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1.
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
2.
A new family of heteropolytungstate complexes (NH 4) 21[Ln(H 2O) 5{Ni(H 2O)} 2As 4W 40O 140]· xH 2O(Ln=Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na 27[NaAs 4W 40O 140]·60H 2O with NiCl 2·6H 2O and Ln(NO 3) 3· xH 2O at pH≈4.5. The crystal structures of (NH 4) 21[Gd(H 2O) 5{Ni(H 2O)} 2As 4W 40O 140]·51H 2O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P2 1/ n with a=19.754(3), b=24.298(4), c=39.350(6) Å, β=100.612(3)°, V=18564(5) Å 3, Z=2, R1( wR2)=0.0544(0.0691). The central site S1 and two opposite sites S2 of the big cyclic ligand [As 4W 40O 140] 28− are occupied by one Ln 3+and two Ni 2+, respectively, each site supply four O d coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni 2+and Ln 3+. Polyanion [Ln(H 2O) 5{Ni(H 2O)} 2As 4W 40O 140] 21− has C2v symmetry. IR and UV–vis spectra of [NaAs 4W 40O 140] 27− of the title compounds are discussed. 相似文献
3.
Three small organic molecular co-crystal compounds (C 3N 6H 6)·(C 6H 10O 4)·H 2O(1), C 3H 8N 2O(3) and (H 4btec) 2·(4,4'-bipy)(4)(H 4btec=1,2,4,5-benzenetetracarboxylic acid, 4,4'-bipy=4,4'-bipyridine) and one coordination supramolecular compound [Mn(C 2O 4)(H 2O) 2]·C 6H 11NO 2(2) were synthesized by hydrothermal reaction. They were characterized by elemental analysis, infrared(IR) spectroscopy and single crystal X-ray diffraction(XRD). Structural analyses reveal that these 2D or 3D supramolecular networks of the compounds were formed by C―H···O, N―H···O, N―H···N, O―H···O and O―H···N hydrogen bonds. Therein, the functional groups of ―COOH, ―NH 2 and ―OH play important roles in constructing supramolecular architectures. 相似文献
4.
Condensation of thiosemicarbazide or N(4)-ethylthiosemicarbazide with 1,2,8,9-tetraphenyl-3,7-diazanona-1,9-dione in the presence of copper(II) acetate in 96% ethanol leads to Δ 6-5,6-diphenyl-5-methoxy-1,2,4-triazacyclohexene-3-thione, C 16H 15N 3OS, or Δ 6-4-methyl-5,6-diphenyl-5-ethoxy-1,2,4-triazacyclohexene-3-thione, C 18H 19N 3OS. For C 16H 15N 3OS the crystal data are monoclinic, P2 1/ c, a=9.7780(7), b=8.5120(3), c=18.2210(13) Å, β=100.958(3)°, V=1488.89(16) Å 3, and Z=4 in agreement with an earlier report. For C 18H 19N 3OS the crystal data are orthorhombic, P2 12 12 1, a=8.6940(3), b=12.9946(3), c=15.5139(5) Å, V=1752.68(9) Å 3, and Z=4. 相似文献
5.
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
6.
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
7.
在水热和弱酸性反应条件下,螯合型表面活性剂前驱体乙二胺三乙酸分别与氯化锌、氯化钴反应,形成水合乙二胺三乙酸金属配合物[M(H 2O) 6][M(ED3A)(H 2O)] 2·2H 2O[M=Zn(1),Co(2);H 3ED3A=乙二胺三乙酸,C 8H 14N 2O 6]。 产物经元素分析、红外、热重、液体核磁共振和X射线单晶衍射结构表征。 乙二胺三乙酸和锌(Ⅱ)、钴(Ⅱ)五配位,并与水一起形成典型的[MN 2O 4]或[MO 6]八面体结构。 13C核磁共振实验结果表明,溶液中乙二胺三乙酸与锌形成配合物在弱酸性条件下(pH值3~7)稳定存在,在酸性溶液中完全解离,乙二胺三乙酸进一步经分子内成环反应生成3-酮哌嗪二乙酸(H 2kpda=C 8H 12N 2O 5)。 相似文献
8.
Lamellar crystalline calcium phenylphosphonate, as anhydrous Ca(HO 3PC 6H 5) 2 and hydrated Ca(HO 3PC 6H 5) 2·2H 2O compounds, were used as hosts for intercalation of polar n-alkylmonoamine molecules of the general formula CH 3(CH 2) nNH 2 ( n=0–4, 7) in water or 1,2-dichloroethane. An increase in the interlayer distance was observed. The exothermic enthalpic values for intercalation increased with the number of carbon atoms and with increasing concentration of the amines. The intercalation followed by a titration procedure in the solid/liquid interface with Ca(HO 3PC 6H 5) 2·2H 2O and Ca(HO 3PC 6H 5) 2 gave the enthalpy/number of carbons correlations: Δ intH=−(1.74±0.43)–(1.30±0.13) nc and Δ intH=−(4.15±0.15)–(1.07±0.03) nc, for water and 1,2-dichloroethane, respectively. A similar correlation Δ intH=−(4.27±0.80)–(1.85±0.21) nc was obtained in water by using the ampoule breaking procedure for Ca(HO 3PC 6H 5) 2·2H 2O. The increase in exothermic enthalpic values with the increase in n-aliphatic carbon atoms is more pronounced for the anhydrous compound and also when using the ampoule breaking procedure. The Gibbs free energies are negative. Positive entropic values favor intercalation in these systems. 相似文献
9.
In this paper, we summarise our recent research interest in the hydrothermal synthesis and structural characterisation of multi-dimensional coordination polymers. The use of N-(phosphonomethyl)iminodiacetic acid (also referred to as H 4pmida) in the literature as a versatile chelating organic ligand is briefly reviewed. This molecule plays an important role in the formation of centrosymmetric dimeric [V 2O 2(pmida) 2] 4− anionic units, which were first used by us as building blocks to construct novel coordination polymers. Starting with [V 2O 2(pmida) 2] 4− in solution, we have isolated [M 2V 2O 2(pmida) 2(H 2O) 10] species (where M 2+ = Mn 2+, Co 2+ or Cd 2+) via the hydrothermal synthetic approach, which were then employed for the construction of [CdVO(pmida)(4,4′-bpy)(H 2O) 2]·(4,4′-bpy) 0.5·(H 2O), [CoVO(pmida)(4,4′-bpy)(H 2O) 2]·(4,4′-bpy) 0.5, [Co(H 2O) 6][CoV 2O 2(pmida) 2(pyr)(H 2O) 2]·2(H 2O) and [Cd 2V 2O 2(pmida) 2(pyr) 2(H 2O) 4]·4(H 2O) by the inclusion of bridging organic ligands in the reactive mixtures, such as pyrazine (pyr) and 4,4′-bipyridine (4,4′-bpy). These materials can contain channel systems, and exhibit magnetic behaviour, not only due to the V 4+ centres but also to the transition metal centres which establish the links between neighbouring dimeric [V 2O 2(pmida) 2] 4− anionic units. A closely related anionic moiety, [Ge 2(pmida) 2(OH) 2] 2−, was engineered to allow the study of such crystalline hybrid materials using one- and two-dimensional high-resolution solid-state NMR. 相似文献
10.
The hexaaquacobalt(II)bis(phthalhydrazidato)tetrahydrate, [Co(H 2O) 6](C 8N 2O 2H 5) 2·4H 2O is examined using single crystal X-ray diffraction analysis. The crystals are triclinic, space group , with a = 9.757(1), b = 10.955(2), c = 11.106(1), = 100.79(2), β = 90.35(3), γ = 91.54(1) and Z = 2. In [Co(H 2O) 6](C 8N 2O 2H 5) 2·4H 2O, the cobalt(II) is coordinated by six water ligands and the [Co(H 2O) 6] 2+ is associated with the two O-deprotonated phthalhydrazidato ions only by hydrogen bonds. The infrared and Raman spectra of phthalhydrazide (PH) and infrared spectra of deuterated derivative phthalhydrazide (PD) and of [Co(H 2O) 6](C 8N 2O 2H 5) 2·4H 2O are reported. The theoretical wavenumbers, infrared intensities and Raman scattering activities have been calculated using density functional (B3LYP) method with the 6-311++G(d,p) basis set. The calculated potential energy distribution has proved to be of great help in assigning the spectra PH, its deuterated derivative and [Co(H 2O) 6](C 8N 2O 2H 5) 2·4H 2O. The results from natural bond orbital (NBO) analysis for keto-hydroxy form of PH are presented. 相似文献
11.
In an effort to utilize the [Co(NH 3) 6] 3+ cation as a new anion receptor (binding agent) for dihydroxy dicarboxylate anion i.e., tartrate, orange single crystals of hexaamminecobalt(III) chloride ( R, R)-tartrate monohydrate, [Co(NH 3) 6]Cl(C 4H 4O 6)·H 2O, were obtained by reacting hexaamminecobalt(III) chloride with potassium–sodium tartrate tetrahydrate in a 1:1 molar ratio in hot water. The single crystal X-ray structure determination of [Co(NH 3) 6]Cl(C 4H 4O 6)·H 2O revealed that a distinctive network of hydrogen bonding interactions (N–HO, N–HCl −, O–HO) stabilize the crystal lattice. This is the first complex salt of hexaamminecobalt(III) with dihydroxy dicarboxylate anion i.e., tartrate. 相似文献
12.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
13.
(C 5H 5) 2Lu(μ-Cl 2)Na(dme) 2 reacts with LiSi(CH 3) 3 in dimethoxyethane with formation of [Li(dme) 3][(C 5H 5) 2Lu(Si(CH 3) 3) 2]. The crystal structure study shows the compound to consist of discrete ions [Li(dme) 3] + and [(C 5H 5) 2Lu(Si(CH 3) 3) 2] −. The compound crystallizes in the space group P2/ n with a 14.497(5) b 9.041(2), c 14.672(6) Å, β 103.85(3)° and V 1867(2) Å 3. The crystal and molecular structure was refined to R = 0.0473 for 2491 observed reflections with Fo 3σ( Fo). 相似文献
14.
Polarized absorption spectra of Ba(MnO 4) 2·3H 2O/Ba(ClO 4) 2·3H 2O mixed single crystals are reported at 4.2°K. Previous 1T 2 → 1A 1 assignments for the 5200 Å and 3000 Å absorption bands of MnO 4− are substantiated; further support is provided for the 1T 1 → 1A 1 assignment of the 3600 Å absorption band of MnO 4−. The site-splitting of the 5200 Å 1T 2 state is E( 1E)− E( 1A) ≈ −150 cm −1; that of the 3000 Å 1T 2 state is E( 1E)− E( 1A) ≈ 300 cm −1. A significant e vibronic intensity component is observed in the 5200 Å 1T 2 state. 相似文献
15.
Cd II complexes with glycine (gly) and sarcosine (sar) were studied by glass electrode potentiometry, direct current polarography, virtual potentiometry, and molecular modelling. The electrochemically reversible Cd II–glycine–OH labile system was best described by a model consisting of M(HL), ML, ML 2, ML 3, ML(OH) and ML 2(OH) (M = Cd II, L = gly) with the overall stability constants, as log β, determined to be 10.30 ± 0.05, 4.21 ± 0.03, 7.30 ± 0.05, 9.84 ± 0.04, 8.9 ± 0.1, and 10.75 ± 0.10, respectively. In case of the electrochemically quasi-reversible Cd II–sarcosine–OH labile system, only ML, ML 2 and ML 3 (M = Cd II, L = sar) were found and their stability constants, as log β, were determined to be 3.80 ± 0.03, 6.91 ± 0.07, and 8.9 ± 0.4, respectively. Stability constants for the ML complexes, the prime focus of this work, were thus established with an uncertainty smaller than 0.05 log units. The observed departure from electrochemical reversibility for the Cd–sarcosine–OH system was attributed mainly to the decrease in the transfer coefficient . The MM2 force field, supplemented by additional parameters, reproduced the reported crystal structures of diaqua-bis(glycinato-O,N)nickel(II) and fac-tri(glycinato)-nickelate(II) very well. These parameters were used to predict structures of all possible isomers of (i) [Ni(H 2O) 4(gly)] + and [Ni(H 2O) 4(sar)] +; and (ii) [Ni(H 2O) 3(IDA)] and [Ni(H 2O) 3(MIDA)] (IDA = iminodiacetic acid, MIDA = N-methyl iminodiacetic acid) by molecular mechanics/simulated annealing methods. The change in strain energy, Δ Ustr, that accompanies the substitution of one ligand by another (ML + L′ → ML′ + L), was computed and a strain energy Δ Ustr = +0.28 kcal mol −1 for the reaction [Ni(H 2O) 4(gly)] + + sar → [Ni(H 2O) 4(sar)] + + gly was found. This predicts the monoglycine complex to be marginally more stable. By contrast, for the reaction [Ni(H 2O) 3IDA] + MIDA → [Ni(H 2O) 3MIDA] + IDA, Δ Ustr = −0.64 kcal mol −1, and the monoMIDA complex is predicted to be more stable. This correlates well with (i) stability constants for Cd–gly and Cd–sar reported here; and (ii) known stability constants of ML complex for glycine, sarcosine, IDA, and MIDA. 相似文献
16.
The complexes, M[M(C 2O 4) 3]· xH 2 O, where x=4 for M=Cr(III), x=2 for M=Sb(III) and x=9 for M=La(III) have been synthesized and their thermal stability was investigated. The complexes were characterized by elemental analysis, IR and electronic spectral data, conductivity measurement and powder X-ray diffraction (XRD) studies. The chromium(III)tris(oxalato)chromate(III)tetrahydrate (COT), Cr[Cr(C 2 O 4) 3]·4H 2O, released water in a stepwise fashion. Removal of the last trace of water was accompanied by a partial decomposition of the oxalate group. Thermal investigation using TG, DTG and DTA techniques in air produced Cr 2O 3 at 858°C through the intermediate formation of Cr 2O 3 and CrC 2O 4 at around 460°C. While DSC study in nitrogen up to 670°C produced a mixture of Cr 2O 3 and CrC 2O 4. In antimony(III)tris(oxalato)antimonate(III)dihydrate (AOD), Sb[Sb(C 2O 4) 3]·3H 2O the dehydration took place during the decomposition of precursor at 170–290°C and finally at ca. 610°C Sb 2 O 5 along with trace amounts of Sb 2O 4 were produced. Trace amount of Sb 2O 3 and Sb along with Sb 2O is proposed as the end product at 670°C of AOD in nitrogen. The oxide La 2O 3 is formed at 838°C from the study with TG, DTG and DTA in air of lanthanum(III)tris(oxalato)lanthanum(III)nonahydrate (LON), La[La(C 2O 4) 3]·9H 2O. Intermediate dioxycarbonate, La 2O 2CO 3 was generated at 526°C prior to its decomposition to lanthanum oxide in air; whereas in N 2 the formation of La 2(CO 3) 3 at 651°C was proposed. The thermal parameters have been evaluated for each step of the dehydration and decomposition of COT, AOD and LON using five non-mechanistic equations i.e. Flynn and Wall, Freeman and Carroll, Modified Freeman and Carroll, Coats–Redfern and MacCallum–Tanner equations. Kinetic parameters, such as, E*, ko, Δ H*, Δ S* etc. were also supplemented by DSC studies in nitrogen for all the three complexes. Some of the intermediate species have been identified by analytical and powder XRD studies. Tentative schemes has been proposed for the decomposition of all three compounds in air and nitrogen. 相似文献
17.
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
18.
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
19.
以磷钼酸、 2-氨基吡啶、 五氧化二钒、 氯化锌和氯化镍等为主要原料, 采用水热方法合成了2个簇基超分子化合物[H 3PMo 12O 40] 2[C 5H 6N 2] 6(1)和[H 2PMo 12V 2O 42][C 5H 6N 2] 5·3H 2O(2)(C 5H 6N 2=2-氨基吡啶). 通过元素分析、 红外光谱、 紫外-可见光谱、 X射线光电子能谱、 热重分析、 X射线单晶衍射及X射线粉末衍射等手段对化合物进行了结构表征. 结构分析显示, 簇单元不同的2个超分子化合物以各自独特的堆积方式形成三维超分子网络. 利用苯乙烯的环氧化反应研究了2个化合物的催化性能. 相似文献
20.
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
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