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1.
《Journal of Coordination Chemistry》2012,65(23):4067-4076
Design and synthesis of a triangular manganese compound, [Mn3O4(H2O)2(phen)4](NO3)4?·?3H2O (1) with mono-µ-oxo and di-µ-oxo, is described. The complex has been characterized by elemental analysis, spectroscopy, single crystal and powder diffraction measurements, thermogravimetric analysis, etc. Bond Valence Sum calculations and X-ray photoelectron spectroscopy reveal that each manganese at each vertex of the triangle is +IV oxidation state. Variable temperature magnetic measurements show strong antiferromagnetic coupling between metal ions with the following set of parameters: g?=?1.99, J 1?=??50.0?cm?1, and J 2?=??90.2?cm?1 (where J 1 describes the interaction across the two mono-µ-oxo bridges and J 2 is the exchange coupling across the di-µ-oxo bridge). The compound breaks down in three steps when heated from room temperature to 900°C. The final ash of the compound is confirmed by infrared spectrum with standard MnO2. 相似文献
2.
Synthesis,Crystal Structure and Magnetic Properties of a 1‐D Polymer, [Cu(NITpPy)2(H2TCB)(H20)]·2H2O
A novel complex [Cu(NnpPy)2(HlTCB)(H1O)]·2H2O (NITpPy = 2‐(pyrid‐4′‐yl)‐4,4,5,5‐tetramethyl‐1, 3‐dioxoimidazoline; H2TCB = 1, 5‐dicarboxybenzene carboxylic‐2, 4‐diacid) has been synthesized and characterized by X‐ray crystallography analysis. The crystal structure consists of infinite chains of Cu‐(NITpPy)2(H2O) units linked by H2TCB ligands. The complex crystallizes in triclinic system with space group PI. Crystal data: a = 1.0594(2) nm, b = 1.3830(3) nm, c = 1.5551(3) nm, a = 67.75(3)°, β = 89.83(3)°, γ = 70.54(3)°. The variable magnetic susceptibility studies lead to magnetic coupling constant values of J1= ?11.18 cm‐1 (Cu—Rad) and J2 = ?4.06 cm?1 (Cu—Cu). 相似文献
3.
Jean Devillers Jacques Navech Jean-Pierre Albrand 《Magnetic resonance in chemistry : MRC》1971,3(2):177-186
The 31P decoupled PMR spectra of the title oxazaphospholanes give rise to well resolved ABXY patterns. Among the eight possible solutions, six can be readily eliminated from chemical shifts considerations and the choice between the remaining two is based on tickling experiments. Good fits are observed between experimental and calculated spectra. The relative signs of the 3J(P? O? C? H) and 3J(P? N? C? H) coupling constants are given by tickling and Indor experiments. The ring conformation is discussed. 相似文献
4.
All J(P? H) and J(P? C) values, including signs, have been obtained in acetylenic and propynylic phosphorus derivatives, R2P(X)? C?C? H and R2P(X)? C?C? CH3 (X ? oxygen, lone pair and R ? C6H5, N(CH3)2, OC2H5, N(C6H5)2, Cl) from 1H and 13C NMR spectra. In PIV derivatives the following signs are obtained: 1J(P? C)+, 2J(P? C)+, 3J(P? C)+, 3J(P? H)+, 4J(P? H)? . Linear relations are observed between 1J(P? C), 2J(P? C) and 3J(P? C) versus 3J(P? H), indicating that these coupling constants are mainly dependent on the Fermi contact term, though the other terms of the Ramsey theory do not seem to be negligible for 1J(P? C) and 2J(P? C). In PIII derivatives these signs are: 1J(P? C)- and +, 2J(P? C)+, 3J(P? C)-, 3J(P? H)-, 4J(P? H)+. Only 3J(P? C) and 3J(P? H) reflect a small contribution of the Fermi contact term while in 1J(P? C) and 2J(P? C) this contribution seems to be negligible relative to the orbital and/or spin dipolar coupling mechanisms. 相似文献
5.
《Journal of Coordination Chemistry》2012,65(8):1456-1468
Weak anti-ferromagnetic coupling is observed in a mononuclear copper(II) complex, [Cu(Pid)(OSO3)(H2O)]?·?(H2O) (Pid?=?2,2′-(1,10-phenanthrolin-2-ylimino)diethanol). The Cu(II) complex is a distorted square pyramid. Analysis of the crystal structure indicates that there are two types of magnetic coupling pathways, where one pathway involves π–π stacking between adjacent complexes and the second one involves the O–H?···?O hydrogen bonds between adjacent complexes. The variable-temperature magnetic susceptibilities show that there is a weak anti-ferromagnetic coupling between adjacent Cu(II) ions with Curie–Weiss constant θ?=??13.71?K?=??9.93?cm?1. Theoretical calculations reveal that the π–π stacking resulted in anti-ferromagnetic coupling with 2J?=??6.30?cm?1, and the O–H?···?O hydrogen-bonding pathway led to a weaker anti-ferromagnetic interaction with 2J?=??3.38?cm?1. The theoretical calculations also indicate that anti-ferromagnetic coupling sign from the π–π stacking accords with the McConnell I spin-polarization mechanism. 相似文献
6.
《Journal of Coordination Chemistry》2012,65(7):763-769
A novel dinuclear nickel(II) complex Ni2(NO3)4(APTY)4 (1) (APTY?=?1,5-dimethyl-2-phenyl-4-{[(1E)-pyridine-4-ylmethylene]amino}-1,2-dihydro-3H-pyrazol-3-one), was synthesized by solvothermal reaction of Ni(NO3)2?·?6H2O with APTY in methanol at 353?K. The structure consists of centrosymmetric dimers resulting from octahedrally coordinated Ni atoms bridged by APTY ligands. Weak intermolecular interactions (C–H?···?N, C–H?···?O hydrogen bonding, C–H?···?π and π–π stacking interactions) are responsible for a supramolecular assembly of molecules in the lattice. Magnetic measurements over 1.8–300?K show weak antiferromagnetic coupling between Ni(II) ions with J?=?2.969?cm?1, g?=?2.280, θ?=??5.903. 相似文献
7.
Pertti yrs 《Magnetic resonance in chemistry : MRC》1977,9(11):663-664
The vicinal 3J(C H3C?CH ) coupling constants were determined for a number of propylene derivatives and compared with the 3J(H C?CH ) couplings of the corresponding ethylenes. A linear regression analysis yielded the correlation 3J(CH) = 0.46 ×3 J(HH)+1.58 Hz, the correlation coefficient being 0.956. 相似文献
8.
Intramolecular Antiferromagnetism in [Cr2(μ-NH2)3(NH3)6]I3 The magnetism of [Cr2(μ-NH2)3(NH3)6]I3 which consists of binuclear cations with NH2?-bridged face-sharing octahedral coordination polyhedra and a metal-metal separation of 264.9 pm can be explained by antiferromagnetically exchange-coupled CrIII-3d3 pairs. The magnetochemical analysis in the temperature range 5 K – 295 K on the basis of the isotropic Heisenberg model (spin Hamiltonian ? = ?2 J?1 · ?2) leads to the parameter value J = ?98(3) cm?1. Compared to the exchange coupling in corresponding binuclear chromium compounds with OH? bridges and identical metal-metal separation the strength of the coupling is significantly enhanced (JNH2/JOH ≈? 1.6). 相似文献
9.
Sylvain Hamman Claude Bguin Claude Charlon Cuong Luu-Duc 《Magnetic resonance in chemistry : MRC》1983,21(6):361-366
The analysis of the ABKX spectra of thirteen compounds of the series RC(H-K)(F-X)C(H-A)(H-B)X gave the four vicinal proton-proton and fluorine-proton coupling constants. These coupling constants of conformationally mobile structures were used (i) to calculate the populations of the rotational states of the ? CHF? CH2? bond, (ii) to calculate the vicinal trans proton-proton J(HH)t and gauche and trans fluorine-proton coupling constants J(FH)g and J(FH)t and (iii) to give the unambiguous assignment of protons H-A and H-B. The dependence of the gauche and trans coupling constants with substituent electronegativity is explored. The results extend known correlations towards smaller electronegativity values. More quantitatively, the results and those in the literature, excluding those where deformations of torsional or bond angles occur, give a good fit of the data: a linear fit for J(HH)t = 15.0-0.77 Σ(ΔE), an exponential fit for J(FH)g = 15.35 exp [-0.266 Σ (ΔE)] and a linear fit for J(FH)t = 65.75 - 7.52 Σ (ΔE), where Σ (ΔE) is the sum of the electronegativity difference between hydrogen and the six atoms or groups on the CH? CF fragment. 相似文献
10.
Per-Olov Lwdin 《International journal of quantum chemistry》1982,21(1):69-92
Instead of the Schródinger equation ??Ψ = EΨ subject to the boundary condition 〈φ|Ψ〉 = 1, where φ is a normalized reference function in the Hilbert space, one studies the inhomogeneous equation (?? ? ?)Ψ? = aφ, where ? is a complex variable, with the same boundary condition, which gives a = 〈φ|??|Ψ?〉 ? ? = ?1 ? ?. Introducing the projector P = 1 ? |φ〉〈φ| for the complement to O = |φ〉〈φ|, one finds easily the explicit solution Ψ? = (1 ? P??/?)?1φ = (1 + T???)φ, where T? = (? ? P??)?1P = P(? ? P??P)?1P is the reduced resolvent associated with the auxiliary Hamiltonian H? = P??P. The existence of these operators is discussed. It is shown that, if the parameter ? is real in the “discrete part” of the spectrum to ??, then ? and ?1 = 〈φ|??|Ψ?〉 = 〈φ|?? + ??T???|Φ〉 ≡f(?) bracket a true eigenvalue E satisfying the relation E = f(E). The Newton-Raphson solution to the equation F(?) = ? ? f(?) = 0 is related to the variation principle. Putting ?? = ??0 + V and expanding the inverse (? ? P??0 ? PV)?1 in terms of powers of V or (V ? α), one gets various expansions relating to finite-order perturbation theory. Exact expressions for the ordinary wave and reaction operators are obtained. If A is an arbitrary nonsingular operator and h = {h1,h2,…,hn} is a linearly independent set, the inner projection Án = | h 〉 〈 h |A?1| h 〉?1〈 h | is a “rational approximation” to the operator A which converges toward A when n→∞ and the set h becomes complete. If A is positive (or has a finite negative part) the convergence is from below. Applying this principle to the partitioning technique, one gets rational perturbation approximations instead of the standard power series, similar to the Padé approximants but derived in a different way with the remainder term under control. The method has been used to calculate lower bounds to eigenvalues. 相似文献
11.
E. C. Chukovskaya V. I. Dostovalova T. T. Vasil'eva R. Kh. Freidlina 《Magnetic resonance in chemistry : MRC》1976,8(5):229-232
13C n.m.r. spectra have been measured for thirty-two polychloroalkenes including (i) monosubstituted compounds CH2?CHCClnH2?nX, where ? X stands for ? H, ? Cl, alkyl, and trisubstituted alkenes CCl2?CHAlk, none of which form geometric isomers; (ii) disubstituted compounds RCH?CHR′; (iii) and (iv) trisubstituted compounds of the types RCCl?CHR′ and CHCl?CClR, respectively. Compounds (ii) to (iv) represent either individual isomers or mixtures of the Z and E forms. In the case of compounds (ii) and (iii), the ordering of chemical shifts is δE > δZ for the sp2-carbon atoms and δE < δz for the adjacent tetrahedral ones. On the contrary, the signals of the sp2-carbon atoms of compounds (iv) obey the rule δE < δz. The effect of vinyl and allyl groups as substituents on the 13C chemical shifts of chlorine-containing groups is discussed. The dependence of the sp2-carbon spin–spin coupling constants J(13C? 1H) on the number of chlorinated substituents in the molecule is also considered. 相似文献
12.
G. A. Kalabin D. F. Kushnarev V. M. Bzesovsky G. A. Tschmutova 《Magnetic resonance in chemistry : MRC》1979,12(10):598-604
The 1H, 13C and 77Se chemical shifts and the 1J[C(Me)H(Me)], 1.2J(SeC) and 2J(SeH) coupling constants in 14 para- or meta-substituted selenoanisoles, R? C6H4? Se? CH3, have been measured and the dependence of these parameters on the electronic effects of the substituent R is discussed. A significant (up to 6 ppm) deviation from additivity of the substituent influence on the shielding of the 13C ring carbons has been found. 相似文献
13.
G. Haeffler U. Ljungblad I. Yu. Kiyan D. Hanstorp 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,42(4):263-266
The energies of the As? fine structure components 4p4 3 P 1 and 4p4 3 P 0 have been determined relative to the 4p4 3P2 ground state by using photodetachment electron spectroscopy. Fine structure splittings of ΔE(3 P 1 ? 3 P 2) = 125(3) meV and ΔE(3 P 0 ? 3 P 2) = 166(5) meV have been obtained. It is the first experimental determination of the energy of the J = 1 level and an improvement of the accuracy for the J = 0 level. Previous isoelectronic extrapolations are consistent with the experimental values. 相似文献
14.
K. Kamienska-Trela Z. Biedrzycka R. Machinek B. Knieriem W. Lüttke 《Magnetic resonance in chemistry : MRC》1984,22(5):317-322
1J(13C?13C) nuclear spin–spin coupling constants in derivatives of acetylene have been measured from natural abundance 13C NMR spectra and in one case (triethylsilyllithiumacetylene) from the 13C NMR spectrum of a 13C-enriched sample. It has been found that the magnitude of J(C?C) depends on the electronegativity of the substituents at the triple bond. The equation 1J(13C?13C) = 43.38 Ex + 17.33 has been derived for one particular series of the compounds Alk3SiC?CX, where X denotes Li, R3Sn, R3Si, R3C, I, Br or Cl. The 1J(C?C) values found in this work cover a range from 56.8 Hz (in Et3SiC?Li) to 216.0 Hz (in PhC?CCI). However, the 1J(C?C) vs Ex equation combined with the Egli–von Philipsborn relationship allows the calculation of the coupling constants in Li2C2 (32 Hz) and in F2C2 (356 Hz). These are probably the lowest and the highest values, respectively, which can be attained for 1J(CC) across a triple bond. The unusually large changes of the 1J(C?C) values are explained in terms of substituent effects followed by a re-hybridization of the carbons involved in the triple bond. INDO FPT calculations performed for two series of acetylene derivatives, with substituents varied along the first row of the Periodic Table, corroborate the conclusions drawn from the experimental data. 相似文献
15.
Frantiek Turef
ek Francis Maquin Nicholas Hill Daniel Stahl Tino Gumann 《Journal of mass spectrometry : JMS》1988,23(2):91-97
The loss of methyl from unstable, metastable and collisionally activated [CH2?CH? C(OH)?CH2]+˙ ions (1+˙) was examined by means of deuterium and 13C labelling, appearance energy measurements and product identification. High-energy, short-lived 1+˙ lose methyl groups incorporating the original enolic methene (C(1)) and the hydroxyl hydrogen atom (H(0)). The eliminations of C(1)H(1)H(1)H(4) and C(4)H(4)H(4)H(0) are less frequent in high-energy ions. Metastable 1+˙ eliminate mainly C(1)H(1)H(1)H(4), the elimination being accompanied by incomplete randomization of the five carbon-bound hydrogen atoms. The resulting [C3H3O]+ ions have been identified as the most stable CH2?CH? CO+ species. The appearance energy for the loss of methyl from 1 was measured as AE[C3H3O]+ = 10.47 ± 0.05 eV. The critical energy for 1+˙ → [C3H3O]+ + CH3˙ is assessed as Ec ? 173 kJ mol?1. Reaction mechanisms are proposed and discussed. 相似文献
16.
《Journal of Coordination Chemistry》2012,65(12):2208-2216
One polar noncentrosymmetric complex, [Zn(phen)(H2O)2L]L (HL = m-nitro-benzoic acid, phen = 1,10-phenanthroline) has been prepared and characterized. The title complex is crystallized in a noncentrosymmetric space group P21. The compound is a typical ferroelectric and its electric hysteresis loop shows a remnant polarization (P r) of ca. 0.04?μC?cm?2 and coercive field (E c) of 1.26?V/cm. It may be a potential ferroelectric with a relatively large spontaneous polarization (P s) of 0.11?μC?cm?2. Moreover, permittivity property measurements reveal a dielectric constant (? r) of 5.63 and dielectric loss (tan δ) of 2.5%. 相似文献
17.
T. N. Mitchell 《Magnetic resonance in chemistry : MRC》1975,7(1):59-60
The linear relationship between the coupling constants 1J(Sn? 13C) and 2J(Sn? H), observed for a number of organotin compounds, does not hold for coupling in the Sn? CHnCl3?n group of mono- and dichloromethyltin compounds. A complete determination of all NMR parameters of the compounds Me3Sn-CHnCl3?n (n = 0 to 3) shows no further anomalies, indicating that steric factors must be responsible for the unusually low values of 2J(Sn? H) in the SnCHnCl3?n group. Molecular weight measurements support this theory, showing that the chlorine-containing compounds are associated. 相似文献
18.
《Journal of Coordination Chemistry》2012,65(19):3431-3440
[Ni(hmp)(MeOH)Br]4 ? 2H2O has been prepared by the reaction of 2-hydroxymethylpyridine with NiBr2 ? 3H2O and characterized by IR, elemental analysis, powder X-ray diffraction, thermogravimetric analyses, magnetic measurements, and single crystal X-ray diffraction. The crystal structure shows two independent [Ni(hmp)(MeOH)Br]4 molecules in the asymmetric unit and [Ni4O4]4+ cubane-type cores. Each octahedral Ni(II) is bridged by four μ3-CH2O ? fragments from four hmp ? ligands. Magnetic studies show that ferromagnetic coupling gives an S = 4 ground state with significant magnetoanisotropy, and the parameters are J 1 = 8.56, J 2 = 2.28, D = ?0.65 cm?1, and g ≈ 2.13. 相似文献
19.
Vicinal C,H spin coupling in substituted alkenes. Stereochemical significance and structural effects
Vicinal C,H spin coupling (3JC,H) in substituted alkenes has been investigated systematically. Emphasis is laid on the stereochemical significance (Jtrans/Jcis) and on the various structural factors which influence 3JC,H, such as π-bond order, torsional angle ?, bond angle θ, electronegativity of substituents and steric effects. A new type of γ-effect is observed in 3JtransC,H which appears to have the same origin as the γ-shift effect. By comparison of 3J and 3JH,H, it was found that the relation 3JC,H ≈? 0·6 3JH,H holds for both trans and cis coupling constants. Finally, it is concluded that 3JC,H constitutes a valuable criterion to distinguish E- and Z-isomers, particularly in trisubstituted alkenes. Applications to natural products are presented. 相似文献
20.
Magnetic Properties of a Single‐Molecule Lanthanide–Transition‐Metal Compound Containing 52 Gadolinium and 56 Nickel Atoms
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Da‐Peng Liu Xin‐Ping Lin Hui Zhang Xiu‐Ying Zheng Dr. Gui‐Lin Zhuang Prof. Dr. Xiang‐Jian Kong Prof. Dr. La‐Sheng Long Prof. Dr. Lan‐Sun Zheng 《Angewandte Chemie (International ed. in English)》2016,55(14):4532-4536
Monodisperse metal clusters provide a unique platform for investigating magnetic exchange within molecular magnets. Herein, the core–shell structure of the monodisperse molecule magnet of [Gd52Ni56(IDA)48(OH)154(H2O)38]@SiO2 ( 1 a @SiO2) was prepared by encapsulating one high‐nuclearity lanthanide–transition‐metal compound of [Gd52Ni56(IDA)48(OH)154(H2O)38]?(NO3)18?164 H2O ( 1 ) (IDA=iminodiacetate) into one silica nanosphere through a facile one‐pot microemulsion method. 1 a @SiO2 was characterized using transmission electron microscopy, N2 adsorption–desorption isotherms, and inductively coupled plasma‐atomic emission spectrometry. Magnetic investigation of 1 and 1 a revealed J1=0.25 cm?1, J2=?0.060 cm?1, J3=?0.22 cm?1, J4=?8.63 cm?1, g=1.95, and z J=?2.0×10?3 cm?1 for 1 , and J1=0.26 cm?1, J2=?0.065 cm?1, J3=?0.23 cm?1, J4=?8.40 cm?1 g=1.99, and z J=0.000 cm?1 for 1 a @SiO2. The z J=0 in 1 a @SiO2 suggests that weak antiferromagnetic coupling between the compounds is shielded by silica nanospheres. 相似文献