Ce20Mg19Zn81: a new structure type with a giant cubic cell

Icosacerium nonadecamagnesium henoctacontazinc, Ce₂₀Mg₁₉Zn₈₁, synthesized by fritting of the pure elements with subsequent arc melting, crystallizes with an unusually large cubic unit cell [space group F3m, a = 21.1979 (8) Å] and represents a new structure type among the technologically important family of ternary rare earth–transition metal–magnesium intermetallics. The majority of atoms (two Ce and five Zn) display .3m site symmetry, two Ce and one Mg atom occupy three 2.mm positions, one Mg and one Zn have 3m site symmetry, one Mg and three Zn atoms sit in ..m positions, and one Zn atom is in a general position. The Ce₂₀Mg₁₉Zn₈₁ structure can be described using the geometric concept of nested polyhedral units, by which it consists of four different polyhedral units, viz.A (Zn+Zn₄+Zn₄+Zn₁₂+Ce₆), B (Mg+Zn₁₂+Ce₄+Zn₂₄+Ce₄), C (Zn₄+Zn₁₂+Mg₆) and D (Zn₄+Zn₄+Mg₁₂+Ce₆), with the outer construction unit being an octahedron or tetrahedron. All interatomic distances in the structure indicate metallic‐type bonding.     

La4.27Mg2.89Zn30, a new structure type with strong positional disorder

Ternary tetralanthanum trimagnesium tricontazinc, La_4.27Mg_2.89Zn₃₀, crystallizes as a new structure type. It belongs to the structural family that may be derived from the hexagonal CaCu₅ and Th₂Ni₁₇ structure types by combination of internal deformation and multiple substitution. The triangular 3₆ and hexagonal 6₃ nets are alternately stacked with Kagomé 3636 nets. The atoms with the largest radius (La) are enclosed in 18‐vertex polyhedra (distorted pseudo‐Frank–Kasper polyhedra). The coordination polyhedra of the two Mg atoms are bicapped and monocapped hexagonal antiprisms, with coordination numbers of 14 and 13, respectively. For all the Zn atoms, the typical icosahedral coordination is observed. In the direction of the six‐ and threefold axes, strong positional disorder is observed as a result of partial substitutions of La atoms by pairs of Mg atoms.     

Quaternary indides LaTIn3Mg (T = Rh and Ir) and CeIrIn3Mg with LaCoAl4 type structure

The quaternary indides LaTIn₃Mg (T = Rh and Ir) and CeIrIn₃Mg were prepared from the elements in sealed tantalum ampoules in an induction furnace. The samples were characterized by X-ray powder and single crystal data: LaCoAl₄ type, Pmma, Z = 2, a = 830.5(1), b = 436.1(1), c = 745.1(1) pm, wR2 = 0.038, 467 F ² values for LaRhIn_3.075Mg_0.925, a = 832.9(1), b = 436.5(1), c = 746.9(1) pm, wR2 = 0.077, 471 F ² values for LaIrIn_3.091Mg_0.909, and a = 832.2(1), b = 434.1(1), c = 743.9(1) pm, wR2 = 0.066, 465 F ² values for CeIrIn_3.07Mg_0.93 with 25 variables for each refinement. The transition metal, indium, and magnesium atoms build up three-dimensional [TIn₃Mg] networks which leave pentagonal prismatic voids for the lanthanum and cerium atoms. The transition metal atoms have tricapped trigonal prismatic coordination and the magnesium atoms fill distorted square prisms. All three crystals revealed a small degree of Mg/In mixing on the latter site.     

Spatial Separation of Covalent,Ionic, and Metallic Interactions in Mg11Rh18B8 and Mg3Rh5B3

The crystal structures of Mg₁₁Rh₁₈B₈ and Mg₃Rh₅B₃ have been investigated by using single‐crystal X‐ray diffraction. Mg₁₁Rh₁₈B₈: space group P4/mbm; a=17.9949(7), c=2.9271(1) Å; Z=2. Mg₃Rh₅B₃: space group Pmma; a=8.450(2), b=2.8644(6), c=11.602(2) Å; Z=2. Both crystal structures are characterized by trigonal prismatic coordination of the boron atoms by rhodium atoms. The [BRh₆] trigonal prisms form arrangements with different connectivity patterns. Analysis of the chemical bonding by means of the electron‐localizability/electron‐density approach reveals covalent B? Rh interactions in these arrangements and the formation of B? Rh polyanions. The magnesium atoms that are located inside the polyanions interact ionically with their environment, whereas, in the structure parts, which are mainly formed by Mg and Rh atoms, multicenter (metallic) interactions are observed. Diamagnetic behavior and metallic electron transport of the Mg₁₁Rh₁₈B₈ and Mg₃Rh₅B₃ phases are in agreement with the bonding picture and the band structure.     

Hydrothermal synthesis and crystal structure of a layered coordination polymer: [Zn2(C2O4)2(C3N2H4)2] n

A new metal-organic coordination polymer [Zn₂(C₂O₄)₂(C₃N₂H₄)₂] _n (1) has been hydrothermally synthesized with ZnCl₂·2H₂O, oxalic acid and imidazole. The compound has a 2D network, consisting of infinite zinc(II) oxalate chains connected to each other by three-coordinate oxygen atoms. Within the chains, the zinc atoms are each octahedrally coordinated by one nitrogen atom from imidazole and five oxygen atoms from oxalate groups. Furthermore, there are two coordination modes of oxalate to zinc ions: chelate bis-bidentate and chelate/bridging bis-bidentate in compound 1, and the latter is rare among related compounds. Crystal data: monoclinic, P2(1)/c, a?=?8.4310(17), b?=?9.4060(19), c?=?8.2790(17)?Å, β?=?93.15(3)°, V?=?655.5(2)?ų, Z?=?2, R ₁?=?0.0322, wR ₂?=?0.0850.     

Structure and coordination in mono and dinuclear Zn(II)-pyrrolidine dithiocarbamate complexes

The structures of the chelate Zn(PDTC)₂ and its dimeric form Zn₂(PDTC)₄ are investigated theoretically at B3LYP/cc-pVDZ level. The natural bond orbital (NBO) analysis has been performed to explore the metal–ligand coordination of these chelates. In Zn(PDTC)₂, the sulfur atoms mainly use 3p sub-shells to coordinate with mixed (4s + 4p _x  + 4p _y  + 4p _z ) orbital of zinc having sp ³ hybridization. In Zn₂(PDTC)₄, each zinc atom coordinates with one terminal and two bridging PDTC ligands. The contribution of bridging sulfur atoms in chelation is much more than terminal sulfurs. The bridging sulfur atoms use 3s and 3p sub-shells to coordinate with 4s and 4p sub-shells of metal center zinc. The charge transfer interactions between sulfur and metal center involving 4d, 5s, and 5p sub-shells of zinc are much feeble compared to those involving 4s and 4p sub-shells of zinc.     

A novel two‐dimensional zinc(II) coordination polymer with 6‐mercaptonicotinic acid

The novel title Zn^II coordination polymer, poly[bis(μ‐6‐thioxo‐1,6‐dihydropyridine‐3‐carboxylato‐κ²S:O)zinc(II)], [Zn(C₆H₄NO₂S)₂]_n, consists of two crystallographically independent zinc centers and two 6‐mercaptonicotinate (Hmna⁻) ligands. Each Zn^II atom is four‐coordinated and lies at the center of a distorted tetrahedral ZnS₂O₂ coordination polyhedron, bridged by four Hmna⁻ ligands to form a two‐dimensional (4,4)‐network. Each Hmna⁻ ion acts as a bridging bidentate ligand, coordinating to two Zn^II atoms through the S atom and a carboxyl O atom. The metal centers reside on twofold rotation axes. The coordination mode of the S atoms and N—H...O hydrogen‐bonding interactions between the protonated N atoms and the uncoordinated carboxyl O atoms give the extended structure a wavelike form.     

Motive dichtester Kugelpackungen: Die Verbindungen Zn3(PS4)2 und LiZnPS4

Motifs of Closest Packings: The Compounds Zn₃(PS₄)₂ and LiZnPS₄ The crystal structure of Zn₃(PS₄)₂ was determined by single crystal X‐ray methods. The compound crystallizes tetragonally (P4¯n2; a = 7.823(1), c = 9.053(1)Å; Z = 2) with a new structure type built up by corner‐sharing ZnS₄ tetrahedra, which form two‐dimensional layers. Between them the P atoms are coordinated likewise tetrahedrally by sulfur. The PS₄ tetrahedra are arranged according to the motif of the cubic closest packing with zinc in three quarters of the tetrahedral voids. LiZnPS₄ (I4¯; a = 5.738(1), c = 8.914(1)Å; Z = 2) was synthesized by heating the elements at 400 °C. In comparison with Zn₃(PS₄)₂ one Zn atom is replaced by two Li atoms. The metal atoms are located in the centres of the sulfur tetrahedra in such a way that the unit cell volume is only about half that of the zinc compound. In this packing of the PS₄ units all the tetrahedral voids are occupied by lithium and zinc atoms. Chemical bonding in LiZnPS₄ is discussed by means of the electron localization function ELF.     

Zn11Rh18B8 and Zn10MRh18B8 with M = Sc,Ti, V,Cr, Mn,Fe, Co,Ni, Cu,Al, Si,Ge, Sn – New Ternary and Quaternary Zinc Rhodium Borides

Zn₁₁Rh₁₈B₈ and Zn₁₀MRh₁₈B₈ with M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Si, Ge and Sn are obtained by reaction of the elemental components in sealed tantalum tubes at 1500 K. They crystallize tetragonally with Z = 2 in the spacegroup P4/mbm with lattice constants a = 1771.2(2) pm, c = 286.40(4) pm for Zn₁₁Rh₁₈B₈ and in the range a = 1767.65(9) pm, c = 285.96(3) pm (Zn₁₀NiRh₁₈B₈) to a = 1774.04(9) pm, c = 286.79(2) pm (Zn₁₀SnRh₁₈B₈) for the quaternary compounds. According to powder photographs all compounds are isotypic. Struture determinations based on single crystal X-ray data were performed with Zn₁₁Rh₁₈B₈, Zn₁₀FeRh₁₈B₈ and Zn₁₀NiRh₁₈B₈. The structure of Zn₁₁Rh₁₈B₈ is related to the Ti₃Co₅B₂ type. Along the short axis planar nets of rhodium atoms composed of triangles, squares, pentagons and elongated hexagons alternate with layers containing the boron and zinc atoms. The rhodium atoms form trigonal prisms centered by boron atoms, two kinds of tetragonal and pentagonal prisms centered by zinc atoms and elongated hexagonal prisms containing pairs of zinc atoms. In the quaternary compounds Zn₁₀MRh₁₈B₈ the zinc atoms in one sort of tetragonal prisms are replaced by M atoms.     

Binary Compounds of Rhodium and Zinc: RhZn,Rh2Zn11, and RhZn13

The title compounds were prepared by reaction of the elements at elevated temperatures in sealed silica tubes. Single crystals of RhZn and RhZn₁₃ were obtained by slow cooling of samples with a high zinc content after dissolving the zinc‐rich matrix in hydrochloric acid. Their crystal structures were determined from single‐crystal X‐ray diffractometer data. RhZn has a CsCl type structure: Pm3m, a = 300.9(1) pm. RhZn₁₃ has a CoZn₁₃ type structure: C2/m, a = 1090.8(2) pm, b = 753.7(2) pm, c = 512.7(1) pm, β = 101.02(2)°. The structure of Rh₂Zn₁₁ is isotypic with Cu₅Zn₈, the γ‐brass structure. It was refined from X‐ray diffractometer powder data: I43m, a = 909.1(1) pm. In these structures all atoms have high coordination numbers. The structure of RhZn₁₃ contains relatively large unoccupied voids. It is suggested that they accommodate nonbonding electrons. Electrical conductivity measurements of Rh₂Zn₁₁ and RhZn₁₃ indicate metallic behavior, however, with an unexpectedly high resistivity for Rh₂Zn₁₁. The expected Pauli paramagnetism of these compounds is overcompensated by the core diamagnetism, suggesting a low density of states at the Fermi level especially for Rh₂Zn₁₁. This correlates with the high electrical resistivity of this compound.     

Crystal structure of a new transition metal-organic Zn(II) complex

A novel Zn(II) coordination polymer [Zn₂(phen)₂]L₄·3H₂O(1) is synthesized by the reaction of Zn(NO₃)₂, Phen(1,10-phenanthroline), and L(2-mercaptonicotinic acid) at room temperature and structurally characterized by X-ray single crystal diffraction along with IR spectra and elemental analysis. Title complex 1 belongs to the triclinic system with the space group (P-1), a = 10.9373(11) Å, b = 11.6201(12) Å, c = 13.1371(14) Å; α = 116.100(1)°, β = 97.717(2)°, γ = 108.652(2)°, V = 1344.4(2) ų; Z = 2, ρ_calc = 1.596 g·cm^?3, F(000) = 664, R ₁ = 0.0708 and wR ₂ = 0.1823 independent reflections for 18523 observed ones (I > 2σ(I)), and the zinc atom is rendered five-coordinated in a distorted tetragonal pyramid coordination geometry by two nitrogen atoms from the phen molecule, two oxygen atoms from two L molecules, and an oxygen atom from the H₂O molecule. Complex 1 forms a 1D chain by O-H…O hydrogen bonds from free-water, while the 2D layer structure is formed by C-H…O hydrogen bonds through the L ligand of adjacent chains. These compounds further result in a 3D network structure by the intermolecular π…π stacking interaction of the neighbouring layers.     

Discrete Magnesium Hydride Aggregates: A Cationic Mg13H18 Cluster Stabilized by NNNN‐Type Macrocycles

Large magnesium hydride aggregates [Mg₁₃(Me₃TACD)₆(μ₂‐H₁₂)(μ₃‐H₆)][A]₂ ((Me₃TACD)H=1,4,7‐trimethyl‐1,4,7,10‐tetraazacyclododecane; A=AlEt₄, AlnBu₄, B{3,5‐(CF₃)₂C₆H₃}₄) were synthesized stepwise from alkyl complexes [Mg₂(Me₃TACD)R₃] (R=Et, nBu) and phenylsilane in the presence of additional Mg^II ions. The central magnesium atom is octahedrally coordinated by six hydrides as in solid α‐MgH₂ of the rutile type. Further coordination to six magnesium atoms leads to a substructure of seven edge‐sharing octahedra as found in the hexagonal layer of brucite (Mg(OH)₂). Upon protonolysis in the presence of 1,2‐dimethoxyethane (DME), this cluster was degraded into a tetranuclear dication [Mg₂(Me₃TACD)(μ‐H)₂(DME)]₂[A]₂.     

Geometric and topological analysis of icosahedral structures of samson Mg2Zn11 (cP39) Phases, K6Na15Tl18H (cP40), and Tm3In7Co9 (cP46): Nanocluster precursors, self-assembly mechanism, and superstructure ordering

Geometric and topological analysis and 3D reconstruction of self-assembly of icosahedral structures of Samson Mg₂Zn₁₁ clusters (space group Pm[`3]Pm\bar 3, cP39, 10 compounds) and the K<sub>6</sub>Na<sub>15</sub>Tl<sub>18</sub>H and Tm<sub>3</sub>In<sub>7</sub>Co<sub>9.29</sub> structures were performed by computer methods (the TOPOS program package). The complete decomposition of the 3D graph of the crystal structures into cluster substructures showed the existence of the crystal-forming nanocluster precursor A comprising 45 atoms (A-45). The S-6 cluster spacers were identified in Mg<sub>2</sub>Zn<sub>11</sub>, and the S-7 cluster spacers were found in K<sub>6</sub>Na<sub>15</sub>Tl<sub>18</sub>H. In Tm<sub>3</sub>In<sub>7</sub>Co<sub>9.29</sub>, the S-6 and S-7 cluster spacers with the centers statistically occupying the same position were determined. The A-45, S-6 (octahedron), and S-7 (centered octahedron) clusters have symmetry [`3]m\bar 3m. The A-45 nanocluster contains an inner Zn(Zn)₁₂ template icosahedron and an external quasi-spherical shell composed of 32 atoms (deltahedron D32). A-45 is equivalent to the Bergman cluster used as the approximant of the local structure of quasicrystals. For deltahedron D32, the existence of a hierarchical structure was identified as a result of self-assembly involving two types of cyclic clusters: K-7 with an atom in the center of the sixth ring and three-atom cyclic clusters K-3. The atoms of the K-3 and K-7 clusters occupy all possible positions over the 12 vertices and 20 faces of an icosahedron and thereby form an edge net of bonds made of triangles. For the K₆(Na₁₄MTl₁₈) structures (M = Mg, An, Cd, Hg), the cluster nature of superstructure ordering of three chemically different atoms (14Na, M, and 18Tl) over 33 positions of the Zn atoms in the unit cell of the basis Mg₂Zn₁₁(Mg₆Zn₃₃) structure was considered.     

Nd4.67Ru3Mg8.83 – A Magnesium‐rich Compound with Ru@Mg4Nd4 Square Antiprisms and Mg@Mg8 Cubes as ­Basic Building Units

The magnesium‐rich intermetallic compound Nd_4.67Ru₃Mg_8.83 was synthesized from the elements in a sealed tantalum tube in a resistance furnace. Nd_4.67Ru₃Mg_8.83 was characterized by X‐ray powder and single crystal diffraction: new structure type,I4/mmm, tI66, a = 946.0(1), c = 1789.5(4) pm, wR2 = 0.0368, 725 F² values and 36 variables. Two of the five crystallographically independent magnesium sites show a small degree of Mg/Nd mixing. The ruthenium atoms have square anti‐prismatic Nd₄Mg₄ coordination. Always six of such anti‐prisms are condensed via common edges, leading to a CsCl analogous neodymium coordination for the Mg4 atoms. The two‐dimensional networks of edge‐sharing Ru@Nd₄Mg₄ antiprisms are condensed to a three‐dimensional network via Mg5@Mg3₄Mg1₄ cubes. The extended magnesium substructure shows a broad range of Mg–Mg distances from 308 to 351 pm.     

A novel 8‐carboxyindeno[1,2‐b]quinoxalin‐11‐one thio­semi­carbazone zinc(II) Schiff base complex

In the novel title binuclear zinc(II) Schiff base complex, bis­(μ‐11‐thio­semicarbazonoindeno[1,2‐b]quinoxaline‐8‐carboxylato)bis­[(dimethyl sulfoxide)zinc(II)] dimethyl sulfoxide tri­solvate, [Zn₂(C₁₇H₉N₅O₂S)₂(C₂H₆OS)₂]·3C₂H₆OS, each Zn^II atom is five‐coordinated and situated in a distorted square‐pyramidal environment, coordinated by two L²⁻ ligands and one dimethyl sulfoxide mol­ecule. Each L²⁻ ligand, which coordinates to two Zn^II atoms, has two parts. One part, acting in a tridentate chelating mode, coordinates to one Zn^II atom through two N atoms and one S atom, while another part coordinates to another Zn^II atom through a monodentate carboxylate group. The whole complex has a dimeric structure. The coordination mode of the nearly planar L²⁻ ligand is quite different from the most common mode for Schiff bases.     

Crystal and electronic structures of La2LiGe6−x (x = 0.21) and La2LiGe4Si2

The synthesis and characterization of a new ternary dilanthanum lithium hexagermanide, La₂LiGe_6−x (x = 0.21), belonging to the Pr₂LiGe₆ structure type, and a quaternary dilanthanum lithium tetragermanium disilicide, La₂LiGe₄Si₂, which crystallizes as an ordered variant of this type, are reported. In both structures, Li is on a site of mmm symmetry. All other atoms are on sites of m2m symmetry. These structures are new representatives of a homologous linear structure series based on structural fragments of the AlB₂, CaF₂ and ZrSi₂ structure types. The observed 17‐vertex polyhedra are typical for La atoms and the environment of the Li atom is cubic. Two Ge atoms are enclosed in a tetragonal prism with one added atom (nine‐vertex polyhedron). The trigonal prismatic coordination is typical for Ge or Si atoms. The metallic nature of the bonding is indicated by the interatomic distances and electronic structure calculations.     

Mg5TiO4(BO3)2

Single crystals of pentamagnesium titanium(IV) tetraoxide bis(borate), Mg₅TiO₄(BO₃)₂, were prepared by slow cooling of the melt from 1623 K in air. The crystal is isostructural with the mineral ludwigite (Mg₂FeO₂BO₃). The Mg and Ti atoms are coordinated by six O atoms and the B atom is coordinated by three O atoms. There are three Mg sites and one mixed site statistically occupied by Mg and Ti atoms. Atoms are at the following special positions: 2a (0, 0, 0) and 2d (0, , ) for two Mg atoms, 4g (x, y, 0) for the mixed Ti/Mg site and the BO₃ group, and 4h (x, y, ) for a third Mg and two oxide O atoms. MgO₆ and (Ti/Mg)O₆ octahedra are connected by sharing of edges to form zigzag folding layers along the c axis. Triangular prismatic tunnels are formed between the folding layers by sharing apical O atoms of the MgO₆ and (Ti/Mg)O₆ octahedra.     

(2,2′‐Biquinoline‐κ2N,N′)dichloropalladium(II), ‐copper(II) and ‐zinc(II)

In the three title complexes, namely (2,2′‐biquinoline‐κ²N,N′)dichloro­palladium(II), [PdCl₂(C₁₈H₁₂N₂)], (I), and the corresponding copper(II), [CuCl₂(C₁₈H₁₂N₂)], (II), and zinc(II) complexes, [ZnCl₂(C₁₈H₁₂N₂)], (III), each metal atom is four‐coordinate and bonded by two N atoms of a 2,2′‐biquinoline molecule and two Cl atoms. The Pd^II atom has a distorted cis‐square‐planar coordination geometry, whereas the Cu^II and Zn^II atoms both have a distorted tetra­hedral geometry. The dihedral angles between the N—M—N and Cl—M—Cl planes are 14.53 (13), 65.42 (15) and 85.19 (9)° for (I), (II) and (III), respectively. The structure of (II) has twofold imposed symmetry.     

Structure and Properties of γ‐Brass‐Type Pt2Zn11—δ (0.2 < δ < 0.3)

The γ‐brass type phase Pt₂Zn_11—δ (0.2 < δ < 0.3) was prepared by reaction of the elements in evacuated silica ampoules. The structures of crystals grown in the presence of excess zinc or alternatively excess platinum were determined from single crystal X‐ray diffraction intensities and confirmed by Rietveld profile fits. Pt₂Zn_10.72(1) crystallizes in the space group I4¯3m, a = 908.55(4) pm, Z = 4. The structure refinement converged at R_F = 0.0302 for I_o > 2σ (I_o) for 293 symmetrically independent intensi ties and 19 variables. The structure consists of a 26 atom cluster which is comprised of four crystallographically distinct atoms. The atoms Zn(1), Pt(1), Zn(2) and Zn(3) form an inner tetrahedron IT, an outer tetrahedron OT, an octahedron OH, and a distorted cuboctahedron CO respectively. About 14 % of the Zn(1) sites are unoccupied. Pt₂Zn_10.73 melts at 1136(2) K. It is a moderate metallic conductor (ρ₂₉₈ = 0.2—0.9 mΩ cm) whose magnetic properties (χ_mol = —4.6 10^—10 to —5.4 10^—10 m³ mol^—1) are dominated by the core diamagnetism of its components.     

New quaternary carbide Mg1.52Li0.24Al0.24C0.86 as a disorder derivative of the family of hexagonal close‐packed (hcp) structures and the effect of structure modification on the electrochemical behaviour of the electrode

Magnesium alloys are the basis for the creation of light and ultra‐light alloys. They have attracted attention as potential materials for the accumulation and storage of hydrogen, as well as electrode materials in metal‐hydride and magnesium‐ion batteries. The search for new metal hydrides has involved magnesium alloys with rare‐earth transition metals and doped by p‐ or s‐elements. The synthesis and characterization of a new quaternary carbide, namely dimagnesium lithium aluminium carbide, Mg_1.52Li_0.24Al_0.24C_0.86, belonging to the family of hexagonal close‐packed (hcp) structures, are reported. The title compound crystallizes with hexagonal symmetry (space group Pm2), where two sites with m2 symmetry and one site with 3m. symmetry are occupied by an Mg/Li statistical mixture (in Wyckoff position 1a), an Mg/Al statistical mixture (in position 1d) and C atoms (2i). The cuboctahedral coordination is typical for Mg/Li and Mg/Al, and the C atom is enclosed in an octahedron. Electronic structure calculations were used for elucidation of the ability of lithium or aluminium to substitute magnesium, and evaluation of the nature of the bonding between atoms. The presence of carbon in the carbide phase improves the corrosion resistance of the Mg_1.52Li_0.24Al_0.24C_0.86 alloy compared to the ternary Mg_1.52Li_0.24Al_0.24 alloy and Mg.