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DOE OSTI2020

Materials Data on Mo2N5Cl9O by Materials Project

Mo2N5OCl9 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded to five Cl1- atoms to form corner-sharing MoCl5 square pyramids. There are four shorter (2.35 Å) and one longer (2.40 Å) Mo–Cl bond lengths. In the second Mo6+ site, Mo6+ is bonded to five Cl1- atoms to form distorted corner-sharing MoCl5 trigonal bipyramids. There are a spread of Mo–Cl bond distances ranging from 2.27–2.71 Å. There are three inequivalent N+0.20- sites. In the first N+0.20- site, N+0.20- is bonded in a 5-coordinate geometry to one O2- and four Cl1- atoms. The N–O bond length is 3.36 Å. There are a spread of N–Cl bond distances ranging from 3.43–3.69 Å. In the second N+0.20- site, N+0.20- is bonded in a 1-coordinate geometry to one O2- and eight Cl1- atoms. The N–O bond length is 3.04 Å. There are a spread of N–Cl bond distances ranging from 3.26–3.77 Å. In the third N+0.20- site, N+0.20- is bonded in a 7-coordinate geometry to seven Cl1- atoms. There are a spread of N–Cl bond distances ranging from 3.26–3.59 Å. O2- is bonded in a single-bond geometry to three N+0.20- and one Cl1- atom. The O–Cl bond length is 1.54 Å. There are seven inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Mo6+ and four N+0.20- atoms. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Mo6+ and three N+0.20- atoms. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Mo6+ and four N+0.20- atoms. In the fourth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Mo6+ and four N+0.20- atoms. In the fifth Cl1- site, Cl1- is bonded in a bent 120 degrees geometry to one Mo6+, four N+0.20-, and one O2- atom. In the sixth Cl1- site, Cl1- is bonded in a single-bond geometry to one Mo6+ and five N+0.20- atoms. In the seventh Cl1- site, Cl1- is bonded in a single-bond geometry to one Mo6+ and three N+0.20- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La4BrCl3O4 by Materials Project

La4O4BrCl3 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. there are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 9-coordinate geometry to four equivalent O2-, one Br1-, and four equivalent Cl1- atoms. All La–O bond lengths are 2.39 Å. The La–Br bond length is 3.32 Å. All La–Cl bond lengths are 3.24 Å. In the second La3+ site, La3+ is bonded in a 9-coordinate geometry to four equivalent O2- and five Cl1- atoms. All La–O bond lengths are 2.40 Å. There are four shorter (3.23 Å) and one longer (3.29 Å) La–Cl bond lengths. In the third La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2-, four equivalent Br1-, and one Cl1- atom. All La–O bond lengths are 2.39 Å. All La–Br bond lengths are 3.28 Å. The La–Cl bond length is 3.41 Å. In the fourth La3+ site, La3+ is bonded in a 9-coordinate geometry to four equivalent O2- and five Cl1- atoms. All La–O bond lengths are 2.39 Å. There are four shorter (3.24 Å) and one longer (3.31 Å) La–Cl bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four La3+ and two equivalent Cl1- atoms to form a mixture of face, edge, and corner-sharing OLa4Cl2 tetrahedra. Both O–Cl bond lengths are 3.33 Å. In the second O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. Br1- is bonded in a 5-coordinate geometry to five La3+ and four equivalent Cl1- atoms. All Br–Cl bond lengths are 3.49 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 5-coordinate geometry to five La3+ atoms. In the second Cl1- site, Cl1- is bonded in a 5-coordinate geometry to five La3+, four equivalent O2-, and four equivalent Br1- atoms. In the third Cl1- site, Cl1- is bonded in a 5-coordinate geometry to five La3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti2HCSe4Cl16O5 by Materials Project

Ti2Se4O5Cl14CHCl2 is alpha iridium vanadium structured and crystallizes in the monoclinic Pc space group. The structure is zero-dimensional and consists of two dichloromethane molecules and two Ti2Se4O5Cl14 clusters. In each Ti2Se4O5Cl14 cluster, there are two inequivalent Ti+3.50+ sites. In the first Ti+3.50+ site, Ti+3.50+ is bonded to three O2- and three Cl1- atoms to form distorted corner-sharing TiCl3O3 octahedra. The corner-sharing octahedral tilt angles are 17°. There is one shorter (1.82 Å) and two longer (2.14 Å) Ti–O bond length. There are a spread of Ti–Cl bond distances ranging from 2.26–2.45 Å. In the second Ti+3.50+ site, Ti+3.50+ is bonded to three O2- and three Cl1- atoms to form distorted corner-sharing TiCl3O3 octahedra. The corner-sharing octahedral tilt angles are 17°. There are a spread of Ti–O bond distances ranging from 1.81–2.16 Å. There are a spread of Ti–Cl bond distances ranging from 2.26–2.45 Å. There are four inequivalent Se+3.50+ sites. In the first Se+3.50+ site, Se+3.50+ is bonded in a 1-coordinate geometry to one O2- and two Cl1- atoms. The Se–O bond length is 1.68 Å. Both Se–Cl bond lengths are 2.21 Å. In the second Se+3.50+ site, Se+3.50+ is bonded in a 1-coordinate geometry to one O2- and two Cl1- atoms. The Se–O bond length is 1.68 Å. Both Se–Cl bond lengths are 2.21 Å. In the third Se+3.50+ site, Se+3.50+ is bonded in a 1-coordinate geometry to one O2- and two Cl1- atoms. The Se–O bond length is 1.68 Å. There are one shorter (2.20 Å) and one longer (2.22 Å) Se–Cl bond lengths. In the fourth Se+3.50+ site, Se+3.50+ is bonded in a 1-coordinate geometry to one O2- and two Cl1- atoms. The Se–O bond length is 1.68 Å. There are one shorter (2.20 Å) and one longer (2.22 Å) Se–Cl bond lengths. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Ti+3.50+ and one Se+3.50+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Ti+3.50+ and one Se+3.50+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Ti+3.50+ and one Se+3.50+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ti+3.50+ and one Se+3.50+ atom. In the fifth O2- site, O2- is bonded in a linear geometry to two Ti+3.50+ atoms. There are fourteen inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti+3.50+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti+3.50+ atom. In the fifth Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti+3.50+ atom. In the sixth Cl1- site, Cl1- is bonded in a single-bond geometry to one Ti+3.50+ atom. In the seventh Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the eighth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the ninth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the tenth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the eleventh Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Ti+3.50+ atom. In the twelfth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Ti+3.50+ atom. In the thirteenth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom. In the fourteenth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se+3.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Nd4NCl9O by Materials Project

Na2Nd4NOCl9 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six Cl1- atoms. There are a spread of Na–Cl bond distances ranging from 2.80–3.08 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six Cl1- atoms. There are a spread of Na–Cl bond distances ranging from 2.82–3.06 Å. There are four inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded in a 8-coordinate geometry to one N3-, one O2-, and six Cl1- atoms. The Nd–N bond length is 2.31 Å. The Nd–O bond length is 2.36 Å. There are a spread of Nd–Cl bond distances ranging from 2.82–3.18 Å. In the second Nd3+ site, Nd3+ is bonded in a 2-coordinate geometry to one N3-, one O2-, and five Cl1- atoms. The Nd–N bond length is 2.34 Å. The Nd–O bond length is 2.31 Å. There are a spread of Nd–Cl bond distances ranging from 2.95–3.13 Å. In the third Nd3+ site, Nd3+ is bonded in a 2-coordinate geometry to one N3-, one O2-, and five Cl1- atoms. The Nd–N bond length is 2.27 Å. The Nd–O bond length is 2.39 Å. There are a spread of Nd–Cl bond distances ranging from 2.91–3.13 Å. In the fourth Nd3+ site, Nd3+ is bonded in a 8-coordinate geometry to one N3-, one O2-, and six Cl1- atoms. The Nd–N bond length is 2.32 Å. The Nd–O bond length is 2.37 Å. There are a spread of Nd–Cl bond distances ranging from 2.84–3.09 Å. N3- is bonded to four Nd3+ atoms to form NNd4 tetrahedra that share edges with two equivalent ONd4 tetrahedra. O2- is bonded to four Nd3+ atoms to form ONd4 tetrahedra that share edges with two equivalent NNd4 tetrahedra. There are nine inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three Nd3+ atoms. In the second Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Na1+ and two Nd3+ atoms. In the third Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Na1+ and two Nd3+ atoms. In the fourth Cl1- site, Cl1- is bonded in a rectangular see-saw-like geometry to two Na1+ and two Nd3+ atoms. In the fifth Cl1- site, Cl1- is bonded in a distorted see-saw-like geometry to one Na1+ and three Nd3+ atoms. In the sixth Cl1- site, Cl1- is bonded in a distorted see-saw-like geometry to one Na1+ and three Nd3+ atoms. In the seventh Cl1- site, Cl1- is bonded in a distorted see-saw-like geometry to two Na1+ and two Nd3+ atoms. In the eighth Cl1- site, Cl1- is bonded in a distorted see-saw-like geometry to two Na1+ and two Nd3+ atoms. In the ninth Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three Nd3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Lewis Acidity of the SbCl 3 / o ‐chloranil System

Abstract While SbCl 3 is typically inert toward oxidation by ortho ‐quinones, we use o ‐chloranil to show that the outcome of such reactions may be altered by the presence of a donor such as triphenylphosphine oxide, which readily traps the SbCl 3 (cat Cl ) synthon (cat Cl = tetrachlorocatecholate) in the form of the corresponding adduct Ph 3 PO→SbCl 3 (cat Cl ). The same reaction in the presence of a chloride salt affords the corresponding antimonate anion [Cl 4 Sb(cat Cl )] − . Computational studies indicate that the putative SbCl 3 (cat Cl ) synthon has a higher chloride ion affinity than SbCl 5 , suggesting significant Lewis acidity. This property is further demonstrated by the use of the SbCl 3 / o ‐chloranil system for both THF polymerization and a Friedel–Crafts‐type alkylation of benzene using 1‐fluorooctane. Finally, the reaction of E ‐stilbene with o ‐chloranil in the presence of SbCl 3 affords the corresponding benzodioxene, suggesting that SbCl 3 may also operate as a redox‐active catalyst.

Şit, Ferit [Department of Chemistry Texas A&amp,M ↗
DOE OSTI2025

Lewis Acidity of the SbCl 3 /o-chloranil System

While SbCl 3 is typically inert toward oxidation by ortho-quinones, we use o-chloranil to show that the outcome of such reactions may be altered by the presence of a donor such as triphenylphosphine oxide, which readily traps the SbCl 3 (cat Cl ) synthon (cat Cl = tetrachlorocatecholate) in the form of the corresponding adduct Ph 3 PO→SbCl 3 (cat Cl ). The same reaction in the presence of a chloride salt affords the corresponding antimonate anion [Cl 4 Sb(cat Cl )] − . Computational studies indicate that the putative SbCl 3 (cat Cl ) synthon has a higher chloride ion affinity than SbCl 5 , suggesting significant Lewis acidity. This property is further demonstrated by the use of the SbCl 3 /o-chloranil system for both THF polymerization and a Friedel–Crafts-type alkylation of benzene using 1-fluorooctane. Finally, the reaction of E-stilbene with o-chloranil in the presence of SbCl 3 affords the corresponding benzodioxene, suggesting that SbCl 3 may also operate as a redox-active catalyst.

Antimony↗
DOE OSTI2020

Solution-Based, Anion-Doping of Li 4 Ti 5 O 12 Nanoflowers for Lithium-Ion Battery Applications

Solution–based, anionic doping represents a convenient strategy with which to improve upon the conductivity of candidate anode materials such as Li 4 Ti 5 O 12 (LTO). As such, novel synthetic hydrothermally–inspired protocols have primarily been devised herein, aimed at the large–scale production of unique halogen–doped, micron–scale, three–dimensional, hierarchical LTO flower–like motifs. Although fluorine (F) doping has been explored, the use of chlorine (Cl) dopants is the primary focus here. Several experimental variables, such as dopant amount, lithium hydroxide concentration, and titanium butoxide purity, were probed and perfected. Furthermore, the Cl doping process did not damage the intrinsic LTO morphology. The analysis, based on interpreting a compilation of SEM, XRD, XPS, and TEM–EDS results, was used to determine an optimized dopant concentration of Cl. Electrochemical tests demonstrated an increased capacity via cycling of 12 % for a Cl–doped sample as compared with pristine LTO. Moreover, the Cl–doped LTO sample described in this study exhibited the highest discharge capacity yet reported at an observed rate of 2C for this material at 143mAh g –1 . Overall, these data suggest that the Cl dopant likely enhances not only the ion transport capabilities, but also the overall electrical conductivity of our as–prepared structures. Furthermore, to help explain these favorable findings, theoretical DFT calculations were used to postulate that the electronic conductivity and Li diffusion were likely improved by the presence of increased Ti 3+ ion concentration coupled with widening of the Li migration channel.

25 ENERGY STORAGE↗
DOE OSTI2022

Model‐Based Approach to Selecting Pegfilgrastim Dose for Pharmacokinetic and Pharmacodynamic Similarity Studies in Biosimilar Development

This study applied modeling and simulation (M&S) approaches to evaluate the sensitivity of pegfilgrastim pharmacokinetics (PKs) and pharmacodynamics (PDs) to changes in dose amount, and linear or nonlinear clearance (CL) over pegfilgrastim subcutaneous dose of 2–6 mg. A previously published model was adapted to better describe pegfilgrastim PK and PD data in healthy subjects and used in simulation. Nonlinear CL accounts for 98% and 77%, respectively, of the total CL of pegfilgrastim at 2 and 6 mg. The sensitivity analyses showed: (i) PK of 2 and 6 mg doses are similarly sensitive to detect differences for a 5% change in dose; (ii) PK of 2 mg dose is more sensitive to changes in receptor binding affinity, a model parameter for nonlinear CL, and a product quality attribute characterized with orthogonal methods as part of demonstrating analytical similarity between products; (iii) PK of approved 6 mg dose is more sensitive to changes in linear CL, which has not been associated with any specific product quality attributes, and (iv) the PDs are not sensitive to changes in linear or nonlinear CL. Taken together, our analyses support that the approved pegfilgrastim dose of 6 mg is appropriate for detecting differences between a biosimilar and the reference products in pegfilgrastim PK and PD similarity studies. The described M&S approaches can be adopted to support dose selection for biosimilars with nonlinear PK and complex PK–PD interplay.

Pharmacology & Pharmacy↗
DOE OSTI2025

Benchmarking fast-neutron response of 7 Li-enriched C 7 LYC scintillators: Simulations and experiment

New insights into the fast neutron response of 7 Li-enriched C 7 LYC scintillators have been obtained through detailed Geant4 simulations of 35 Cl(n,p) and 35 Cl(n, α) reactions that are primarily responsible for the fast neutron response of C 7 LYC. The light output of a 1” x1” C 7 LYC detector was simulated using the Birks equation for light quenching in scintillators. The simulations were benchmarked against neutron scattering data from a 12 C target obtained with a white neutron beam at the Los Alamos LANSCE facility and fourteen 1”x1” C 7 LYC detectors. Incident neutron energies extracted from time-of-flight measurements, and appropriate recoil corrections for the different detector angles were used to map the response of C 7 LYC to mono-energetic neutrons. Resonances in the 35 Cl(n,p) reaction cross-section below 3 MeV incident neutron energy were directly observed in C 7 LYC. The experimental data and simulations are compared with ENDF databases, as well as recent direct cross-section measurements of neutrons scattered from a 35 Cl target. In conclusion, the results suggest a scrutiny of the 35 Cl(n,p) and 35 Cl(n, α) cross sections at low energy in the ENDF library.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Controls on the 36 Cl/Cl input ratio of paleo-groundwater in arid environments: New evidence from 81 Kr/Kr data

In this study, measurements of the long-lived 81 Kr and 36 Cl radioisotopes in groundwater from the Negev Desert (Israel) were used to assess the 36 Cl/Cl input ratios and Cl – contents for paleorecharge into the Nubian Sandstone Aquifer (NSA). The reconstructed Cl – content of the recharge flux was on the order of 300–400 mg/L. An initial 36 Cl/Cl ratio of 50 × 10 –15 was assessed for the groundwater replenishment in the Negev Desert since the late Pleistocene, in agreement with the 36 Cl/Cl ratios in recent local rainwater. This is despite possible changes in the climatic conditions and the 36 Cl production rates in the atmosphere over this timeframe. This similarity in values is explained by the major role played by the erosion and weathering of near-surface materials in the desert environment that dominate the hydrochemistry of rains, floods, and the consequent groundwater recharge. Spatial variation in the reconstructed initial 36 Cl/Cl ratio is accounted for by the differences in the mineral aerosol sources for specific recharge areas of the NSA. Accordingly, regional variations in the 36 Cl/Cl input in groundwater reservoirs surrounding the Mediterranean Sea indicate various processes that govern the 36 Cl/Cl system. Finally, the results of this study highlight the great advantage of integrating 81 Kr age information in evaluating the initial 36 Cl/Cl and Cl – input, which is essential for the calibration of 36 Cl radioisotope as an available long-term dating tool for a given basin.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Ultrafast Oxygen Conduction in Sillén Oxychlorides

Oxygen ion conductors are crucial for enhancing the efficiency of various clean energy technologies, including fuel cells, solid oxide air batteries, electrolyzers, membranes, sensors, and more. In this study, a structure-similarity analysis of ≈62k oxygen-containing compounds identified the MBi 2 O 4 X (M = rare-earth element, X = halogen element) family as promising candidates for fast oxygen transport. Among these, LaBi 2 O 4 Cl is found as an ultrafast oxygen conductor with an ultralow migration barrier of 0.1 eV based on ab initio studies. Its 2D layered structure, featuring a “triple fluorite” layer, supports diffusion of both oxygen vacancies and interstitials. In addition to vacancy diffusion with a 0.1 eV barrier, ab initio studies show interstitial diffusion exhibits a modest barrier of 0.6–0.8 eV. Frenkel pairs are found to be the dominant defects in intrinsic LaBi 2 O 4 Cl, facilitating significant vacancy-mediated oxygen diffusion at elevated temperatures. With 2.8% oxygen vacancies, LaBi 2 O 4 Cl is predicted to achieve a conductivity of 0.3 S/cm at 25 °C in a single crystal. Experimental synthesis and characterization of polycrystalline LaBi 2 O 4 Cl and Sr-doped LaBi 2 O 4 Cl revealed conductivity exceeding that of YSZ and LSGM below 400 °C, with lower activation energies, achieving a total conductivity of 0.1−0.2 mS/cm at 300 °C. Here, while these results confirm its potential of fast oxygen transport, we suggest further experimental optimization of LaBi 2 O 4 Cl, including aliovalent doping and microstructure refinement, could significantly enhance its performance, facilitating fast oxygen conduction approaching room temperature.

Defects↗
DOE OSTI2022

Mercury Removal from Contaminated Water by Wood-Based Biochar Depends on Natural Organic Matter and Ionic Composition

Biochars can remove potentially toxic elements, such as inorganic mercury [Hg(II)] from contaminated waters. However, their performance in complex water matrices is rarely investigated, and the combined roles of natural organic matter (NOM) and ionic composition in the removal of Hg(II) by biochar remain unclear. Here, we investigate the influence of NOM and major ions such as chloride (Cl – ), nitrate (NO 3 – ), calcium (Ca 2+ ), and sodium (Na + ) on Hg(II) removal by a wood-based biochar (SWP700). Multiple sorption sites containing sulfur (S) were located within the porous SWP700. In the absence of NOM, Hg(II) removal was driven by these sites. Ca 2+ bridging was important in enhancing removal of negatively charged Hg(II)-chloro complexes. In the presence of NOM, formation of soluble Hg-NOM complexes (as seen from speciation calculations), which have limited access to biochar pores, suppressed Hg(II) removal, but Cl – and Ca 2+ could still facilitate it. The ability of Ca 2+ to aggregate NOM, including Hg-NOM complexes, promoted Hg(II) removal from the dissolved fraction (<0.45 μm). Hg(II) removal in the presence of Cl – followed a stepwise mechanism. Weakly bound oxygen functional groups in NOM were outcompeted by Cl – , forming smaller-sized Hg(II)-chloro complexes, which could access additional intraparticle sorption sites. Therein, Cl – was outcompeted by S, which finally immobilized Hg(II) in SWP700 as confirmed by extended X-ray absorption fine structure spectroscopy. We conclude that in NOM containing oxic waters, with relatively high molar ratios of Cl – : NOM and Ca 2+ : NOM, Hg(II) removal can still be effective with SWP700.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Homoleptic Perchlorophenyl “Ate” Complexes of Thorium(IV) and Uranium(IV)

The reaction of AnCl 4 (DME) n (An = Th, n = 2; U, n = 0) with 5 equiv of LiC 6 Cl 5 in Et 2 O resulted in the formation of homoleptic actinide-aryl “ate” complexes [Li(DME) 2 (Et 2 O)] 2 [Li(DME) 2 ][Th(C 6 Cl 5 ) 5 ] 3 ([Li][1]) and [Li(Et 2 O) 4 ][U(C 6 Cl 5 ) 5 ] ([Li][2]). Similarly, the reaction of AnCl 4 (DME)n (An = Th, n = 2; U, n = 0) with 3 equiv of LiC 6 Cl 5 in Et 2 O resulted in the formation of heteroleptic actinide-aryl “ate” complexes [Li(DME) 2 (Et 2 O)][Li(Et 2 O) 2 ][ThCl 3 (C 6 Cl 5 ) 3 ] ([Li][3]) and [Li(Et 2 O) 3 ][UCl 2 (C 6 Cl 5 ) 3 ] ([Li][4]). Density functional calculations show that the An–C ipso σ-bonds are considerably more covalent for the uranium complexes vs the thorium analogues, in line with past results. Additionally, good agreement between experiment and calculations is obtained for the 13 C ipso NMR chemical shifts in [Li][1] and [Li][3]. Here, the calculations demonstrate a deshielding by ca. 29 ppm from spin–orbit coupling effects originating at Th, which is a direct consequence of 5f orbital participation in the Th–C bonds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Plutonium Hybrid Materials: A Platform to Explore Assembly and Metal–Ligand Bonding

In this work, we report the synthesis of five new hybrid materials containing the [PuCl 6 ] 2- anion and charge balancing, non-covalent interaction donating 4-X-pyridinium (X = H, Cl, Br, I) cations. Single crystals of the title compounds were grown and harvested from acidic, chloride-rich, aqueous media and their structures were determined via X-ray diffraction. Compounds 1-4, (4XPyH) 2 [PuCl 6 ] and 5, (4IPyH) 4 [PuCl 6 ] · 2Cl, exhibit two distinct sheet-like structure types. Structurally relevant non-covalent interactions were tabulated from crystallographic data and verified computationally using electrostatic surface potential maps and the quantum theory of atoms in molecules (QTAIM) approach. The strength of the hydrogen and halogen bonds was quantified using Kohn-Sham density functional theory and a hierarchy of acceptor-donor pairings established. In turn, the PuIV-Cl bonds were studied using the QTAIM and natural localized molecular orbital (NLMO) approaches to delineate the underlying bond mechanism and hybrid atomic orbital contributions therein. Energy decomposition (ED) and natural ED analyses were also explored to probe the bond mechanism and, more broadly, explore the efficacy of these techniques in studying these anionic systems. The results of the PuIV-Cl bond analyses were compared across composition via analogous treatments of previously reported [PuO 2 Cl 4 ] 2- and [PuCl 3 (H 2 O) 5 ] molecular units. In summary, our study indicates that the Pu-Cl bonds are predominately ionic, yet exhibit small varying degrees of covalent character that increase from [PuCl 3 (H 2 O) 5 ], [PuO 2 Cl 4 ] 2- , to [PuCl 6 ] 2- , while the participation of the Pu based s/d and f orbitals concurrently decrease and increase, respectively.

transuranic↗
DOE OSTI2023

Hydrophilic and Apolar Hydration in Densely Grafted Cationic Brushes and Counterions with Large Mobilities

We employ all-atom molecular dynamics (MD) simulation framework to unravel water microstructure and ion properties for cationic [Poly(2-(methacryloyloxy)ethyl trimethylammonium chloride] (PMETAC) brushes with chloride ions as counterions. First, we identify locally separate water domains (or first hydration shells) each around the {N(CH 3 ) 3 } + and the C=O functional groups of the PMETAC chain and one around the Cl - ion. These first hydration shells around the respective moieties overlap and the extent of the overlap depends on the nature of the species triggering it. Second, despite the overlap, the water molecules in these domains demonstrate disparate properties dictated by the properties of the atoms/groups around which they are located. For example, the presence of the methyl groups make the {N(CH 3 ) 3 } + group trigger apolar hydration as evidenced by the corresponding orientation of the dipole of the water molecules around the {N(CH 3 ) 3 } + moiety. These water molecules around the N(CH 3 ) 3 } + group also have enhanced tetrahedrality as compared to the water molecules constituting the hydration layer around the C=O group and the Cl - counterion. Our simulations also identify that there is an intervening water layer between the Cl - ion and {N(CH 3 ) 3 } + group: this layer prevents the Cl - ion from coming very close to the {N(CH 3 ) 3 } + group. As a consequence, there is a significantly large mobility of the Cl - ions inside the PMETAC brush layer. Furthermore, the C=O group of the PE chain, due to the partial negative charge on the oxygen atom and the specific structure of the PMETAC brush system, demonstrates strongly hydrophilic behavior and enforces a specific dipole response of water molecules analogous to that experienced by water around anionic species of high charge density. As a result, our findings confirm that PMETAC brushes undergo hydrophilic hydration at one site, apolar hydration at another site, and ensures large mobility of the supported Cl- counterions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Chlorine Gas as a Lewis Acid–Base Probe for Molten Salts of Divalent Metal Ions

In the context of energy applications for salts and, more specifically, in the case of molten salt reactors, the solvation of corrosion species, the nature and behavior of radiation-produced excess electrons, transient radicals, and molecular gas species all depend on the Lewis acid–base behavior of the constituent salt melt. Speciation of dissolved species and their transport properties are also influenced by the ability of the melt to form networks. This article focuses on the structural properties of melts composed of alkaline earth metal ions coupled with the Cl – anion, and the quantum mechanical behavior of Cl 2 , a typical product of the reaction of radiation-produced chlorine radicals in Cl – -based molten salts. We explore the effect of M 2+ Lewis acidity on chlorobasicity, seen in this work as the availability of Cl – ions to chemically react with Cl 2 to produce Cl 3 – .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

All-Atom Molecular Dynamics Simulations of Cationic Polyelectrolyte Brushes in the Presence of Halide Counterions

Understanding the response of the charged polyelectrolyte (PE) brushes and brush-supported water and ions to the changes in the nature of screening counterions is significant in developing strategies for utilizing PE brushes in various applications. In this paper, we employ all-atom molecular dynamics (MD) simulations for studying the behavior of cationic [poly(2-(methacryloyloxy)ethyl) trimethylammonium] (PMETA) brushes and brush-supported water and ions in the presence of different halide (X: I – , Br – , Cl – , and F – ) screening counterions. We find that despite the F– ion having the largest charge density, the extent of binding of the counterions on the PMETAX brushes varies as I – > Br – > Cl – > F – , leading to PMETAX brush height being least with I– counterions and greatest with F – counterions. This trend in the binding of the halide ions matches the previous experimental result and can be explained by identifying the chaotropic nature of the I – and Br – ions that promote a disruption of water structure and a more favorable binding of the ions to the polymer chains. Such a binding trend also ensures that the order of the water molecules around the PMETAX chains or the counterions as well as the number of water–water hydrogen bonds inside the brush layer increases in the following order of the counterion-specific PMETAX brushes: F – > Cl – > Br – > I – . Furthermore, halide-ion-PMETAX-chain binding takes place via both interchain and intrachain bridging: intrachain bridging dominates for the case of counterions that show enhanced binding (I – and Br – ), while interchain bridging is more favored for the case of counterions that show weakened binding (F – and Cl – ). Also, a greater degree of intrachain bridging leads to greater compressibility and flexibility of the brush layer. Lastly, we show that the mobility of the halide ions follows a nonmonotonic trend with the charge density: the mobility decreases as I – < Br – < Cl – (as their binding to the PMETAX chains varies as I – > Br – > Cl – ), but the mobility of F – ions is in between that of I – and Br – ions. We argue that the strongly attached hydration layer and the ensuing friction inside the brush layer lead to such a reduced mobility of the F – ions.

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