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

Abstract

The exploration of phase formation in the f-element-bearing iodate selenate system has resulted in 14 novel rare-earth-containing iodate selenates, Ln(IO 3 )(SeO 4 ) (Ln = La, Ce, Pr, Nd; LnISeO-1), Ln(IO 3 )(SeO 4 )(H 2 O) (Ln = Sm, Eu; LnISeO-2), and Ln(IO 3 )(SeO 4 )(H 2 O) 2 •H 2 O (Ln = Gd, Dy, Ho, Er, Tm, Yb, Lu, Y; LnISeO-3), as well as two new thorium iodate selenates, Th(OH)(IO 3 )(SeO 4 )(H 2 O) (ThISeO-1) and Th(IO 3 ) 2 (SeO 4 ) (ThISeO-2). LnISeO-3 and ThISeO-2 crystallize in the chiral space group P2 1 2 1 2 1 , while LnISeO-1, LnISeO-2, and ThISeO-1 crystallize in the centrosymmetric space group P2 1 /c. The numbers of both coordinating and hydrating water molecules crystallized in LnISeO-1, LnISeO-2, and LnISeO-3 increase along these three series, in line with the increasingly negative values of hydration enthalpies of heavier trivalent lanthanide ions. Such a systematic change in compositions, especially the first coordination sphere of Ln, further induces structural rearrangements, including coordination number and dimensional reductions. More specifically, the structures of LnISeO-1, LnISeO-2, and LnISeO-3 have undergone transitions from 2D Ln−oxo layers with 10-coordinate Ln centers to 1D Ln−oxo chains with 9-coordinate Ln centers and then to 0D Ln−oxo monomers with 8coordinate Ln centers, respectively. The formation and characterization of this large family of Ln/Th iodate selenates suggest that such a mixed-anion system not only exhibits richer structural chemistry but also can be capable of generating intriguing properties, such as the second-harmonic generation (SHG) effect.

REI5O14 (RE=Y and Gd): Promising SHG Materials Featuring the Semicircle‐Shaped I5O143− Polyiodate Anion

“…IR spectra revealed that REI 5 O 14 (RE=Y and Gd) are transparent from 2.5–11.3 μm (4000–885 cm −1 ), (Figure S8), and in Table S5 the absorption peaks were assigned in detail . The maximum IR transparent ranges are 13.6, 12.5, and 12.1 μm for RbIO 3 , NaI 3 O 8 , and CsI 4 O 11 , respectively .…”

Structural Complexity and Magnetic Orderings in a Large Family of 3d–4f Heterobimetallic Sulfates

“…The reduction in ionic radii across the 4f series allows for phase changes of the afforded metal–ligand complexes. , A large family of lanthanide borates is particularly interesting because it shows a rare case of structural transitions between six distinct phases under the same synthetic conditions across the 4f series . Other systems, such as lanthanide iodate selenite, exhibit similar structural evolution with dimensional and coordination number reductions induced by the lanthanide contraction . In this work, two types of structural evolutions, from LnCuSO-1 to LnCuSO-2 and from LnCuSO-3 to LnCuSO-4 , can be observed.…”

The Role of Acidity in the Synthesis of Novel Uranyl Selenate and Selenite Compounds and Their Structures

“…In the case of NLO materials, stereo active lone pair possessing cations Se 4+ and I 5+ are commonly utilized as their possession of periodic polarizable free lone pair electrons within NSC lattices allow materials with superior second harmonic generation (SHG) properties to be obtained. A growing theme among recent NLO and SHG Se and I related material development studies has been the extension of these to uranium and actinide compounds, as it has been shown that their related properties can often exceed those of non-actinide variants [5][6][7][8]. The properties of these materials can be further improved through the increased polymerization of IO 3 − and SeO 3 2− units into polyiodate and polyselenite units [9,10].…”

“…A key component driving these promising applications is the combination of traditional functional chemical components such as stereo-active lone pair possessing IO 3 − and SeO 3 2− units with that of the uranium's unique chemical character as a 5f element which, together, drives the properties of obtained structures to often rival or excede those of non-uranium/actinide analogues [14,36]. This has been exemplified by UPI-1 and other monoiodate and monoselenite/monoselenate possessing uranyl compounds [5,6,14]. Compared to uranyl iodates, there is relatively less known about selenites and selenates in respect of synthesis conditions and control, despite the interest these receive in context of NLO and SHG materials development.…”