Crystal structures of a family of layered coordination polymers containing divalent metal ions (Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) and the 3-amino 4-methyl benzoate ion

The syntheses and crystal structures of the layered coordination polymers M(C₈H₈NO₂)₂ [M = Mn (1), Co (2), Ni (3) and Zn (4)] are described. These isostructural compounds contain centrosymmetric trans-MN₂O₄ octahedra as parts of infinite sheets; the ligand bonds to three adjacent metal ions in μ³-N,O,O′ mode from both its carboxylate O atoms and its amine N atom. In each case, weak intra-sheet N–H?O and C–H?O hydrogen bonds may help to consolidate the structure. Crystal data: 1, C₁₆H₁₆MnN₂O₄, M _r = 355.25, monoclinic, P2₁/c (No. 14), a = 10.6534(2) Å, b = 4.3990(1) Å, c = 15.5733(5) Å, β = 95.1827(10)°, V = 726.85(3) ų, Z = 2, R(F) = 0.026, wR(F ²) = 0.067. 2, C₁₆H₁₆CoN₂O₄, M _r = 359.24, monoclinic, P2₁/c (No. 14), a = 10.6131(10) Å, b = 4.3374(4) Å, c = 15.3556(17) Å, β = 95.473(4)°, V = 703.65(12) ų, Z = 2, R(F) = 0.041, wR(F ²) = 0.091. 3, C₁₆H₁₆N₂NiO₄, M _r = 359.02, monoclinic, P2₁/c (No. 14), a = 10.6374(4) Å, b = 4.2964(2) Å, c = 15.2827(8) Å, β = 95.9744(14)°, V = 694.66(6) ų, Z = 2, R(F) = 0.028, wR(F ²) = 0.070. 4, C₁₆H₁₆N₂O₄Zn, M _r = 365.68, monoclinic, P2₁/c (No. 14), a = 10.6385(5) Å, b = 4.2967(3) Å, c = 15.2844(8) Å, β = 95.941(3)°, V = 694.89(7) ų, Z = 2, R(F) = 0.038, wR(F ²) = 0.107.     

Reaction of transsilylation of <Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="Italic">N</Emphasis>-trimethylsilylacetamide with silanes ClCH<Subscript>2</Subscript>SiR<Superscript>1</Superscript>R<Superscript>2</Superscript>Cl

The reaction of N-methyl-N-trimethylsilylacetamide with silanes ClCH₂SiR¹R²Cl (R¹, R² = H, Me; H, Ph; Ph₂) leads to the formation of (O→Si) chelate compounds with pentacoordinate silicon: N-[chloro(methyl)-silyl]methyl-, N-[chloro(phenyl)silyl]methyl-, and N-[chloro(diphenyl)silyl]methyl-N-methylacetamides. From the data of multinuclear NMR spectroscopy, the intermediates of the reaction of N-methyl-N-trimethylsilylacetamide with ClCH₂SiPhHCl and ClCH₂SiPh²Cl are stable in CDCl₃ solution at room temperature during several days and slowly rearrange to the final (O–Si) chelate compounds.     

Synthesis and crystal structure of EnH<Superscript>2</Superscript>[IrCl<Superscript>6</Superscript>]

The preparation of EnH²[IrCl⁶] is described. Crystal data for C₂H₁₀Cl₆IrN₂ are: a = 6.8972(11) Å, b = 6.9435(16) Å, c = 7.3354(11) Å; α = 88.269(3)°, β = 65.495(2)°, γ = 60.305(2)°, V = 270.76(9) ų, space group P1, Z = 1, d_calc = 2.864 g/cm³. Crystal chemical analysis of the general motif of the structure was performed by the translation sublattice identification technique. It has been found that complex anions [IrCl₆]^2? follow the nodes of a rather regular rhombohedral subcell with the parameters a_c = 7.1 Å, α_c = 64°.     

Formation of mononuclear rhodium(III) sulfates: <Superscript>103</Superscript>Rh and <Superscript>17</Superscript>O NMR study

It was shown that the monomeric rhodium sulfate complexes [Rh(H₂O)₄(SO₄)]⁺, trans-[Rh(H₂O)₂(SO₄)₂]^?, cis-[Rh(H₂O)₂(SO₄)₂]^?, and [Rh(SO₄)₃]^3? were not predominant forms in aqueous solutions. The ¹⁰³Rh NMR chemical shifts of the complexes were assigned, and the conditions for their formation in solutions, concentration parameters, and acidity at which the fraction of the monomers was maximal were determined. The constants of formation of the complexes and ion pair (IP) were estimated: K _IP = 8 ± 3.5, K ₁ ≈ 8, K _2trans ≈ 1, K _2cis ≈ 1, and K ₃ ≈ 2.     

Synthesis,structure, and luminescent properties of Pr<Superscript>III</Superscript> complexes with pyrazole-derived 1,3-diketone and 1,10-phenanthroline

The interaction of PrCl₃ with 1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione in aqueous ethanol in the presence of a base and 1,10-phenanthroline was studied. It was shown that the composition of the products was dependent on the reaction conditions. The solvate [Pr(L)₃(Phen)]?3PrⁱOH crystallizes in a monoclinic crystal system (P2₁/c space group, a = 12.2239(12) Å, b = 20.3403(19) Å, c = 26.134(3) Å, β = 102.380(2)° at 150 K). Absorption spectra of the complex in solution, as well as the spectra and the kinetic parameters of photo-luminescence were investigated.     

Influence of the nature of the substituent in 3-(2-pyridyl)-1,2,4-triazole for complexation with Pd<Superscript>2+</Superscript>

The structure of four new palladium complexes [Pd(HL ² )Cl ₂ and Pd(L ^1–3 ) ₂ ] with 3-(2-pyridyl)-5-R-1,2,4-triazoles (R=H, CH₃, Ph respectively HL ¹ , HL ² , HL ³ ) was proposed based on IR, NMR, UV spectroscopy and MALDI mass spectrometry data analysis. It is found that the complexation of HL ² and HL ³ with Pd²⁺ ions results in a decrease of their fluorescence intensity and it is vice versa in case of HL ¹ . Furthermore, the influence of the substituent (R) in the 3-(2-pirydyl)-5-R-1,2,4-triazoles on the fluorescent and protolytic properties of HL ^1–3 was investigated.     

Synthesis,structure formation,and thermal expansion of A<Superscript>+</Superscript>M<Superscript>2+</Superscript>MgE<Superscript>4+</Superscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>

The compounds AMMgE(PO₄)₃ (A = Na, K, Rb, Cs; M = Sr, Pb, Ba; E = Ti, Zr) were synthesized by the sol–gel procedure followed by heat treatment and studied by X-ray diffraction, differential thermal and electron microprobe analysis, and IR spectroscopy. The phosphates crystallize in the kosnarite (KZr₂(PO₄)₃, space group \(R\bar 3\)) and langbeinite (K₂Mg₂(SO₄)₃, space group P2₁3) structural types. The structure of KPbMgTi(PO₄)₃ was refined by full-profile analysis (space group P2₁3, Z = 4, a = 9.8540(3) Å, V = 956.83(4) ų). The structure is formed by a framework of vertex-sharing MgO₆ and TiO₆ octahedra and PO₄ tetrahedra. The K and Pb atoms fully occupy the extra-framework cavities and are coordinated to nine oxygen atoms. A variable-temperature X-ray diffraction study of KPbMgTi(PO₄)₃ showed that the compound expands isotropically and refer to medium-expansion class (linear thermal expansion coefficients α _a = α _b = α _c = 8 × 10^–6°C^–1). The number of stretching and bending modes of the PO₄ tetrahedron observed in the IR spectra is in agreement with that predicted by the factor group analysis of vibrations for space groups \(R\bar 3\) and P2₁3. A structural transition from the cubic langbeinite to the rhombohedral kosnarite was found for CsSrMgZr(PO₄)₃. In the morphotropic series of ASrMgZr(PO₄)₃ (A = Na, K, Rb, Cs) the kosnarite–langbeinite transition occurs upon the Na → K replacement. The effect of the sizes and electronegativities of cations combined in AMMgE(PO₄)₃ on the change of the structural type was analyzed.     

Application of an experimental design to optimize a segregation method of <Superscript>129</Superscript>I and <Superscript>14</Superscript>C

In this work, the optimization of a segregation method of ¹²⁹I and ¹⁴C, two long-living radionuclides, main constituents of nuclear radioactive waste, has been developed. To be able to carry out this project, a fractional factorial experimental design was applied using 5 factors and 2 levels by factor (2^5–2). Only 8 experiments were necessary to identify the variables affecting the process, and very good recoveries of both radionuclides were obtained: (94?±?2)% for ¹²⁹I, and (99?±?1)% for ¹⁴C. The segregation of ¹²⁹I was influenced by flow (Q), volume of H₂SO₄ (V_H+), and carriers (CR), while V_H+ and time (t) played a major role in the segregation of ¹⁴C.     

Synthesis,scope, <Superscript>1</Superscript>H and <Superscript>13</Superscript>C spectral assignments of isomeric dibenzofuran carboxaldehydes

Two isomeric dibenzofuran carboxaldehydes, namely 2-methoxydibenzo[b,d]furan-1-carbaldehyde (4) and 2-methoxydibenzo[b,d]furan-3-carbaldehyde (5), were synthesized. Formylation of 2-methoxydibenzo[b,d]furan (3) with α,α-dichloromethyl methyl ether and tin(IV) chloride gave a mixture of aldehydes 4 and 5 in 95 % yield and in a 35:65 ratio. Their ¹H and ¹³C NMR spectral signals were not sufficiently resolved in CDCl₃ solution to achieve their complete assignment, but this was possible in DMSO-d ₆ with the help of 2D-NMR techniques: NOESY for ¹H–¹H interactions and HSQC and HMQC experiments for ¹H–¹³C correlations. These aldehydes were used in the synthesis of novel β-phenylethylamines and NBOMe derivatives, which are undergoing biological evaluation.     

Enhancing single-molecule magnet behavior of linear Co<Superscript>II</Superscript>-Dy<Superscript>III</Superscript>Co<Superscript>II</Superscript> complex by introducing bulky diamagnetic moiety

Single-molecule magnets (SMMs) are regarded as promising candidates for ultrahigh-density storage, quantum information processing and molecular spintronics. It is a crucial challenge for chemists to modulate magnetic dynamics of SMMs. Here, we successfully synthesized two 3d-4f polynuclear compounds [Co₂Dy(TTTT^Cl)₂(MeOH)]NO₃·3MeOH (1) and [Co₂Dy(TTTT^Cl)₂ (MeOH)][Co(HTTTT^Cl)](NO₃)₂·2.5MeOH·2H₂O (2), where H₃TTTT^Cl=2,2′,2′′-(((nitrilotris(ethane-2,1-diyl)) tris(azanediyl)) tris(methylene))tris-(4-chlorophenol). On applying the approach by co-crystallization of bulky diamagnetic moiety, the effective energy barrier enhances from 401 K (1) to 536 K (2), which are both among the highest d-f heterometallic SMMs.     

The mechanism of Pu<Superscript>VI</Superscript> oxidation with ozone and other reagents in alkaline solutions

The analysis of reported data on the interaction of ozone with alkaline solutions of Pu^VI leads to the conclusion that the process of ozonation involves reactions O₃ + OH^– → HO ₂ ^- + O₂, O₃ + + HO ₂ ^- + OH^– → O ₃ ^- + O ₂ ^- + H₂O and O₃ + O ₂ ^- → O ₃ ^- + O₂. The O ₃ ^- radical ion oxidizes Pu^VI, the HO ₂ ^- and O ₂ ^- anions reduce Pu^VII and Pu^VI and react with O ₃ ^- . Using persulfate instead of O₃ in aerated solution at 80—95 °C results in thermal decomposition of the S₂O ₈ ^2- anion into radical ions of SO ₄ ^- , oxidizing OH^– to the O^– ion, which in reaction with O₂ forms O ₃ ^- . The oxidation of PuVI proceeds via the formation of an activated complex with O ₃ ^- . where charge transfer occurs with the simultaneous elimination of two H⁺ ions. A similar mechanism is operating in reactions of Pu^VI with BrO^–, Fe(CN) ₆ ^3– , Am^VI, and Am^VII. Upon the γ-radiolysis of alkaline solutions of Pu^VI saturated with N₂O or containing S₂O ₈ ^2– , e _aq ^– is converted into O^– and then into O ₃ ^- ; F₂ and XeF₂ in alkaline solutions are decomposed with the formation of H₂O₂, which prevents producing Pu^VII.     

Synthesis and X-ray diffraction study of ferrites ErM<Superscript>I</Superscript>Fe<Subscript>2</Subscript>O<Subscript>5</Subscript> (M<Superscript>I</Superscript> = Li,Na, K,Cs)

Ferrites of composition ErM^IFe₂O₅ (M^I = Li, Na, K, Cs) were synthesized by a solid-phase method. The structure of the ferrites was for the first time studied by X-ray powder diffraction. Crystal systems, unit cell parameters, and X-ray and pycnometric densities were determined. For ErLiFe₂O₅, a = 10.510 Å, c = 14.270 Å, V°= 1616.16 ų, Z = 16, V _subcell ^° = 101.01 ų, ρ_x = 6.01 g/cm³, ρ_pyc = 5.97 ± 0.04 g/cm³; for ErNaFe₂O₅, a = 10.519 Å, c = 15.510 Å, V° = 1759.56 ų, Z = 16, V _subcell ^° = 109.90 ų, ρ_x = 5.77 g/cm³, ρ_pyc = 5.72 ± 0.08 g/cm³; for ErKFe₂O₅, a = 11.050 Å, c = 15.480 Å, V° = 1937.33 ų, Z = 16, V _subcell ^° = 121.08 ų, ρ_x = 5.46 g/cm³, ρ_pyc = 5.41 ± 0.04 g/cm³; and for ErCsFe₂O₅, a = 10.78 Å, c = 16.01 Å, V° = 1905.37 ų, Z = 16, V _subcell ^° = 119.09 ų, ρ_x = 6.86 g/cm³, ρ_pyc = 6.61 ± 0.01 g/cm³.     

Ca<Superscript>2+</Superscript> and Mg<Superscript>2+</Superscript> incorporated barium hexaferrites: structural and magnetic properties

BaM hexaferrites substituted with both Ca²⁺ and Mg²⁺ ions, namely, Ba_1-2×Ca_xMg_xFe₁₂O₁₉ (0.0?≤?x?≤?0.1), synthesized during a sol–gel auto-combustion route. The hexaferrite phase and morphology of all samples were investigated using X-ray powder diffraction, a field emission scanning electron microscope, a high-resolution transmission microscope, and Fourier transform infrared spectroscopy. In addition, an M-type hexagonal structure was confirmed using XRD for all samples. FE-SEM and TEM revealed the shape of the hexagonal plate. Measurements of the magnetization versus the field M(H) of Ba_1-2×Ca_xMg_xFe₁₂O₁₉ (0.0?≤?x?≤?0.1) nanohexaferrites were conducted at 300 and 10?K. A hard-ferrimagnetic behavior at both 300 and 10?K was noted for the different products produced. The squareness ratio indicates the uniaxial anisotropy for various products. The deduced values of saturation magnetization (M_s) in all substituted samples are higher than in the pristine sample (x?=?0). The Ba_0.96Ca_0.02Mg_0.02Fe₁₂O₁₉ nanosized hexaferrite showed the highest values of M_s, remanence M_r, magneton number (n_B), and magnetocrystalline anisotropy constant (K_eff). In contrast, the values of the coercive field (H_c) and intrinsic coercivity (H_ci) diminish with the increase in the amount of the substituted Ca and Mg elements.

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Structure of binuclear platinum(III) acetamidate complexes in solutions as probed by <Superscript>195</Superscript>Pt, <Superscript>13</Superscript>C,and <Superscript>1</Superscript>H NMR spectroscopy

¹⁹⁵Pt, ¹H, and ¹³C NMR spectroscopy was used to study the structure of binuclear platinum(III) acetamidate complexes with 1,10-phenanthroline and 2,2′-bipyridine ligands [Pt₂(phen)₂(acam)₄](NO₃)₂ (1) and [Pt₂(bipy)₂(acam)₄](NO₃)₂ (2) in aqueous solutions. The ¹⁹⁵Pt NMR spectra of solutions of complexes 1 and 2 in D₂O exhibit two signals with satellites due to the ¹⁹⁵Pt–¹⁹⁵Pt spin-spin coupling (¹ J(Pt–Pt) ≈ 6345 Hz), whereas their ¹H and ¹³C NMR spectra contain four sets of signals for the protons and the carbon atoms of the heterocyclic and acetamidate ligands. The signals were assigned using the COSY, NOESY, and HSQC/ HMBC experiments and comparing the coordination shifts of the signals for the protons of heterocycles. These data allowed us to draw a conclusion that binuclear complexes 1 and 2 in solution have a head-to-head structure with nonequivalent platinum(III) atoms (coordination cores PtN₅ and PtN₃O₂), the axial-equatorial coordination of the bidentate heterocyclic molecules, and two bridging and two terminal acetamidate ligands.     

Synthesis and Characterization of New Os<Subscript>2</Subscript><Superscript>5+</Superscript> and Os<Subscript>2</Subscript><Superscript>6+</Superscript> Azido Complexes

Reaction of Os₂(OAc)₄Cl₂ with an excess of HDPhF (HDPhF = N,N′-diphenylformamidine) gives a high yield of Os₂(DPhF)₄Cl₂ (1), which can be converted to its azido analog, Os₂(DPhF)₄(N₃)₂ (3), by treatment with NaN₃. We report a major improvement on the preparation of Os₂(chp)₄Cl (2; Hchp = 2-chloro-6-hydroxypyridine) by synthesizing the compound in the reducing solvent ethanol. Reaction of 2 with NaN₃ affords the azido complex Os₂(chp)₄N₃ (4). Compound 3 has been examined by X-ray crystallography, and has an Os–Os bond distance of 2.45 Å, suggesting a (π*)² ground state for the molecule.     

Theoretical study on the H<Subscript>2</Subscript>S activation by PtCH<Subscript>2</Subscript><Superscript>+</Superscript> in the gas phase

The reaction mechanism of the gas-phase PtCH₂ ⁺ with H₂S has been systematically investigated on the doublet and quartet potential energy surfaces at BPW91/6-311++G(2d, p)∪ SDD level. The Pt in PtCH₂ ⁺ prefers to attack S–H bond in H₂S. For PtCH₂ ⁺ + H₂S reaction, the potential energy surfaces (PESs), including three reaction pathways of hydrogen (including one and two hydrogen elimination) and methane elimination, have been explored and characterized. By contrast with hydrogen elimination, methane elimination reaction channel is energetically favorable, which is in good agreement with the experimental observation. The optimal S–H bond activation is the first step, followed by cleavage of Pt–C and Pt–S bond. About the path a and b, the lowering of activation barrier is mainly caused by the more stabilizing transition state interaction \(\varDelta E_{\text{int}}^{ \ne }\), which is the actual interaction energy between the deformed reactants in the transition state.     

Thermodynamic Study on the Protonation and Na<Superscript>+</Superscript>, Ca<Superscript>2+</Superscript>, Mg<Superscript>2+</Superscript>-Complexation of a Biodegradable Chelant (HEIDA) at Different Ionic Strengths and Temperatures

A potentiometric method has been used for the determination of the protonation constants of N-(2-hydroxyethyl)iminodiacetic acid (HEIDA or L) at various temperatures 283.15?≤?T/K?≤?383.15 and different ionic strengths of NaCl_(aq), 0.12?≤?I/mol·kg^?1?≤?4.84. Ionic strength dependence parameters were calculated using a Debye–Hückel type equation, Specific Ion Interaction Theory and Pitzer equations. Protonation constants at infinite dilution calculated by the SIT model are \( \log_{10} \left( {{}^{T}K_{1}^{\text{H}} } \right) = 8.998 \pm 0.008 \) (amino group), \( \log_{10} \left( {{}^{T}K_{2}^{\text{H}} } \right) = 2.515 \pm 0.009 \) and \( \log_{10} \left( {{}^{T}K_{3}^{\text{H}} } \right) = 1.06 \pm 0.002 \) (carboxylic groups). The formation constants of HEIDA complexes with sodium, calcium and magnesium were determined. In the first case, the formation of a weak complex species, NaL, was found and the stability constant value at infinite dilution is log₁₀K_NaL?=?0.78?±?0.23. For Ca²⁺ and Mg²⁺, the CaL, CaHL, CaL₂ and MgL species were found, respectively. The calculated stability constants for the calcium complexes at T?=?298.15 K and I?=?0.150 mol·dm^?3 are: log₁₀β_CaL?=?4.92?±?0.01, log₁₀β_CaHL?=?11.11?±?0.02 and \( \log_{10} \beta_{\text{Ca{L}}_{2}} \)?=?7.84?±?0.03, while for the magnesium complex (at I?=?0.176 mol·dm^?3): log₁₀β_MgL?=?2.928?±?0.006. Protonation thermodynamic functions have also been calculated and interpreted.     

Paramagnetic Cu<Superscript>II</Superscript> complexes with 1-(hetarylmethyl)silatranes

The structures of paramagnetic complexes CuCl₂?L with L = HetCH₂Si(OCH₂CH₂)₃N [Het = pyrrol-1-yl (1), indol-1-yl (2), carbazol-9-yl (3), imidazole-1-yl (4), 3,5-dimethylpyrazol-1-yl (5), 1,2,4-triazol-1-yl (6), benzimidazol-1-yl (7), and 1,2,3-benzotriazol-1-yl (8)] were studied by the ESR and quantum chemical methods in terms of the density functional theory (DFT) approximation. The difference in structures of complexes CuCl₂?1—CuCl₂?8 is mainly determined by the nature of the five-membered heterocycle. The ESR spectra at room temperature are typical of the mononuclear complexes of Cu^II of axial symmetry with various types of distortions. In complexes CuCl₂?1—CuCl₂?3, narrow symmetric signals of zero-valent copper are recorded. These signals remain in the spectra for at least six months, which can characterize them as efficient stabilizing matrices of nanoparticles.     

Complex formation of maleic acid with the Zn<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> in aqueous solution

The process of complex formation of maleic acid (H₂L) with the ions Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO₃). The moieties ZnL, CoL, NiL, NiL ₂ ^2? , CuL, and CuL ₂ ^2? were detected and their stability constants were determined.     

Synthesis,crystal structures,and antibacterial activities of Schiff base zinc(II) complexes [Zn(L<Superscript>1</Superscript>)<Subscript>2</Subscript>] and [Zn(L<Superscript>2</Superscript>)<Subscript>2</Subscript>]

The reaction of cyclopentylamine with 2-hydroxy-1-naphthaldehyde and 5-nitrosalicylaldehyde, respectively, in methanol affords two new Schiff bases, 1-(cyclopentyliminomethyl)naphthalen-2-ol (HL¹) and 4-nitro-2-(cyclopentyliminomethyl)phenol (HL²). Two new zinc(II) complexes, [Zn(L¹)₂] (I) and [Zn(L²)₂] (II), derived from the Schiff bases, have been prepared and characterized by single-crystal X-ray diffraction, FT-IR, and elemental analysis. Complex I crystallizes in the monoclinic space group P2₁/c with a = 17.834(4), b = 14.738(3), c = 9.868(2) Å, β = 91.20(3)°, V = 2593.1(9) ų, Z = 4. Complex II crystallizes in the triclinic space group P \(\bar 1\) with a = 10.206(1), b = 10.502(1), c = 12.554(1) Å, α = 66.771(2)°, β = 78.133(2)°, γ = 76.292(2)°, V = 1191.8(1) ų, Z = 2. The Zn atom in each complex is coordinated by two N and two O atoms from two Schiff base ligands, forming a tetrahedral geometry. The Schiff bases and the complexes were assayed for antibacterial activities.