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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Synthesis,and structural characterization of [(CH3(C5H4N))Ga(SCH2(CO)O)]-[(4-MepyH)]+, a novel Ga(III) five coordinate complex.

The synthesis and structural characterization of a novel ionic Ga(III) five coordinate complex [{CH3(C5H4N)}Ga(SCH2(CO)O)2]-[(4-MepyH)]+, (4-Mepy = CH3(C5H5N)) from the reaction between Ga2Cl4 with sodium mercapto-acetic acid in 4-methylpyridine is described. Under basic reaction conditions the mercapto ligand is found to behave as a 2e- bidentate ligand. Single crystal X-ray diffraction studies show the complex to have a distorted square pyramidal geometry with the [(-SCH2(CO)CO-)] ligands in a trans conformation. The compound crystallizes in the P2(sub 1)/c (No. 14) space group with a = 7.7413(6) A, b = 16.744(2) A, c = 14.459(2) A, V = 1987.1(6) A(sup 3), R(F) = 0.032 and R(sub w) = 0.038.

Banger, Kulbinder K.↗
NASA NTRS2016

Filled Nd(sub z) Fe(sub x) Co(sub 4-x) Sb(sub 12-y) Ge(sub y) Skutterudites: Processing and Thermoelectric Properties

Skutterudites have proven to be a useful thermoelectric system as a result of their enhanced figure of merit (ZT1), cheap material cost, favorable mechanical properties, and good thermal stability. The majority of skutterudite interest in recent years has been focused on binary skutterudites like CoSb3. Binary skutterudites are often double and triple filled, with a range of elements from the lanthanide series, in order to reduce the lattice component of thermal conductivity. Ternary and quaternary skutterudites, such as Co4Ge6Se6 or Ni4Sb8Sn4, provide additional paths to tune the electronic structure. The thermal conductivity can further be improved in these complex skutterudites by the introduction of fillers. The Nd (sub z) Fe (sub x) Co (sub 4-x) Sb (sub 12-y)Ge (sub y) system has been investigated as a p-type thermoelectric material, and is stable up to 600 degrees Centigrade. The influence of Fe and Ge content, along with filler Nd, was investigated on thermoelectric transport properties. In addition to the chemical influence on properties, some processing details of the system will also be addressed.

Electical Conductivity↗
DOE OSTI2020

Materials Data on Fe3PWC15BrO15 by Materials Project

WFe(CO)4Fe2C6O6BrP(CO)5 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of twenty formaldehyde molecules, four phosphine molecules, four tungsten molecules, four Fe(CO)4 clusters, and four Fe2C6O6Br clusters. In each Fe(CO)4 cluster, Fe+2.67+ is bonded in a distorted see-saw-like geometry to four C+0.80+ atoms. There are a spread of Fe–C bond distances ranging from 1.79–1.84 Å. There are four inequivalent C+0.80+ sites. In the first C+0.80+ site, C+0.80+ is bonded in a linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.15 Å. In the second C+0.80+ site, C+0.80+ is bonded in a distorted single-bond geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.15 Å. In the third C+0.80+ site, C+0.80+ is bonded in a distorted linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+0.80+ site, C+0.80+ is bonded in a distorted linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.15 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In each Fe2C6O6Br cluster, there are two inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded in a distorted trigonal pyramidal geometry to three C+0.80+ and one Br1- atom. There are a spread of Fe–C bond distances ranging from 1.79–1.82 Å. The Fe–Br bond length is 2.47 Å. In the second Fe+2.67+ site, Fe+2.67+ is bonded in a distorted see-saw-like geometry to three C+0.80+ and one Br1- atom. There are a spread of Fe–C bond distances ranging from 1.79–1.82 Å. The Fe–Br bond length is 2.46 Å. There are six inequivalent C+0.80+ sites. In the first C+0.80+ site, C+0.80+ is bonded in a linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. In the second C+0.80+ site, C+0.80+ is bonded in a distorted linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. In the third C+0.80+ site, C+0.80+ is bonded in a distorted linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+0.80+ site, C+0.80+ is bonded in a linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. In the fifth C+0.80+ site, C+0.80+ is bonded in a distorted linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. In the sixth C+0.80+ site, C+0.80+ is bonded in a distorted linear geometry to one Fe+2.67+ and one O2- atom. The C–O bond length is 1.16 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one C+0.80+ atom. Br1- is bonded in a 3-coordinate geometry to two Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HOs6C18S2O19 by Materials Project

Os(CO)4Os5C14HS2O15 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two Os(CO)4 clusters and two Os5C14HS2O15 clusters. In each Os(CO)4 cluster, Os+1.17- is bonded in a rectangular see-saw-like geometry to four C+2.67+ atoms. There are a spread of Os–C bond distances ranging from 1.91–1.95 Å. There are four inequivalent C+2.67+ sites. In the first C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In each Os5C14HS2O15 cluster, there are five inequivalent Os+1.17- sites. In the first Os+1.17- site, Os+1.17- is bonded in a 5-coordinate geometry to three C+2.67+, one S2-, and one O2- atom. There are a spread of Os–C bond distances ranging from 1.89–1.93 Å. The Os–S bond length is 2.51 Å. The Os–O bond length is 2.17 Å. In the second Os+1.17- site, Os+1.17- is bonded in a distorted rectangular see-saw-like geometry to three C+2.67+ and one S2- atom. There is one shorter (1.88 Å) and two longer (1.91 Å) Os–C bond length. The Os–S bond length is 2.36 Å. In the third Os+1.17- site, Os+1.17- is bonded in a distorted square pyramidal geometry to three C+2.67+ and two S2- atoms. There is two shorter (1.90 Å) and one longer (1.91 Å) Os–C bond length. There are one shorter (2.44 Å) and one longer (2.46 Å) Os–S bond lengths. In the fourth Os+1.17- site, Os+1.17- is bonded in a 5-coordinate geometry to three C+2.67+, one S2-, and one O2- atom. There are two shorter (1.88 Å) and one longer (2.14 Å) Os–C bond lengths. The Os–S bond length is 2.46 Å. The Os–O bond length is 2.18 Å. In the fifth Os+1.17- site, Os+1.17- is bonded in a 5-coordinate geometry to three C+2.67+ and two S2- atoms. There are a spread of Os–C bond distances ranging from 1.89–2.08 Å. Both Os–S bond lengths are 2.47 Å. There are fourteen inequivalent C+2.67+ sites. In the first C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the third C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the fourth C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the fifth C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.17 Å. In the sixth C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the seventh C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the eighth C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the ninth C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the tenth C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.17 Å. In the eleventh C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.17 Å. In the twelfth C+2.67+ site, C+2.67+ is bonded in a distorted linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the thirteenth C+2.67+ site, C+2.67+ is bonded in a linear geometry to one Os+1.17- and one O2- atom. The C–O bond length is 1.16 Å. In the fourteenth C+2.67+ site, C+2.67+ is bonded in a distorted single-bond geometry to two Os+1.17- and one O2- atom. The C–O bond length is 1.19 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to four Os+1.17- atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Os+1.17- atoms. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the eleventh O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the fourteenth O2- site, O2- is bonded in a single-bond geometry to one C+2.67+ atom. In the fifteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Os+1.17- and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Femtosecond Core-Level Spectroscopy Reveals Involvement of Triplet States in the Gas-Phase Photodissociation of Fe(CO) 5

Excitation of iron pentacarbonyl [Fe(CO) 5 ], a prototypical photocatalyst, at 266 nm causes the sequential loss of two CO ligands in the gas phase, creating catalytically active, unsaturated iron carbonyls. Despite numerous studies, major aspects of its ultrafast photochemistry remain unresolved because the early excited-state dynamics have so far eluded spectroscopic observation. This has led to the long-held assumption that ultrafast dissociation of gas-phase Fe(CO) 5 proceeds exclusively on the singlet manifold. Herein, we present a combined experimental–theoretical study employing ultrafast extreme ultraviolet transient absorption spectroscopy near the Fe M 2,3 -edge, which features spectral evolution on 100 fs and 3 ps time scales, alongside high-level electronic structure theory, which enables characterization of the molecular geometries and electronic states involved in the ultrafast photodissociation of Fe(CO) 5 . We assign the 100 fs evolution to spectroscopic signatures associated with intertwined structural and electronic dynamics on the singlet metal-centered states during the first CO loss and the 3 ps evolution to the competing dissociation of Fe(CO) 4 along the lowest singlet and triplet surfaces to form Fe(CO) 3 . Calculations of transient spectra in both singlet and triplet states as well as spin–orbit coupling constants along key structural pathways provide evidence for intersystem crossing to the triplet ground state of Fe(CO) 4 . Finally, our work presents the first spectroscopic detection of transient excited states during ultrafast photodissociation of gas-phase Fe(CO) 5 and challenges the long-standing assumption that triplet states do not play a role in the ultrafast dynamics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Operando APXPS for direct probing of Li ion battery LCO electrode/electrolyte interface chemistry during lithiation/delithiation

The real-time interface chemistry between the lithium cobalt oxide (LCO) working electrode and the LiClO 4 /propylene carbonate (PC) electrolyte is investigated during lithiation/delithiation using dip-and-pull ambient pressure photoelectron spectroscopy (APXPS). The APXPS results appear to exhibit the seldom discussed Co 2+ state in the LCO structure, where the operando measurements indicate electron transfer among Co 2+ , Co 3+ , and Co 4+ states. Specifically, the lithiation of LCO reduces the Co 4+ state to both Co 3+ and Co 2+ states, where, as a function of voltage, reduction to the Co 2+ state is initially more pronounced followed by Co 3+ formation. In addition, a delay in surface delithiation is observed during the reverse potential steps. This is discussed in terms of overpotential at the interface measurement position as a consequence of the dip-and-pull setup for this experiment. Finally, the shifts in the apparent binding energies of the spectral features corresponding to the electrolyte and LCO at their interface show that the electrochemical potentials at delithiation voltage steps are different from the lithiation steps at the same applied voltages. This further explains the non-responsive delithiation. The BE shift observed from the LCO surface is argued to be dominantly due to the semi-conductive nature of the sample. Overall, this article shows the importance of operando APXPS for probing non-equilibrium states in battery electrodes for understanding electron transfer in the reactions.

Liu, Qianhui [Uppsala Univ. (Sweden)] (ORCID:00000↗
DOE OSTI2020

Revisiting the reactivity between HCO and CH 3 on interstellar grain surfaces

The formation of interstellar complex organic molecules is currently thought to be dominated by the barrierless coupling between radicals on the interstellar icy grain surfaces. Previous standard density functional theory (DFT) results on the reactivity between CH 3 and HCO on amorphous water surfaces showed that the formation of CH 4 + CO by H transfer from HCO to CH 3 assisted by water molecules of the ice was the dominant channel. In contrast, the adopted description of the electronic structure of the biradical (i.e. CH 3 /HCO) system was inadequate [without the broken-symmetry (BS) approach]. In this work, we revisit the original results by means of BS-DFT both in gas phase and with one water molecule simulating the role of the ice. Results indicate that the adoption of BS-DFT is mandatory to describe properly biradical systems. In the presence of the single water molecule, the water-assisted H transfer exhibits a high energy barrier. In contrast, CH 3 CHO formation is found to be barrierless. Yet, direct H transfer from HCO to CH 3 to give CO and CH 4 presents a very low energy barrier, hence being a potential competitive channel to the radical coupling and indicating, moreover, that the physical insights of the original work remain valid.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Materials Data on Co(Bi3O5)4 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2024

Precision Gas System Isotope Analyzer (PGSISO) Instrument Handbook

The PGSISO is a combination of several systems in series; (1) gas processing components that pressurize and prevent liquid water entering the sample stream, and (2) the Spectronus FTIR spectrometer, which measures continuous CO 2 , 12 CO 2 , 13 CO 2 , CH 4 , CO, N 2 O, and H 2 O. The Spectronus analyzer has been developed by the Centre for Atmospheric Chemistry at the University of Wollongong, Australia, and manufactured by Ecotech Pty Ltd, headquartered in Melbourne, Australia.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Iron Carbonyl Complexes of [2.2.2]Hericene as a Rigid Tris(1,3-diene) Ligand

Hericene is an unusual hexaolefin consisting of three 1,3-diene units located on a rigid bicyclo [2.2.2]octane framework that restricts the geometrical relationships of metal atoms bonded to these olefinic units. In order to explore possible effects of this rigidity limiting metal–metal interaction in polynuclear derivatives possibly stabilizing coordinatively unsaturated species, the structures and energetics of the hericene iron carbonyl complexes (hericene)Fem(CO)n (m = 1, n = 3; m = 2, n = 6, 5; m = 3, n = 9, 8) have been investigated by density functional theory. The lowest-energy (hericene)Fem(CO)3m (m = 1, 2, 3) structures have the cavities of the hericene ligand filled with a single Fe(CO)3 moiety bonded to a 1,3-diolefin unit. Such species have been synthesized by the reaction of Fe2(CO)9 with hericene. For the (hericene)Fe2(CO)5 system, the lowest energy structures are singlet structures with an Fe(CO)3 unit bonded to a 1,3-diene unit in one hericene cavity and an Fe(CO)2 unit in another hericene cavity bonded to three C=C double bonds from two 1,3-diene units. Higher energy (hericene)Fe2(CO)5 structures include a structure in which a single hericene cavity contains a Fe2(CO)4(µ-CO) moiety with each iron atom bonded to a 1,3-diene unit. In addition, both singlet and triplet (hericene)Fe2(CO)5 structures are found in which an Fe(CO)3 moiety and an Fe(CO)2 moiety located in separate hericene cavities are each bonded to a 1,3-diene unit. The lowest-energy (hericene)Fe3(CO)8 structures have two hericene cavities containing Fe(CO)3 moieties fully bonded to 1,3-diene units and a third hericene cavity containing an Fe(CO)2 moiety fully bonded to a 1,3-diene unit.

Luo, Jinfeng↗
NASA NTRS1978

Photochemical preparation of olefin addition catalysts

Novel polymer supported catalysts are prepared by photo-irradiation of low valent transition metal compounds such as Co.sub.2 (CO).sub.8, Rh.sub.4 (CO).sub.12 or Ru.sub.3 (CO).sub.12 in the presence of solid polymers containing amine ligands such as polyvinyl pyridine. Hydroformylation of olefins to aldehydes at ambient conditions has been demonstrated.

Gray, Harry B.↗
DOE OSTI2022

Photocatalytic Aqueous CO 2 Reduction to CO and CH 4 Sensitized by Ullazine Supramolecular Polymers

There has been rapid progress on the chemistry of supramolecular scaffolds that harness sunlight for aqueous photocatalytic production of hydrogen. However, great efforts are still needed to develop similar photosynthetic systems for the great challenge of CO 2 reduction especially if they avoid the use of nonabundant metals. This work investigates the synthesis of supramolecular polymers capable of sensitizing catalysts that require more negative potentials than proton reduction. The monomers are chromophore amphiphiles based on a diareno-fused ullazine core that undergo supramolecular polymerization in water to create entangled nanoscale fibers. Under 450 nm visible light these fibers sensitize a dinuclear cobalt catalyst for CO 2 photoreduction to generate carbon monoxide and methane using a sacrificial electron donor. The supramolecular photocatalytic system can generate amounts of CH 4 comparable to those obtained with a precious metal-based [Ru(phen) 3 ](PF 6 ) 2 sensitizer and, in contrast to Ru-based catalysts, retains photocatalytic activity in all aqueous media over 6 days. Furthermore, the present study demonstrates the potential of tailored supramolecular polymers as renewable energy and sustainability materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Coupling between the nickel-carbon and carbon-oxygen stretch motion in NiCO

Linear-combination-of-Gaussian-type-orbital (LCGTO) X-alpha calculations are performed on NiCO for various linear Ni-CO and NiC-O bond distances. The basis sets used are moderately large, approximately double zeta, and thus are fairly accurate within the X-alpha approximation. The electronic structure and equilibrium bond distances are consistent with recent CI calculations, indicating a much stronger Ni-CO bond than occurs in Ni(CO)4. The calculations agree to within 100/cm with the experimentally observed NiC-O stretch frequency. The Ni-CO stretch is predicted to occur at 656/cm, although at an intensity that is 640 times less. Compared with experimental results for CO adsorbed on single crystal Ni(100), the computed vibrational frequencies and intensities are less appropriate than the relevant experimental values for Ni(CO)4. This is interpreted to mean that an accurate description of the electronic structure of the nickel atom participating directly in the surface bond requires proper accounting of the bonds to its other nearest neighbors.

Dunlap, B. I.↗
DOE OSTI2025

Single-shot femtosecond laser-induced breakdown spectroscopy in low-density gases

Single-shot fs laser-induced breakdown spectroscopy (LIBS) has been used to interrogate low-density gases of H 2 ⁠, CH 4 ⁠, CO 2 ⁠, and H 2 O ranging from 0.5 × 10 15 to 9.1 × 10 15 cm −3 (15–275 mTorr). Strong spectral signatures were observed above the noise baseline for each test gas at all densities considered. Unique molecular signatures were observed for both CH 4 and CO 2 along with atomic features for each gas. The LIBS intensity response with respect to density was determined for each species using Voigt lineshape fitting or numerical integration. Finally, the collection and analysis of LIBS spectra of composite mixtures of CH 4 –CO 2 and CH 4 –H 2 demonstrates that the extraction of individual densities from gas mixtures is feasible at low densities.

Artificial neural networks↗
DOE OSTI2021

Paramagnetic Mn 8 Fe 4 -co-Polystyrene Nanobeads as a Potential T 1 –T 2 Multimodal Magnetic Resonance Imaging Contrast Agent with In Vivo Studies

In developing a cluster-nanocarrier design, as a magnetic resonance imaging contrast agent, we have investigated the enhanced relaxivity of a manganese and iron-oxo cluster grafted within a porous polystyrene nanobead with increased relaxivity due to a higher surface area. The synthesis of the cluster-nanocarrier for the cluster Mn 8 Fe 4 O 12 (O 2 CC 6 H 4 CH=CH 2 ) 16 (H 2 O) 4 , cross-linked with polystyrene (the nano-carrier), under miniemulsion conditions is described. By including a branched hydrophobe, iso-octane, the resulting nanobeads are porous and similar to 70 nm in diameter. The increased surface area of the nanobeads compared to nonporous nanobeads leads to an enhancement in relaxivity; r 1 increases from 3.8 to 5.2 ± 0.1 mM -1 s -1 , and r 2 increases from 11.9 to 50.1 ± 4.8 mM -1 s -1 , at 9.4 teslas, strengthening the potential for T 1 and T 2 imaging. Several metrics were used to assess stability, and the porosity produced no reduction in metal stability. Synchrotron X-ray fluorescence microscopy was used to demonstrate that the nanobeads remain intact in vivo . In depth, physicochemical characteristics were determined, including extensive pharmacokinetics, in vivo imaging, and systemic biodistribution analysis.

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

Materials Data on Sn2As2H22C7(ClO2)2 by Materials Project

C2H3Sn2AsH8(CO)4CAsH6Cl(H2)2HCl crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one ethylene molecule, one hydrochloric acid molecule, two hydrogen molecules, one CAsH6Cl cluster, and one Sn2AsH8(CO)4 cluster. In the CAsH6Cl cluster, C+1.71- is bonded in a distorted water-like geometry to one As3-, two H1+, and one Cl1- atom. The C–As bond length is 1.97 Å. Both C–H bond lengths are 1.10 Å. The C–Cl bond length is 2.23 Å. As3- is bonded in a distorted T-shaped geometry to one C+1.71- and two H1+ atoms. Both As–H bond lengths are 1.55 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one As3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one As3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one Cl1- atom. The H–Cl bond length is 1.30 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one Cl1- atom. The H–Cl bond length is 1.58 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. Cl1- is bonded in a distorted T-shaped geometry to one C+1.71- and two H1+ atoms. In the Sn2AsH8(CO)4 cluster, there are two inequivalent Sn3+ sites. In the first Sn3+ site, Sn3+ is bonded in a distorted tetrahedral geometry to two C+1.71- and two O2- atoms. There are one shorter (2.18 Å) and one longer (2.32 Å) Sn–C bond lengths. There are one shorter (2.01 Å) and one longer (2.20 Å) Sn–O bond lengths. In the second Sn3+ site, Sn3+ is bonded in a 4-coordinate geometry to two C+1.71- and two O2- atoms. There are one shorter (2.15 Å) and one longer (2.48 Å) Sn–C bond lengths. There are one shorter (2.04 Å) and one longer (2.29 Å) Sn–O bond lengths. There are four inequivalent C+1.71- sites. In the first C+1.71- site, C+1.71- is bonded in a distorted bent 120 degrees geometry to one Sn3+, one H1+, and one O2- atom. The C–H bond length is 1.11 Å. The C–O bond length is 1.22 Å. In the second C+1.71- site, C+1.71- is bonded in a distorted trigonal non-coplanar geometry to one Sn3+ and three H1+ atoms. There is two shorter (1.09 Å) and one longer (1.10 Å) C–H bond length. In the third C+1.71- site, C+1.71- is bonded in a distorted trigonal planar geometry to one Sn3+ and two H1+ atoms. There is one shorter (1.09 Å) and one longer (1.10 Å) C–H bond length. In the fourth C+1.71- site, C+1.71- is bonded in a distorted bent 120 degrees geometry to one Sn3+, one As3-, one H1+, and one O2- atom. The C–As bond length is 2.04 Å. The C–H bond length is 1.11 Å. The C–O bond length is 1.28 Å. As3- is bonded in a 3-coordinate geometry to one C+1.71-, one H1+, and one O2- atom. The As–H bond length is 1.56 Å. The As–O bond length is 1.88 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C+1.71- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one As3- atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two Sn3+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to one C+1.71- atom. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to two Sn3+ and one As3- atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C+1.71- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

C 1 Chemistry on Metal Carbide Nanoparticles: Boosting the Conversion of CO 2 and CH 4

The studies described in this Perspective show that transition metal carbide (TMC) nanoparticles can be very useful for the activation of three molecules located at the heart of C 1 chemistry: H 2 , CH 4 , and CO 2 . They also can play a major role in the trapping and conversion of two major greenhouse gases. A combination of experiment and theory has shed light on the physical and chemical properties of these systems, which can be very different from those of bulk carbides. Molecular clusters of these compounds, which can be inserted inside the cages of zeolites or carbon nanotubes, have unsaturated metal and carbon atoms that frequently work in a cooperative way when dealing with hard-to-activate molecules, such as CH 4 and CO 2 . These molecular clusters can evolve into nanoparticles of small to medium size (<15 nm) that have unique carbon/metal ratios and structures not seen in the bulk metal carbides. Even when their structures are cuts from bulk lattices, the TMC nanoparticles have corner or edge atoms that are active for the cleavage and conversion of C–H and C–O bonds. In this paper, we cover experimental and theoretical studies with well-defined metal carbide nanoparticles prepared by different methods, free and supported on diverse substrates. The Perspective ends with a discussion of current challenges and potential applications.

03 NATURAL GAS↗