Tetrahedral Coordination Research Articles

Highly efficient circularly polarized electroluminescence based on chiral manganese(ii) complexes.

Currently reported circularly polarized luminescent devices are primarily based on rare earth and noble metal complexes or lead perovskite materials. Reports on electroluminescent devices employing eco-friendly luminescent materials are notably scarce. In this study, we strategically designed and synthesized manganese complexes featuring Binapo as the chiral ligand. The complex structure reveals a tetrahedral coordination configuration, with the R/S configurations exhibiting a mirror relationship. Leveraging the strong ligand field and chiral structural characteristics of Binapo, the enantiomers display red emission and exhibit significant circularly polarized luminescence with a circularly polarized luminescence asymmetric factor (g lum) of 5.1 × 10-3. The circularly polarized electroluminescent performance was investigated by using a solution processing method and host-guest doping strategy. Our efforts resulted in device performance with an external quantum efficiency (EQE) exceeding 4%, and its electroluminescent asymmetric factor (g EL) reached an impressive -8.5 × 10-3. This surpasses the performance of most devices relying on platinum (Pt) and iridium (Ir) metal complexes and perovskite related materials. Our work establishes a pathway for the development of cost-effective and environmentally friendly chiral electroluminescent materials and devices.

Anticancer, antioxidant, and antimicrobial studies and molecular docking of a new hexanuclear Zn(II) complex, together with its X-ray crystal analysis.

A new hexanuclear Zn(II) complex with the ligand 2,2'-(piperazine-1,4-diyl)bis(ethan-1-amine), [L3Zn6(OH)6][ClO4]6·3MeOH·7H2O, was synthesized. The crystal structure of this complex showed that each Zn atom is in a distorted tetrahedral coordination environment, surrounded by two nitrogen atoms from each ligand and two hydroxide groups, each of which bridges to another Zn atom. The anticancer activities of the ligand and its metal complex against the breast cancer cell line (MCF-7) indicated that the zinc complex had a greater anticancer activity. The free ligand and its metal complex were evaluated for antioxidant activity using the DPPH scavenging method. In addition, the antibacterial activities of both compounds were screened against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The interaction of these compounds with DNA and AChE was also investigated using molecular docking.

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

This review summarizes recent advances in the synthesis, characterization and application of heteroatom (Ti, Zr, Sn, and Hf) Lewis acid zeolites in the conversion of biomass-derived oxygenates.

Хлорид и аренсульфонаты тетраорганилфосфония

The interaction of equimolar amounts of triphenylphosphorus dichloride with pentaphenylphosphorus in benzene have synthesized tetraphenylphosphonium chloride (1), which reacts with arenesulfonic acids to form tetraphenylphosphonium arenesulfonates [Ph4P][OSO2C6H3(OH-4)(COOH-3]∙H2O (2), [Ph4P][OSO2C10H5(OH-1)(NO2)2-2,4] (3), yielding up to 82%. A similar reaction of cyclohexyltriphenylphosphonium chloride with 2-sulfobenzoic acid is accompanied by the synthesis of cyclohexyltriphenylphosphonium 2-carboxybenzenesulfonate [Ph3P(С6H11-cyclo)][OSO2C6H4(COOH-2)] (4), yielding 80%. Structural features of complexes 24 have been established by X-ray diffraction. It has been shown that in cations 2–4 the phosphorus atoms have a distorted tetrahedral coordination, and for arenesulfonate anions the usual geometry with a tetrahedral sulfur atom is observed.

Structural, electronic and magnetic properties of greigite Fe3S4 by GGA and GGA+U versus SCAN meta-GGA density functionals

The performance of exchange-correlation functional of density functional theory represented in generalized gradient approximation (GGA) and in the strongly constrained and appropriately normed (SCAN) meta-GGA scheme to study structural, electronic, and magnetic properties of greigite (Fe3S4) was investigated. The effects of inclusion of strong electron correlations represented by on-site Hubbard correction U, and nonlocality of the long-range van der Waals (vdW) interactions were also considered. Geometry optimization yielded the inverse spinel structure and lattice parameter of greigite in good agreement with experimental data. Calculated electronic structure revealed a half-metallic nature of the greigite bands for the applied functionals except for GGA, which predicts metallic behavior. Antiferromagnetic coupling of iron ions in tetrahedral and octahedral coordinations makes the overall crystal structure ferrimagnetic. In general the GGA+U and SCAN show comparable performance in prediction physical properties of greigite. Inclusion of the vdW correction does not change the character of the bands.

Synthesis and characterization of Ag(I) and Cu(I) complexes of triphenylphosphine: crystal structures, Hirshfeld surface analyses, and molecular docking with SARS-CoV-2 and its Omicron variant

Two new coordination complexes, a Ag(I) complex [Ag(PPh3)3(Sal)] (1) and a Cu(I) complex [Cu(PPh3)3Cl] (2), have been synthesized (PPh3 = triphenylphosphine, Sal = 3,5-dichlorosalicylaldehyde). Both complexes were characterized via single crystal X-ray crystallography. Complexes 1 and 2 were crystallized in monoclinic and trigonal crystal systems, respectively, in the P21/c and P3 space groups. Both possess tetrahedral coordination geometries. DFT calculations provided structure-property information. The Hirshfeld surface analyses and 2D fingerprint plots were performed to investigate the intermolecular interactions in the crystal structures. To explore potential SARS-CoV-2 drug candidates, we have examined the molecular docking of 1 and 2 with the SARS-CoV-2 spike protein (PDB ID: 8GOP) and with the SARS-CoV-2 Omicron spike protein (PDB ID: 7WRV). Complexes 1 and 2 showed good docking results with the SARS-CoV-2 spike protein (PDB ID: 8GOP) where the binding energies (ΔG) and respective inhibition constants (K i) correlation values are −7.4 kcal/mol (4.321 µM) and −7.9 kcal/mol (5.012 µM), respectively. The molecular docking results revealed that 1 and 2 with the SARS-CoV-2 Omicron spike protein (PDB ID: 7WRV) resulted in the binding energy (ΔG) of −7.6 kcal/mol and −8.2 kcal/mol with an inhibition constant (K i) of 4.639 and 5.742 µM, respectively. The study predicts that 1 and 2 may be used as anti-SARS CoV-2 agents.

Mechanism of Negative Thermal Expansion in Monoclinic Cu2P2O7 from First Principles.

Negative thermal expansion (NTE) materials generally have high-symmetry space groups, large average atomic volumes, and corner-sharing octahedral and tetrahedral coordination structures. By contrast, monoclinic α-Cu2P2O7, which has a small average atomic volume and edge-sharing structure, has been reported to exhibit NTE, the detailed mechanism of which is unclear. In this study, we investigate the A2B2O7 polymorphs and analyze the NTE behavior of α-Cu2P2O7 using first-principles lattice-dynamics calculations. From the polymorphism investigation in 20 A2B2O7 compounds using 6 representative crystal structures, small A and B cationic radii are found to stabilize the α-Cu2P2O7-type structure. We then analyze the NTE behavior of α-Cu2P2O7 using quasi-harmonic approximation. Our calculated thermal expansion coefficients and anisotropic atomic displacement parameters were in good agreement with those of the experimental reports at low temperatures. From the mode-Grüneisen parameter distribution plotted over the entire first-Brillouin zone, we found that the phonon contributing most significantly to NTE emerges not into the special points but between them. In this phonon mode, the O connecting two PO4 tetrahedra rotates, and the Cu and O vibrate perpendicular to the bottom of the CuO5 pyramidal unit, which folds the ac lattice plane. This vibration behavior can explain the experimentally reported anisotropic NTE behavior of α-Cu2P2O7. Our results demonstrate that the most negative mode-Grüneisen parameter contributing to NTE behavior is not always located on high-symmetry special points, indicating the importance of lattice vibration analyses for the entire first-Brillouin zone.

Mixed Thioether/Amine‐Functionalized Expanded Calixarenes, Related Macropolycycles, and Metal Complexes thereof

AbstractA series of tetraaza‐expanded calix[4]arene analogues (2–4), in which two of the four aryl groups are ethylene‐protected thiophenol components were prepared from tetraaldehyde 1. Two of these strapped macrocycles were characterized crystallographically, as well as the dipalladium complex of 4. The same tetraaldehyde had been previously used for the synthesis of a macrotricycle (5) and a macropentacycle (6), the coordination properties of which have been investigated. In particular, ligand 6 was shown to be able to encapsulate a Cu+ or a Ag+ ion in the tetrahedral coordination pocket offered by a bridgehead nitrogen atom and the three proximal thioether sulfur atoms.

Mössbauer spectroscopy and gamma-ray shielding performance for iron phosphate glasses containing various heavy metals oxides

Mössbauer spectroscopy analysis and gamma (γ)-ray shielding performance for some iron phosphate glasses with composition 50 %P2O5 + 20 %Na2O + 20 %Fe2O3 + 10 %X, whereX = As2O3, SrO, BaO, CdO, and Sb2O3 w.t.% were investigated. The melt quenching technique was used for glass sample preparation, where the XRD patterns investigated the amorphous nature of the prepared glasses. Moreover, SEM and EDS mapping were used to provide information on the element distribution of the added heavy metals. Mössbauer spectroscopy showed that, most of the iron is present in the glass as Fe3+oxidation state, which is composed of tetrahedral and octahedral coordination states. The remaining iron ions have the form Fe2+ which occupied the tetrahedral coordination state. The γ-ray attenuation parameters like, mass attenuation coefficient (MAC), half value layer (HVL) and the effective atomic number (Zeff) were experimentally measured at different γ-ray energies using 133Ba, 137Cs, and 60Co radioactive sources. Results indicated that the sample containing Sb2O3 is the best-modified glass for gamma radiation protection.

Influence of ZSM-5 Crystal Size on Methanol-to-Olefin (MTO) vs. Ethanol-to-Aromatics (ETA) Conversion.

Crystal size is a key parameter of zeolites applied as catalysts. Herein, ZSM-5 crystals with similar physicochemical and acid properties, few defects, and aluminum exclusively in tetrahedral coordination are synthesized and the influence of the crystal size on the MTO and ETA conversion is investigated. Short olefins are the main products of the MTO conversion, whereas larger olefins and aromatics dominate the products after ETA conversion. In the case of both feeds, an increased crystal size decreases the catalyst's lifetime. The MTO conversion over larger ZSM-5 altered the product distribution, which was not the case for the ETA conversion. The reason is that the instantly available aromatics during ETA conversion lead to fast coking and zeolite crystals only active in the outer layers. Thus, the different reactivity of different-sized ZSM-5 is direct proof of a different conversion mechanism for both alcohols.

Incommensurately Modulated Cu0.9Pb1.2Sb2.9Se6 in the Lillianite Structure Type.

Samples with the nominal composition Cu0.9Pb1.2Sb2.9Se6 mainly contain a phase with incommensurately modulated lillianite-type structure with the respective composition. Single crystal diffraction with synchrotron radiation enabled a detailed refinement using the superspace group Cmcm(α00)00s with lattice parameters a = 4.16537(5), b = 14.0821(2), c = 19.8234(3) Å, and a modulation vector q = 0.6890(2)a* at room temperature. The structure is built up from tilted and distorted NaCl-type slabs that are interconnected by bicapped trigonal prisms, which mainly host Pb atoms, according to a 4L arrangement. Satellites up to the second order reveal positional and occupational modulation that mainly involves a sequence of Sb and Cu atoms and allows the Se substructure to adapt in a way that Sb and Cu feature predominantly octahedral and tetrahedral coordination, respectively. Above 523 K, satellite reflections disappear, and the crystal structure becomes more disordered with average coordination spheres of both Sb and Cu atoms corresponding to distorted octahedra. This phase transition leads to discontinuities in the evolution of lattice parameters and physical properties as functions of temperature. HRTEM investigations corroborate centrosymmetry and highlight atoms that are strongly affected by the modulation. Measurements of transport properties reveal a p-type semiconductor with a thermoelectric figure of merit up to 0.1 at 623 K. In accordance with B factor analysis, a small amount of substitution could increase zT significantly by optimizing the carrier concentration.

Hyperfine splitting and ferromagnetism in CdS : Mn nanoparticles for optoelectronic device applications

Manganese (Mn) doped cadmium sulphide (CdS) nanoparticles were synthesized using a chemical method. It was possible to decrease CdS : Mn particle size by increasing Mn concentration. Investigation techniques such as ultraviolet−visible (UV−Vis) absorption spectroscopy and photoluminescence (PL) spectroscopy were used to determine optical properties of CdS : Mn nanoparticles. Size quantization effect was observed in UV−Vis absorption spectra. Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping CdS nanoparticles with Mn element. Orange emission was observed at wavelength ~630 nm due to 4T1 → 6A1 transition. Isolated Mn2+ ions arranged in tetrahedral coordination are mainly responsible for luminescence. Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of CdS nanoparticles were also discussed. The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy (AAS). Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction (XRD) technique. CdS : Mn nanoparticles show ferromagnetism at room temperature. Transmission electron microscopy (TEM) images show spherical clusters of various sizes and selected area electron diffraction (SAED) patterns show the polycrystalline nature of the clusters. The electronic states of diluted magnetic semiconductors (DMS) of Ⅱ−Ⅵ group CdS nanoparticles give them great potential for applications due to quantum confinement. In this study, experimental results and discussions on these aspects have been given.

In silico screening and characterization, inhibition mechanism on ACE, and stability of antihypertensive peptides with Zn-chelating capacity identified from millet bran albumin hydrolysates

To obtain Angiotensin-I-Converting Enzyme (ACE) inhibition peptides with Zn-chelating capacity, millet bran albumin hydrolysates (MBAH) were subjected to Sephadex G-15 gel and reverse phase-high liquid performance chromatography, and UPLC-ESI-MS/MS analysis. Five oligopeptides including Val-Gly-Ser-Asp-Gly-Leu (VGSDGL), Thr-Gly-His-Gly-Val-Ala (TGHGVA), Gly-Cys-His-His-Tyr (GCHHY), Leu-Val-Glu-Ala-Val-Pro-Arg-Gly (LVEAVPRG) and Val-Leu-Ala-Gln-Glu-Glu (VLAQEE) were identified in MBAH. Of these, only pentapeptide GCHHY showed both ACE-inhibitory activity (IC50: 134.78 μmol/L) and Zn-chelating capacity (14.16 mg/g). Molecular docking and inhibition kinetics showed that GCHHY was a competitive inhibitor of ACE, because it could bind with Lys511 of ACE which belongs to the central S2 pocket. Moreover, GCHHY can affect zinc tetrahedral coordination in ACE through binding with Glu411 and His383. The sulfhydryl, amino and carboxyl groups of GCHHY can bind with zinc ions. Under the gastrointestinal digestion, the ACE-inhibitory activity of GCHHY was relatively stable, and the zinc solubility of GCHHY-Zn complexes was more stable than zinc sulfate (P < 0.05). In addition, both GCHHY and GCHHY-Zn complexes lowered the diastolic blood pressure and systolic blood pressure of spontaneous hypertensive rats at dose of 50–200 mg/kg body weight. These results suggested the potential applications of millet albumin peptides as ingredients for antihypertension or zinc fortification.

Hydroboration of aldehydes with pinacolborane catalyzed by bulky 2‐iminopyrrolyl copper(I) triphenylphosphine complexes

Eight new copper(I) triphenylphosphine complexes of bulky 5‐substituted‐2‐iminopyrrolyl ligands [Cu{κ2N,N′‐5‐R‐NC4H2–2‐C(H) = N(2,6‐iPr2C6H3)}(PPh3)n] (for n = 2: R = 2,6‐Me2C6H3 (1), 3,5‐(CF3)2C6H3 (2); for n = 1: R = 2,4,6‐iPr3C6H2 (3), CPh3 (4), 2,6‐(OMe)2C6H3 (5), 2,4,6‐Ph3C6H2 (6), 2,6‐Me2C6H3 (7), 3,5‐(CF3)2C6H3 (8)) are presently reported. The complexes were prepared in good yields by: (1) the reaction of the previously reported binuclear complexes [Cu{κN,κN'‐5‐R‐NC4H2‐2‐C(H) = N(2,6‐iPr2C6H3)}]2 (D1–D6) with triphenylphosphine (PPh3); (2) the reaction of the respective 5‐R‐2‐iminopyrrolyl potassium salts (KL1–KL3 and KL5) and [Cu(NCMe)2(PPh3)2]BF4; or (3) the abstraction of one PPh3 ligand present in complexes 1 and 2 with one equivalent of tris(pentafluorophenyl)borane (only for complexes 7 and 8, respectively). All complexes were characterized by NMR spectroscopy, elemental analysis and, in selected cases, by single crystal X‐ray diffraction. The single crystal X‐ray diffraction structures of 1, 3, and 5–7 displayed tetrahedral (for 1) and trigonal planar (for 3 and 5–7) coordination geometries. All complexes catalyzed the 1,4‐hydroboration of some α,β‐unsaturated (E)‐2‐enals with pinacolborane (HBPin), with 1,4:1,2‐addition selectivities as high as 29:1, the maximum turnover frequencies being equal to 9.9 min−1, and the 1,4‐hydroboration selectivity being favored by increasing steric protection of the 5‐substituted‐2‐iminopyrrolyl scaffold. Additionally, these complexes also catalyzed the hydroboration of an array of other aldehydes, reaching TOFs as high as 9.9 min−1. A combination of control experiments suggests that the catalyst system operates via a non‐classical copper‐hydride outer sphere route.

Evidence for Mixed Mg Coordination Environments in Silicate Glasses: Results from 25Mg NMR Spectroscopy at 35.2 T.

The Mg-O coordination environment of silicate glasses of composition CaMgSi2O6, Na2MgSi3O8, and K2MgSi5O12 is probed using ultrahigh-field (35.2 T) 25Mg magic angle spinning nuclear magnetic resonance (MAS NMR) and triple-quantum MAS NMR spectroscopy. These spectra clearly reveal the coexistence of 4-fold- (MgIV) and 6-fold- (MgVI) coordinated Mg in all glasses. The MgIV/MgVI ratio implies an average Mg-O coordination number of ∼5 for CaMgSi2O6 glass, bringing NMR results for the first time in good agreement with those reported in previous studies based on diffraction and X-ray absorption spectroscopy, thus resolving a decade-long controversy regarding Mg coordination in alkaline-earth silicate glasses. The Mg-O coordination number decreases to ∼4.5 in the alkali-Mg silicate glasses, indicating that Mg competes effectively with the low field strength alkali cations for the nonbridging oxygen in the structure to attain tetrahedral coordination. This work illustrates the promise of ultrahigh-field NMR spectroscopy in structural studies involving nuclides with low gyromagnetic ratio.

Design of bifunctional 1D nanostructures for the catalytic conversion of carbon dioxide into cyclic carbonates

One dimensional silica-based nanotubes represent an innovative and promising morphology in the context of heterogeneous catalysis. Here these nanostructures were prepared for the first time as bifunctional materials, with hafnium or tin atoms inserted as single sites in the silica structure and imidazolium moieties anchored at the surface. The low dimensional solids thus present both acid sites owing to the presence of metal cations in tetrahedral coordination (co-catalyst) and nucleophilic species coming from the counterion of the imidazolium moieties (catalyst). The design of the catalysts consisted of two main steps. The Hf- or Sn-doped silica solids were initially prepared using a straightforward sol-gel method including a pH adjustment step allowing a quantitative insertion of the metal cations in the silica framework. These materials were post-functionalized with imidazolium moieties. The solids were extensively characterized thus confirming the presence of well-defined and open tubular structure, high specific surface area, successful insertion of Hf and Sn in the silica framework, and a correct functionalization with imidazolium salts. The different catalysts were tested in the valorization of CO2 with styrene oxide to give the corresponding cyclic carbonate. The bifunctional solids were stable and recyclable. The versatility of the best catalyst, represented by the Hf-based material, was confirmed using different epoxides. Finally, by tuning the reaction conditions or changing the imidazolium salt, a further boost of the catalytic performances was achieved.

Effect of chromium substitution on structural and optical properties of Ca3(VO4)2 for laser and SRS applications

Crystal structures of Czochralski-grown Ca3(VO4)2 single crystals doped with over-stoichiometric 0.01, 0.05, and 0.1 wt% Cr2O3 (CVO:Cr) are solved and refined. A whitlockite-like structure with five Ca sites, two-capped (Ca1 and Ca3) and mono-capped (Ca2) trigonal prisms, distorted octahedron (Ca4) and tetrahedron (Ca5), is determined for CVO:Cr. Single-crystal synchrotron X-ray diffraction analysis revealed the presence of chromium in Ca2, Ca3, Ca4 sites. In CVO:Cr, chromium has octahedral (Cr3+) and tetrahedral (Cr4+) coordination, which suggests structural superpositions of CaO8, CaO7, CaO6 and Cr3+O6 or Cr4+O4 polyhedra. X-ray diffraction, EPR and spectroscopic studies showed that green or yellow color of CVO:Cr is related to chromium valence state, Cr3+ or Cr4+, respectively. An increase in the Cr4+ concentration is accompanied by increased vacancy content in two of three vanadium sites. Structural behavior of transition metal ions with a variable formal charge (Co, Mn, Cr) in CVO structure is summarized, analyzed and discussed. Three absorption bands around 23900, 16300 and 14000 cm−1, typical for Cr3+ ions, are revealed in the UV-VIS spectra of green samples. An additional broad band with a maximum at 21254 cm−1 refers to Cr4+ ions, the appearance of which after annealing in air was established by X-ray diffraction analysis.

Synthesis, spectral, thermal properties, and crystal structure of bis(2,4-dichlorobenzoato-O)bis(thiourea-S)zinc(II)

AbstractThe complex compound bis(2,4-dichlorobenzoato-O)bis(thiourea-S)zinc(II) has been prepared and characterized by elemental analysis, thermal analysis, IR spectroscopy, and single-crystal X-ray analysis. During the thermal decomposition in inert atmosphere, thiourea, dichlorobenzene and carbon dioxide are evolved. The solid intermediate was confirmed by IR spectroscopy, and the final product of the thermal decomposition was proven by powder diffractometry. The coordination environment of the zinc(II) atom is built up by two sulphur atoms from two thiourea ligands and two oxygen atoms from two monodentate 2,4-dichlorobenzoate anions to form a distorted tetrahedral coordination around the zinc(II) atom (chromophore ZnO2S2). The mode of the carboxylate binding was assigned from the IR spectrum using the magnitude of the separation between the carboxylate stretches (Δ), and it is in good agreement with the crystal structure. The structure is also stabilized with hydrogen bonds of N–H···O and N–H···Cl type.

Potential usage of cesium manganese halide for multi-functional optoelectronic devices: Display & photodetector application

The composition of manganese, which exhibits tetrahedral coordination with halogen ligands, makes it excellent for use in green light-emitting materials. In particular, zero-dimensional Cs3MnBr5 material has continuously been researched as a lead-free all-inorganic light emitting material. It has excellent optical properties such as center wavelength and full width at half maximum. The most recent studies on Cs3MnBr5 have synthesized it using a bottom-up method. However, the problem of notably poor particle uniformity or efficiency remains. The aim of this study was to develop sub-micron-sized Cs3MnBr5 particles with octahedron or truncated shapes by modifying the existing hot-injection synthesis method. Sub-micron Cs3MnBr5 particles showed 60% photoluminescence quantum yield (PLQY) under blue light excitation and absorbed light in the entire visible light region, including the absorption edge by PLE. Therefore, we explored existing research on light conversion films for LED & micro-LED and photodetector applications with a focus on optical properties of Cs3MnBr5 particles.

Point Defects in Silicon-Doped β-Ga2O3: Hybrid-DFT Calculations.

In this work, hybrid density functional theory calculations are used to evaluate the structural and electronic properties and formation energies of Si-doped β-Ga2O3. Overall, eight interstitial (Sii) and two substitutional (SiGa) positions are considered. In general, our results indicate that the formation energy of such systems is significantly influenced by the charge state of the defect. It is confirmed that it is energetically more favorable for the substitution process to proceed under Ga-poor growth conditions than under Ga-rich growth conditions. Furthermore, it is confirmed that the formation of SiGaI with a tetrahedral coordination geometry is more favorable than the formation of SiGaII with an octahedral one. Out of all considered interstitial positions, due to the negative formation energy of the Si +3 charge state at i8 and i9 interstitial positions over the wide range of Fermi energy, this type of defect can be spontaneously stable. Finally, due to a local distortion caused by the presence of the interstitial atom as well as its charge state, these systems obtain a spin-polarized ground state with a noticeable magnetic moment.