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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
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
(C)2PbC2O4 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional and consists of four ethyne molecules and one PbC2O4 framework. In the PbC2O4 framework, Pb2+ is bonded to eight equivalent O2- atoms to form distorted edge-sharing PbO8 hexagonal bipyramids. There are four shorter (2.62 Å) and four longer (2.74 Å) Pb–O bond lengths. C+1.50+ is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.27 Å. O2- is bonded in a distorted single-bond geometry to two equivalent Pb2+ and one C+1.50+ atom.
Mg(HCOO)2(CH)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of twenty-four methane molecules and one Mg(HCOO)2 framework. In the Mg(HCOO)2 framework, there are four inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 63–65°. There are a spread of Mg–O bond distances ranging from 2.10–2.16 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 63°. There are a spread of Mg–O bond distances ranging from 2.08–2.16 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form edge-sharing MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.05–2.15 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 65°. There are a spread of Mg–O bond distances ranging from 2.06–2.16 Å. There are six inequivalent C+0.50+ sites. In the first C+0.50+ site, C+0.50+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the second C+0.50+ site, C+0.50+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the third C+0.50+ site, C+0.50+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fourth C+0.50+ site, C+0.50+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the fifth C+0.50+ site, C+0.50+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. In the sixth C+0.50+ site, C+0.50+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.11 Å. There is one shorter (1.25 Å) and one longer (1.29 Å) C–O bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50+ atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.50+ atom. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Mg2+ and one C+0.50+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one C+0.50+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Mg2+ and one C+0.50+ atom. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one C+0.50+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one C+0.50+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one C+0.50+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C+0.50+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one C+0.50+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C+0.50+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two Mg2+ and one C+0.50+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Mg2+ and one C+0.50+ atom. In the twelfth O2- site, O2- is bonded in a trigonal planar geometry to two Mg2+ and one C+0.50+ atom.
A facile catalytic protocol achieves the homocoupling of pyrazole boronic esters, enabling access to the structurally-flexible metal–organic framework Co(bpz).
Two new alkali vanadate carbonates with divalent transition metals have been synthesized as large single crystals via a high-temperature (600 °C) hydrothermal technique. Compound I, Rb 2 Mn 3 (VO 4 ) 2 CO 3 , crystallizes in the trigonal crystal system in the space group P[3 with combining macron]1c, and compound II, K 2 Co 3 (VO 4 ) 2 CO 3 , crystallizes in the hexagonal space group P6 3 /m. Both structures contain honeycomb layers and triangular lattices made from edge-sharing MO 6 octahedra and MO 5 trigonal bipyramids, respectively. The honeycomb and triangular layers are connected along the c-axis through tetrahedral [VO 4 ] groups. The MO 5 units are connected with each other by carbonate groups in the ab-plane by forming a triangular magnetic lattice. The difference in space groups between I and II was also investigated with Density Functional Theory (DFT) calculations. Single crystal magnetic characterization of I indicates three magnetic transitions at 77 K, 2.3 K, and 1.5 K. The corresponding magnetic structures for each magnetic transition of I were determined using single crystal neutron diffraction. At 77 K the compound orders in the MnO 6 -honeycomb layer in a Néel-type antiferromagnetic orientation while the MnO 5 triangular lattice ordered below 2.3 K in a colinear ‘up–up–down’ fashion, followed by a planar ‘Y’ type magnetic structure. K 2 Co 3 (VO 4 ) 2 CO 3 (II) exhibits a canted antiferromagnetic ordering below T N = 8 K. Here, the Curie–Weiss fit (200–350 K) gives a Curie–Weiss temperature of –42 K suggesting a dominant antiferromagnetic coupling in the Co 2+ magnetic sublattices.
Spent nuclear fuel contains heavy element fission products that must be separated for effective reprocessing for a safe and sustainable nuclear fuel cycle. 93 Zr and 99 Tc are high-yield fission products that co-transport in liquid-liquid extraction processes. Here we seek atomic-level information of this co-extraction process, as well as fundamental knowledge about Zr IV (and Hf IV ) aqueous speciation in the presence of topology-directing ligands such as pertechnetate (TcO 4 – ) and non-radioactive surrogate perrhenate (ReO 4 – ). In this context, we show that the flat tetrameric oxyhydroxyl-cluster [M IV 4 (OH) 8 (H 2 O) 16 ] 8+ (and related polymers) is dissociated by perrhenate/pertechnetate to yield isostructural dimers, M 2 (OH) 2 (XO 4 – ) 6 (H 2 O) 6 • 3H 2 O (M=Zr/Hf IV ; X=Re/Tc VII ), elucidated by single-crystal X-ray diffraction. We used these model compounds to understand the pervasive 93 Zr- 99 Tc coextraction with further speciation studies in water, nitric acid, and tetrabutylphosphate (TBP) -kerosene; where the latter two media are relevant to nuclear fuel reprocessing. SAXS (small angle X-ray scattering), compositional evaluation, and where experimentally feasible, ESI-MS (electrospray ionization mass spectrometry) showed that perrhenate/pertechnetate influence Zr/Hf IV -speciation in water. Here, in Zr-XO 4 solvent extraction studies to simulate fuel reprocessing, we provide evidence that TcO 4 – enhances extraction of Zr IV , and compositional analysis of the extracted metal-complexes (Zr-ReO 4 study) is consistent with the crystallized Zr IV 2 (OH) 2 (Re VII O 4 – ) 6 (H 2 O) 6 •dimer.
Here, we employ ultrafast mid-infrared transient absorption spectroscopy to probe the rapid loss of carbonyl ligands from gas-phase nickel tetracarbonyl following ultraviolet photoexcitation at 261 nm. Here, nickel tetracarbonyl undergoes prompt dissociation to produce nickel tricarbonyl in a singlet excited state; this electronically excited tricarbonyl loses another CO group over tens of picoseconds. Our results also suggest the presence of a parallel, concerted dissociation mechanism to produce nickel dicarbonyl in a triplet excited state, which likely dissociates to nickel monocarbonyl. Mechanisms for the formation of these photoproducts in multiple electronic excited states are theoretically predicted with one-dimensional cuts through the potential energy surfaces and computation of spin–orbit coupling constants using equation of motion coupled cluster methods (EOM-CC) and coupled cluster theory with single and double excitations (CCSD). Bond dissociation energies are calculated with CCSD, and anharmonic frequencies of ground and excited state species are computed using density functional theory (DFT) and time-dependent density functional theory (TD-DFT).
The [FeFe]-hydrogenase can be matured using a defined semisynthetic approach in which the synthetic complex [2Fe] E bypasses the need for HydE and HydG, and glycine cleavage system components synthesize DTMA on [2Fe] E while it is bound to HydF.
Abstract not provided.
The Airborne Laser Infrared Absorption Spectrometer II (ALIAS-II) is a lightweight, high-resolution (0.0003 cm-1), scanning, mid-infrared absorption spectrometer based on cooled (80 K) lead-salt tunable diode laser sources.
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A novel solution-mixing method was proposed to synthesize Co 3 O 4 /graphene nanocomposites (Co 3 O 4 @Gr) using a green tea leaf (Camellia sinensis) extract as the reducing agent. XRD analysis shows that the as-prepared Co 3 O 4 @Gr exhibits a cubic spinel crystal structure. From morphological analysis, the obtained Co 3 O 4 NS forms spherical clusters that are uniformly distributed on the graphene surface. FT-IR and Raman analyses confirmed the strong molecular and vibrational interactions between the Co 3 O 4 NS and Gr. The suppressed PL intensity peak of the Co 3 O 4 @Gr NCs indicated significant inhibition in the recombination of charge carriers between the hybrid orbitals within the composites. As a result, the catalytic efficiency of Co 3 O 4 @Gr NCs increased to 80% compared to pristine Co 3 O 4 , which exhibited only 45% efficiency against methylene blue (MB) dye. Moreover, the as-prepared NCs exhibited a detection limit of 0.01−224 μM, demonstrating a superior low-DPA detection with high sensitivity. The Co 3 O 4 @Gr/GCE exhibits admirable selectivity for various pesticides, fungicides, and metal ions, with outstanding reproducibility and stability. From electrochemical investigations, the highest specific capacitance values of the as-synthesized Co 3 O 4 @Gr were 349 F/g at a scan rate of 5 mV/s and 158 F/g at a current density of 1 A/g.
Co(CO)4(Co(CO)3)2Ge crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of eight akos016035116 molecules, four germanium molecules, and four Co(CO)4 clusters. In each Co(CO)4 cluster, Co2+ is bonded in a 4-coordinate geometry to four C1+ atoms. There are a spread of Co–C bond distances ranging from 1.76–1.91 Å. There are four inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a linear geometry to one Co2+ and one O2- atom. The C–O bond length is 1.16 Å. In the second C1+ site, C1+ is bonded in a linear geometry to one Co2+ and one O2- atom. The C–O bond length is 1.16 Å. In the third C1+ site, C1+ is bonded in a distorted single-bond geometry to one Co2+ and one O2- atom. The C–O bond length is 1.18 Å. In the fourth C1+ site, C1+ is bonded in a linear geometry to one Co2+ 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 C1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one C1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one C1+ atom.