The effects of fluorine substitution on the 35Cl NQR spectra of fluoroaromatic compounds containing element-chlorine bonds

The ³⁵Cl NQR spectra of pentafluorosubstituted derivatives of benzene C₆F₅X (X = NPCl₃, CONPCl₃, SO₂NPCl₃, NCCl₂, SCl, COCl, SO₂NCl₂, CONCl₂, PCl₂, SO₂Cl) and phosphazocompounds (dimers, [RNPCl₃]₂; R = C₆F₅, C₆H₅, 2,3,5,6-tetrafluoropyridyl) have been recorded and interpreted. On passing from phenyl to pentafluorophenyl derivatives, the ³⁵Cl NQR frequencies increased. The influence of the relative numbers and positions of the fluorine atoms in the benzene ring on the ³⁵Cl NQR frequencies of fluoro-containing benzoyl chlorides has been discussed. The results are explained in terms of charge alteration on chlorine under the influence of the aromatic fluorine atoms. A linear correlation has been found between ³⁵Cl NQR frequencies of pentafluorophenyl derivatives and those of their hydrocarbon analogues. A relationship between elecronegativity of the element and the ionic character of the element-chlorine bond has been revealed. The reactivities of pentafluorophenyl and phenyl derivatives containing element-chlorine bonds have been predicted using the ν_Cl values.     

35Cl, 93Nb, 181Ta,and 121Sb NQR in Cl5MV · OPCl3 (MV = Nb,Ta, Sb,or P) Complexes

The behavior of ³⁵Cl NQR spectra in Cl₅M · OPCl₃ complexes is affected by the nature of the metal center and the distortion of its surrounding geometry. In all cases considered, the ³⁵Cl NQR frequencies in the OPCl₃ fragment shift toward higher frequencies upon complex formation, whereas the frequencies of axial chlorine atoms in the Cl₅M group in the phosphorus and antimony complexes lie below those for the equatorial atoms, and in the niobium and tantalum complexes, the frequencies of the axial atoms are higher than those of the equatorial ones.     

Coexistence of 3d‐Ferromagnetism and Superconductivity in [(Li1−xFex)OH](Fe1−yLiy)Se

Superconducting [(Li_1?xFe_x)OH](Fe_1?yLi_y)Se (x≈0.2, y≈0.08) was synthesized by hydrothermal methods and characterized by single‐crystal and powder X‐ray diffraction. The structure contains alternating layers of anti‐PbO type (Fe_1?yLi_y)Se and (Li_1?xFe_x)OH. Electrical resistivity and magnetic susceptibility measurements reveal superconductivity at 43 K. An anomaly in the diamagnetic shielding indicates ferromagnetic ordering near 10 K while superconductivity is retained. The ferromagnetism is from the iron atoms in the (Li_1?xFe_x)OH layer. Isothermal magnetization measurements confirm the superposition of ferromagnetic and superconducting hysteresis. The internal ferromagnetic field is larger than the lower, but smaller than the upper critical field of the superconductor. The formation of a spontaneous vortex phase where both orders coexist is supported by ⁵⁷Fe‐Mössbauer spectra, ⁷Li‐NMR spectra, and μSR experiments.     

Cl35 nuclear quadrupole resonance spectra of chloro-substituted 6-pyridazone derivatives

The effect of substituents in the pyridazone ring (including the carbonyl oxygen atom) on the chlorine atoms in the 3,4, or 5 positions was investigated on the basis of data from the Cl³⁵ nuclear quadrupole resonance (NQR) spectra of chloro-substituted 6-pyridazones. The NQR frequencies of 1-phenyl-4,5-dichloro-6-pyridazone were compared with the reactivities of chlorine atoms in this compound in nucleophilic substitution reactions.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.3, pp. 392–395, March, 1976.     

35Cl NQR and mobility of partly chlorinated methyl groups in crystals

The temperature dependence of the ³⁵Cl NQR frequencies, their temperature coefficients, and spin-lattice relaxation times was studied for crystalline compounds Cl_xH_3?xCR with RC₆H₅, COOH, and CONH_2?y(CH₃)_y(x=1,2 and y=0,1,2) in the temperature range from 77 K to the sample melting points. It is found that for the mono- and dichloromethyl groups the shape of the experimental curves on the upper part of the temperature range often differs essentially from that predicted by the Bayer theory. These deviations may be interpreted as due to the appearance of the considerable anharmonicity of the autonomous librations of the groups mentioned.     

35Cl NQR spectra, structure, and mutual influence of substituents in the series of chlorine-containing organic compounds of pentavalent phosphorus

Regularities of transmission of the effect of equatorial and axial substituents were established for a number of chlorine-containing organic compounds of pentatalent phosphorus using³⁵Cl NQR spectra. The field constants of³⁵Cl NQR frequencies of the chlorine atoms participating in the P−Cl bond were estimated for a series of tetrahedral phosphorus ions. The³⁵Cl NQR frequencies of chlorine atoms in tetracoordinated ions of pentavalent phosphorus and in analogous isoelectronic silicon compounds are related by a linear dependence. Deceased Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 915–922, May, 1999.     

35Cl NQR spectra of organyltrichlorogermanes containing theCl_3 Ge - \mathop C\limits_|^| - \mathop N\limits_| - C(O)X fragment

³⁵C1 NQR spectra of compounds containing the fragment C1₃Ge-C-N-C(O)X, which were acquired at 77 K, indicate that in most of the investigated compounds the germanium atom is pentacoordinated owing to the intramolecular interaction Ge ← 0. The³⁵C1 NQR frequencies in these compounds satisfactorily correlate with the bond length of the corresponding Ge-C1 bond. The relationship between the length of the axial Ge-C1 bond and the Ge...O spacing is described by an exponential function. The charge on the chlorine atoms in the investigated models was estimated from the experimental NQR frequencies.     

A Study of Transition‐Metal Organometallic Complexes Combining 35Cl Solid‐State NMR Spectroscopy and 35Cl NQR Spectroscopy and First‐Principles DFT Calculations

A series of transition‐metal organometallic complexes with commonly occurring metal? chlorine bonding motifs were characterized using ³⁵Cl solid‐state NMR (SSNMR) spectroscopy, ³⁵Cl nuclear quadrupole resonance (NQR) spectroscopy, and first‐principles density functional theory (DFT) calculations of NMR interaction tensors. Static ³⁵Cl ultra‐wideline NMR spectra were acquired in a piecewise manner at standard (9.4 T) and high (21.1 T) magnetic field strengths using the WURST‐QCPMG pulse sequence. The ³⁵Cl electric field gradient (EFG) and chemical shielding (CS) tensor parameters were readily extracted from analytical simulations of the spectra; in particular, the quadrupolar parameters are shown to be very sensitive to structural differences, and can easily differentiate between chlorine atoms in bridging and terminal bonding environments. ³⁵Cl NQR spectra were acquired for many of the complexes, which aided in resolving structurally similar, yet crystallographically distinct and magnetically inequivalent chlorine sites, and with the interpretation and assignment of ³⁵Cl SSNMR spectra. ³⁵Cl EFG tensors obtained from first‐principles DFT calculations are consistently in good agreement with experiment, highlighting the importance of using a combined approach of theoretical and experimental methods for structural characterization. Finally, a preliminary example of a ³⁵Cl SSNMR spectrum of a transition‐metal species (TiCl₄) diluted and supported on non‐porous silica is presented. The combination of ³⁵Cl SSNMR and ³⁵Cl NQR spectroscopy and DFT calculations is shown to be a promising and simple methodology for the characterization of all manner of chlorine‐containing transition‐metal complexes, in pure, impure bulk and supported forms.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXXIII. Verbindungen vom Typ Ba6−xSrxB2−y3+SEy3+W3□O18

On Hexagonal Perovskites with Cationic Vacancies. XXXIII. Compounds of Type Ba_6?xSr_xB_2?y³⁺SE_y³⁺W₃□O₁₈ In the series Ba_6?xSr_xLu_2?ySE_y³⁺W₃□O₁₈ a substitution of Sr²⁺ for Ba²⁺ is possible. According to intensity calculations on powder data of BaSr₅Lu_1,6Ho_0,4W₃□O₁₈ the compounds crystallize in a rhombohedral 18 L type with the sequence (hhcccc)₃; space group R3 m. The refined, intensity related R' value is 11.5%. The differences in properties (diffuse reflectance spectra, photoluminescence) between the hexagonal modifications Ba₆B_2?y³⁺SE_y³⁺W₃□O₁₈ (B³⁺ ? Gd, Y, Lu; SE³⁺ ? Sm, Eu, Tb, Dy, Ho, Er, Tm) and the corresponding cubic HT modifications are discussed.     

Quantum-chemical study of chlorophosphoranes: I. Structure of the (C<Subscript>6</Subscript>H<Subscript>5</Subscript>)<Subscript>2</Subscript>PCl<Subscript>3</Subscript> molecule in gaseous and crystalline states

The quantum-chemical calculations of the (C₆H₅)₂PCl₃ molecule were performed by the methods RHF/6-31G(d) and MP2/6-31G(d) with complete and partial optimization of its geometry. The results of calculations were used for evaluating the NQR frequencies of ³⁵Cl and the parameters of asymmetry of the of electric field gradient on the ³⁵Cl nuclei of this molecule. According to the results of calculations with the partial optimization of geometry and to the experimental data of ³⁵Cl NQR the bond lengths were found of central atom P in the solid state of this compound. The mutual influence of its axial and equatorial bonds was studied. It is shown that in chlorophosphoranes the ³⁵Cl NQR frequencies of the axial and equatorial chlorine atoms decrease with the decrease in the bond lengths of phosphorus atom.     

Assessment of substituent effects on the parameters of 35Cl nuclear quadrupole resonance in para‐substituted benzene‐sulphenyl chloride via quantum chemical calculations

In this research, substituent effects on the parameters of ³⁵Cl nuclear quadrupole resonance (NQR) in para‐substituted benzene‐sulphenyl chloride were studied at M062X/6‐311G(d,p) theory level. The ³⁵Cl NQR parameters of the quadrupole coupling constant (QCC) and electric‐field gradient (EFG) tensor, as well as an asymmetric parameter, were shown to be correlated with Hammett constant following their calculations. The frontier orbital energy levels, HOMO‐LUMO gaps, hardness, electrophilicity, and chemical potential values of these molecules were calculated as well. natural bond orbital (NBO) analysis was applied for calculating natural populations at chlorine atoms.     

Color Point Tuning in Lu3−x−yMnxAl5−xSixO12:yCe3+ for White LEDs

A series of the solid‐solution phosphors Lu_3?x?yMn_xAl_5?xSi_xO₁₂:yCe³⁺ is synthesized by solid‐state reaction. The obtained phosphors possess the garnet structure and exhibit similar excitation properties as the phosphor Lu₃Al₅O₁₂:Ce³⁺, but with an effectively improved red component in the emission spectrum. This can be attributed to the energy transfer from Ce³⁺ to Mn²⁺. Our investigation reveals that electric dipole–quadrupole interactions dominate the energy‐transfer mechanism and that the critical distance determined by the spectral overlap method is about 9.21 Å. The color‐tunable emissions of the Lu_3?x?yMn_xAl_5?xSi_xO₁₂:yCe³⁺ phosphor as a function of Mn₃Al₂Si₃O₁₂ content are realized by continuously shifting the chromaticity coordinates from (0.354, 0.570) to (0.462, 0.494). They indicate that the obtained material may have potential application as a blue radiation‐converting phosphor for white LEDs with high‐quality white light.     

Molecular structure of trichlorophosphazo compounds from ab initio calculation and chlorine-35 NQR spectroscopy data

The molecular structures of trichlorophosphazo compounds Cl₃P=NR with R = C(CH₃)₃, C(C₂H₅)₃, C(CF₃)₃, CCl(CF₃)₂, CCl₂CF₃, CCl₃, CCl₂CCl₃, and CCl(CCl₃)₂ were analyzed by combined consideration of the results of ab initio MP2/6-31G* calculations and previously measured ³⁵Cl NQR frequencies. The conformational peculiarity of these molecules caused by the relative spatial orientations of the P-Cl and N-C bonds is reflected in the calculated geometric parameters of the Cl₃P=NC fragments and in the pattern of ³⁵Cl quadrupole resonance spectra for PCl₃ groups. For these atomic groups, the ³⁵Cl NQR frequencies were brought in correlation with the charges of the chlorine atoms found by quantum-chemical calculations.     

Conformations and intermolecular interactions pattern in solid chloroxylenol and triclosan (API of anti‐infective agents and drugs). A 35Cl NQR, 1H‐14 N NQDR,X‐ray and DFT/QTAIM study

Two antibacterial and antifungal agents, chloroxylenol (4‐chloro‐3,5‐dimethyl‐phenol) and triclosan (5‐chloro‐2‐(2’,4’‐dichlorophenoxy)‐phenol), were studied experimentally in solid state with an X‐ray, ³⁵Cl‐nuclear quadrupole resonance (NQR) and ¹⁷O‐nuclear quadrupole double resonance (NQDR) spectroscopies and, theoretically, with the density functional theory/quantum theory of atoms in molecules (DFT/QTAIM). The crystallographic structure of triclosan, which crystallises in space group P3₁ with one molecule in the asymmetric unit [a = 12.64100(10), b = 12.64100(10), c = 6.71630(10) Å], was solved with an X‐ray and refined to a final R‐factor of 2.81% at room temperature. The NQR frequencies of ³⁵Cl and ¹⁷O were detected with the help of the density functional theory (DFT) assigned to particular chlorine and oxygen sites in the molecules of both compounds. The NQR frequencies at ³⁵Cl sites in chloroxylenol and triclosan were found to be more differentiated than frequencies at the ¹⁷O site. The former better describes the substituent withdrawing effects connected to π‐electron delocalization within the benzene rings and the influence of temperature; whereas, those at the ¹⁷O site provide more information on O‐H bond and intermolecular interactions pattern. The conformation adopted by diphenyl ether of triclosan in solid state was found to be typical of diphenyl ethers, but the opposite to those adopted when it was bound to different inhibitors. According to an X‐ray study, temperature had no effect on the conformation of the diphenyl ring of triclosan, which was the same at 90 K and at room temperature (RT). The scattering of NQR frequencies reproduced by the DFT under assumption of the X‐ray data at 90 K and RT is found to be a good indicator of the quality of resolution of the crystallographic structure. Copyright © 2012 John Wiley & Sons, Ltd.     

Substituent chemical shifts of the organotin moiety in compounds of the type RSnMenCl3 − n (n = 0 to 3; R = n-alkyl)

The ¹³C and ¹¹⁹Sn NMR spectra of 33 organotin compounds of the type RSnMe_nCl_{3 ? n} and related types are discussed. The substituent effects of the groups SnMe₃, SnMe₂Cl, SnMeCl₂ and SnCl₃ (and of some related groups) on the carbon chemical shifts in the alkyl group R have been determined; the SnMe₃ group causes a small upfield shift of the carbon attached to it, while the other groups cause downfield shifts. The shifts show a monotonic change on replacing methyl groups in Me₃Sn by chlorine atoms. The effects on carbons further removed from the tin atom are discussed. Variation in R causes little change in ⁿJ(Sn? C) or δ(¹¹⁹Sn).     

Electronic structure of thiazides studied by 35Cl‐NQR spectroscopy and DFT calculations

NQR frequencies were determined for the ³⁵Cl isotope in a few benzodithiazine derivatives, chlorothiazide (CTZ), hydrochlorothiazide (HCTZ), althiazide (ATZ), trichloromethiazide (TCTZ), benzthiazide (BTZ) and furosemide (FSE), at liquid nitrogen and room temperatures. It was found that changes of the substituent at C‐3 are transferred through a system of coupled rings on to the chlorine atom at C‐6. The substituents occurring in thiazides can be ordered according to increasing electron‐acceptor properties as —CH₂SCH₂Ph < —CH₂SCH₂CH?CH₂ <—CHCl₂. At the liquid nitrogen temperature —CH₂SCH₂Ph and —CH₂SCH₂CH?CH₂ are electron donors, and CHCl₂ is an electron acceptor, whereas at room temperature —CH₂SCH₂Ph is an electron donor and —CH₂SCH₂CH?CH₂ and —CHCl₂ are electron acceptors. The character of the substituent properties is preserved irrespective of whether the system is aromatic or aliphatic. The NQR frequencies and substituents properties are well reproduced by the DFT B3LYP/6–311+G(2d,p) method. The topological properties of the Laplacian of the electron density were analysed within the AIM (atoms in molecules) approach. The changes in the electron density at C‐3 are correlated with the biological activity of the compounds studied. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and Structure of the new Fluoride Bromide Ba6.668(2)Ca0.332(2)F12Br2 and Solid Solutions with Composition Ba7−xCaxF12(ClyBr1−y)2 with x = ∼0.5, 0 < y < 1

Crystals of the chemical composition Ba₇F₁₂Cl₂ were modified by adding a small amount of Ca²⁺ to allow the synthesis of the corresponding bromine compound Ba^[Ca]₇F₁₂Br₂. These samples were prepared in a NaBr flux and characterized by single crystal x‐ray diffraction. The new structure crystallizes in a disordered arrangement in the hexagonal space group P6₃/m (176). The calcium ion has a coordination number of 6. Solid solutions on the heavy halide position can be synthesised in a NaCl/NaBr flux to obtain the compounds Ba_7?xCa_xF₁₂(Cl_yBr_1?y)₂ with x = ～0.5 and 0 < y < 1. Regardless the amount of calcium used in the preparation process, the Ca stoichiometry in the compound is always between 0.3 and 0.5. The lattice parameters differ depending on the Ca‐ and Br‐content between 1053.81(5) ? a = b ? 1058.93(3) pm and 421.21 ? c ? 426.78(3) pm.     

Photolumineszenz im System A2II B1/4II Gd1/2−x Eux □1/4 WO6 ≙ A8II BII Gd2−x Eux □ W4O24 (AII,BII = Sr,Ba)

Photoluminescence in the System A₂^II B_1/4^IIGd_1/2?xEu_x□_1/4WO₆ ? A₈^IIB^IIGd_2?xEu_xW₄O₂₄ (A^II, B^II = Sr, Ba) The emission and excitation spectra for the series Sr₈SrGd_2?xEu_x□W₄O₂₄ (HT- and LT-modifications) and Sr_9?yBa_yEu₂□W₄O₂₄ are reported and discussed. HT- and LT-Sr₈SrEu₂□W₄O₂₄ show an intense red emission, no concentration quenching is present.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXXII. Die Photolumineszenz der dreiwertigen Seltenen Erden in den Systemen Ba2−ySryLa2−xSExMgW2□O12

On Hexagonal Perovskites with Cationic Vacancies. XXXII. Photoluminescence of Trivalent Rare Earth in the Systems Ba_2?ySr_yLa_2?xRE_xMgW₂□O₁₂ In the series Ba_2?ySr_yLa_2?xRE_xMgW₂□O₁₂ the Ba²⁺ can be completely substituted by Sr²⁺. All compounds crystallize in the rhombohedral 12 L-type (space group R3 m; sequence (hhcc)₃). By doping the stacking polytypes with some of the trivalent rare earths efficient visible photoluminescence is obtained. The simultaneous incorporation of two different rare earth ions leads to two-color-phosphors, which, according to the excitation energy used, emit either mainly the typical spectrum from one or the other activator; the corresponding luminescence mechanism are discussed.     

Etude spectroscopique de derives mercuriques d'amides-thiols: Partie III. Spectres de vibration et structure de complexes mercuriques des thiol-2N-méthylacétamide,thiol-3N-méthylpropanamide et N-thiol-2 éthyle)acétamide

Raman and IR spectra of (CH₃NHCOCH₂S)₂Hg, (CH₃CONHCH₂CH₂S)₂Hg and CH₃NHCOCH₂CH₂SHgCl have been recorded between 3800 and 60 cm^?1. Mercury is covalently bonded to two sulphur atoms in the first two compounds and to one sulphur atom and one chlorine atom in the third compound. (CH₃NHCOCH₂S)₂Hg forms a tenatom ring by intramolecular hydrogen bonding NH?OC. In the two other complexes, weak interactions Hg?O are consistent with experimental results.