Tetra(chlorido/iodido)(1,10-phenanthroline)platinum(IV) hemi[di(chlorine/iodine)]

The asymmetric unit of the title compound, [PtCl3.66I0.34(C12H8N2)]·0.5(Cl0.13I1.87), contains a neutral PtIV complex and one half of a halogen molecule. The PtIV ion is six-coordinated in a distorted octa­hedral environment by two N atoms of the 1,10-phenanthroline ligand and Cl or I atoms. The refinement of the structure and the EDX analysis indicate that the compound is a solid solution in which there is some substitution of Cl for I and vice versa. The chemical formula of the pure state of the compound would have been [PtCl4(C12H8N2)]·0.5I2. In the analysed crystal, two Cl atoms are partially (ca 25% and 9%) replaced by I atoms, and the I2 mol­ecule has a minor component modelled as ICl. As a result of the disorder, the different trans effects of the N and Cl/I atoms are not distinct. The complex displays inter­molecular π–π inter­actions between the six-membered rings, with a centroid–centroid distance of 3.771 (4) Å. There are also weak intra­molecular C—H⋯Cl hydrogen bonds

4,11-Diaza-1,8-diazo­niacyclo­tetra­decane bis­(pyridine-2-carboxyl­ate) dihydrate

The asymmetric unit of the title compound, C10H26N4 2+·2C6H4NO2 −·2H2O, consists of half of a doubly protonated 1,4,8,11-tetra­azacyclo­tetra­decane (cyclam) dication, a pyridine-2-carboxyl­ate anion and a solvent water mol­ecule. The complete dication is generated by a crystallographic centre and adopts an endodentate conformation which may be influenced by intra­molecular N—H⋯N hydrogen bonding. The carboxyl­ate group of the anion appears to be delocalized on the basis of the C—O bond lengths [1.257 (2) and 1.250 (2) Å]. In the crystal structure, the components are linked by inter­molecular N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds

6,12-Dihydro­dipyrido[1,2-a:1′,2′-d]pyrazinium bis­(perchlorate)

In the title compound, C12H12N2 2+·2ClO4 −, the dihedral angle between the two outer pyridine rings of the dication is 44.8 (1)°. In the crystal, weak intermolecular C—H⋯O hydrogen bonds occur

Butane-1,4-diammonium bis­(pyridine-2-carboxyl­ate) monohydrate

The asymmetric unit of the title compound, C4H14N2 2+·2C6H4NO2 −·H2O, consists of half of a doubly protonated tetra­methyl­enediammonium dication, a pyridine-2-carboxyl­ate anion and half of a solvent water mol­ecule; the dication is located on a centre of inversion and a twofold rotation axis passes through the O atom of the water mol­ecule. The carboxyl­ate group of the anion appears to be delocalized on the basis of the C—O bond lengths. In the crystal structure, the components are linked by inter­molecular N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds

Electrochemical Performance and Structural Interpretation of Sodium Metal Pyrophosphates as a Cathode for Sodium-Ion Batteries

Department of Energy Engineering (Battery Science and Technology)Recently, sodium-ion batteries (SIBs) become promising alternatives for lithium-ion batteries (LIBs) due to abundance and cheap cost of sodium resources compared with lithium sources. Like cathode materials for LIBs, various compounds of layered oxides and polyanion materials are synthesized through several methods. However, conventional active materials have difficulties for satisfying both kinetics and safety issues. Here, new types of polyanion material, sodium metal pyrophosphate, are synthesized having composition of Na3.12M2.44(P2O7)2 (M = Fe, Fe0.5Mn0.5, Mn, Co). Among them, sodium iron pyrophosphates are made into two ways: stoichiometric and off-stoichiometric ratio. This compounds have triclinic structure having three-dimensional tunnels, with sub-micron- or micron-sized particles. Indeed, the off-stoichiometric sodium iron pyrophosphate, involving continuous solid solution system, shows 85 mA h g-1 of reversible capacity with excellent cycleability and kinetics. Inspired by that, compounds containing Mn and Co, which are expected higher redox potentials, are tried. They are also investigated in electrochemical and structural ways.ope

Cyclo­hexane-1,2-diammonium bis­(pyridine-2-carboxyl­ate)

In the dication of the title salt, C6H16N2 2+·2C6H4NO2 −, the two ammonium groups are in the equatorial positions of the chair-shaped cyclo­hexyl ring. In the crystal, the cations and anions are linked by N—H⋯O and N—H⋯N hydrogen bonds, forming a layer network parallel to the ac plane. Weak π–π inter­actions between adjacent pyridine rings with a centroid–centroid distance of 3.589 (2) Å are also present

Bis(2,2′-bipyridine-κ2 N,N′)dichlorido­platinum(IV) dichloride monohydrate

In the title complex, [PtCl2(C10H8N2)2]Cl2·H2O, the Pt4+ ion is six-coordinated in a distorted octa­hedral environment by four N atoms from the two 2,2′-bipyridine ligands and two Cl atoms. As a result of the different trans influences of the N and Cl atoms, the Pt—N bonds trans to the Cl atom are slightly longer than those trans to the N atom. The compound displays inter­molecular hydrogen bonding between the water mol­ecule and the Cl anions. There are inter­molecular π–π inter­actions between adjacent pyridine rings, with a centroid–centroid distance of 3.962 Å

Triclinic Na3.12Co2.44(P2O7)(2) as a High Redox Potential Cathode Material for Na-Ion Batteries

Two types of sodium cobalt pyrophosphates, triclinic Na3.12Co2.44(P2O7)(2) and orthorhombic Na2CoP2O7, are compared as high-voltage cathode materials for Na-ion batteries. Na2CoP2O7 shows no electrochemical activity, delivering negligible capacity. In contrast, Na3.12Co2.44(P2O7)(2) exhibits good electrochemical performance, such as high redox potential at ca. 4.3 V (vs. Na/Na+) and stable capacity retention over 50 cycles, although Na3.12Co2.44(P2O7)(2) delivered approximately 40 mA h g(-1). This is attributed to the fact that Na2CoP2O7 (similar to 3.1 angstrom) has smaller diffusion channel size than Na3.12Co2.44(P2O7)(2) (similar to 4.2 angstrom). Moreover, the electrochemical performance of Na3.12Co2.44(P2O7)(2) is examined using Na cells and Li cells. The overpotential of Na cells is smaller than that of Li cells. This is due to the fact that Na3.12Co2.44(P2O7)(2) has a smaller charge transfer resistance and higher diffusivity for Na+ ions than Li+ ions. This implies that the large channel size of Na3.12Co2.44(P2O7)(2) is more appropriate for Na+ ions than Li+ ions. Therefore, Na3.12Co2.44(P2O7)(2) is considered a promising high-voltage cathode material for Na-ion batteries, if new electrolytes, which are stable above 4.5 V vs. Na/Na+, are introduced.

[(2,3,5,6-η)-Bicyclo­[2.2.1]hepta-2,5-diene]dibromidopalladium(II)

In the title complex, [PdBr2(C7H8)], the PdII ion lies in a distorted square-planar environment defined by the two Br atoms and the mid-points of the two π-coordinated double bonds of bicyclo­[2.2.1]hepta-2,5-diene. The complex is disposed about a crystallographic mirror plane parallel to the ac plane passing through the Pd, Br atoms and the centre of the diene ligand

catena-Poly[[diaqua­dibromidoman­ganese(III)]-μ-pyridine-2-carboxyl­ato]

The asymmetric unit of the title compound, [MnBr2(C6H4NO2)(H2O)2]n, contains one monomeric unit of the neutral linear coordination polymer. The Mn3+ ions are bridged by anionic pyridine-2-carboxyl­ate (pic) ligands, thereby forming a chain-like structure along the c axis, and are six-coordinated in a distorted octa­hedral environment by two O atoms of the two different carboxyl­ate groups, two O atoms of two water mol­ecules and two Br atoms. The complex displays inter­molecular O—H⋯Br, O—H⋯N, O—H⋯O, C—H⋯O and C—H⋯Br hydrogen bonding. There may also be inter­molecular π–π inter­actions between adjacent pyridine rings, with a centroid–centroid distance of 3.993 (8) Å