INAA of Ca, Cl, K, Mg, Mn, Na, P, and Sr contents in the human cortical and trabecular bone

Summary Concentration of Ca, Cl, K, Mg, Mn, Na, P, and Sr were determined by instrumental neutron activation analysis using short-lived radionuclides in intact cortical and trabecular bone of femoral neck and iliac crest of 81 relatively healthy 15-55 years old women (n = 36) and men (n = 45). In cortical bone the Ca, P, and Mg mass fractions in the femoral neck were statistically significantly higher, and Cl, K, and Na lower, than the values for the iliac crest. In trabecular bone the Cl, K, and Na mass fractions in the iliac crest were significantly higher, and Ca, P also higher, than the values for the femoral neck.     

Application of INAA in the assessment of selected elements in cancellous bone of human iliac crest

The effect of age and sex was investigated on the concentration of chemical elements in intact cancellous bone of iliac crest of 74 relatively healthy, 15–55 years old women (n = 29) and men (n = 45). Concentrations of Ca, Cl, K, Mg, Mn, Na, P, and Sr in bone samples were determined by instrumental neutron activation analysis using short-lived radionuclides. Mean values (M±S.E.M.) of the mass fraction of the investigated elements (on dry weight basis) for female and male all together were: 127±4 g/kg, 1620±80 mg/kg, 1310±70 mg/kg, 1550±50 mg/kg, <0.32±0.02 mg/kg, 4240±110 mg/kg, 61.8±1.8 g/kg, and 235±18 mg/kg, respectively. The statistically significant (≤0.05) decrease of Ca, Mg, and P concentrations in the iliac cancellous bone with age was found only for women. Sex-related comparison has shown that the mean values of Mg mass fractions in male bone samples were less than in female ones.     

Bildung von Diphosphaten aus geschmolzenem Natriumtrimetaphosphat, 3. Mitt.

Zusammenfassung Beim Auflösen der Oxide von Ti(IV), Ni und Co in geschmolzenem Na₃P₃O₉ bilden sich die Diphosphate Na₂(TiO) P₂O₇, Na₂NiP₂O₇ und Na₂CoP₂O₇. Beim Auslaugen der erstarrten Schmelze mit Wasser tritt auch Na₂Co₃(P₂O₇)₂·4 H₂O auf; ein entsprechendes Hydrat wird auch bei Mn(II) gefunden. Außerdem bildet Mn (II) ein Polyphosphat [Mn (PO₃)₂] _n . — Beim Auflösen eines Gemisches aus SrO und PbO in wechselnden Mengenverhältnissen entstehen nebeneinander Mischkristalle von Na₂(Sr, Pb) P₂O₇ mit wechselndem Verhältnis Sr,Pb und von einem Ultraphosphat [(Sr, Pb) P₄O₁₁] _n mit dem konstanten Verhältnis Sr,Pb=0,66,0,34. — Die Polyphosphate von Mn und von Sr–Pb werden papierchromatographisch und IR-spektroskopisch untersucht. — Die Bildung von Diphosphaten aus einer Polyphosphatschmelze wird an Hand der hier und früher beschriebenen Befunde zu deuten versucht.

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On dissolving the oxides of Ti(IV), Ni or Co in molten Na₃P₃O₇ the diphosphates Na₂(TiO) P₂O₇, Na₂NiP₂O₇ and Na₂CoP₂O₇ are formed respectively. Mn(II) forms a polyphosphate [Mn(PO₃)₂] _n . On dissolving a mixture of SrO and PbO of varying ratio one obtains at the same time mixed crystals of Na₂(Sr,Pb)P₂O₇ with a variable ratio of Sr,Pb and an ultraphosphate [(Sr,Pb)P₄O₁₁] _n with a constant ratio Sr,Pb=0,66,0,34. An interpretation of the formation of diphosphates from a melt of polyphosphates is attempted, using the present and previous observations.

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Mit 1 Abbildung

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Herrn Prof. Dr.E. Hayek zum 60. Geburtstag gewidmet.     

Synthesis,crystal structures,fluorescence, electrochemiluminescent properties,and Hirshfeld surface analysis of four Cu/Mn Schiff-basecomplexes

Four new complexes [Cu(L¹)₂]_n ( 1 ), [Mn(L¹)₂]_n ( 2 ), [Cu(L²)₂]_n ( 3 ), [Mn(L²)₂]_n ( 4 , HL¹ = 2-(((4H-1,2,4-triazol-4-yl)imino)methyl)-4,6-dichlorophenol; HL ² = 2-(((4H-1,2,4-triazol-4-yl)imino)methyl)-4,6-dibromophenol) were synthesized by microreaction bottle method. Complexes 1 and 3 and 2 and 4 are isomorphous heterostructures having the same molecular structure. The structures of 1 – 4 were characterized using single X-ray diffraction, Fourier-transform infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analysis, and their potential applications were analyzed by detecting their fluorescence and electrochemical luminescence (ECL). Hirshfeld surface analysis indicates that X···H (X = Br, Cl) interactions play a crucial role in stabilizing the self-assembly process of 1 – 4 , which show highly intense ECL in N,N-dimethylformamide solution and high thermal stability.     

Calibration strategies for quantifying the Mn content of tooth and bone samples by LA-ICP-MS

There is a growing interest in using biomonitoring of tooth and bone specimens to assess human exposure to manganese (Mn). Information on historical exposure to Mn can be obtained through micro-spatial analysis of such specimens by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The principal aim of this study was to compare several calibration strategies for determining Mn content in tooth and bone by LA-ICP-MS including: (a) a six-point calibration curve based on synthesized hydroxyapatite (HA) materials, and single-point calibrations based on (b) NIST SRM 1400 Bone Ash, (c) NIST SRM 1486 Bone Meal, and (d) NIST SRM 612 Trace Elements in Glass. Performance was similar between different ICP-MS platforms (quadrupole ICP-MS, dynamic reaction cell ICP-MS, and sector field ICP-MS). Data based on calibration using the ⁵⁵Mn count rate were compared to that based on using the ⁵⁵Mn/⁴³Ca count rate ratio to obtain results as the Mn mass fraction. Reasonable performance was obtained by calibration using either SRM 612 or SRM 1400, in combination with the ⁵⁵Mn/⁴³Ca count rate ratio and using either the synthesized HA standards or SRM 1400 as calibrators, combined with ⁵⁵Mn count rate. By contrast, calibration based on SRM 1486 resulted in a systematic low bias. While there are several options for quantifying the Mn content of tooth and bone using LA-ICP-MS, users should be aware of the potential for strong matrix effects that may affect results. Overall, determining the ⁵⁵Mn/⁴³Ca count rate ratio, rather than the mass fraction, may represent a better approach for reporting the content of Mn in tooth and bone by LA-ICP-MS.     

Synthesis,structures, and physicochemical properties of Sr<Subscript>2</Subscript>A<Superscript>II</Superscript>UO<Subscript>6</Subscript> (A<Superscript>II</Superscript> = Mg,Ca, Sr,Ba, Mn,Fe, Co,Ni, Zn,and Cd) compounds

Sr₂A^IIUO₆ (A^II = Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Zn, and Cd) compounds were synthesized by high-temperature reactions in the solid phase. The crystal structure (space group P2₁/n) was refined by the Rietveld method for Sr₂MgUO₆, (Sr_0.5Ba_0.5)₂SrUO₄, and Sr₂CdUO₆, which were synthesized for the first time. IR spectral characteristics were studied. The standard enthalpies of formation of the compounds were determined by reaction calorimetry.     

Physicochemical characterization of nanobidentate ferrocene‐based Schiff base ligand and its coordination complexes: Antimicrobial,anticancer, density functional theory,and molecular operating environment studies

A novel bidentate Schiff base ligand (HL, Nanobidentate Ferrocene based Schiff base ligand L (has one replaceable proton H)) was prepared via the condensation of 2‐amino phenol with 2‐acetyl ferrocene. The ligand was characterized using elemental analysis, mass spectrometry, infrared (IR) spectroscopy, ¹proton nuclear magnetic resonance (H‐NMR) spectroscopy, scanning electron microscopy (SEM), and thermal analysis. The corresponding 1:1 metal complexes with some transition‐metal ions were additionally characterized by their elemental analysis, molar conductance, SEM, and thermogravimetric ana1ysis (TGA). The complexes had the general formula [M(L)(Cl)(H₂O)₃]xCl·nH₂O (M = Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)), (x = 0 for Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), x = 1 for Cr(III) and Fe(III)), (n = 1 for Cr(III), n = 3 for Mn(II) and Co(II), n = 4 for Fe(III), Ni(II), Cu(II), Zn(II), and Cd(II)). Density functional theory calculations on the HL ligand were also carried out in order to clarify molecular structures by the B31YP exchange‐correlation function. The results were subjected to molecular orbital diagram, highest occupied mo1ecu1ar orbital–lowest occupied molecular orbital, and molecular electrostatic potential calculations. The parent Schiff base and its eight metal complexes were assayed against four bacterial species (two Gram‐negative and two‐Gram positive) and four different antifungal species. The HL ligand was docked using molecular operating environment 2008 with crystal structures of oxidoreductase (1CX2), protein phosphatase of the fungus Candida albicans (5JPE), Gram(?) bacteria Escherichia coli (3T88), Gram(+) bacteria Staphylococcus aureus (3Q8U), and an androgen‐independent receptor of prostate cancer (1GS4). In order to assess cytotoxic nature of the prepared HL ligand and its complexes, the compounds were screened against the Michigan cancer foundation (MCF)‐7 breast cancer cell line, and the IC₅₀ values of compounds were calculated.     

Comparison of analytical methods: ICP-QMS,ICP-SFMS and FF-ET-AAS for the determination of V,Mn, Ni,Cu, As,Sr, Mo,Cd and Pb in ground natural waters

Three analytical methods, namely, inductively coupled plasma sector field mass spectrometry (ICP-SFMS); inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and filter-furnace electrothermal atomic-absorption spectroscopy (FF-ET-AAS) for the determination of V, Mn, Ni, Cu, As, Sr, Mo, Cd and Pb in ground natural water samples were compared and evaluated for their capacity to provide reliable and precise results. Two certified reference materials (SLEW-3 Estuarine Water; SLRS-4 River Water) were analysed to prove that accurate results could be obtained by using all the listed methods with properly optimised parameters. The limit of detection (LOD) for V, Mn, Ni, Cu, As, Sr, Mo, Cd and Pb provided by the ICP-MS methods ranged from 0.001 to 0.05 µg L^?1. Such LOD proved sufficient for the reliable determination of the listed elements in ground natural waters. However, the LOD of the FF-ET-AAS was approximately two orders of magnitude higher than that of ICP-MS, which made it impossible to quantify V, Mn, Ni, Mo and Pb. The effects of the usage of the collision cell mode in ICP-QMS and of the desolvation system Apex for ICP-SFMS to eliminate oxide ions levels were investigated. For all three analytical methods, the influence of the matrix effect on the results of the determination of the investigated elements using matrix model solution, external calibration and standard addition methods was evaluated. A comparison using a paired Student’s t-test between the results obtained by both ICP-MS methods for V, Mn, Ni, Cu, As, Sr, Mo, Cd and Pb concentrations in ground natural waters showed that there was no significant difference on a 95% confidence level. The precision of the results for ICP-SFMS, ICP-QMS and FF-ET-AAS varied between ~0.5 and 11; 2.5 and 12.5; 3 and 13.5%, respectively. Moreover, ICP-SFMS equipped with the desolvation system APEX proved a better choice for As, Cu and Mn analysis due to its better LOD (0.008, 0.03 and 0.02 µg L^?1, respectively) and precision (S_r ≤ 5.0; 7.5; 9.0%, respectively) compared to ICP-QMS and FF-ET-AAS.     

Reactions of Hydrated Singly Charged First‐Row Transition‐Metal Ions M+(H2O)n (M=V,Cr, Mn,Fe, Co,Ni, Cu,and Zn) toward Nitric Oxide in the Gas Phase

Reactions of M⁺(H₂O)_n (M=V, Cr, Mn, Fe, Co, Ni, Cu, Zn; n≤40) with NO were studied by Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. Uptake of NO was observed for M=Cr, Fe, Co, Ni, Zn. The number of NO molecules taken up depends on the metal ion. For iron and zinc, NO uptake is followed by elimination of HNO and formation of the hydrated metal hydroxide, with strong size dependence. For manganese, only small HMnOH⁺(H₂O)_n?1 species, which are formed under the influence of room‐temperature black‐body radiation, react with NO. Here NO uptake competes with HNO formation, both being primary reactions. The results illustrate that, in the presence of water, transition‐metal ions are able to undergo quite particular and diverse reactions with NO. HNO is presumably formed through recombination of a proton and ³NO^? for M=Fe, Zn, preferentially for n=15–20. For manganese, the hydride in HMnOH⁺(H₂O)_n?1 is involved in HNO formation, preferentially for n≤4. The strong size dependence of the HNO formation efficiency illustrates that each molecule counts in the reactions of small ionic water clusters.     

Determination of ultratrace levels of dissolved metals in seawater by reaction cell inductively coupled plasma mass spectrometry after ammonia induced magnesium hydroxide coprecipitation

A method for the determination of ultratrace amounts of Cr, Fe, Mn, Pb and Zn in seawater has been developed. It combined the low-blank magnesium hydroxide coprecipitation procedure with quadrupole inductively coupled plasma mass spectrometry and used the dynamic reaction cell technique to resolve the polyatomic interferences arising from the residual matrix, the solvent and plasma gases. Detection limits (3σ_B, n = 10) for Cr, Fe, Mn, Pb and Zn were 0.02, 0.10, 0.01, 0.002 and 0.19 nM, respectively, using 50 mL of seawater sample. The accuracy of the analytical procedure was verified by the analysis of the seawater reference materials CASS-4, NASS-5, SAFe D2 and SAFe S. The analytical precision ranged from 3% to 16% (n = 6), with a sample throughput of about 6 samples h⁻¹.     

Polymerization by alkaline earth metal compounds—II Polymerization of 2- and 4-vinylpyridine,styrene and butadiene by triphenylmethyl derivatives of calcium,strontium and barium

Investigations are reported on polymerizations of 2- and 4- vinylpyridine, styrene and butadiene by a series of related alkaline earth metal initiators, Ph₃CMX(THF)_n (M = Ca, Ba, X = Cl, n = 2; M = Ca, X = Br, n = 4; M = Sr, X = Cl, n = 4; M = Sr, X = Br, n = 5) in tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME) at various temperatures and in the absence of solvent. The polymers have been examined by GPC and aspects of their microstructures determined by ¹³C and/or ¹H NMR spectroscopy and, for polybutadiene, i.r. spectroscopy. Poly-2-vinylpyridine produced by Ph₃CMX(THF)_n is rich in isotactic content; the isotacticity is higher for polymer formed in THF than DME solution, falls with change of initiator in the order M = Ca > Sr > Ba and, in DME, is greater when X = Br. The tacticities of poly-4-vinylpyridine and polystyrene are similar to those obtained from related organometallic initiators. The 1,4-content of polybutadiene decreases with initiator Ph₃CMX(THF)_n in the order M = Ba > Sr > Ca; the trans-1,4 structure generally predominates except when M = Ba from which cis-1,4 links are formed in comparable amounts.     

A New Azide-Bridged Three-Dimensional Supramolecular Manganese(II) Compound: Synthesis,Crystal Structure and Magnetic Properties

A three-dimensional supramolecular compound [Mn(N₃)₂(H₂O)₃(hmt)] ₂ , where hmt stands for hexamethylenetetramine, was synthesized and characterized by IR, crystal structure and magnetic susceptibility. The compound [Mn(N₃)₂(H₂O)₃(hmt)] _n , crystallizes in the orthorhombic system, space group P_n 2₁ a, with a = 6.5201(9), b = 9.322(2), c = 22.192(3) Å, β = 90° and Z = 2. The Mn atom is coordinated in an octahedral arrangement by three nitrogen atoms from three azido ions, and three oxygen atoms from three water molecules, respectively. The azide ligand bridges Mn atoms in μ-1,3 fashion, forming a zigzag chain. Hmt connected with the zigzag chain by hydrogen bonds, to form a three-dimensional supramolecular structure. The magnetic susceptibility data show that there is an antiferromagnetic exchange interaction in the title compound. The data were modeled using an infinite chain model leading to J = -4.8 cm^?1.     

Four metal–organic architectures from a triphenyl-tricarboxylic acid: synthesis,crystal structures,and catalytic features

Semi-flexible aromatic polycarboxylic acids are gaining impetus in crystal engineering of functional coordination polymers. This work opens up the use of a triphenyl-tricarboxylic acid, 3,5-(4'-carboxylphenyl) benozoic acid (H₃cba), as a versatile and still unexplored linker for the synthesis of four new Mn(II), Ni(II), Zn(II), and Cd(II) coordination polymers, formulated as [Mn(μ₃-Hcba)(bpy)]_n?nH₂O (1), [Ni(μ-Hcba)(py)(H₂O)]_n (2), [Zn(μ-Hcba)(phen)(H₂O)]_n?nH₂O (3), and [Cd(μ₃-Hcba)(bpy)]_n?nH₂O (4). These compounds were prepared via a facile hydrothermal procedure using metal(II) chlorides, H₃cba, and supporting N-donor ligands (2,2?-pyridine, bpy; pyridine, py; 1,10-phenanthroline, phen) acting as crystallization mediators. Compounds 1–4 were fully characterized and their X-ray crystal structures were established, disclosing the metal–organic architectures that range from 1D double chains (1, 4) to 1D chains (2, 3). Thermal and catalytic properties of 1–4 were also investigated. In particular, catalytic potential of the obtained coordination polymers in the Knoevenagel condensation of benzaldehydes with propanedinitrile was evaluated, disclosing an excellent performance of several heterogeneous catalysts with up to 100% product yield.

Graphical abstract

Four new Mn(II), Ni(II), Zn(II), and Cd(II) 1D coordination polymers have been constructed and the structures and catalytic properties of the polymers were investigated.

     

On the novel double perovskites A2Fe(Mn0.5W0.5)O6 (A= Ca,Sr, Ba). Structural evolution and magnetism from neutron diffraction data

New A₂Fe(Mn_0.5W_0.5)O₆ (A = Ca, Sr, Ba) double perovskite oxides have been prepared by ceramic techniques. X-ray diffraction (XRD) complemented with neutron powder diffraction (NPD) indicate a structural evolution from monoclinic (space group P2₁/n) for A = Ca to cubic (Fm-3m) for A = Sr and finally to hexagonal (P6₃/mmc) for A = Ba as the perovskite tolerance factor increases with the A²⁺ ionic size. The three oxides present different tilting schemes of the FeO₆ and (Mn,W)O₆ octahedra. NPD data also show evidence in all cases of a considerable anti-site disordering, involving the partial occupancy of Fe positions by Mn atoms, and vice-versa. Magnetic susceptibility data show magnetic transitions below 50 K characterized by a strong irreversibility between ZFC and FC susceptibility curves. The A = Ca perovskite shows a G-type magnetic structure, with weak ordered magnetic moments due to the mentioned antisite disordering. Interesting magnetostrictive effects are observed for the Sr perovskite below 10 K.     

Neutron activation analysis of Ca,Cl, K,Mg, Mn,Na, P,and Sr contents in the crowns of human permanent teeth

The effect of age and gender on chemical element contents in intact crowns of permanent teeth of 84 apparently healthy 15–55 year old women (n = 38) and men (n = 46) was investigated. Mass fractions of Ca, Cl, K, Mg, Mn, Na, P, and Sr in crowns were determined by instrumental neutron activation analysis using short-lived radionuclides. Mean values (M ± SΕΜ) for female and male combined were (on dry weight basis): 350 ± 5 g/kg, 2920 ± 150 mg/kg, 839 ± 80 mg/kg, 4880 ± 240 mg/kg, 3.20 ± 0.30 mg/kg, 6240 ± 140 mg/kg, 181 ± 4 g/kg, and 293 ± 24 mg/kg respectively. A statistically significant decrease of Sr (P ≤ 0.01) and increase of Na (P ≤ 0.01) content in the tooth crowns with age was found for women. Sex-related comparison did not show any differences.     

Gas-phase reactions of doubly charged alkaline earth and transition metal complexes of acetonitrile, pyridine, and methanol generated by electrospray ionization

Formation and low energy collision-induced dissociation (CID) of doubly charged metal(II) complexes ([metal(II)+L _n ]²⁺, metal(II)=Co(II), Mn(II), Ca(II), Sr(II) and L = acetonitrile, pyridine, and methanol) were investigated. Complexes of [metal(II)+L _n ]²⁺ where n≤7 were obtained using electrospray ionization. Experimental parameters controlling the dissociation pathways for [Co(II)+(CH₃CN)₂]²⁺ were studied and a strong dependence of these processes on the collision energy was found. However, the dissociation pathways appear to be independent of the cone potential, indicating low internal energy of the precursor ions. In order to probe how these processes are related to intrinsic parameters of the ligand such as ionization potential and metal ion coordination, low energy CID spectra of [metal(II)+L _n ]²⁺ for ligands such as acetonitrile, pyridine, and methanol were compared. For L = pyridine, all metals including the alkaline earth metals Ca and Sr were reduced to the bare [metal(I)]⁺ species. Hydride transfer was detected upon low energy CID of [metal(II)+L _n ]²⁺ for metal(II)=Co(II) and Mn(II) and L = methanol, and corroborated by signals for [metal(II)+H^?]⁺ and [metal(II)+H^?+CH₃OH]⁺, as well as by the complementary ion [CH₃O]⁺.     

Formation and reactivity of metal carbonyl anions in the gas phase

The reactions of metal carbonyl anions (M(CO)_n^?; M = Cr, Mn and Fe; n = 1–3) with n-heptane, water and methanol were studied with use of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with an external ion source. The M(CO)_n^? ions were formed in the FT-ICR cell by collision-induced dissociation of the most abundant primary ion generated by electron impact of the appropriate metal carbonyl compound present in the external ion source. The M(CO)_n^? ions were allowed subsequently to undergo non-reactive collisions with argon in order to remove possible excess internal/translational energy prior to the ion/molecule reaction. Only the Cr(CO)₃^?, Mn(CO)₃^? and Fe(CO)₂^? ions react with n-heptane. This reaction proceeds by loss of H₂ from the collision complex and the Cr(CO)₃^? and Fe(CO)₂^? ions react about three times more efficiently than the Mn(CO)₃^? ion. With water, Mn(CO)^? and Fe(CO)₃^? are unreactive, whereas the other ions react by loss of one or two CO molecules from the collision complex. The rate of the reaction with water decreases in the order Cr(CO)₃^?, Fe(CO)₂^?, Cr(CO)₂^?, Fe(CO)^?, Mn(CO)₃^? and Mn(CO)₂^?. With methanol, the Cr(CO)₂^? ion reacts by loss of two CO molecules from the collision complex, whereas loss of one CO molecule and elimination of CO + H₂ occur in the reaction with Cr(CO)₃^?. Competing loss of CO and one or two H₂ molecules occurs in the reactions of Mn(CO)₃^? and Fe(CO)₂^? with methanol. The rate of the reaction with methanol decreases in the order Cr(CO)₃^?, Fe(CO)₂^?, Cr(CO)₂^? and Mn(CO)₃^?.     

High Magnetic Moments in Manganese‐Doped Silicon Clusters

We report on the structural, electronic, and magnetic properties of manganese‐doped silicon clusters cations, Si_nMn⁺ with n=6–10, 12–14, and 16, using mass spectrometry and infrared spectroscopy in combination with density functional theory computations. This combined experimental and theoretical study allows several structures to be identified. All the exohedral Si_nMn⁺ (n=6–10) clusters are found to be substitutive derivatives of the bare Si_n+1⁺ cations, while the endohedral Si_nMn⁺ (n=12–14 and 16) clusters adopt fullerene‐like structures. The hybrid B3P86 functional is shown to be appropriate in predicting the ground electronic states of the clusters and in reproducing their infrared spectra. The clusters turn out to have high magnetic moments localized on Mn. In particular the Mn atoms in the exohedral Si_nMn⁺ (n=6–10) clusters have local magnetic moments of 4 μ_B or 6 μ_B and can be considered as magnetic copies of the silicon atoms. Opposed to other 3d transition‐metal dopants, the local magnetic moment of the Mn atom is not completely quenched when encapsulated in a silicon cage.     

The chemistry,properties, and characterization of organotin(IV) complexes of 2-(N-naphthylamido)benzoic acid

2-(N-naphthylamido)benzoic acid was synthesized by the reaction of phthalic anhydride with naphthylamine in glacial acetic acid at room temperature. Complexes 1–9 were synthesized under reflux in good yield with general formula R_{4? n} SnL _n (R = Me, n-Bu, Ph, n-Oct, Bz and n = 2, 3), which were studied by microanalysis, IR, NMR (¹H, ¹³C, ¹¹⁹Sn), and mass spectrometry. Cytotoxicity of the synthesized compounds was checked against Brine-shrimp larvae. In vitro activities against some Gram-positive and Gram-negative bacteria and fungi were also determined. Antimicrobial activities show that species with tetrahedral geometry in solution are more toxic.     

The Valence Orbitals of the Alkaline-Earth Atoms

Quantum chemical calculations of the alkaline-earth oxides, imides and dihydrides of the alkaline-earth atoms (Ae=Be, Mg, Ca, Sr, Ba) and the calcium cluster Ca₆H₉[N(SiMe₃)₂]₃(pmdta)₃ (pmdta=N,N,N′,N′′,N′′-pentamethyldiethylenetriamine) have been carried out by using density functional theory. Analysis of the electronic structures by charge and energy partitioning methods suggests that the valence orbitals of the lighter atoms Be and Mg are the (n)s and (n)p orbitals. In contrast, the valence orbitals of the heavier atoms Ca, Sr and Ba comprise the (n)s and (n−1)d orbitals. The alkaline-earth metals Be and Mg build covalent bonds like typical main-group elements, whereas Ca, Sr and Ba covalently bind like transition metals. The results not only shed new light on the covalent bonds of the heavier alkaline-earth metals, but are also very important for understanding and designing experimental studies.