Publications by authors named "Brian L Scott"

211 Publications

Crystallographic characterization of (CHSiMe)U(BH).

Acta Crystallogr E Crystallogr Commun 2021 Apr 12;77(Pt 4):383-389. Epub 2021 Mar 12.

Department of Chemistry, University of California, Irvine, California 92697, USA.

New syntheses have been developed for the synthesis of (borohydrido-κ)tris-[η-(tri-methyl-sil-yl)cyclo-penta-dien-yl]uranium(IV), [U(BH)(CHSi)] or Cp'U(BH) (Cp' = CHSiMe) and its structure has been determined by single-crystal X-ray crystallography. This compound crystallized in the space group and the structure features three -coordinated Cp' rings and a -coordinated (BH) ligand.
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http://dx.doi.org/10.1107/S2056989021002425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8025856PMC
April 2021

A lobulated mass on the upper back with prominent vasculature: A giant basal cell carcinoma.

Dermatol Reports 2021 Mar 7;13(1):9046. Epub 2021 Apr 7.

Department of Dermatology, UT Southwestern Medical Center, Dallas, TX.

Basal cell carcinoma (BCC) is characterized by slow but locally invasive growth. Although there is low metastatic potential, if not treated early, these skin cancers can lead to significant morbidity and mortality. In this case report, we present a man with a neglected BCC that developed into what is termed a giant BCC or one that is greater than 5 cm. This tumor was discovered only upon workup of orthostatic lightheadedness and iron deficiency anemia. Although rare, basal cell carcinoma must be included on the differential of a large cutaneous lesion and may be a source of significant blood loss.
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http://dx.doi.org/10.4081/dr.2021.9046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8056320PMC
March 2021

Autologous Fat Grafting in Facial Cosmetic Surgery: A National Survey.

Facial Plast Surg 2021 Feb 12;37(1):136-138. Epub 2021 Apr 12.

Department of Otolaryngology - Head and Neck Surgery, Oregon Health and Science University, Portland, Oregon.

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http://dx.doi.org/10.1055/s-0040-1721098DOI Listing
February 2021

Expanding the Nonaqueous Chemistry of Neptunium: Synthesis and Structural Characterization of [Np(NR)Cl], [Np(NR)Cl], and [Np{(R)(SiMeH)}(NR)] (R = SiMe).

Inorg Chem 2021 Feb 4;60(4):2740-2748. Epub 2021 Feb 4.

Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States.

Reaction of 3 equiv of NaNR (R = SiMe) with NpCl(DME) in THF afforded the Np(IV) silylamide complex, [Np(NR)Cl] (), in good yield. Reaction of with 1.5 equiv of KC in THF, in the presence of 1 equiv of dibenzo-18-crown-6, resulted in formation of [{K(DB-18-C-6)(THF)}(μ-Cl)][Np(NR)Cl] (), also in good yield. Complex represents the first structurally characterized Np(III) amide. Finally, reaction of NpCl(DME) with 5 equiv of NaNR and 1 equiv of dibenzo-18-crown-6 afforded the Np(IV) bis(metallacycle), [{Na(DB-18-C-6)(EtO)(κ-DME)}(μ-DME)][Np{(R)(SiMeH)}(NR)] (), in moderate yield. Complex was characterized by H NMR spectroscopy and X-ray crystallography and represents a rare example of a structurally characterized neptunium-hydrocarbyl complex. To support these studies, we also synthesized the uranium analogues of and , namely, [K(2,2,2-cryptand)][U(NR)Cl] (), [K(DB-18-C-6)(THF)][U(NR)Cl] (), [Na(DME)][U{(R)(SiMeH)}(NR)] (), and [{Na(DB-18-C-6)(EtO)(κ-DME)}(μ-DME)][U{(R)(SiMeH)}(NR)] (). Complexes , , , and were characterized by a number of techniques, including NMR spectroscopy and X-ray crystallography.
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http://dx.doi.org/10.1021/acs.inorgchem.0c03616DOI Listing
February 2021

Structural and Spectroscopic Comparison of Soft-Se vs. Hard-O Donor Bonding in Trivalent Americium/Neodymium Molecules.

Angew Chem Int Ed Engl 2021 Apr 10;60(17):9459-9466. Epub 2021 Mar 10.

Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.

Covalency is often considered to be an influential factor in driving An vs. Ln selectivity invoked by soft donor ligands. This is intensely debated, particularly the extent to which An /Ln covalency differences prevail and manifest as the f-block is traversed, and the effects of periodic breaks beyond Pu. Herein, two Am complexes, [Am{N(E=PPh ) } ] (1-Am, E=Se; 2-Am, E=O) are compared to isoradial [Nd{N(E=PPh ) } ] (1-Nd, 2-Nd) complexes. Covalent contributions are assessed and compared to U/La and Pu/Ce analogues. Through ab initio calculations grounded in UV-vis-NIR spectroscopy and single-crystal X-ray structures, we observe differences in f orbital involvement between Am-Se and Nd-Se bonds, which are not present in O-donor congeners.
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http://dx.doi.org/10.1002/anie.202017186DOI Listing
April 2021

Monolithic Nanoporous Gold Foams with Catalytic Activity for Chemical Vapor Deposition Growth of Carbon Nanostructures.

ACS Appl Mater Interfaces 2021 Jan 24;13(1):1204-1213. Epub 2020 Dec 24.

Los Alamos National Laboratory MS J964, Los Alamos, New Mexico 87545, United States.

While bulk gold is generally considered to be a catalytically inactive material, nanostructured forms of gold can in fact be highly catalytically active. However, few methods exist for preparing high-purity macroscopic forms of catalytically active gold. In this work, we describe the synthesis of catalytically active macroscopic nanoporous gold foams via combustion synthesis of gold bis(tetrazolato)amine complexes. The resulting metallically pure porous gold nanoarchitectures exhibit bulk densities of <0.1 g/cm and Brunauer-Emmett-Teller (BET) surface areas as high as 10.9 m/g, making them among the lowest-density and highest-surface-area monolithic forms of gold produced to date. Thanks to the presence of a highly nanostructured gold surface, such gold nanofoams have also been found to be highly catalytically active toward thermal chemical vapor deposition (CVD) growth of carbon nanotubes, providing a novel method for direct synthesis of carbon nanostructures on macroscopic gold substrates. In contrast, analogous copper nanofoams were found to be catalytically inactive toward the growth of graphitic nanostructures under the same synthesis conditions, highlighting the unusually high catalytic propensity of this form factor of gold. The combustion synthesis process described herein represents a never-wet approach for directly synthesizing macroscopic catalytically active gold. Unlike sol-gel and dealloying approaches, combustion synthesis eliminates the time-consuming diffusion-mediated steps associated with previous methods and offers multiple degrees of freedom for tuning morphology, electrical conductivity, and mechanical properties.
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http://dx.doi.org/10.1021/acsami.0c17624DOI Listing
January 2021

Low-spin 1,1'-diphosphametallocenates of chromium and iron.

Chem Commun (Camb) 2021 Jan;57(5):595-598

Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA. and Department of Chemistry, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.

We report two anionic diphosphametallocenates, [K(2.2.2-crypt)][M(PC4Me4)2] (M = Cr, 2-Cr; Fe, 2-Fe). Both are low-spin (S = ½) by EPR spectroscopy and SQUID magnetometry. This contrasts the high-spin (S = 3/2) ferrocenate, [K(2.2.2-crypt)][Fe(C5H2-1,2,4-tBu)2] (4-Fe). Quantum chemical calculations suggest this is due to significant differences in ligand field splitting of the d-orbitals which also explain structural features in the 2-M complexes.
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http://dx.doi.org/10.1039/d0cc06518hDOI Listing
January 2021

Lanthanide Complexes of Bis(tetrazolato)amine: A Route to Lanthanide Nitride Foams.

Inorg Chem 2020 Nov 4;59(22):16109-16116. Epub 2020 Nov 4.

Naval Research Laboratory, Code 6030, Washington, D.C. 20375, United States.

Metal nitrides are strong refractory ceramic materials known for applications in the coatings, catalysis, and semiconductor industries. Lanthanide nitrides are difficult to prepare in high purity and often require high temperatures and sophisticated equipment. In this work, we present an approach to the synthesis of high-purity f-element nitrides through the use of simple lanthanide salts and the nitrogen-rich ligand 5,5'-bis(1H-tetrazolyl)amine (HBTA) to form lanthanide complexes of 5,5'-bis(tetrazolato)amine (BTA). We have demonstrated that, when dehydrated, these types of complexes undergo a self-sustained combustion reaction under an inert atmosphere to yield nanostructured f-element nitride foams for lanthanum and cerium. The synthesis, characterization, and single-crystal X-ray crystallography of the BTA complexes of lanthanum, cerium, praseodymium, neodymium, and europium are also discussed.
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http://dx.doi.org/10.1021/acs.inorgchem.0c02480DOI Listing
November 2020

Case Report of Delayed Auricular Reconstruction Using a Porous Polyethylene Implant for an Advanced Skin Cancer.

Ear Nose Throat J 2020 Aug 18:145561320950500. Epub 2020 Aug 18.

Department of Otolaryngology-Head and Neck Surgery, 6684Oregon Health & Science University, Portland, OR, USA.

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http://dx.doi.org/10.1177/0145561320950500DOI Listing
August 2020

Hydration of α-UO following storage under controlled conditions of temperature and relative humidity.

Dalton Trans 2020 Aug 17;49(30):10452-10462. Epub 2020 Jul 17.

Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Changes in chemical speciation of uranium oxides following storage under varied conditions of temperature and relative humidity are valuable for characterizing material provenance. In this study, subsamples of high purity α-UO were stored under four sets of controlled conditions of temperature and relative humidity over several years, and then measured periodically for chemical speciation. Powder X-ray diffraction (XRD) analysis and extended X-ray absorption fine structure spectroscopy confirm hydration of α-UO to a schoepite-like end product following storage under each of the varied storage conditions, but the species formed during exposure to the lower relative humidity and lower temperature condition follows different trends from those formed under the other three storage conditions (high relative humidity with high or low temperatures, and low relative humidity with a high temperature). Thermogravimetry coupled with XRD analysis was carried out to distinguish desorption pathways of water from the hydrated end products. Density functional theory calculations discern changes in the structure of α-UO following incorporation of 1, 2 or 3 HO molecules or 1, 2 or 3 OH groups into the orthorhombic lattice, revealing differences in lattice constants, U-O bond lengths, and U-U distances. The collective results from this analysis are in contrast to analogous studies that report that UO is oxidized and hydrated in air during storage under high relative humidity conditions.
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http://dx.doi.org/10.1039/d0dt01852jDOI Listing
August 2020

Employing Lewis Acidity to Generate Bimetallic Lanthanide Complexes.

Inorg Chem 2020 Jul 17;59(13):8642-8646. Epub 2020 Jun 17.

Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87544, United States.

With the advent of lanthanide-based technologies, there is a clear need to advance the fundamental understanding of 4f-element chelation chemistry. Herein, we contribute to a growing body of lanthanide chelation chemistry and report the synthesis of bimetallic 4f-element complexes within an imine/hemiacetalate framework, [Ln = lanthanide; TPT = tris(pyridineimine)(Tren)tris(methoxyhemiacetalate); Tren = tris(2-aminoethylamine)]. These products are generated from hydrolysis and methanolysis of the cage ligand tris(pyridinediimine)bis(Tren) (; Tadanobu et al. , (5), 859-862) likely facilitated by inductive effects stemming from the Lewis acidic lanthanide cations. These complexes are interesting because they result from imine cleavage to generate two metal binding sites: one pocketed site within the macrocycle and the other terminal site capping a hemiacetalate moiety. A clear demarcation in reactivity is observed between samarium and europium, where the lighter and larger lanthanides generate a mixture of products, and . Meanwhile, the heavier and smaller lanthanides generate exclusively bimetallic . The cleavage reactivity to form was extended beyond methanol to include other primary alcohols.
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http://dx.doi.org/10.1021/acs.inorgchem.0c00775DOI Listing
July 2020

Violaceous nodules in an HIV-positive man.

Dermatol Online J 2020 Feb 15;26(2). Epub 2020 Feb 15.

University of Texas Southwestern Medical Center, Dallas, TX.

Plasmablastic lymphoma (PBL) is a rare and aggressive malignancy associated with immunosuppression and the oncogenic effects of the Epstein-Barr virus (EBV). We present an HIV-positive man with PBL that presented as ulcers and violaceous exophytic nodules on the legs. The clinical features, histologic appearance, and differential diagnosis of this malignancy are briefly reviewed.
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February 2020

Actinide 2-metallabiphenylenes that satisfy Hückel's rule.

Nature 2020 02 26;578(7796):563-567. Epub 2020 Feb 26.

Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM, USA.

Aromaticity and antiaromaticity, as defined by Hückel's rule, are key ideas in organic chemistry, and are both exemplified in biphenylene-a molecule that consists of two benzene rings joined by a four-membered ring at its core. Biphenylene analogues in which one of the benzene rings has been replaced by a different (4n + 2) π-electron system have so far been associated only with organic compounds. In addition, efforts to prepare a zirconabiphenylene compound resulted in the isolation of a bis(alkyne) zirconocene complex instead. Here we report the synthesis and characterization of, to our knowledge, the first 2-metallabiphenylene compounds. Single-crystal X-ray diffraction studies reveal that these complexes have nearly planar, 11-membered metallatricycles with metrical parameters that compare well with those reported for biphenylene. Nuclear magnetic resonance spectroscopy, in addition to nucleus-independent chemical shift calculations, provides evidence that these complexes contain an antiaromatic cyclobutadiene ring and an aromatic benzene ring. Furthermore, spectroscopic evidence, Kohn-Sham molecular orbital compositions and natural bond orbital calculations suggest covalency and delocalization of the uranium f electrons with the carbon-containing ligand.
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http://dx.doi.org/10.1038/s41586-020-2004-7DOI Listing
February 2020

Advancing Chelation Chemistry for Actinium and Other +3 f-Elements, Am, Cm, and La.

J Am Chem Soc 2019 12 3;141(49):19404-19414. Epub 2019 Dec 3.

Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States of America.

A major chemical challenge facing implementation of Ac in targeted alpha therapy-an emerging technology that has potential for treatment of disease-is identifying an Ac chelator that is compatible with applications. It is unclear how to tailor a chelator for Ac binding because Ac coordination chemistry is poorly defined. Most Ac chemistry is inferred from radiochemical experiments carried out on microscopic scales. Of the few Ac compounds that have been characterized spectroscopically, success has only been reported for simple inorganic ligands. Toward advancing understanding in Ac chelation chemistry, we have developed a method for characterizing Ac complexes that contain highly complex chelating agents using small quantities (μg) of Ac. We successfully characterized the chelation of Ac by DOTP using EXAFS, NMR, and DFT techniques. To develop confidence and credibility in the Ac results, comparisons with +3 cations (Am, Cm, and La) that could be handled on the mg scale were carried out. We discovered that all M cations (M = Ac, Am, Cm, La) were completely encapsulated within the binding pocket of the DOTP macrocycle. The computational results highlighted the stability of the M(DOTP) complexes.
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http://dx.doi.org/10.1021/jacs.9b10354DOI Listing
December 2019

[Am(C Me H) ]: An Organometallic Americium Complex.

Angew Chem Int Ed Engl 2019 Aug 25;58(34):11695-11699. Epub 2019 Jul 25.

Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.

We report the small-scale synthesis, isolated yield, single-crystal X-ray structure, H NMR solution spectroscopy /solid-state UV/Vis-nIR spectroscopy, and density functional theory (DFT)/ab initio wave function theory calculations on an Am organometallic complex, [Am(C Me H) ] (1). This constitutes the first quantitative data on Am-C bonding in a molecular species.
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http://dx.doi.org/10.1002/anie.201905225DOI Listing
August 2019

Laryngomalacia and Swallow Dysfunction.

Ear Nose Throat J 2019 Dec 23;98(10):613-616. Epub 2019 May 23.

Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, OR, USA.

Objectives: Laryngomalacia is an established cause of stridor and sleep-disordered breathing in children. However, the relationship between laryngomalacia and dysphagia has not been well characterized. The objectives of this study were to (1) describe the patient characteristics, symptoms, and prevalence of dysphagia in children with laryngomalacia and (2) examine the effectiveness of supraglottoplasty in improving feeding.

Methods: This was a retrospective study of patients with laryngomalacia who underwent a modified barium swallow study (MBSS) at a tertiary academic pediatric medical center between March 1, 2014, and March 1, 2018. Patients were excluded if they did not undergo a MBSS. Comorbidities, airway and feedings symptoms, MBSS results, and surgical history were recorded from each patient's electronic medical record.

Results: Forty-four children met inclusion/exclusion criteria. The median age at presentation was 96 days. There was a male predominance (66%). About one-third had a genetic or neuromuscular comorbidity. Most children had stridor (93%) and feeding difficulty (86%), while 50% had parent-reported poor weight gain. Fifty-seven percent of patients had evidence of penetration or aspiration on MBSS. All patients with a positive MBSS had dysphagia symptoms. Fifty-seven percent of patients underwent supraglottoplasty. Postoperatively, 92% reported improvement in dysphagia symptoms.

Conclusion: Dysphagia is prevalent among a subset of children with laryngomalacia. Symptomatic children may benefit from a swallow evaluation to help determine the need for further intervention. Children who undergo supraglottoplasty for laryngomalacia have improved dysphagia at follow-up, though the amount of improvement directly attributable to surgery is unclear and warrants further investigation.
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http://dx.doi.org/10.1177/0145561319847459DOI Listing
December 2019

Oxidation of uranium(iv) mixed imido-amido complexes with PhEEPh and to generate uranium(vi) bis(imido) dichalcogenolates, U(NR)(EPh)(L).

Dalton Trans 2019 Aug 3;48(29):10865-10873. Epub 2019 May 3.

Chemistry Division, Los Alamos National Laboratory, MS J514, Los Alamos, New Mexico 87545, USA.

This work provides new routes for the conversion of U(iv) into U(vi) bis(imido) complexes and offers new information on the manner in which the U(vi) compounds form. Many compounds from the series described by the general formula U(NR)(EPh)(L) (R = 2,6-diisopropylphenyl, tert-butyl; E = S, Se, Te; L = py, EPh) were synthesized via oxidation of an in situ generated U(iv) amido-imido species with PhE. This synthetic sequence provides a general route into bis(imido) U(vi) chalcogenolate complexes, circumventing the need to perform problematic salt metathesis reactions on U(vi) iodides. Investigation into the speciation of the U(iv) complexes that form prior to oxidation found a significant dependence on the identity of the ancillary ligands, with Bubpy forming the isolable imido-(bis)amido complex, U(NDipp)(NHDipp)(Bubpy). Together, these data are consistent with the view that the bis(imido) U(vi) motif - much like the uranyl ion, UO- is a thermodynamic sink into which simple ligand frameworks are unable to prevent uranium from falling when in the presence of a suitable retinue of imido proligands.
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http://dx.doi.org/10.1039/c9dt00680jDOI Listing
August 2019

Encapsulated Sinonasal Schwannoma.

Ear Nose Throat J 2019 Apr-May;98(4):205-206. Epub 2019 Mar 5.

1 Division of Facial Plastic and Reconstructive Surgery, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, OR, USA.

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http://dx.doi.org/10.1177/0145561318823321DOI Listing
December 2019

Complexation of High-Valency Mid-Actinides by a Lipophilic Schiff Base Ligand: Synthesis, Structural Characterization, and Progress toward Selective Extraction.

Inorg Chem 2019 Mar 26;58(6):3559-3563. Epub 2019 Feb 26.

Department of Chemical and Biomolecular Engineering , University of California-Irvine , Irvine , California 92697-2580 , United States.

Separation of U, Np, and Pu from used nuclear fuel (UNF) would result in lower long-term radiotoxicity, alleviating constraints on the storage and handling of the material. The complexity of UNF requires several industrial-scale processes with multiple waste streams. A one-step solution to the group removal of the elements, U-Pu, is desirable. Here we present a possible solution to group actinide separation utilizing the unique dioxy conformation of An(V/VI) cations and demonstrate the ability of a tetradentate lipophilic Schiff base ligand (L) to yield isostructural complexes of the general formula [(AnO)(L)(CHCN)] (where An = U, Np, or Pu). Extraction of An(VI) with the ligand follows the order U > Pu > Np, likely reflecting the decreased stability of the hexavalent actinide across the series. While the results indicate a promising path toward a one-step process, further improvement in the ligand stability and control of the redox chemistry is required.
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http://dx.doi.org/10.1021/acs.inorgchem.8b02849DOI Listing
March 2019

Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries.

ChemSusChem 2019 Apr 7;12(7):1304-1309. Epub 2019 Feb 7.

Materials Synthesis and Integrated Devices Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.

The use of nickel complexes utilizing non-innocent ligands based on picolinamide to function as redox carriers in flow batteries was explored. The picolinamide moiety was linked together with -CH CH - (bpen), -CH CH CH - (bppn), and -C H - (bpb) moieties, resulting in two, three, and four quasi-reversible waves, respectively, for the nickel complexes and >3 V difference between the outermost positive and negative waves. The redox events were theoretically modelled for each complex, showing excellent agreement (<0.3 V difference) between the experimental and modelled potentials. Bulk cycling of the most soluble complex, Ni(bppn), indicated only one of the three waves was reversible. Therefore, Ni(bppn) has the ability to act as a negative charge redox carrier in flow cells.
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http://dx.doi.org/10.1002/cssc.201802985DOI Listing
April 2019

Plutonium coordination and redox chemistry with the CyMe-BTPhen polydentate N-donor extractant ligand.

Chem Commun (Camb) 2018 Nov 23;54(89):12582-12585. Epub 2018 Oct 23.

School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.

Complexation of Pu(iv) with the actinide extractant CyMe-BTPhen (2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-1,10-phenanthroline) was followed by vis-NIR spectroscopy in acetonitrile solution. The solid-state structure of the crystallized product suggests that Pu(iv) is reduced to Pu(iii) upon complexation. Analysis by DFT modeling is consistent with metal-based rather than ligand-based reduction.
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http://dx.doi.org/10.1039/c8cc06015kDOI Listing
November 2018

A sulphur and uranium fiesta! Synthesis, structure, and characterization of neutral terminal uranium(vi) monosulphide, uranium(vi) η-disulphide, and uranium(iv) phosphine sulphide complexes.

Dalton Trans 2018 Dec;48(1):50-57

Los Alamos National Laboratory, Mail Stop J-514, Los Alamos, NM 87545, USA.

Three new uranium species (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)([double bond, length as m-dash]S), (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)(η2-S2), and (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)(S[double bond, length as m-dash]PMe3) were synthesized and fully characterized by a combination of NMR, IR, and UV/vis-NIR spectroscopies, elemental analysis, and cyclic voltammetry. The solid state structures of (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)([double bond, length as m-dash]S) and (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)(η2-S2) were also determined. The compound (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)([double bond, length as m-dash]S) is the first neutral uranium complex with a terminal sulphido ligand, and (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)(S[double bond, length as m-dash]PMe3) is the first uranium compound with a coordinated phosphine sulphide ligand. The phosphine sulphide adduct, (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)(S[double bond, length as m-dash]PMe3), can be synthesized either by reaction of the uranium(iv) complex (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)(thf) with S[double bond, length as m-dash]PMe3 or by the reaction of the uranium(vi) terminal sulphido complex (C5Me5)2U([double bond, length as m-dash]N-2,6-iPr2-C6H3)([double bond, length as m-dash]S) with PMe3.
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http://dx.doi.org/10.1039/c8dt02932fDOI Listing
December 2018

Crystal structure and redox potentials of the tppz-bridged {RuCl(bpy)} dimer.

Acta Crystallogr E Crystallogr Commun 2018 Sep 16;74(Pt 9):1250-1253. Epub 2018 Aug 16.

Los Alamos National Laboratory, Los Alamos, NM 87545, USA.

We report the structural and electrochemical characterization of the binuclear complex [μ-(CHN){RuCl(CHN)}](PF), which contains the bis-tridentate bridging ligand 2,3,5,6-tetra-kis-(pyridin-2-yl)pyrazine (tppz), the monodentate ligand Cl, and the bidentate ligand 2,2'-bi-pyridine (bpy) {systematic name: μ-2,3,5,6-tetra-kis-(pyridin-2-yl)pyrazine-bis-[(2,2'-bi-pyridine)-chlorido-ru-thenium(II)] bis-(hexa-fluorido-phosphate)}. The complete [(bpy)(Cl)Ru(tppz)Ru(Cl)(bpy)] dication is generated by crystallographic twofold symmetry; the tppz bridging ligand has a significantly twisted conformation, with an average angle of 42.4° between the mean planes of adjacent pyridyl rings. The metal-coordinated chloride ligands are in a configuration relative to each other across the {Ru(tppz)Ru} unit. The Ru ion exhibits a distorted octa-hedral geometry due to the restricted bite angle [160.6 (3)°] of the tppz ligand. For bpy, the bond lengths of the Ru-N bonds are 2.053 (8) and 2.090 (8) Å, with the shorter bond being opposite to Ru-Cl. For the tridentate tppz, the Ru-N distances involving the outer N atoms to each other are 2.069 (8) and 2.072 (9) Å, whereas the Ru-N bond involving the central N atom has the much shorter length of 1.939 (7) Å as a result of the geometric constraints and stronger π-acceptor ability of the pyrazine-centered bridge. The Ru-Cl distance is 2.407 (3) Å and the intra-molecular distance between Ru centers is 6.579 (4) Å. In the crystal, weak C-H⋯Cl and C-H⋯F inter-actions consolidate the packing.
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http://dx.doi.org/10.1107/S2056989018011258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127700PMC
September 2018

A series of dithiocarbamates for americium, curium, and californium.

Dalton Trans 2018 Oct;47(41):14452-14461

Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Characterizing how actinide properties change across the f-element series is critical for improving predictive capabilities and solving many nuclear problems facing our society. Unfortunately, it is difficult to make direct comparisons across the 5f-element series because so little is known about trans-plutonium elements. Results described herein help to address this issue through isolation of An(S2CNEt2)3(N2C12H8) (Am, Cm, and Cf). These findings included the first single crystal X-ray diffraction measurements of Cm-S (mean of 2.86 ± 0.04 Å) and Cf-S (mean of 2.84 ± 0.04 Å) bond distances. Furthermore, they highlight the potential of An(S2CNEt2)3(N2C12H8) for providing a test bed for comparative analyses of actinide versus lanthanide bonding interactions.
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http://dx.doi.org/10.1039/c8dt02658kDOI Listing
October 2018

Identification of the Formal +2 Oxidation State of Neptunium: Synthesis and Structural Characterization of {Np[CH(SiMe)]}.

J Am Chem Soc 2018 06 5;140(24):7425-7428. Epub 2018 Jun 5.

Department of Chemistry , University of California-Irvine , Irvine , California 92697-2025 , United States.

We report a new formal oxidation state for neptunium in a crystallographically characterizable molecular complex, namely Np in [K(crypt)][NpCp″] [crypt = 2.2.2-cryptand, Cp″ = CH(SiMe)]. Density functional theory calculations indicate that the ground state electronic configuration of the Np ion in the complex is 5f6d.
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http://dx.doi.org/10.1021/jacs.8b03907DOI Listing
June 2018

Cs[TfN]: a second polymorph with a layered structure.

Acta Crystallogr E Crystallogr Commun 2018 Apr 23;74(Pt 4):551-554. Epub 2018 Mar 23.

Materials Physics and Applications Division, Associate Directorate for Experimental Physical Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.

The structural determination of the ionic liquid, caesium bis-[(tri-fluoro-meth-yl)sulfon-yl]imide or poly[[μ-bis-[(tri-fluoro-meth-yl)sulfon-yl]imido]caesium(I)], Cs[N(SOCF)] or Cs[TfN], reveals a second polymorph that also crystallizes in a layer structure possessing monoclinic 2/ symmetry at 120 K instead of 2/ for the known polymorph [Xue (2002 ▸). , 1535-1545]. The caesium ions in the cationic layers are coordinated by the sulfonyl groups of the bis-triflimide mol-ecules from anion layers while the tri-fluoro-methyl groups are oriented in the opposite direction, forming a non-polar surface separating the layers. The layer direction is (100).
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http://dx.doi.org/10.1107/S2056989018004401DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946987PMC
April 2018

The multidisciplinary tumor board for the management of cutaneous neoplasms: A national survey of academic medical centers.

J Am Acad Dermatol 2018 Jun;78(6):1216-1218.e3

Department of Dermatology, University of Texas Southwestern Medical Center, Dallas, Texas. Electronic address:

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http://dx.doi.org/10.1016/j.jaad.2016.12.029DOI Listing
June 2018

Non-aqueous neptunium and plutonium redox behaviour in THF - access to a rare Np(iii) synthetic precursor.

Chem Commun (Camb) 2018 Jun;54(48):6113-6116

Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.

Solvent exchange of NpCl4(DME)2 with THF proceeds simply to yield NpCl4(THF)3, whereas PuCl4(DME)2 is unstable in THF, partially decomposing to the mixed valent [PuIIICl2(THF)5][PuIVCl5(THF)] salt. Reduction of NpCl4(THF)3 with CsC8 ultimately afforded NpCl3(py)4, the only example of a structurally characterized solvated Np(iii) halide. The method demonstrates a route to a well-defined Np(iii) starting material without the need to employ scarcely available Np metal.
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http://dx.doi.org/10.1039/c8cc02611dDOI Listing
June 2018

Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA); Synthesis and Structure of MTTA (M = Zr, Hf, Ce, Th, U, Np, Pu) and M(TTA) (M = Ce, Nd, Sm, Yb).

Inorg Chem 2018 Apr 21;57(7):3782-3797. Epub 2018 Mar 21.

University of New Mexico , Albuquerque , New Mexico 87131 , United States.

Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.g. bulk uranium). It is well-established that this procedure enables +4 actinides to be selectively removed from +3, + 5, and +6 f-elements. However, even highly skilled and well-trained researchers find this process complicated and (at times) unpredictable. It is difficult to improve the HTTA extraction-or find alternatives-because little is understood about why this separation works. Even the identities of the extracted species are unknown. In addressing this knowledge gap, we report here advances in fundamental understanding of the HTTA-based extraction. This effort included comparatively evaluating HTTA complexation with +4 and +3 metals (M = Zr, Hf, Ce, Th, U, Np, and Pu vs M = Ce, Nd, Sm, and Yb). We observed +4 metals formed neutral complexes of the general formula M(TTA). Meanwhile, +3 metals formed anionic M(TTA) species. Characterization of these M(TTA) ( x = 0, 1) compounds by UV-vis-NIR, IR, H and F NMR, single-crystal X-ray diffraction, and X-ray absorption spectroscopy (both near-edge and extended fine structure) was critical for determining that Np(TTA) and Pu(TTA) were the primary species extracted by HTTA. Furthermore, this information lays the foundation to begin developing and understanding of why the HTTA extraction works so well. The data suggest that the solubility differences between M(TTA) and M(TTA) are likely a major contributor to the selectivity of HTTA extractions for +4 cations over +3 metals. Moreover, these results will enable future studies focused on explaining HTTA extractions preference for +4 cations, which increases from Np to Pu, Hf, and Zr.
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http://dx.doi.org/10.1021/acs.inorgchem.7b03089DOI Listing
April 2018

Magnetic circular dichroism of UCl in the ligand-to-metal charge-transfer spectral region.

Phys Chem Chem Phys 2017 Jul;19(26):17300-17313

Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA.

We present a combined ab initio theoretical and experimental study of the magnetic circular dichroism (MCD) spectrum of the octahedral UCl complex ion in the UV-Vis spectral region. The ground state is an orbitally non-degenerate doublet E and the MCD is a -term spectrum caused by spin-orbit coupling. Calculations of the electronic spectrum at various levels of theory indicate that differential dynamic electron correlation has a strong influence on the energies of the dipole-allowed transitions and the envelope of the MCD spectrum. The experimentally observed bands are assigned to dipole-allowed ligand-to-metal charge transfer into the 5f shell, and 5f to 6d transitions. Charge transfer excitations into the U 6d shell appear at much higher energies. The MCD-allowed transitions can be assigned via their signs of the -terms: Under O double group symmetry, E → E transitions have negative -terms whereas E → F transitions have positive -terms if the ground state g-factor is negative, as it is the case for UCl.
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http://dx.doi.org/10.1039/c7cp02572fDOI Listing
July 2017