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Motta LC, Autschbach J. Actinide inverse trans influence versus cooperative pushing from below and multi-center bonding. Nat Commun 2023; 14:4307. [PMID: 37463900 DOI: 10.1038/s41467-023-39626-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 06/22/2023] [Indexed: 07/20/2023] Open
Abstract
Actinide-ligand bonds with high multiplicities remain poorly understood. Decades ago, an effect known as 6p pushing from below (PFB) was proposed to enhance actinide covalency. A related effect-also poorly understood-is inverse trans influence (ITI). The present computational study of actinide-ligand covalent interactions with high bond multiplicities quantifies the energetic contributions from PFB and identifies a hitherto overlooked fourth bonding interaction for 2nd-row ligands in the studied organometallic systems. The latter are best described by a terminal O/N ligand exhibiting quadruple bonding interactions with the actinide. The 4th interaction may be characterized as a multi-center or charge-shift bond involving the trans ligand. It is shown in this work that the 4th bonding interaction is a manifestation of ITI, assisted by PFB, and provides a long-sought missing piece in the understanding of actinide chemistry.
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Affiliation(s)
- Laura C Motta
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY, 14260-3000, USA
- Department of Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543-1050, USA
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY, 14260-3000, USA.
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2
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Motta LC, Autschbach J. Theoretical Evaluation of Metal-Ligand Bonding in Neptunium Compounds in Relation to 237Np Mössbauer Spectroscopy. Inorg Chem 2022; 61:13399-13412. [PMID: 35960509 DOI: 10.1021/acs.inorgchem.2c01516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 237Np Mössbauer isomer shift and quadrupole splitting (QS) are powerful probes for the metal-ligand bonding of neptunium, a 5f-element of vital importance in the nuclear fuel cycle. A large set of Np compounds with different oxidation states (III) to (VII) is studied to investigate, by first-principles calculations, isomer shifts and the QS trends in relation to the Np oxidation state. Natural Bond Orbital analysis reveals that in addition to donation bonding to the 5f shell, participation of the 6d and 7s neptunium shells in covalent (donation) bonding substantially impacts the isomer shifts. The isomer shift cannot be interpreted solely by the 5f shell electron count. The isomer shift for Np(II) compounds is estimated to be in the range of 31-34 mm/s, less positive than for Np(III) compounds. For the QS, density functional calculations fail to reproduce the quadrupole splitting for some Np(VI) ionic solids. A multiconfigurational wave function approach reproduces the observed QS trends. The calculations give a semiquantitative interpretation of the trends for Np oxidation states (V) to (VII). The contrasting QS for standard and "reverse" neptunyl(VI), at the opposite extremes of the observed QS scale, arises predominantly from the different crystal environments.
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Affiliation(s)
- Laura C Motta
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States
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Yang YH, Kwon SY, Tsui MTK, Motta LC, Washburn SJ, Park J, Kim MS, Shin KH. Ecological Traits of Fish for Mercury Biomonitoring: Insights from Compound-Specific Nitrogen and Stable Mercury Isotopes. Environ Sci Technol 2022; 56:10808-10817. [PMID: 35852377 DOI: 10.1021/acs.est.2c02532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We coupled compound-specific isotopic analyses of nitrogen (N) in amino acids (δ15NGlu, δ15NPhe) and mercury stable isotopes (δ202Hg, Δ199Hg) to quantify ecological traits governing the concentration, variability, and source of Hg in largemouth bass (LB) and pike gudgeon (PG) across four rivers, South Korea. PG displayed uniform Hg concentration (56-137 ng/g), trophic position (TPcorrected; 2.6-3.0, n = 9), and N isotopes in the source amino acid (δ15NPhe; 7-13‰), consistent with their specialist feeding on benthic insects. LB showed wide ranges in Hg concentration (45-693 ng/g), TPcorrected (2.8-3.8, n = 14), and δ15NPhe (1.3-16‰), reflecting their opportunistic feeding behavior. Hg sources assessed using Hg isotopes reveal low and uniform Δ199Hg in PG (0.20-0.49‰), similar to Δ199Hg reported in sediments. LB displayed site-specific δ202Hg (-0.61 to -0.04‰) and Δ199Hg (0.53-1.09‰). At the Yeongsan River, LB displayed elevated Δ199Hg and low δ15NPhe, consistent with Hg and N sourced from the atmosphere. LB at the Geum River displayed low Δ199Hg and high δ15NPhe, both similar to the isotope values of anthropogenic sources. Our results suggest that a specialist fish (PG) with consistent ecological traits and Hg concentration is an effective bioindicator species for Hg. When accounting for Hg sources, however, LB better captures site-specific Hg sources.
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Affiliation(s)
- Yo Han Yang
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, South Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, South Korea
- Institute for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, South Korea
| | - Martin Tsz-Ki Tsui
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, South Block, Science Centre, Shatin, Hong Kong SAR 999077, China
| | - Laura C Motta
- Department of Chemistry, State University of New York at Buffalo, 312 Natural Sciences Complex, Buffalo, New York 14260-3000, United States
| | - Spencer J Washburn
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Jaeseon Park
- Environmental Measurement & Analysis Center, National Institute of Environmental Research, 42 Hwangyong-Ro, Seo-Gu, Incheon 22689, South Korea
| | - Min-Seob Kim
- Environmental Measurement & Analysis Center, National Institute of Environmental Research, 42 Hwangyong-Ro, Seo-Gu, Incheon 22689, South Korea
| | - Kyung-Hoon Shin
- Department of Marine Sciences and Convergent Technology, Hanyang University, 55 Hanyangdaehak-Ro, Sangnok-Gu, Ansan 15588, South Korea
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Li ML, Kwon SY, Poulin BA, Tsui MTK, Motta LC, Cho M. Internal Dynamics and Metabolism of Mercury in Biota: A Review of Insights from Mercury Stable Isotopes. Environ Sci Technol 2022; 56:9182-9195. [PMID: 35723432 PMCID: PMC9261262 DOI: 10.1021/acs.est.1c08631] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Monitoring mercury (Hg) levels in biota is considered an important objective for the effectiveness evaluation of the Minamata Convention. While many studies have characterized Hg levels in organisms at multiple spatiotemporal scales, concentration analyses alone often cannot provide sufficient information on the Hg exposure sources and internal processes occurring within biota. Here, we review the decadal scientific progress of using Hg isotopes to understand internal processes that modify the speciation, transport, and fate of Hg within biota. Mercury stable isotopes have emerged as a powerful tool for assessing Hg sources and biogeochemical processes in natural environments. A better understanding of the tissue location and internal mechanisms leading to Hg isotope change is key to assessing its use for biomonitoring. We synthesize the current understanding and uncertainties of internal processes leading to Hg isotope fractionation in a variety of biota, in a sequence of better to less studied organisms (i.e., birds, marine mammals, humans, fish, plankton, and invertebrates). This review discusses the opportunities and challenges of using certain forms of biota for Hg source monitoring and the need to further elucidate the physiological mechanisms that control the accumulation, distribution, and toxicity of Hg in biota by coupling new techniques with Hg stable isotopes.
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Affiliation(s)
- Mi-Ling Li
- School
of Marine Science and Policy, University
of Delaware, 201 Robinson Hall, Newark, Delaware 19716, United
States
| | - Sae Yun Kwon
- Division
of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro,
Nam-Gu, Pohang 37673, South Korea
- Institute
for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon 21983, South Korea
| | - Brett A. Poulin
- Department
of Environmental Toxicology, University
of California Davis, One Shields Avenue, Davis, California 95616, United States
| | - Martin Tsz-Ki Tsui
- School
of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR 999077, China
| | - Laura C. Motta
- Department
of Chemistry, University at Buffalo, 359 Natural Sciences Complex, Buffalo, New York 14260-3000, United States
| | - Moonkyoung Cho
- Division
of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro,
Nam-Gu, Pohang 37673, South Korea
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Motta LC, Autschbach J. 237Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes. J Chem Theory Comput 2022; 18:3483-3496. [PMID: 35594193 DOI: 10.1021/acs.jctc.2c00194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A large set of neptunium compounds with different oxidation states (III to VII) was assembled to study the Mössbauer isomer shift by wave function calculations and better understand covalency in f-elements complexes. The contact density approach was used to calculate the isomer shift using complete active space self-consistent field (CASSCF) multiconfiguration wave functions, as well as matrix product states [from Density Matrix Renormalization Group (DMRG) algorithms] for large active spaces. Dynamic correlation effects for the isomer shifts were treated via CASPT2 energy derivatives with respect to the nuclear radius. The CASSCF calculations appear to produce different orbital overlocalization errors for low and high Np oxidation states. For compounds with low Np oxidation numbers, the errors can be attributed to the overlocalization of the 5f orbitals. For the compounds with high Np oxidation numbers, the main errors arise from an overlocalization of ligand orbitals and concomitant to weak donation bonding. Attempts to mitigate the overlocalization errors with large active spaces using DMRG were only partially successful, showing that explicit treatment of dynamic correlation is necessary for accurate predictions of Mössbauer isomer shifts. The CASPT2 calculations perform very satisfactorily. For a subset of Np compounds, both static and dynamic correlation effects were substantial. A rational active space selection based on orbital entanglement diagrams proved beneficial for determining the optimal reference wave function.
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Affiliation(s)
- Laura C Motta
- Department of Chemistry, University at Buffalo State University of New York, Buffalo, New York 14260-3000, United States
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo State University of New York, Buffalo, New York 14260-3000, United States
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Jung S, Kwon SY, Hong Y, Yin R, Motta LC. Isotope investigation of mercury sources in a creek impacted by multiple anthropogenic activities. Chemosphere 2021; 282:130947. [PMID: 34119733 DOI: 10.1016/j.chemosphere.2021.130947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/09/2021] [Accepted: 05/18/2021] [Indexed: 06/12/2023]
Abstract
To investigate mercury (Hg) sources responsible for contamination at Gumu Creek in South Korea, Hg concentration (THg) and Hg isotope ratios were measured in the soil and sediment of Gumu Creek and the samples from a hazardous waste landfill (HWL). The THg ranged between 0.29-327 mg kg-1 and 9.5-414 mg kg-1 in the soil and sediment, respectively, reflecting heterogeneous distribution and elevated levels across the entire Gumu Creek. Without the soil with the lowest THg (0.30 ± 0.01 mg kg-1, n = 3), the δ202Hg (-0.83 to -0.18‰) and Δ199Hg (-0.24 to 0.01‰) of the sediment and soil of Gumu Creek were within the ranges of the HWL samples (δ202Hg; -1.29 to -0.38‰, Δ199Hg; -0.31 to 0.01‰). The comparison with the literature reporting sediment Hg isotope ratios impacted by various anthropogenic Hg sources revealed a presence of diverse Hg sources at Gumu Creek, including commercial liquid Hg, phenyl-Hg, and fly ash, consistent with the types of waste deposited within the HWL. Using commercial liquid Hg, fly ash, and the soil with the lowest THg as end-members, the ternary mixing model yielded 25-88% and 12-57% contributions from commercial liquid Hg and fly ash to the Gumu Creek sediment, respectively. The results of our study suggest that Hg isotope ratios are an effective tool for screening potential Hg sources at sites where the distribution of Hg is heterogeneous and multiple anthropogenic activities exist.
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Affiliation(s)
- Saebom Jung
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, South Korea
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, South Korea; Institute for Convergence Research and Education in Advanced Technology, Yonsei University, 85 Songdogwahak-Ro, Yeonsu-Gu, Incheon, 21983, South Korea.
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University, 2511 Sejong-Ro, Sejong City, 30019, South Korea
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550081, Guiyang, China
| | - Laura C Motta
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, 37673, South Korea
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Abstract
Different theoretical approaches for the calculation of 237Np Mössbauer isomer shifts are investigated. The traditional contact density route is compared to a previously proposed alternative approach that uses energy derivatives with respect to the nuclear radius. Both approaches yield similar results as long as suitable basis sets augmented with large exponents and relativistic methods are used. Density functional theory (DFT) calculations do not show a strong dependency of the 237Np isomer shift on the chosen functional. Wavefunction calculations show that dynamic electron correlation can be important when covalent bonding influences the isomer shift. Effects from spin-orbit coupling are small. The isomer shifts of ionic solids and Np(III) organometallic complexes are largely governed by the oxidation state of Np. Isomer shifts of organometallic Np(IV) complexes are strongly affected by donation bonding. Detailed analysis of the wavefunction results with different active spaces demonstrates that correlation among the outer core Np and occupied ligand frontier orbitals contributes significantly to isomer shifts of Np(IV) compounds.
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Affiliation(s)
- Laura C Motta
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States
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Abstract
Large mass-independent fractionation signatures in Hg have been observed in the laboratory and the environment, prompting deep questions about the chemical reasons behind these signatures. Since the relative lack of mechanistic information about Hg chemistry in the environment has precluded explanations of these isotope effects, the present study uses high-level electronic structure methods to evaluate the possible photochemical mechanisms of mass-independent isotope effects (MIEs) in HgX2 and CH3HgX (X = Cl, Br, I, and SCH3). The results show that spin-orbit coupling wipes out the potential of MIEs for Hg bound to Br or I, but that complexes involving lighter elements, HgX2 and CH3HgX (X = Cl and SCH3), have relatively small spin-orbit couplings upon photolysis. This unexpected finding shows that magnetic isotope fractionation due to hyperfine coupling is possible, depending on the identity of the Hg complex. By examination of the photolysis potential energy profiles, this study shows that HgX2 complexes can have a positive or a negative MIE (depending on reaction conditions), while CH3HgX complexes exclusively result in a positive MIE. These findings agree with MIE recorded in natural samples, demonstrating a plausible mechanism for the surprising mass-independent fractionation of Hg in the environment.
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Affiliation(s)
- Laura C Motta
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Alan D Chien
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Alan E Rask
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Paul M Zimmerman
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
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Motta LC, Kritee K, Blum JD, Tsz-Ki Tsui M, Reinfelder JR. Mercury Isotope Fractionation during the Photochemical Reduction of Hg(II) Coordinated with Organic Ligands. J Phys Chem A 2020; 124:2842-2853. [DOI: 10.1021/acs.jpca.9b06308] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laura C. Motta
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - K. Kritee
- Environmental Defense Fund, Boulder, Colorado 80302, United States
| | - Joel D. Blum
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Martin Tsz-Ki Tsui
- Department of Biology, University of North Carolina at Greensboro, North Carolina 27402, United States
| | - John R. Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey 08901, United States
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