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1.
Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA ( N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C 5H 6N 2O 2)(C 4H 5NO 4) 2−(H 2O) 2]·H 2O, [Ni(C 5H 6N 2O 2)(C 5H 7NO 4) 2−(H 2O) 2]·H 2O and [Ni(C 5H 6N 2O 2)(C 6H 8N 2O 5) 2−(H 2O) 2]·1.5H 2O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy ( E*), enthalpy (Δ H*), entropy (Δ S*) and free energy change of decomposition (Δ G*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate. 相似文献
2.
The magnetic susceptibility of 1,1′,2,2′-tetramethylcobaltocene, Co[C 5H 3(CH 3) 2] 2, and 1,1′-diethylcobaltocene, Co(C 5H 4C 2H 5) 2, has been studied between 0.99 and 296 K. The data are well reproduced by a calculation of the dynamic Jahn-Teller effect for the 2E 1g(a 1g2e 2g4e 1g) ground state of D 5d symmetry. A suitable set of parameter values is given by ζ = 100 cm −1, δ = 150 cm −1, kJT = 0.40, κ = 0.70. The magnetism of cobaltocene, Co(C 5H 5) 2, may be described by parameter values of comparable magnitude. The results imply a significantly larger reduction of the spin-orbit coupling parameter ζ due to covalency than of the orbital reduction factor κ. 相似文献
3.
MoO 2(C 5H 7O 2) 2, where C 5H 7O 2 is 2,4-pentanedione (acac), reacts with 2-2′ pyridylbenzoxazole in acetone to give a product with stoichiometry, Mo 3C 24H 16N 6O 12. This product dissolves readily in dimethylformamide to give a brown solution which on standing for several weeks yielded crystals. An X-ray structure determination showed these crystals to contain uncoordinated 2-2′pyridylbenzoxazole and [(CH 3) 2NH 2] 4+[Mo 8O 26] 4−. 相似文献
4.
The infrared spectra of solid samples of C 4H 7K and C 4D 7K have been investigated in the 4000 to 30 cm −1 range. A complete assignment of intramolecular fundamentals of C 4H 7− and C 4D 7− ions and of potassium-allyl vibrations is proposed and the intramolecular force constants are calculated. The C(CH 2) 32− anion has been identified spectroscopically. Structures of C 3H 5−, C 4H 7− and C(CH 3) 32− are discussed and compared with those optimised by the MINDO/3 method. 相似文献
5.
Nickel(II) chromate complex with imidazole (HIm) was isolated from the [Ni 2+–HIm–CrO 42−] system in various experimental conditions, i.e. reagent molar ratios and nickel(II) salts. The catena( μ-CrO 4- O, O′)[Ni(HIm) 3H 2O] (1) crystallizes in monoclinic crystal system—space group P2 1/ n with cell parameters: a=11.784(2), b=8.899(2), c=13.934(3) (Å), β=95.19(3) (°). The unit cell contains two independent helixes, left- and right-handed, stabilized by intrahelical and interhelical hydrogen bonds (HB) and π–π interactions. The cis coordination of the CrO 42− anions and the HB systems appeared to be the main determinants of the helical architecture. To the best of our knowledge the cis-chromate coordination was observed for the first time. The cis coordination causes the distortion of the nickel octahedron, which was analysed by 4 K single crystal electronic spectra with D4h symmetry approximation (gaussian resolution and crystal field parameters). This symmetry was also confirmed with the polarised electronic spectra. The magnetic properties of the complex suggest the occurrence of weak intrachain antiferromagnetic interactions between the magnetic Ni II center. The computational DFT studies of complex 1 assuming three possible isomers mer[(HIm) 3]– cis[(CrO 42−) 2], mer– trans and fac– cis suggested that the main contribution to the stability of 1 might have interhelical and intrahelical hydrogen bonds. 相似文献
6.
The hydrothermal reactions of vanadium oxide starting materials with divalent transition metal cations in the presence of nitrogen donor chelating ligands yield the bimetallic cluster complexes with the formulae [{Cd(phen 2) 2V 4O 12]·5H 2O (1) and [Ni(phen) 3] 2[V 4O 12]·17.5H 2O (2). Crystal data: C 48H 52Cd 2N 8O 22V 4 (1), triclinic.
a=10.3366(10), b=11.320(3), c=13.268(3) Å, =103.888(17)°, β=92.256(15)°, γ=107.444(14)°, Z=1; C 72H 131N 12Ni 2O 29.5V 4 (2), triclinic.
a=12.305(3), b=13.172(6), c=15.133(4), =79.05(3)°, β=76.09(2)°, γ=74.66(3)°, Z=1. Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range 1.59° <θ<26.02° and 2.01°<θ<25.01° using the ω-scan technique, respectively. The structure of 1 consists of a [V 4O 12] 4− cluster covalently attached to two {Cd(phen) 2} 2+ fragments, in which the [V 4O 12] 4− cluster adopts a chair-like configuration. In the structure of 2, the [V 4O 12] 4− cluster is isolated. And the complex formed a layer structure via hydrogen bonds between the [V 4O 12] 4− unit and crystallization water molecules. 相似文献
7.
The synthesis, crystal structure and magnetic measurements of three new polynuclear tetracarboxylato-bridged copper(II) complexes, i.e. {[Cu 4(phen) 2(μ-O 2CC 2H 5) 8] · (H 2O)} n (1), [Cu 2(μ-O 2CC 6H 4OH) 4(C 7H 7NO) 2] · 6H 2O (2) and [Cu 2(μ-O 2CCH 3) 4(C 7H 7NO) 2] (3) (phen = 1,10-phenanthroline, O 2CC 6H 4OH = 3-hydroxy benzoate, C 7H 7NO = 4-acetylpyridine) are reported. All compounds consist of dinuclear units, in which two Cu(II) ions are bridged by four syn, syn-η 1:η 1:μ carboxylates, showing a paddle-wheel cage type with a square-pyramidal geometry, arranged in different ways. The structure of compound 1 consists of an one-dimensional structure generated by an alternating classical dinuclear paddle-wheel unit and an unusual dinuclear Cu 2(μ-OCOC 2H 5) 2(μ-O 2CC 2H 5) 2(phen) 2unit, which are connected to each other via a syn, anti-triatomic propionato bridge in an axial-equatorial configuration. The adjacent chains are connected to generate a 2D structure through the face-to-face π–π interaction between phen rings. Structures of compounds 2 and 3 both consist of a symmetric dinuclear Cu(II) carboxylate paddle-wheel core and pyridyl nitrogen atoms of 4-acetylpyridine ligand at the apical position, and just differ in the substituents of the equatorial ligands. The magnetic properties have been measured and correlated with the molecular structures. It is found that in the two classical paddle-wheel compounds the Cu(II) ions are strongly antiferromagnetically coupled with J = −278.5 and −287.0 cm−1 for complexes 2 and 3, respectively. In compound 1 the magnetic susceptibility could be fitted with two different, independent Cu(II) units, one strongly coupled and one weakly coupled; the paddle-wheel dinuclear unit has the strongest antiferromagetic coupling with a value for J of −299.5 cm−1, whereas the Cu(II) ions in the propionato-bridged dinuclear unit of 1 display a very weak antiferromagnetic coupling with a value for J = −0.75 cm−1, due to the orthogonality of the magnetic orbitals. Also the exchange within the chain is therefore very weak. The magneto-structural correlations for complexes 1, 2, and 3 are discussed on the basis of the structural parameters and magnetic data for the complexes. 相似文献
8.
The equilibrium constant K for the ion-pair formation fac-[Co(pic) 3] 3+ + C 2O22− fac-[Co(pic) 3] 3+/C 2O 42−1 where pic = 2-aminomethylpyridine, has been determined spectrophotometrically at 0.35 M (KCl) ionic strength and 25.0°C, using four different calculation approaches. The best results were obtained when the concentration of the minor component (the cobalt complex ion) was not neglected in comparison with the oxalate ion concentration. The value of K (5.3 M −1) increases when the supporting electrolyte is LiCl (K = 8.2 M −1). The effect of the ionic strength variation from 0.35 to 2.0 M (LiCl) was also investigated. 相似文献
9.
The emission intensity at 517 nm from Pt 2(pop) 44− (pop = P 2O 5H 22−) is quenched by the addition of sulphur dioxide. The sulphur dioxide coordinates at the axial platinum(II) sites by a η 1-SO 2 bond. This coordination is supported by 31p NMR and Raman spectroscopy of aqueous solutions. The electronic spectrum of a sulphur dioxide saturated solution of Pt 2(pop) 44− shows an absorption at 428.5nm ( = 4.1 × 10 4). From the decrease in the chromophore for uncomplexed Pt 2(pop) 44− the equilibrium constant for SO 2 binding is estimated to be 1.74 M 2l −2. The effect of adding different quenchers to aqueous solutions of Pt 2(pop)44− is discussed. The compound Pt 2(pop) 44− will undergo 2-electron reduction with chromous ion. 相似文献
10.
The interaction between Mo 2(O 2CCH 3) 4, Me 3SiI and I 2 in THF resulted in oxygen abstraction from the solvent and formation of [Mo 2(μ-O)(μ-I)(μ-O 2CCH 3) I 2(THF) 4] +[MoOI 4(THF)] − and I---(CH 2) 4---I. The molybdenum complex has been characterized by X-ray diffractometry. Crystal data: triclinic, space group P
, a = 13.827(3) Å; b = 15.803(7) Å; c = 9.950(3) Å; = 93.34(4)°; β = 102.40(2)°; γ = 90.09(2)°; V = 2120(2) Å 3; Z = 2; dcalc = 2.559 g cm −3; R = 0.0476 ( Rw = 0.0613) for 370 parameters and 3938 data with F02> 3σ( F02). The metal-metal distance in the cation is 2.527(2) Å and indicates a strong interaction. The magnetic behavior is consistent with the assignment of one unpaired electron to the Mo 27+ core of the cation and one to the d1 Mo(V) center of the anion. The interaction between Mo(CO) 6 and I 2 in THF also results in the formation of 1,4-diiodobutane. 相似文献
11.
A novel tetranuclear terbium(III) complex [Tb 4(OH) 4(pybet) 6(H 2O) 8][Tb 4(OH) 4(pybet) 6(H 2O) 7 (NO 3)](ClO 4) 14·6H 2O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb 4(μ 3-OH) 4(μ 2-carboxylato-O,O′) 6 core. The ligand pybet is pyridinoacetate, C 5H 5+N-CH 2CO 2−. Magnetic susceptibility data were measured for this Tb 4 complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction ( J = −0.015 cm −1) or there is a small crystal-field splitting of the 7F 6 Tb III ground state. 相似文献
12.
The IR polarized spectra of gypsum CaSO 4·2H 2O were recorded at incidence angles of approximately 10 and 16 degrees. Band singlet or doublet was observed for the higher frequency ν 3(SO 42−) mode of Bu symmetry type, depending on polarization ( n or p). A doublet was observed for the lower frequency ν 3(SO 42−) mode of Bu symmetry type too, irrespectively of the type of polarization. In order to give an explanation for the doublets origin, a model permittivity function was constructed. Quite good agreement exists between the reflectance based on the model permittivity function and the experimentally measured one for the high-frequency doublet. The origin of the lower frequency doublet could not be explained in this way, but may be speculated to result from an Evans type interaction between a combination of a water libration and ν 2(SO 42−), with the lower frequency ν 3(SO 42−) mode. 相似文献
13.
The photophysics of three complexes of the form Ru(bpy) 3−(pypm) 2+ (where bpy2,2′-bipyridine, pypm 2-(2′-pyridyl)pyrimidine and P=1, 2 or 3) was examined in H 2O, propylene carbonate, CH 3CN and 4:1 (v/v) C 2H 5OH---CH 3OH; comparison was made with the well-known photophysical behavior of Ru(bpy) 32+. The lifetimes of the luminescent metal-to-ligand charge transfer (MLCT) excited states were determined as a function of temperature (between −103 and 90 °C, depending on the solvent), from which were extracted the rate constants for radiative and non-radiative decay and Δ E, the energy gap between the MLCT and metal-centered (MC) excited states. The results indicate that *Ru(bpy) 2(pypm) 2+ decays via a higher lying MLCT state, whereas *Ru(pypm) 32+ and *Ru(pypm) 2(bpy) 2+ decay predominantly via the MC state. 相似文献
14.
The coordinatively unsaturated uranium(IV) complex U[N(C 6H 5) 2] 4 has been prepared via the stoichiometric reaction of diphenylamine with [(Me 3Si) 2N] 2
H 2. U[N(C 6H 5) 2] 4 coordinates Lewis bases such as Et 2O, THF, pyridine or (EtO) 3PO, based on electronic absorption spectroscopy and 1H NMR studies. Exchange between U[N(C 6H 5) 2] 4 and U[N(C 6H 5) 2] 4(L), where L is THF or pyridine, is rapid on the NMR time-scale between 307 and 323 K. Measurement of equilibrium constants for L = THF provides Δ H and Δ S values of −60 kJ mol −1 and −1.8 × 10 2 J K −1 mol −1, respectively. U[N(C 6H 5) 2] 4 coordinates and binds (EtO) 3PO much more tightly ( Keq = & > 10 4 M −1) than THF or pyridine with the exchange rate between U[N(C 6H 5) 2] 4 and U[N(C 6H 5) 2] 4[OP(OEt) 3] being close to the NMR time-scale. 相似文献
15.
Large-scale CEPA-1 calculations have been carried out for linear C 5, a molecule of substantial interest to combustion processes and astrochemistry. The equilibrium bond lengths are predicted to be 1.289 Å (outer CC bond) and 1.283 Å (inner CC bond), with an accuracy of 0.002 Å. The calculated ν 3 band origins of 2161 cm −1 (105 CGTO basis) and 2137 cm −1 (150 CGTO basis) are in good agreement with the experimental value of 2169 cm −1. This band has an extremely large transition moment of 0.74 D. The less intense stretching fundamental ν 4 (μ=0.18 D) is predicted to occur at 1478 ± 10 cm −1. Predictions for the totally symmetric stretching and the bending vibrational frequencies (in cm −1) are 2008 (1σ g+), 792 (2σ g+), 570 (1π u), 209 (1π g) and 119 (2π u). 相似文献
16.
The effects of cyclopentadienyl ring size on the geometry of bimetallic organosamarium complexes have been studied by comparing the X-ray crystal structure of [(C 5H 4Me) 2(THF)Sm(μ-Cl)] 2, prepared from KC 5H 4Me and SmCl 3 in THF, with C 5Me 5 analogs. The complex crystallizes from THF at −30°C in space group Pbcn with a = 20.312(5), b = 9.626(2), c = 16.225(3) Å, V = 3172.5(12) Å 3 and Dcalc = 1.74 g cm −3 for Z = 4. Least-squares refinement of the model based on 1759 reflections [| Fo| > 2.0σ(| Fo|)] converged to a final RF = 5.0%. The complex adopts a geometry which has a molecular two-fold rotation axis perpendicular to the Sm 2Cl 2 plane and a crystallographic inversion center. Hence, both methyl groups of each (C 5H 4Me) 2Sm unit are located on the side opposite of the THF ligands, which are trans to each other, and the four C 5H 4Me ring centroids define a square plane. The Sm---Cl distances are 2.759(3) and 2.819(3) Å. 相似文献
17.
Variable temperature (−105 to −150 °C) studies of the infrared spectra (3500–400 cm −1) of 1,1-dimethylhydrazine, (CH 3) 2NNH 2, in liquid krypton have been carried out. No convincing spectral evidence could be found for the trans conformer which is expected to be at least 600 cm −1 less stable than the gauche form. The structural parameters, dipole moments, conformational stability, vibrational frequencies, and infrared and Raman intensities have been predicted from MP2/6-31G(d) ab initio calculations. The predicted infrared and Raman spectra are compared to the experimental ones. The adjusted r0 parameters from MP2/6-311+G(d,p) calculations are compared to those reported from an electron diffraction study. The energy differences between the gauche and trans conformers have been obtained from MP2 ab initio calculations as well as from density functional theory by the B3LYP method calculations from a variety of basis sets. All of these calculations indicate an energy difference of 650–900 cm −1 with the B3LYP calculations predicted the larger values. The potential function governing the conformational interchange has been predicting from both types of calculations and comparisons have been made. The barrier to internal rotation by the independent rotor model of the inner methyl group is predicted to have a value of 1812 cm −1 and that of the outer one of 1662 cm −1 from ab initio MP2/6-31G(d) calculations. These values agree well with the experimentally determined values of 1852±16 and 1558±12 cm −1, respectively, from a fit of the torsional transitions with the coupled rotor model. For the coupled rotor model the predicted V′ 33 (sin 3τ 0 sin 3τ 1 term) value which ranged from 190 to 232 cm −1 is in reasonable agreement with the experimental value of 268±3 cm −1 but the predicted V33 (cos 3τ 0 cos 3τ 1 term) value of −73 to −139 cm −1 is 25% smaller and of the opposite sign of the experimental value of 333±22 cm −1. These theoretical and spectroscopy results are compared to similar quantities of some corresponding molecules. 相似文献
18.
Rate constants for the tunneling reaction (HD + D → h + D 2) in solid HD increase steeply with increasing temperature above 5 K, while they are almost constant below 4.2 K. The apparent activation energy for the tunneling reaction above 5 K is 95 K, which is consistent with the energy (91–112 K) for vacancy formation in solid hydrogen. The results above 5 K were explained by the model that the tunneling reaction was accelerated by a local motion of hydrogen molecules and hydrogen atoms. The model of the tunneling reaction assisted by the local motion of the reactans and products was applied to the temperature dependence of the proton-transfer tunneling reaction (C 6H 6− + C 2H 5OH → C 6H 7 + C 2H 5O −) in solid ethanol, the tunneling elimination of H 2 molecule of H 2 molecule ((CH 3) 2 CHCH(CH 3) 2+ → (CH 3) 2 C = C(CH 3) 2+ + H 2) in solid 2,3-dimethylbutane, and the selective tunneling reaction of H atoms in solid neo-C 5H 12-alkane mixtures. 相似文献
19.
The compound [Zn(H 2O) 4] 2[H 2As 6V 15O 42(H 2O)]·2H 2O (1) has been synthesized and characterized by elemental analysis, IR, ESR, magnetic measurement, third-order nonlinear property study and single crystal X-ray diffraction analysis. The compound 1 crystallizes in trigonal space group R3, a= b=12.0601(17) Å, c=33.970(7) Å, γ=120°, V=4278.8(12) Å 3, Z=3 and R1( wR2)=0.0512 (0.1171). The crystal structure is constructed from [H 2As 6V 15O 42(H 2O)] 4− anions and [Zn(H 2O) 4] 2+ cations linked through hydrogen bonds into a network. The [H 2As 6V 15O 42(H 2O)] 6− cluster consists of 15 VO 5 square pyramids linked by three As 2O 5 handle-like units. 相似文献
20.
The reaction of the anionic mononuclear rhodium complex [Rh(C 6F 5) 3Cl(Hpz)] t- (Hpz = pyrazole, C 3H 4N 2) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C 6F 5) 3Rh(μ-Cl)(μ-pz)M(L 2)] [M = Rh, L 2 = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO) 2 (4); M = Ir, L 2 = COD (3)]. The complex [Rh(C 6F 5) 3(Hbim)] − (5) has been prepared by treating [Rh(C 6F 5) 3(acac)] − with H 2bim (acac = acetylacetonate; H 2bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C 6F 5) 3Rh(μ-bim)M(L 2)] − [M = Rh, L 2 = COD (6) or TFB (7); M = Ir, L 2 = COD (8); M = Pd, L 2 = η 3-C 3H 5 (9)]. With [Rh(acac)(CO) 2], complex 5 yields the tetranuclear complex [{(C 6F 5) 3Rh(μ-bim)Rh(CO) 2} 2] 2−. Homodinuclear Rh III derivatives [{Rh(C 6F 5) 3} 2(μ-L) 2] ·- [L 2 = OH, pz (11); OH, S tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C 6F 5) 3(μ-OH)} 2] 2− by the corresponding ligands. The reaction of [Rh(C 6F 5) 3(Et 2O) x] with [PdX 2(COD)] produces neutral heterodinuclear compounds [(C 6F 5) 3Rh(μ-X) 2Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh 3+) salts. 相似文献
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