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(CH3)2NH2C3NH6S2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four dimethylazanium molecules and four dimethyldithiocarbamic acid molecules.
Understanding magnetism and its possible correlations to topological properties has emerged to the forefront as a difficult topic in studying magnetic Weyl semimetals. Co 3 Sn 2 S 2 is a newly discovered magnetic Weyl semimetal with a kagome lattice of cobalt ions and has triggered intense interest for rich fantastic phenomena. In this study, we report the magnetic exchange couplings of Co 3 Sn 2 S 2 using inelastic neutron scattering and two density functional theory (DFT) based methods: constrained magnetism and multiple-scattering Green’s function methods. Co 3 Sn 2 S 2 exhibits highly anisotropic magnon dispersions and linewidths below T C , and paramagnetic excitations above T C . The spin-wave spectra in the ferromagnetic ground state is well described by the dominant third-neighbor “across-hexagon” J d model. Our density functional theory calculations reveal that both the symmetry-allowed 120° antiferromagnetic orders support Weyl points in the intermediate temperature region, with distinct numbers and the locations of Weyl points. Our study highlights the important role Co 3 Sn 2 S 2 can play in advancing our understanding of kagome physics and exploring the interplay between magnetism and band topology.
((CH3)2NH2)2SnH6(CCl2)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two dimethylazanium molecules and one SnH6(CCl2)2 cluster. In the SnH6(CCl2)2 cluster, Sn4+ is bonded in an octahedral geometry to two equivalent C+2.67- and four Cl1- atoms. Both Sn–C bond lengths are 2.15 Å. There are two shorter (2.66 Å) and two longer (2.68 Å) Sn–Cl bond lengths. C+2.67- is bonded in a distorted trigonal non-coplanar geometry to one Sn4+ and three H1+ atoms. All C–H bond lengths are 1.09 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+2.67- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+2.67- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+2.67- atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Sn4+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Sn4+ atom.
Here we systematically explore the properties of group-IV (C, Si, Ge, and Sn) and transition metal (Hf, Zr, and Ta) dopants substituting on the cation site in (Al x Ga 1– x ) 2 O 3 (AlGO) alloys using first-principles calculations with a hybrid functional. In Ga 2 O 3 , each of these dopants acts as a shallow donor. In Al 2 O 3 , they are deep defects characterized by the formation of either DX centers or positive- U (+/0) levels. Combining our calculations of dopant charge-state transition levels with information of the AlGO alloy band structure, we estimate the critical Al composition at which each dopant transitions from being a shallow to a deep donor. We identify Si to be the most efficient dopant to achieve n -type conductivity in high Al-content AlGO alloys, acting as a shallow donor over the entire predicted stability range for AlGO solid solution alloys.
CdC2(NS)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Cd2+ is bonded to two N3- and four S2- atoms to form a mixture of distorted edge and corner-sharing CdS4N2 octahedra. The corner-sharing octahedral tilt angles are 53°. There are one shorter (2.25 Å) and one longer (2.26 Å) Cd–N bond lengths. There are a spread of Cd–S bond distances ranging from 2.77–2.90 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.64 Å. In the second C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.64 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted bent 150 degrees geometry to one Cd2+ and one C4+ atom. In the second N3- site, N3- is bonded in a distorted linear geometry to one Cd2+ and one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Cd2+ and one C4+ atom. In the second S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Cd2+ and one C4+ atom.
SnC2O4 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of two SnC2O4 ribbons oriented in the (1, 0, 1) direction. Sn2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are two shorter (2.27 Å) and two longer (2.41 Å) Sn–O bond lengths. C3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) C–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Sn2+ and one C3+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sn2+ and one C3+ atom.
La5Sn3C crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are two inequivalent La sites. In the first La site, La is bonded in a 6-coordinate geometry to six equivalent Sn atoms. All La–Sn bond lengths are 3.36 Å. In the second La site, La is bonded in a 2-coordinate geometry to five equivalent Sn and two equivalent C atoms. There are a spread of La–Sn bond distances ranging from 3.40–3.92 Å. Both La–C bond lengths are 2.66 Å. Sn is bonded in a 9-coordinate geometry to nine La atoms. C is bonded to six equivalent La atoms to form face-sharing CLa6 octahedra.
KAuC2(NS)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 4-coordinate geometry to four N3- atoms. There are a spread of K–N bond distances ranging from 2.86–2.92 Å. There are two inequivalent Au1+ sites. In the first Au1+ site, Au1+ is bonded in a distorted linear geometry to two equivalent S2- atoms. Both Au–S bond lengths are 2.37 Å. In the second Au1+ site, Au1+ is bonded in a distorted linear geometry to two equivalent S2- atoms. Both Au–S bond lengths are 2.36 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.66 Å. In the second C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.66 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted single-bond geometry to two equivalent K1+ and one C4+ atom. In the second N3- site, N3- is bonded in a 1-coordinate geometry to two equivalent K1+ and one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 1-coordinate geometry to one Au1+ and one C4+ atom. In the second S2- site, S2- is bonded in a 2-coordinate geometry to one Au1+ and one C4+ atom.
RbAuC2(NS)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Rb1+ is bonded in a 4-coordinate geometry to four N3- atoms. There are a spread of Rb–N bond distances ranging from 3.02–3.12 Å. There are two inequivalent Au1+ sites. In the first Au1+ site, Au1+ is bonded in a distorted linear geometry to two equivalent S2- atoms. Both Au–S bond lengths are 2.36 Å. In the second Au1+ site, Au1+ is bonded in a distorted linear geometry to two equivalent S2- atoms. Both Au–S bond lengths are 2.36 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.66 Å. In the second C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.66 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted single-bond geometry to two equivalent Rb1+ and one C4+ atom. In the second N3- site, N3- is bonded in a distorted single-bond geometry to two equivalent Rb1+ and one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to one Au1+ and one C4+ atom. In the second S2- site, S2- is bonded in a 2-coordinate geometry to one Au1+ and one C4+ atom.
Abstract Effective control on chemoselectivity in the catalytic hydrogenation of C=O over C=C bonds is uncommon with Pd‐based catalysts because of the favored adsorption of C=C bonds on Pd surface. Here we report a unique orthorhombic PdSn intermetallic phase with unprecedented chemoselectivity toward C=O hydrogenation. We observed the formation and metastability of this PdSn phase in situ. During a natural cooling process, the PdSn nanoparticles readily revert to the favored Pd 3 Sn 2 phase. Instead, using a thermal quenching method, we prepared a pure‐phase PdSn nanocatalyst. PdSn shows an >96 % selectivity toward hydrogenating C=O bonds of various α,β‐unsaturated aldehydes, highest in reported Pd‐based catalysts. Further study suggests that efficient quenching prevents the reversion from PdSn‐ to Pd 3 Sn 2 ‐structured surface, the key to the desired catalytic performance. Density functional theory calculations and analysis of reaction kinetics provide an explanation for the observed high selectivity.
In this work, I 2(g) reactions with 11 metal wires (i.e., Al, Ag, Cu, In, Mo, Nb, Ni, Pd, Pt, Sn, Ta) were evaluated at three temperatures (i.e., 100 ± 3°C, 123 ± 4°C, 139 ± 5°C) with exposure times of 24 hours at each temperature. Over these temperatures, some of the metals showed increased mass gain with higher temperatures (i.e., In, Ag, Cu), Sn showed decreased iodine capture at increased temperatures, and most metals (i.e., Mo, Nb, Ni, Pd, Pt, and Ta) showed little to no mass gain at all temperatures. Silver mordenite (AgZ) was used as a standard during these studies and showed a consistent mass gain (m% I ) of 10.6 → 12.8% over this temperature range. The values of mass of iodine captured per mass of starting metal (g g -1 ) ranged widely across the study with the highest values achieved for (in descending order) Sn-T 100°C (4.37), In-T 139°C (3.34), Sn-T 123°C (1.98), In-T 123°C (1.57), Ag-T 139°C (1.19), In-T 100°C (0.97), and Cu-T 139°C (0.71). In some cases, the metal-iodide complex was not stable at the experimental temperature and it was clear some volatility had occurred during the experiment based on discoloration in the vials. These results show that some metals can have extensive reactions with I 2(g) without showing metal-iodide preferences over metal-oxide formation based on thermodynamic predictions. It is possible that materials such as these could be implemented near nuclear facilities to getter I 2(g) in the event of a nuclear accident.
(C)4(C2N)2SnC10(N2S5)2(SnC7NS6)2SnS2 crystallizes in the monoclinic C2/m space group. The structure is one-dimensional and consists of four aziridine molecules; eight methane molecules; two SnC10(N2S5)2 clusters; two SnS2 clusters; and two SnC7NS6 ribbons oriented in the (0, 1, 0) direction. In each SnC10(N2S5)2 cluster, Sn2+ is bonded in an octahedral geometry to six S2- atoms. There are four shorter (2.99 Å) and two longer (3.00 Å) Sn–S bond lengths. There are three inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a 1-coordinate geometry to one N3- and one S2- atom. The C–N bond length is 1.43 Å. The C–S bond length is 1.64 Å. In the second C2+ site, C2+ is bonded in a single-bond geometry to one S2- atom. The C–S bond length is 1.64 Å. In the third C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.39 Å. N3- is bonded in a 3-coordinate geometry to two C2+ and one S2- atom. The N–S bond length is 1.64 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted bent 120 degrees geometry to one Sn2+ and one C2+ atom. In the second S2- site, S2- is bonded in a distorted bent 150 degrees geometry to one Sn2+ and one C2+ atom. In the third S2- site, S2- is bonded in a single-bond geometry to one N3- atom. In each SnS2 cluster, Sn2+ is bonded in a linear geometry to two equivalent S2- atoms. Both Sn–S bond lengths are 2.24 Å. S2- is bonded in a distorted single-bond geometry to one Sn2+ atom. In each SnC7NS6 ribbon, Sn2+ is bonded in an octahedral geometry to six S2- atoms. There are a spread of Sn–S bond distances ranging from 2.67–2.97 Å. There are four inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a distorted single-bond geometry to one C2+ atom. The C–C bond length is 1.31 Å. In the second C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.30 Å. In the third C2+ site, C2+ is bonded in a distorted single-bond geometry to one S2- atom. The C–S bond length is 1.64 Å. In the fourth C2+ site, C2+ is bonded in a linear geometry to one C2+ and one S2- atom. The C–S bond length is 1.57 Å. N3- is bonded in a trigonal planar geometry to one C2+ and two equivalent S2- atoms. Both N–S bond lengths are 1.72 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a water-like geometry to one Sn2+ and one C2+ atom. In the second S2- site, S2- is bonded in a distorted water-like geometry to one Sn2+ and one N3- atom. In the third S2- site, S2- is bonded in a water-like geometry to one Sn2+ and one C2+ atom.
Effective control on chemoselectivity in the catalytic hydrogenation of C=O over C=C bonds is uncommon with Pd-based catalysts because of the favored adsorption of C=C bonds on Pd surface. Here we report a unique orthorhombic PdSn intermetallic phase with unprecedented chemoselectivity toward C=O hydrogenation. We observed the formation and metastability of this PdSn phase in situ. During a natural cooling process, the PdSn nanoparticles readily revert to the favored Pd 3 Sn 2 phase. Instead, using a thermal quenching method, we prepared a pure-phase PdSn nanocatalyst. Furthermore, PdSn shows an >96% selectivity toward hydrogenating C=O bonds of various α,β-unsaturated aldehydes, highest in reported Pd-based catalysts. Further study suggests that efficient quenching prevents the reversion from PdSn- to Pd 3 Sn 2 -structured surface, the key to the desired catalytic performance. Density functional theory calculations and analysis of reaction kinetics provide an explanation for the observed high selectivity.
The PLB, its cargo, and payload canister must satisfy the cleanliness requirements of visual clean (VC) level 1, 2, 3, or special as stated in NASA document SN-C-0005A. The specific level of cleanliness is chosen by the payload bay customer for their mission. During orbiter turnaround processing at KSC, the payload bay is exposed to the environments of the Orbiter Processing Facility (OPF) and the Payload Changeout Room (PCR). In supportive response to the orbiter payload bay/facility interface, it is necessary that the facility environment be controlled and monitored to protect the cleanliness/environmental integrity of the payload bay and its cargo. Techniques used to meet environmental requirements during orbiter processing are introduced.
SnH8(CI)4 is Protactinium structured and crystallizes in the tetragonal P-42_1c space group. The structure is zero-dimensional and consists of two stannane, tetrakis(iodomethyl)- molecules. Sn4+ is bonded in a tetrahedral geometry to four equivalent C2- atoms. All Sn–C bond lengths are 2.17 Å. C2- is bonded in a 2-coordinate geometry to one Sn4+, two H1+, and one I1- atom. There is one shorter (1.09 Å) and one longer (1.10 Å) C–H bond length. The C–I bond length is 2.16 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. I1- is bonded in a single-bond geometry to one C2- atom.
The structure, magnetic properties, and 151 Eu and 119 Sn Mössbauer spectra of the solid-solution Eu 11– x Sr x Zn 4 Sn 2 As 12 are presented. A new commensurately modulated structure is described for Eu 11 Zn 4 Sn 2 As 12 ( R 3 m space group, average structure) that closely resembles the original structural description in the monoclinic C 2/ c space group with layers of Eu, puckered hexagonal Zn 2 As 3 sheets, and Zn 2 As 6 ethane-like isolated pillars. The solid-solution Eu 11– x Sr x Zn 4 Sn 2 As 12 (0 < x < 10) is found to crystallize in the commensurately modulated R 3 space group, related to the parent phase but lacking the mirror symmetry. Eu 11 Zn 4 Sn 2 As 12 orders with a saturation plateau at 1 T for 7 of the 11 Eu 2+ cations ferromagnetically coupled (5 K) and shows colossal magnetoresistance at 15 K. The magnetic properties of Eu 11 Zn 4 Sn 2 As 12 are investigated at higher fields, and the ferromagnetic saturation of all 11 Eu 2+ cations occurs at ~8 T. The temperature-dependent magnetic properties of the solid solution were investigated, and a nontrivial structure–magnetization correlation is revealed. The temperature-dependent 151 Eu and 119 Sn Mössbauer spectra confirm that the europium atoms in the structure are all Eu 2+ and that the tin is consistent with an oxidation state of less than four in the intermetallic region. The spectral areas of both Eu(II) and Sn increase at the magnetic transition, indicating a magnetoelastic effect upon magnetic ordering.
SnC2(NS)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two diisothiocyanatotin molecules. Sn2+ is bonded in a distorted L-shaped geometry to two N3- atoms. There are one shorter (2.23 Å) and one longer (2.30 Å) Sn–N bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.62 Å. In the second C4+ site, C4+ is bonded in a distorted linear geometry to one N3- and one S2- atom. The C–N bond length is 1.18 Å. The C–S bond length is 1.63 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted bent 150 degrees geometry to one Sn2+ and one C4+ atom. In the second N3- site, N3- is bonded in a linear geometry to one Sn2+ and one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted single-bond geometry to one C4+ atom. In the second S2- site, S2- is bonded in a 1-coordinate geometry to one C4+ atom.
We examined the high pressure behavior of stannous oxalate via Raman and X-ray absorption spectroscopy (XAS) inside a diamond anvil cell. Phase transitions were observed to occur near 2.6 and 15 GPa which were reversible upon decompression to ambient conditions. When further pressurized above 15 GPa, the colorless material sustains irreversible chemical alterations and becomes bright red colored – darkening at higher pressures. Another irreversible phase transition occurred above 20 GPa. Concomitant with color change of the sample, we observed a softening of the ν(C–C) modes of the C 2 O 4 2- anion via Raman spectroscopy. We performed a separate XAS experiment which indicates that the Sn 2+ cation undergoes a partial reduction of the 2+ oxidation state with pressure which persists when the sample was depressurized to ambient conditions. Thus, electron density within the C–C bond in the oxalate anion appears to migrate toward the tin cation with pressure. This observation suggests that pressure can offer a very controllable means to vary cation–anion and unit cell dimensions (and thus the electric interactions causing electron movement) and thus the pressure-induced synthesis of novel materials.