A fluorooxoiodate or fluoroiodate is a chemical compound or ion derived from iodate, by substituting some of the oxygen by fluorine. They have iodine in the +5 oxidation state. The iodine atoms have a stereochemically active lone-pair of electrons. Many are non-centrosymmetric, and are second harmonic generators (SHG) of intense light shining through them. They are under investigation as materials for non-linear optics, such as for generating ultraviolet light from visible or infrared lasers.
Different ions include [IOF4]−, [IO2F2]−, [IO3F]2−, and [I2O5F2]2−.
They are distinct from the iodate fluorides which are mixed anion compounds that do not have fluorine-iodine bonds.
Properties Fluoroiodates are transparent in visible, longer wave ultraviolet and some of the infrared electromagnetic bands.
Compared to iodate, the I-O bonds are shorter, and I-F bonds are longer in fluoroiodates. The I-F bond is about 0.2 Å longer than the I-O bond. The fluorine atoms repel each other in [IO2F2]− and are almost opposite each other. The ∠OIF angle is close to 90° and the oxygen atoms ∠OFO are at about 102°, so they resemble an octahedral arrangement, with two adjacent positions deleted.
List
formulacrystalspace groupunit cellvolumedensityband gap eVSHG × KDP
1064 nmcommentreferenceNH4IO2F2orthorhombicPca21a=8.639 b=6.166 c=8.629 Z=4459.74.531.2(NH4)3(IO2F2)3·H2OorthorhombicPnmaa=15.102 b=12.685 c=7.369 Z=41411.84.55no[C(NH2)3]+[IO2F2]–triclinicPa = 6.6890 b = 10.2880 c = 10.30.92 α = 105.447 β = 108.568 γ = 91.051° Z=4 644.082.6504.81explosive; birefringence Δn = 0.110 (C(NH2)3)2(I2O5F)(IO3)(H2O)monoclinicP21/ca=7.4388 b=19.2679 c=11.0753 β=106.289° Z=41523.704.49birefringence Δn = 0.068C5N2H7)IO2F2 (4-aminopyridine)monoclinicC2/ma=7.4919 b=17.6990 c=6.3050 β=98.893° Z=4825.992.3484.06birefringence 0.30 @ 550 nm(C3N6H8)(IO2F2)2 (melamine)monoclinicC2/ca=19.8063 b=8.0742 c=7.2996 β=96.819° Z=41159.092.9914.10birefringence 0.23 @ 550 nmNaIO2F2orthorhombicCmcma=6.929 b=7.274 c=7.350 Z=4370.420KIO2F2orthorhombicPca21a=8.3943 b=5.9792 c=8.4468 Z=4423.950ferroelastic; when compressed on 001 axis IO2F2 units rotate with abc transforming to cba; CoIO3FmonoclinicP21/na=4.9954 b=5.2110 c=12.5179 β=95.347°NiIO3FmonoclinicP21/nZnIO3FmonoclinicP21/m4.20.00birefringence 0.219 at 546 nm[GaF(H2O)][IO3F]orthorhombicPca21a=13.954 b=6.9261 c=4.76294.3410laser damage threshold 298.40 MW cm−2; decompose 300 °C; dipole moment density: 0.0908 D Å−3NaGaI3O9FmonoclinicP21/c_a=14.120 b=4.9149 c=13.63 β=112.968° Z=4871.04.8534.270∞[Ga2(IO3F)2(IO3)4]2− layers sandwiching Na+; birefringence Δnexp ~ 0.203 at 1064 nmRbIO2F2orthorhombicPca21a=8.567 b=6.151 c=8.652 Z=4455.924.24SrI2O5F2monoclinicP21/ca=10.462 b=7.272 c=8.306 β=109.699° Z=4594.93.680Sr4O(IO3)3(I3O7F3)BF4R3ca=9.7216 c=38.759absorption band at 250 nm; decompose 380 °CCdIO3FP2121214.226.2Rb2MoO2F3(IO2F2) orthorhombicCmc21a 11.806 b 10.128 c 7.66613.775CsIO2F2orthorhombicPca21a=8.781 b=6.377 c=8.868 Z=4496.584.53Cs3(IO2F2)3•H2OPnma3.370Cs(IO2F2)2•H2O•H3OmonoclinicP21/c2.770CsIO4Pnma0Cs2VOF4(IO2F2)orthorhombicCmc21a=12.188 b=10.349 c=7.779 Z=4981.24.1002.885yellow at 1064 nmCs2MoO2F3(IO2F2) orthorhombicCmc21a =12.2153 b =10.4656 c =7.85603.434.5BaIO3FmonoclinicP21/c4.320Ba(IO2F2)2monoclinicP21/ca=10.747 b=7.161 c=9.086 β=93.748° Z=4697.73.990UV cut off 230 nmBaI2O5F2monoclinicP21/ca=10.750 b=7.599 c=8.598 β=109.753°birefringence Δn= 0.174 at 1064 nmBaIO2F3orthorhombicCmcaa=6.334 b=6.343 c=23.3004.270birefringence Δn=0.133 at 1064 nmBa2[GaF5(IO3F)]monoclinicP21/ca=7.5065 b=7.4160 c=14.5932 β=100.363°birefringence Δn=0.068 at 550 nm; UV edge 230 nm; transparent 0.34–11.9 μmCaCe(IO3)3(IO3F)ForthorhombicPna21a=11.068 b=18.15 c=6.0301 Z=41211.35.0332,725pale-yellow; birefringence 0.071 at 1064 nm SHG 5×KDP at 1064 nmRb2WO2F3(IO2F2)orthorhombicCmc21a=11.726 b=10.188 c=7.6664.42Cs2WO2F3(IO2F2)orthorhombicCmc21a=12.1122 b=10.6192 c =7.83334.29Pb4O(IO3)3(I3O7F3)BF4R3ca =9.8184 c =38.867absorption band at 283 nm; decomposes 300 °C
References