Th(H₂O)(I^VO₃)₂[I^VII_0.6V_1.76O₇(OH)]: A Mixed-Valent Iodine Compound Containing Periodate Stabilized by Crystallographically Compatible Lattice Sites

Abstract

Periodate is a strong oxidant and is often reduced to IO or I under hydrothermal conditions. Here, we present a rare case of a mixed-valent iodate(V)/periodate(VII) compound, Th(HO)(IO)[IVO(OH)], prepared with a hydrothermal method starting from periodic acid. Crystallographic results demonstrate that heptavalent iodine adopts IO distorted octahedral geometries, which are stabilized on the crystallographically compatible crystal lattice sites of VO octahedra through an aliovalent substitutional disorder mechanism. X-ray photoelectron and synchrotron radiation X-ray absorption spectroscopes both quantitatively confirm the presence of mixed valent iodine oxoanions with a molar ratio (I/I) of 4:1, consistent with the single crystal X-ray analysis. The crystallization of mixed-valent products with compatible lattice site can be fancily utilized for stabilizing the uncommon oxidation states of other elements in general.

Probing the Influence of Acidity and Temperature to Th(IV) on Hydrolysis, Nucleation, and Structural Topology

“…Large displacement parameters compared to other O atoms further indicate disorder of these O atoms. Modeling these disorder atoms, O(13), O (14), O (15), and O( 16), over two sites with 0.545/0.455 occupancy gave reasonable displacement parameters and Se−O bond distances (Table S1). Selected crystallographic information is listed in Table 2.…”

“…A variety of polynuclear Th­(IV) complexes, including dimers [Th 2 (μ 2 -OH) 2 ] 6+ , trimers [Th 3 (μ 3 -O)­(OH)­(H 2 O) 2 ] 9+ , tetramers [Th 4 Cl 8 (μ 4 -O)­(EO 4 ) 3 ] (EO 4 = tetraethylene glycol), hexamers [Th 6 (μ 3 -OH) 4 ­(μ 3 -O) 4 (H 2 O) 6 ] 12+ , − octamers [Th 8 (μ 3 -O) 4 ­(μ 2 -OH) 8 ] 16+ , and decamers [Th 10 F 16 ­(O) 8 (NH 3 ) 32 ] 8+ , have been isolated from the solution via hydrolysis, nucleation, and condensation. The consequence of the formation of these oligomeric species is the modification of the mobility of the thorium, which largely affects the fate and migration of it in the environment. − Second, thorium has long been used as a surrogate or benchmark for studying the tetravalent transuranic ions, especially Pu­(IV) due to their similarities in coordination. , Both Th­(IV) and Pu­(IV) are typically bonded to eight or nine oxygen atoms, yielding coordination geometries based on square antiprism, tricapped trigonal prism, monocapped square antiprism, etc. − In many cases, however, thorium is not a proper mimic of transuranium elements both in solution and in the solid state. For example, reaction between Th IV and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) leads to the formation of Th 2 (H 2 O) 10 ­(H 2 DOTA) 2 ·4NO 3 · x H 2 O, which contrasts sharply to [An 6 (OH) 4 ­O 4 (H 2 O) 8 ­(HDOTA) 4 ]·HCl/HNO 3 · n H 2 O (An = U, Np, Pu) isolated from the same synthesis route .…”

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

“…Hence, only 11 compounds with a mixed valence of I ions were found based on our research. Among them, the iodates with mixed-valent I 5+ /I 7+ were merely observed in four cases. − Nevertheless, compounds consisting of mixed-valence oxoanions are of special significance because of not only their attractive structural design but also the development of potential applications due to their magnetic, conductive, and optical properties.…”

“…The I 5+ valence state is the one class with a high proportion (79.29%, 448), whereas the I 7+ valence state is followed by 17.17% (97). The mixed-valence states are discovered in the following 11 iodates: I­(OSO 2 F) 2 I (−1 and +3; Figure S5a), Ag 3 I­((MoO 3 ) 2 (IO 3 ) 2 ), Ag 9 I 3 (SeO 4 ) 2 (IO 3 ) 2 , Bi 3 (IO 3 ) 12 (Ag 4 I) (−1 and +5; Figure S5b–d), ((Cl 2 I)­OIO)­F 2 , (I 3 O 6 )­(HSO 4 ) (+3 and +5; Figure S6a,b), (IOF 2 )­(IO 2 F 4 ), I 4 O 12 , Th­(H 2 O)­(IO 3 ) 2 (I 0.6 V 1.76 O 7 (OH)), Bi 2 (IO 3 )­(IO 6 ) (+5 and +7; Figure S7a–d), and the title compound (+5 and +7).…”

A Large Family of Centrosymmetric and Chiral f-Element-Bearing Iodate Selenates Exhibiting Coordination Number and Dimensional Reductions

“…The f-element-bearing oxoanion compounds, including borate, − iodate, − phosphate, − selenite, selenate, − tellurite, , etc., have been extensively studied because of their rich structural features and divergence of physicochemical properties. Within these mentioned oxoanions, the importance of iodate and selenate is highlighted, since the long-lived fission products 129 I ( t 1/2 = 1.57 × 10 7 y) and 79 Se ( t 1/2 = 3.27 × 10 5 y) could be converted to their respective oxoanions by oxidizing acids (e.g., HNO 3 ) during the dissolution of spent fuel.…”