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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Competition between Dissolved Organic Matter and Freshwater Plankton Control Methylmercury Isotope Fractionation during Uptake and Photochemical Demethylation

Isotope fractionation related to photochemical reactions and planktonic uptake at the base of the food web is a major uncertainty in the biological application of mercury (Hg) stable isotopes. In freshwater systems, it is unclear how competitive interactions among methylmercury (MeHg), dissolved organic matter (DOM), and phytoplankton govern the magnitude of mass-dependent and mass-independent fractionation. This study investigated how DOM alters rates of planktonic MeHg uptake and photodegradation and corresponding Hg isotope fractionation in the presence of freshwater phytoplankton species, Raphidocelis subcapitata. Outdoor sunlight exposure experiments utilizing R. subcapitata were performed in the presence of different DOM samples using environmentally relevant ratios of MeHg-DOM thiol groups. The extent of Δ199Hg in phytoplankton incubations (2.99‰ St. Louis River HPOA, 1.88‰ Lake Erie HPOA) was lower compared to paired abiotic control experiments (4.29 and 2.86‰, respectively) after ~30 h of irradiation, resulting from cell shading or other limiting factors reducing the extent of photodemethylation. Although the Δ 199 Hg/Δ 201 Hg ratio was uniform across experiments (~1.4), Δ 199 Hg/δ 202 Hg slopes varied dramatically (from -0.96 to 15.4) across incubations with R. subcapitata and DOM. In addition, no evidence of Hg isotope fractionation was observed within R. subcapitata cells. This study provides a refined examination of Hg isotope fractionation markers for key processes occurring in the lower food web prior to bioaccumulation, critical for accurately accounting for the photochemical processing of Hg isotopes across a wide spectrum of freshwater systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Mercury methylation by metabolically versatile and cosmopolitan marine bacteria

Microbes transform aqueous mercury (Hg) into methylmercury (MeHg), a potent neurotoxin that accumulates in terrestrial and marine food webs, with potential impacts on human health. This process requires the gene pair hgcAB, which encodes for proteins that actuate Hg methylation, and has been well described for anoxic environments. However, recent studies report potential MeHg formation in suboxic seawater, although the microorganisms involved remain poorly understood. In this study, we conducted large-scale multi-omic analyses to search for putative microbial Hg methylators along defined redox gradients in Saanich Inlet, British Columbia, a model natural ecosystem with previously measured Hg and MeHg concentration profiles. Analysis of gene expression profiles along the redoxcline identified several putative Hg methylating microbial groups, including Calditrichaeota, SAR324 and Marinimicrobia, with the last the most active based on hgc transcription levels. Marinimicrobia hgc genes were identified from multiple publicly available marine metagenomes, consistent with a potential key role in marine Hg methylation. Computational homology modelling predicts that Marinimicrobia HgcAB proteins contain the highly conserved amino acid sites and folding structures required for functional Hg methylation. Furthermore, a number of terminal oxidases from aerobic respiratory chains were associated with several putative novel Hg methylators. Our findings thus reveal potential novel marine Hg-methylating microorganisms with a greater oxygen tolerance and broader habitat range than previously recognized.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Anaerobic guilds responsible for mercury methylation in boreal wetlands of varied trophic status serving as either a methylmercury source or sink

Wetlands are common sites of active Hg methylation by anaerobic microbes; however, the amount of methylmercury produced varies greatly, as Hg methylation is dependent upon both the availability of Hg and the composition and activity of the microbial community involved. In this study, we identified the major microbial guilds responsible for Hg methylation along a trophic gradient composed of two sites and three different types of wetlands: a bog–fen peatland gradient and a black alder swamp, serving as net sources and a sink for methylmercury respectively. Iron-reducing bacteria in the Geobacteraceae were important Hg methylators across all wetlands and seasons examined, as evidenced by abundant 16S rRNA and hgcA transcripts clustering with this family. Molybdate inhibited Hg methylation more efficiently in the peatlands than in the swamp, suggesting an increasing role of sulfate-reducing bacteria and/or related syntrophs in the methylation of Hg with decreasing trophic status. Further, sulfate addition failed to increase Hg methylation rates in the peatlands, suggesting that SRBs/syntrophs were instead likely metabolizing alternative substrates such as syntrophic fermentation of organic compounds with methanogens. These results highlight the interconnectivity of anaerobic metabolism and importance of community dynamics on the methylation of Hg in wetlands with different trophic status.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Transcriptional Control of hgcAB by an ArsR-Like Regulator in Pseudodesulfovibrio mercurii ND132

The hgcAB gene pair encodes mercury (Hg) methylation capability in a diverse group of microorganisms, but its evolution and transcriptional regulation remain unknown. Working from the possibility that the evolutionary function of HgcAB may not be Hg methylation, we test a possible link to arsenic resistance. Using model Hg methylator Pseudodesulfovibrio mercurii ND132, we evaluated transcriptional control of hgcAB by a putative ArsR encoded upstream and cotranscribed with hgcAB. This regulator shares homology with ArsR repressors of arsenic resistance and S-adenosylhomocysteine (SAH)- responsive regulators of methionine biosynthesis but is distinct from other ArsR/SahR proteins in P. mercurii. Using quantitative PCR (qPCR) and RNA sequencing (RNA-seq) transcriptome analyses, we confirmed this ArsR regulates hgcAB transcription and is responsive to arsenic and SAH. Additionally, RNA-seq indicated a possible link between hgcAB activity and arsenic transformations, with significant upregulation of other ArsRregulated arsenic resistance operons alongside hgcAB. Interestingly, wild-type ND132 was less sensitive to As(V) (but not As(III)) than an hgcAB knockout strain, supporting the idea that hgcAB may be linked to arsenic resistance. Arsenic significantly impacted rates of Hg methylation by ND132; however, responses varied with culture conditions. Differences in growth and metabolic activity did not account for arsenic impacts on methylation. While arsenic significantly increased hgcAB expression, hgcAB gene and transcript abundance was not a good predictor of Hg methylation rates. Taken together, these results support the idea that Hg and As cycling are linked in P. mercurii ND132. Our results may hold clues to the evolution of hgcAB and the controls on Hg methylation in nature. This work reveals a link between microbial mercury methylation and arsenic resistance and may hold clues to the evolution of mercury methylation genes (hgcAB). Microbes with hgcAB produce methylmercury, a strong neurotoxin that readily accumulates in the food web. This study addresses a critical gap in our understanding about the environmental factors that control hgcAB expression. We show that hgcAB expression is controlled by an ArsR-like regulator responsive to both arsenic and S-adenosylhomocysteine in our model organism, Pseudodesulfovibrio mercurii ND132. Exposure to arsenic also significantly impacted Pseudodesulfovibrio mercurii ND132 mercury methylation rates. However, expression of hgcAB was not always a good predictor of Hg methylation rates, highlighting the roles of Hg bioavailability and other biochemical mechanisms in methylmercury production. This study improves our understanding of the controls on hgcAB expression, which is needed to better predict environmental methylmercury production

RNA-seq↗
DOE OSTI2021

Mercury Remediation Technology Development for Lower East Fork Poplar Creek—FY 2021 Update

Mercury remediation is a high priority for the US Department of Energy (DOE) Oak Ridge Office of Environmental Management. Mercury contamination in the environment can be found at all three DOE facilities in Oak Ridge, Tennessee, but the greatest environmental risk concern relative to Hg on the Oak Ridge Reservation is likely associated with historical Hg losses at and near the Y-12 National Security Complex (Y-12). Mercury in water and fish from East Fork Poplar Creek (EFPC) downstream of Y-12 exceeds regulatory thresholds. Because of the complexities of Hg transport and fate in the aquatic environment, conventional remedial options for EFPC are highly uncertain. DOE is using a phased adaptive management approach to Hg remediation at Y-12, with a focus in the next few years on construction of the Mercury Treatment Facility (MTF) to treat the most contaminated Y-12 outfall entering EFPC (DOE 2017a; DOE 2017b). Once operational, the MTF will provide additional protection against inadvertent releases of Hg into the stream from decontamination and decommissioning of Y-12 Hg-use buildings. Although the MTF is anticipated to substantially decrease Hg water concentrations and flux in upper EFPC (UEFPC), research and technology development are needed to develop appropriate and longer-term remedial solutions for the downstream environment. Since late 2014, the Oak Ridge Office of Environmental Management and URS | CH2M Oak Ridge LLC/Restoration Services Inc. have supported DOE’s Oak Ridge National Laboratory (ORNL) Environmental Sciences Division staff in conducting field and laboratory studies to develop Hg remedial technology solutions for lower EFPC (LEFPC). Whereas previous annual reporting updates for Hg remediation technology development for LEFPC have focused on presenting detailed results from the previous fiscal year, this FY 2021 update takes a comprehensive, higher-level approach to the research and technology development activities conducted since 2014. The report is organized to be consistent with the three tasks defined in the LEFPC strategic plan

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Nutrient Inputs Stimulate Mercury Methylation by Syntrophs in a Subarctic Peatland

Climate change dramatically impacts Arctic and subarctic regions, inducing shifts in wetland nutrient regimes as a consequence of thawing permafrost. Altered hydrological regimes may drive changes in the dynamics of microbial mercury (Hg) methylation and bioavailability. Important knowledge gaps remain on the contribution of specific microbial groups to methylmercury (MeHg) production in wetlands of various trophic status. Here, we measured aqueous chemistry, potential methylation rates (k meth ), volatile fatty acid (VFA) dynamics in peat-soil incubations, and genetic potential for Hg methylation across a groundwater-driven nutrient gradient in an interior Alaskan fen. We tested the hypotheses that (1) nutrient inputs will result in increased methylation potentials, and (2) syntrophic interactions contribute to methylation in subarctic wetlands. We observed that concentrations of nutrients, total Hg, and MeHg, abundance of hgcA genes, and rates of methylation in peat incubations (k meth ) were highest near the groundwater input and declined downgradient. hgcA sequences near the input were closely related to those from sulfate-reducing bacteria (SRB), methanogens, and syntrophs. Hg methylation in peat incubations collected near the input source (FPF2) were impacted by the addition of sulfate and some metabolic inhibitors while those down-gradient (FPF5) were not. Sulfate amendment to FPF2 incubations had higher k meth relative to unamended controls despite no effect on k meth from addition of the sulfate reduction inhibitor molybdate. The addition of the methanogenic inhibitor BES (25 mM) led to the accumulation of VFAs, but unlike molybdate, it did not affect Hg methylation rates. Rather, the concurrent additions of BES and molybdate significantly decreased k meth , suggesting a role for interactions between SRB and methanogens in Hg methylation. The reduction in k meth with combined addition of BES and molybdate, and accumulation of VFA in peat incubations containing BES, and a high abundance of syntroph-related hgcAsequences in peat metagenomes provide evidence for MeHg production by microorganisms growing in syntrophy. Collectively the results suggest that wetland nutrient regimes influence the activity of Hg methylating microorganisms and, consequently, Hg methylation rates. Our results provide key information about microbial Hg methylation and methylating communities under nutrient conditions that are expected to become more common as permafrost soils thaw.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

High methylation potential of mercury complexed with mixed thiolate ligands by Geobacter sulfurreducens PCA

We report some thiols, such as cysteine (CYS) at moderate concentrations (10–500 µM), can enhance methylmercury (MeHg) formation by Geobacter sulfurreducens PCA, whereas others such as dithiol 2,3-dimercaptopropanesulfonate (DMPS) and 2,3-dimercaptosuccinic acid (DMSA) abolish mercury [Hg(II)] methylation. Little is known, however, about whether Hg(II) methylation could be enhanced or inhibited by the presence of mixed thiol ligands at low concentrations observed in the environment. Surprisingly we found that mixing CYS (1 µM) with DMPS (0.025–0.5 µM) or DMSA (0.025–1 µM) substantially increased MeHg production by 1.5–3.5-fold, compared to the no-thiol control, whereas complexation with a single DMPS, or DMSA, or CYS (1 µM) strongly inhibited Hg(II) methylation. Pre-equilibration between Hg(II) and thiols before the addition of cells was necessary to observe enhanced methylation. Spectroscopic analyses indicated the formation of mixed or heteroleptic coordinated Hg(II)-S 3 /S 4 complexes, which likely facilitated exchange of Hg(II) with cells and its uptake and internal transfer to the HgcAB proteins required for methylation. These results suggest that the effects of thiols on Hg(II) methylation were more complex than previously thought (using a single thiol) and thus underscore the importance of understanding how mixed thiols and their interactions with Hg(II) may ultimately influence MeHg production in the natural environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Hg3(TeI)2 by Materials Project

Hg3(TeI)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a rectangular see-saw-like geometry to two Te2- and two equivalent I1- atoms. There are one shorter (2.75 Å) and one longer (2.77 Å) Hg–Te bond lengths. There are one shorter (3.12 Å) and one longer (3.30 Å) Hg–I bond lengths. In the second Hg2+ site, Hg2+ is bonded to two Te2- and two I1- atoms to form distorted HgTe2I2 trigonal pyramids that share corners with three equivalent HgTe2I4 octahedra and corners with two equivalent HgTe2I2 tetrahedra. The corner-sharing octahedra tilt angles range from 53–82°. There are one shorter (2.77 Å) and one longer (2.79 Å) Hg–Te bond lengths. There are one shorter (3.04 Å) and one longer (3.25 Å) Hg–I bond lengths. In the third Hg2+ site, Hg2+ is bonded to two equivalent Te2- and four I1- atoms to form corner-sharing HgTe2I4 octahedra. Both Hg–Te bond lengths are 2.73 Å. There are two shorter (3.58 Å) and two longer (3.76 Å) Hg–I bond lengths. In the fourth Hg2+ site, Hg2+ is bonded to two equivalent Te2- and two equivalent I1- atoms to form distorted HgTe2I2 tetrahedra that share corners with two equivalent HgTe2I4 octahedra and corners with four equivalent HgTe2I2 trigonal pyramids. The corner-sharing octahedral tilt angles are 87°. Both Hg–Te bond lengths are 2.78 Å. Both Hg–I bond lengths are 3.11 Å. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are two inequivalent I1- sites. In the first I1- site, I1- is bonded in a 2-coordinate geometry to three Hg2+ atoms. In the second I1- site, I1- is bonded in a 5-coordinate geometry to four Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg3(SBr)2 by Materials Project

Hg3(SBr)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two S2- and three Br1- atoms. Both Hg–S bond lengths are 2.46 Å. There are a spread of Hg–Br bond distances ranging from 2.94–3.58 Å. In the second Hg2+ site, Hg2+ is bonded to two S2- and four Br1- atoms to form distorted HgS2Br4 octahedra that share corners with four equivalent HgS2Br4 octahedra, a cornercorner with one HgS2Br3 square pyramid, edges with four equivalent HgS2Br4 octahedra, and an edgeedge with one HgS2Br3 square pyramid. The corner-sharing octahedra tilt angles range from 0–4°. There are one shorter (2.43 Å) and one longer (2.44 Å) Hg–S bond lengths. There are a spread of Hg–Br bond distances ranging from 3.21–3.48 Å. In the third Hg2+ site, Hg2+ is bonded to two equivalent S2- and three Br1- atoms to form a mixture of distorted edge and corner-sharing HgS2Br3 square pyramids. The corner-sharing octahedral tilt angles are 64°. Both Hg–S bond lengths are 2.46 Å. There are a spread of Hg–Br bond distances ranging from 2.94–3.38 Å. In the fourth Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two equivalent S2- and three Br1- atoms. Both Hg–S bond lengths are 2.45 Å. There are a spread of Hg–Br bond distances ranging from 3.01–3.31 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are five inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 6-coordinate geometry to six Hg2+ atoms. In the second Br1- site, Br1- is bonded in a 5-coordinate geometry to five Hg2+ atoms. In the third Br1- site, Br1- is bonded in a distorted square co-planar geometry to four equivalent Hg2+ atoms. In the fourth Br1- site, Br1- is bonded in a distorted body-centered cubic geometry to eight Hg2+ atoms. In the fifth Br1- site, Br1- is bonded in a distorted trigonal non-coplanar geometry to three Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TiAgHg2 by Materials Project

TiAgHg2 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ti is bonded to four equivalent Ag and eight equivalent Hg atoms to form TiAg4Hg8 cuboctahedra that share corners with twelve equivalent TiAg4Hg8 cuboctahedra, edges with eight equivalent AgTi4Hg8 cuboctahedra, edges with sixteen equivalent HgTi4Ag4Hg4 cuboctahedra, faces with four equivalent AgTi4Hg8 cuboctahedra, faces with six equivalent TiAg4Hg8 cuboctahedra, and faces with eight equivalent HgTi4Ag4Hg4 cuboctahedra. All Ti–Ag bond lengths are 3.11 Å. All Ti–Hg bond lengths are 3.03 Å. Ag is bonded to four equivalent Ti and eight equivalent Hg atoms to form AgTi4Hg8 cuboctahedra that share corners with twelve equivalent AgTi4Hg8 cuboctahedra, edges with eight equivalent TiAg4Hg8 cuboctahedra, edges with sixteen equivalent HgTi4Ag4Hg4 cuboctahedra, faces with four equivalent TiAg4Hg8 cuboctahedra, faces with six equivalent AgTi4Hg8 cuboctahedra, and faces with eight equivalent HgTi4Ag4Hg4 cuboctahedra. All Ag–Hg bond lengths are 3.03 Å. Hg is bonded to four equivalent Ti, four equivalent Ag, and four equivalent Hg atoms to form distorted HgTi4Ag4Hg4 cuboctahedra that share corners with twelve equivalent HgTi4Ag4Hg4 cuboctahedra, edges with eight equivalent TiAg4Hg8 cuboctahedra, edges with eight equivalent AgTi4Hg8 cuboctahedra, edges with eight equivalent HgTi4Ag4Hg4 cuboctahedra, faces with four equivalent TiAg4Hg8 cuboctahedra, faces with four equivalent AgTi4Hg8 cuboctahedra, and faces with ten equivalent HgTi4Ag4Hg4 cuboctahedra. All Hg–Hg bond lengths are 3.11 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg2NO4 by Materials Project

HgHgONO3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of four nitric acid molecules and one HgHgO sheet oriented in the (1, 0, 0) direction. In the HgHgO sheet, there are two inequivalent Hg+1.50+ sites. In the first Hg+1.50+ site, Hg+1.50+ is bonded in a 2-coordinate geometry to two equivalent O2- atoms. Both Hg–O bond lengths are 2.11 Å. In the second Hg+1.50+ site, Hg+1.50+ is bonded in a 1-coordinate geometry to two equivalent O2- atoms. There are one shorter (2.20 Å) and one longer (3.02 Å) Hg–O bond lengths. O2- is bonded to four Hg+1.50+ atoms to form a mixture of distorted edge and corner-sharing OHg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GaHg2SbCl4 by Materials Project

Hg2GaSbCl4 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two Sb3- and four Cl1- atoms. There are one shorter (2.75 Å) and one longer (2.76 Å) Hg–Sb bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.36–3.59 Å. In the second Hg2+ site, Hg2+ is bonded to two Sb3- and four Cl1- atoms to form distorted HgSb2Cl4 octahedra that share a cornercorner with one HgSb2Cl3 square pyramid, corners with four GaCl4 tetrahedra, and a faceface with one HgSb2Cl3 square pyramid. Both Hg–Sb bond lengths are 2.77 Å. There are a spread of Hg–Cl bond distances ranging from 3.25–3.48 Å. In the third Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two Sb3- and four Cl1- atoms. Both Hg–Sb bond lengths are 2.76 Å. There are a spread of Hg–Cl bond distances ranging from 3.19–3.55 Å. In the fourth Hg2+ site, Hg2+ is bonded to two Sb3- and three Cl1- atoms to form distorted HgSb2Cl3 square pyramids that share a cornercorner with one HgSb2Cl4 octahedra, corners with three GaCl4 tetrahedra, and a faceface with one HgSb2Cl4 octahedra. The corner-sharing octahedral tilt angles are 64°. There are one shorter (2.76 Å) and one longer (2.77 Å) Hg–Sb bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.23–3.46 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four Cl1- atoms to form GaCl4 tetrahedra that share corners with two equivalent HgSb2Cl4 octahedra and corners with two equivalent HgSb2Cl3 square pyramids. The corner-sharing octahedra tilt angles range from 36–64°. There are a spread of Ga–Cl bond distances ranging from 2.18–2.22 Å. In the second Ga3+ site, Ga3+ is bonded to four Cl1- atoms to form GaCl4 tetrahedra that share corners with two equivalent HgSb2Cl4 octahedra and a cornercorner with one HgSb2Cl3 square pyramid. The corner-sharing octahedra tilt angles range from 23–77°. There are a spread of Ga–Cl bond distances ranging from 2.19–2.22 Å. There are two inequivalent Sb3- sites. In the first Sb3- site, Sb3- is bonded to four Hg2+ atoms to form corner-sharing SbHg4 tetrahedra. In the second Sb3- site, Sb3- is bonded to four Hg2+ atoms to form corner-sharing SbHg4 tetrahedra. There are eight inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Ga3+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Ga3+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ and one Ga3+ atom. In the fourth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Ga3+ atom. In the fifth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Ga3+ atom. In the sixth Cl1- site, Cl1- is bonded in a single-bond geometry to two Hg2+ and one Ga3+ atom. In the seventh Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Ga3+ atom. In the eighth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Ga3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlHg2SbCl4 by Materials Project

Hg2AlSbCl4 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to two Sb3- and three Cl1- atoms to form distorted HgSb2Cl3 square pyramids that share a cornercorner with one HgSb2Cl4 octahedra, corners with two equivalent HgSb2Cl3 square pyramids, corners with three AlCl4 tetrahedra, and a faceface with one HgSb2Cl4 octahedra. The corner-sharing octahedral tilt angles are 61°. There are one shorter (2.75 Å) and one longer (2.76 Å) Hg–Sb bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.37–3.46 Å. In the second Hg2+ site, Hg2+ is bonded to two Sb3- and four Cl1- atoms to form distorted HgSb2Cl4 octahedra that share corners with two HgSb2Cl3 square pyramids, corners with four AlCl4 tetrahedra, and faces with two HgSb2Cl3 square pyramids. Both Hg–Sb bond lengths are 2.77 Å. There are a spread of Hg–Cl bond distances ranging from 3.24–3.50 Å. In the third Hg2+ site, Hg2+ is bonded to two Sb3- and three Cl1- atoms to form distorted HgSb2Cl3 square pyramids that share a cornercorner with one HgSb2Cl4 octahedra, corners with two equivalent HgSb2Cl3 square pyramids, corners with three AlCl4 tetrahedra, and a faceface with one HgSb2Cl4 octahedra. The corner-sharing octahedral tilt angles are 64°. There are one shorter (2.76 Å) and one longer (2.77 Å) Hg–Sb bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.23–3.48 Å. In the fourth Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two Sb3- and four Cl1- atoms. Both Hg–Sb bond lengths are 2.76 Å. There are a spread of Hg–Cl bond distances ranging from 3.22–3.57 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four Cl1- atoms to form AlCl4 tetrahedra that share corners with two equivalent HgSb2Cl4 octahedra and corners with three HgSb2Cl3 square pyramids. The corner-sharing octahedra tilt angles range from 35–63°. There are a spread of Al–Cl bond distances ranging from 2.14–2.17 Å. In the second Al3+ site, Al3+ is bonded to four Cl1- atoms to form AlCl4 tetrahedra that share corners with two equivalent HgSb2Cl4 octahedra and corners with three HgSb2Cl3 square pyramids. The corner-sharing octahedra tilt angles range from 23–76°. There are a spread of Al–Cl bond distances ranging from 2.15–2.17 Å. There are two inequivalent Sb3- sites. In the first Sb3- site, Sb3- is bonded to four Hg2+ atoms to form corner-sharing SbHg4 tetrahedra. In the second Sb3- site, Sb3- is bonded to four Hg2+ atoms to form corner-sharing SbHg4 tetrahedra. There are eight inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Al3+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Al3+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ and one Al3+ atom. In the fourth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Al3+ atom. In the fifth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Al3+ atom. In the sixth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two Hg2+ and one Al3+ atom. In the seventh Cl1- site, Cl1- is bonded in a single-bond geometry to one Hg2+ and one Al3+ atom. In the eighth Cl1- site, Cl1- is bonded in a single-bond geometry to two Hg2+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdHg4(AsI2)2 by Materials Project

(Hg2As)2(CdI4) crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to two As3- and three I1- atoms to form HgAs2I3 trigonal bipyramids that share corners with three equivalent CdI4 tetrahedra, corners with two equivalent HgAs2I3 trigonal bipyramids, and an edgeedge with one HgAs2I3 trigonal bipyramid. Both Hg–As bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.48–3.54 Å. In the second Hg2+ site, Hg2+ is bonded in a distorted rectangular see-saw-like geometry to two As3- and two I1- atoms. There are one shorter (2.57 Å) and one longer (2.58 Å) Hg–As bond lengths. There are one shorter (3.39 Å) and one longer (3.63 Å) Hg–I bond lengths. In the third Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two As3- and four I1- atoms. There are one shorter (2.57 Å) and one longer (2.58 Å) Hg–As bond lengths. There are a spread of Hg–I bond distances ranging from 3.58–3.86 Å. In the fourth Hg2+ site, Hg2+ is bonded to two As3- and three I1- atoms to form distorted HgAs2I3 trigonal bipyramids that share corners with three equivalent CdI4 tetrahedra, corners with two equivalent HgAs2I3 trigonal bipyramids, and an edgeedge with one HgAs2I3 trigonal bipyramid. Both Hg–As bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.44–3.87 Å. Cd2+ is bonded to four I1- atoms to form CdI4 tetrahedra that share corners with six HgAs2I3 trigonal bipyramids. There are a spread of Cd–I bond distances ranging from 2.81–2.87 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded to four Hg2+ atoms to form corner-sharing AsHg4 tetrahedra. In the second As3- site, As3- is bonded to four Hg2+ atoms to form corner-sharing AsHg4 tetrahedra. There are four inequivalent I1- sites. In the first I1- site, I1- is bonded in a 1-coordinate geometry to three Hg2+ and one Cd2+ atom. In the second I1- site, I1- is bonded in a 1-coordinate geometry to three Hg2+ and one Cd2+ atom. In the third I1- site, I1- is bonded in a 1-coordinate geometry to three Hg2+ and one Cd2+ atom. In the fourth I1- site, I1- is bonded in a 1-coordinate geometry to three Hg2+ and one Cd2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg3(SeI)2 by Materials Project

Hg3Se2I2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two Se2- and four I1- atoms. There are one shorter (2.58 Å) and one longer (2.60 Å) Hg–Se bond lengths. There are a spread of Hg–I bond distances ranging from 3.17–3.93 Å. In the second Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two equivalent Se2- and four I1- atoms. Both Hg–Se bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.22–3.88 Å. In the third Hg2+ site, Hg2+ is bonded to two Se2- and four I1- atoms to form a mixture of distorted corner and edge-sharing HgSe2I4 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. Both Hg–Se bond lengths are 2.57 Å. There are a spread of Hg–I bond distances ranging from 3.40–3.69 Å. In the fourth Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two equivalent Se2- and two I1- atoms. Both Hg–Se bond lengths are 2.60 Å. There are one shorter (3.07 Å) and one longer (3.23 Å) Hg–I bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are five inequivalent I1- sites. In the first I1- site, I1- is bonded in a 4-coordinate geometry to four Hg2+ atoms. In the second I1- site, I1- is bonded in a distorted trigonal non-coplanar geometry to three Hg2+ atoms. In the third I1- site, I1- is bonded in a 6-coordinate geometry to six Hg2+ atoms. In the fourth I1- site, I1- is bonded in a 8-coordinate geometry to eight Hg2+ atoms. In the fifth I1- site, I1- is bonded in a 4-coordinate geometry to ten Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ga2(Hg4Te5)3 by Materials Project

Ga2(Hg4Te5)3 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are eight inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to four Te2- atoms to form HgTe4 tetrahedra that share corners with two equivalent GaTe4 tetrahedra and corners with nine HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.85–2.89 Å. In the second Hg2+ site, Hg2+ is bonded to four Te2- atoms to form corner-sharing HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.86–2.88 Å. In the third Hg2+ site, Hg2+ is bonded to four Te2- atoms to form HgTe4 tetrahedra that share corners with two equivalent GaTe4 tetrahedra and corners with nine HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.85–2.89 Å. In the fourth Hg2+ site, Hg2+ is bonded to four Te2- atoms to form corner-sharing HgTe4 tetrahedra. There are two shorter (2.86 Å) and two longer (2.88 Å) Hg–Te bond lengths. In the fifth Hg2+ site, Hg2+ is bonded to four Te2- atoms to form corner-sharing HgTe4 tetrahedra. There are three shorter (2.86 Å) and one longer (2.88 Å) Hg–Te bond lengths. In the sixth Hg2+ site, Hg2+ is bonded to four Te2- atoms to form HgTe4 tetrahedra that share corners with two equivalent GaTe4 tetrahedra and corners with nine HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.79–2.93 Å. In the seventh Hg2+ site, Hg2+ is bonded to four Te2- atoms to form corner-sharing HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.86–2.89 Å. In the eighth Hg2+ site, Hg2+ is bonded to four Te2- atoms to form HgTe4 tetrahedra that share corners with two equivalent GaTe4 tetrahedra and corners with nine HgTe4 tetrahedra. There are a spread of Hg–Te bond distances ranging from 2.79–2.93 Å. Ga3+ is bonded to four Te2- atoms to form GaTe4 tetrahedra that share corners with three equivalent GaTe4 tetrahedra and corners with six HgTe4 tetrahedra. There are one shorter (2.68 Å) and three longer (2.71 Å) Ga–Te bond lengths. There are ten inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to four Hg2+ atoms to form corner-sharing TeHg4 tetrahedra. In the second Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to three Hg2+ atoms. In the third Te2- site, Te2- is bonded to four Hg2+ atoms to form corner-sharing TeHg4 tetrahedra. In the fourth Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to one Hg2+ and two equivalent Ga3+ atoms. In the fifth Te2- site, Te2- is bonded to three Hg2+ and one Ga3+ atom to form corner-sharing TeGaHg3 tetrahedra. In the sixth Te2- site, Te2- is bonded in a distorted trigonal non-coplanar geometry to one Hg2+ and two equivalent Ga3+ atoms. In the seventh Te2- site, Te2- is bonded to four Hg2+ atoms to form corner-sharing TeHg4 tetrahedra. In the eighth Te2- site, Te2- is bonded to four Hg2+ atoms to form corner-sharing TeHg4 tetrahedra. In the ninth Te2- site, Te2- is bonded to four Hg2+ atoms to form corner-sharing TeHg4 tetrahedra. In the tenth Te2- site, Te2- is bonded to four Hg2+ atoms to form corner-sharing TeHg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfHg4(PCl3)2 by Materials Project

HfHg4(PCl3)2 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Hf4+ is bonded to six Cl1- atoms to form HfCl6 octahedra that share corners with two equivalent HgP2Cl4 octahedra and an edgeedge with one HgP2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are a spread of Hf–Cl bond distances ranging from 2.45–2.50 Å. There are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to two P3- and four Cl1- atoms to form distorted HgP2Cl4 octahedra that share corners with two equivalent HfCl6 octahedra, an edgeedge with one HfCl6 octahedra, and an edgeedge with one HgP2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 51–58°. There are one shorter (2.46 Å) and one longer (2.47 Å) Hg–P bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.14–3.32 Å. In the second Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two P3- and four Cl1- atoms. There are one shorter (2.43 Å) and one longer (2.44 Å) Hg–P bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.26–3.52 Å. In the third Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two P3- and four Cl1- atoms. There are one shorter (2.45 Å) and one longer (2.46 Å) Hg–P bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.11–3.45 Å. In the fourth Hg2+ site, Hg2+ is bonded in a distorted square co-planar geometry to two P3- and two Cl1- atoms. There are one shorter (2.44 Å) and one longer (2.45 Å) Hg–P bond lengths. There are one shorter (3.27 Å) and one longer (3.47 Å) Hg–Cl bond lengths. There are two inequivalent P3- sites. In the first P3- site, P3- is bonded to four Hg2+ atoms to form corner-sharing PHg4 tetrahedra. In the second P3- site, P3- is bonded to four Hg2+ atoms to form corner-sharing PHg4 tetrahedra. There are six inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 1-coordinate geometry to one Hf4+ and two Hg2+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two Hg2+ atoms. In the third Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two Hg2+ atoms. In the fourth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two Hg2+ atoms. In the fifth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and four Hg2+ atoms. In the sixth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(InHg)2 by Materials Project

Sr(HgIn)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Hg atoms. All Sr–Hg bond lengths are 3.57 Å. Hg is bonded in a 9-coordinate geometry to four equivalent Sr, one Hg, and four equivalent In atoms. The Hg–Hg bond length is 2.85 Å. All Hg–In bond lengths are 3.00 Å. In is bonded to four equivalent Hg atoms to form a mixture of distorted edge and corner-sharing InHg4 tetrahedra.

36 MATERIALS SCIENCE↗