, M = Metal) and fluorooxoiodates (containing the I–F chemical bonds) often have excellent optical properties, such as Bi­(IO 3 )­F 2 , Ce­(IO 3 ) 2 F 2 ·H 2 O, (NH 4 )­Bi 2 (IO 3 ) 3 F 5 , Bi 3 OF 3 (IO 3 ) 4 , Sn­(IO 3 ) 2 F 2 , AIO 2 F 2 (A = Na, Rb, Cs, K, NH 4 ), − M 2 MoO 2 F 3 (IO 2 F 2 ) (M = Rb, Cs), SrI 2 O 5 F 2 , BaI 2 O 5 F 2 , and so on. More importantly, the introduction of the π-conjugated and non-π-conjugated cooperative modules can also effectively regulate the macro-optical properties of linear or nonlinear optical crystals .…”