<Superscript>13</Superscript>C-<Superscript>13</Superscript>C spin-spin coupling constants in structural studies: XL. Conformational analysis of <Emphasis Type="Italic">N</Emphasis>-vinylpyrroles

Conformational analysis of ten N-vinylpyrroles was performed on the basis of experimental ¹³C-¹H and ¹³C-¹³C coupling constants and those calculated by high-level quantum-chemical methods, and principal relations between J _CC and J _CH values and stereochemical structure of these compounds were revealed.     

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.     

Crystalline cadmium dialkyl phosphorodithioate complexes: Synthesis and structural organization as probed by multinuclear <Superscript>13</Superscript>C, <Superscript>31</Superscript>P,and <Superscript>113</Superscript>Cd CP/MAS NMR and single-crystal X-ray diffraction

The cadmium O,O′-dethyl (I) and O,O′-di-sec-butyl phosphorodithioate (II) complexes have been synthesized and characterized in detail by ¹³C, ³¹P, and ¹¹³Cd CP/MAS NMR. X-ray crystallography shows that complex II has a binuclear molecular structure [Cd₂{S₂P(O-s-C₄H₉)₂}₄]. For ³¹P and ¹¹³Cd NMR signals, the chemical shift anisotropy δ_aniso and the asymmetry parameter η have been calculated. The ³¹P NMR signals are assigned to the terminal and bridging ligands in the complexes.     

Crystal structure and <Superscript>121,123</Superscript>Sb NQR parameters of ammonium tridecafluorotetraantimonate(III) NH<Subscript>4</Subscript>Sb<Subscript>4</Subscript>F<Subscript>13</Subscript>

(NH₄)Sb₄F₁₃ crystals (I) are synthesized and their crystal structure (tetragonal crystal system: a = 9.6431(2) Å, c = 6.5503(2) Å, V = 609.11(3) ų, Z = 2, d _calc = 4.100 g/cm³, F(000) = 664, space group I4?) is determined. The main structural units of I are tetranuclear anionic [Sb₄F₁₃]^? complexes and [NH₄]⁺ cations. The anionic complexes are built of four SbF₃ groups linked together by tetrahedral bridging fluorine atom. At room temperature the (NH₄)Sb₄F₁₃ crystals are isostructural to previously studied МSb₄F₁₃ (М = K, Rb, Cs, and Tl). The study of ^121,123Sb NQR spectra of compound I is performed in a range of 77-370 K, which shows that when the temperature decreases (<250 K) the substance exhibits piezoelectric properties, as do other compounds of this group, but with a violation of their isostructurality.     

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.     

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.     

<Superscript>13</Superscript>C-<Superscript>13</Superscript>C spin-spin coupling constants in structural studies: XLIV. Carbonyl-containing oximes

¹³C-¹³C spin-spin coupling constants in carbonyl-containing oximes were calculated in terms of the second-order polarization propagator approximation (SOPPA) with account taken of the results of theoretical conformational analysis. Stable conformations of all carbonyl-containing oximes were found to have s-trans orientation of the carbonyl group in the E and Z isomers. The corresponding ¹³C-¹³C coupling constants showed a characteristic dependence upon internal rotation of the carbonyl-containing substituent, which may be used to determine predominant rotational conformations of these compounds. A relation between orientation of the C=O bond and ¹³C-¹³C coupling constants for the adjacent bonds in oximes was revealed; it may be attributed to hyperconjugation between the corresponding carbon-carbon bond and antibonding orbital of the C=O bond.     

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 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°.     

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.     

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.     

Crystal structure of two polymorphs of molybdenyl salicylidene-2-furfuriliminate (HL<Superscript>1</Superscript>) [MoO<Subscript>2</Subscript>(L<Superscript>1</Superscript>)<Subscript>2</Subscript>]

The crystal structures of two polymorphs of molybdenyl salicylidene-2-furfuryliminate [MoO₂(L¹)₂] have been solved by X-ray diffraction. Both complexes crystallize in centrosymmetric and non-centrosymmetric space groups (P2₁/c and Р2₁, respectively) of monoclinic system and have similar structures and close geometric parameters. The Мо atoms have a distorted octahedral coordination to two terminal oxo ligands in cis-positions to each other and two pairs of the oxygen atoms (cis- to О(oxo)) and the nitrogen atoms (trans- to О(oxo)) of two bidentate chelate ligands (L¹)^–.     

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.     

Solution Thermodynamics of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis><Superscript>/</Superscript>-Ethylenebis-(salicylideneiminato)-diaquochromium(III) Chloride in Aqueous Dimethylsulphoxide

The densities, viscosities and refractive indices of N,N ^/-ethylene-bis(salicylideneiminato)-diaquochromium(III) chloride, [Cr(salen)(H₂O)₂]Cl, in aqueous dimethylsulfoxide (DMSO) with different mass fractions (w ₂ = 0.20, 0.40, 0.60, 0.80 and 1.00) of DMSO were determined at 298.15, 308.15 and 318.15 K under atmospheric pressure. From measured densities, viscosities and refractive indices the apparent molar volumes (V _φ ), standard partial molar volume (V _φ ⁰ ), the slope (S _V ^* ), standard isobaric partial molar expansibility (φ _E ⁰ ) and its temperature dependence (?φ _E ⁰ /?T) _p , the viscosity B-coefficient, its temperature dependence (?B/?T), solvation number (S _n ) and apparent molar refractivity (R _D ^φ ), etc., were calculated and discussed on the basis of ion–ion and ion–solvent interactions. These results revealed that the solutions are characterized by ion–solvent interactions rather than by ion–ion interactions and the complex behaves as a long range structure maker. Thermodynamics of viscous flow was discussed in terms of transition state theory.     

Crystal structures of Ti(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>P<Subscript>4</Subscript>O<Subscript>13</Subscript> and Sn(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>P<Subscript>4</Subscript>O<Subscript>13</Subscript>

The characteristics of crystal structures of the titanium(IV) diammonium (Ti(NH₄)₂P₄O₁₃) and tin(IV) diammonium (Sn(NH₄)₂P₄O₁₃) tetraphosphates, which are isostructural with similar silicon(IV) and germanium(IV) salts, have been obtained by the Rietveld method using X-ray powder diffraction data. The compounds crystallize in the triclinic system, space group P \(\overline 1 \), Z = 2, a = 15.0291(7) Å, b = 7.9236(4) Å, c = 5.0754(3) Å, α = 99.168(3)°, β = 97.059(3)°, γ = 83.459(3)° for Ti(NH₄)₂P₄O₁₃ and a = 15.1454(7) Å, b = 8.0103(5) Å, c = 5.1053(3) Å, α = 99.898(6)°, β = 96.806(3)°, γ = 83.881(4)° for Sn(NH₄)₂P₄O₁₃. The structure is refined in the isotropic approximation using the pseudo-Voigt function: R _p = 0.077, R _Bragg = 0.045, R _F = 0.057 for Ti(NH₄)₂P₄O₁₃; R _p = 0.082, R _Bragg = 0.044, R _F = 0.046 for Sn(NH₄)₂P₄O₁₃. The hydrogen atoms of the ammonium cations are placed in the calculated positions. A comparative analysis of the structures of the compounds of the M^IV(NH₄)₂P₄O₁₃ (M^IV = Si, Ge, Ti, Sn) series has been carried out.     

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.     

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.     

The thermodynamic properties of the [(Me<Subscript>3</Subscript>Si)<Subscript>7</Subscript>C<Subscript>60</Subscript>]<Subscript>2</Subscript> fullerene complex

The temperature dependence of the heat capacity C _p ^o of the [(Me₃Si)₇C₆₀]₂ fullerene complex was measured for the first time using precision adiabatic vacuum calorimetry over the temperature range 6.7–340 K and high-accuracy differential scanning calorimetry at 320–635 K. For the most part, the error in the C _p ^o values was about ±0.5%. An irreversible endothermic effect caused by the splitting of the dimeric bond between fullerene fragments and the thermal decomposition of the complex was observed at 448–570 K. The thermodynamic characteristics of this transformation were calculated and analyzed. Multifractal analysis of the low-temperature (T < 50 K) heat capacity was performed, and conclusions were drawn concerning the character of the heterodynamicity of the structure. The experimental data obtained were used to calculate the standard thermodynamic functions C _p ^o (T), H ^o (T) ? H ^o (0), S ^o (T) ? S ^o (0), and G ^o (T) ? H ^o (0) over the temperature range from T → 0 to 445 K and estimate the standard entropy of formation of the compound from simple substances at 298.15 K. The standard thermodynamic properties of [(Me₃Si)₇C₆₀]₂ are compared with those of the (C₆₀)₂ dimer, the [(η⁶-Ph₂)₂Cr]⁺[C₆₀]^?? fulleride, and the initial C₆₀ fullerene.     

Structural features of monomeric octahedral <Emphasis Type="Italic">d</Emphasis><Superscript>2</Superscript>-rhenium(V) monooxo complexes with oxygen atoms of bidentate-chelating neutral and acidic ligands (O,P)

The structural features of 38 mononuclear d ²-Re(V) octahedral monooxo complexes (I–XXXVIII) with oxygen atoms of bidentate-chelating (O, P) ligands (L ⁿ ) are considered. The atoms O(L ⁿ ) are mostly in trans positions to O(oxo) ligands. In three compounds of general formula [ReO(L_mono)(L ⁿ )₂] (XXXVI–XXXVIII), the O atoms of two L ⁿ ligands occupy both trans and cis positions to oxo ligands. In one complex, namely, in [ReO(L ⁿ )(L _tri ¹¹ )], n = 3 (XXXV), the atom O(L³) is in the cis position to the oxo ligand; the trans position to O(oxo) is occupied by the atom O(L _tri ¹¹ ).