Two novel mononuclear mixed-ligand complexes [Ni(en)2(3-pyt)2] (1) and [Cu(en)2](3-pyt)2 (2), derived from potassium [N′-(pyridine-3-carbonyl)-hydrazinecarbodithioate [K+(H2L)−] and containing en as a co-ligand, have been synthesized. The [K+(H2L)−] undergoes cyclization in the presence of ethylenediamine (en) and is converted to 5-(3-pyridyl)-1,3,4-oxadiazole-2-thione (3-pyt)−. [Ni(en)2(3-pyt)2] and [Cu(en)2](3-pyt)2 have been characterized with the aid of elemental analyses, IR, UV–Vis, magnetic susceptibility and single crystal X-ray studies. The complexes 1 and 2 crystallize in the orthorhombic and monoclinic systems with space groups Pca2(1) and C2/c, respectively. The single crystal X-ray diffraction studies of both complexes indicate that (3-pyt)− adopts a thione form in 1 but is present as a thiolato form in 2. 相似文献
The rate of the reaction has been investigated at 40–65°C with [HClO4] varying from 0.04 to 0.6 M (μ = 0.6 M, NaClO4). The observed rate law has the form: -d[Cr(NH3)5(NCO)2+]/dt = kobs[Cr(NH3)5(NCO)2+] where kobs = a[H+]2{1 + b[H+]2} and ?1 at 55.0°C, a = 0.36 M?1 s?2 and b = 6.9 × 10?3 M?1 s?1. The rate of loss of Cr(NH3)5(NCO)2+ increases with increasing acidity to a limiting value (at [H+] ～ 0.5 M) but the yield of Cr(NH3)63+ decreases with increasing [H+] and increases with increasing temperature. In the kinetic studies the maximum yield of Cr(NH3)63+ was 35% but a synthetic procedure has been developed to give a 60% yield. 相似文献
Lewis-base mediated fragmentation of polymeric nickel(II) fumarate and oxalate are attempted using chelating σ-donor diamines like ethylenediamine (en) and 1,3-diaminopropane (dap) in various conditions which yielded [Ni(en)3](fum)·3H2O (1), [Ni(en)3](ox) (2), [Ni(dap)2(fum)] (3) and [Ni(dap)(ox)]·2H2O (4). While 1 and 2 are molecular products each containing octahedral [Ni(en)3]2+ moieties and the anionic dicarboxylate species, 3 and 4 are dap-incorporated polymeric products. The fumarate derivative 1 containing [Ni(en)3]2+ moieties crystallizes in the monoclinic space group C2/c with a = 17.899(4) Å, b = 11.747(2) Å, c = 10.748(2) Å, β = 125.59(3)°, V = 1837.7(6) Å3, Z = 4, while the oxalate analogue 2 is seen to be in the trigonal space group P−31c with a = 8.8770(13) Å, b = 8.8770(13) Å, c = 10.482(2) Å, γ = 120°, V = 715.3(2) Å3, Z = 2. The octahedral [Ni(en)3] units in both 1 and 2 are seen to be strongly H-bonded to the dicarboxylate moieties through the coordinated en units leading to a three-dimensional network. However, in 1 the water molecules also take part in the H-bonding and contribute to the overall 3D structure. In both 1 and 2 the crystal packing is done with the [Ni(en)3]2+ units with absolute configuration Λ(δδδ) and its mirror conformer with Δ configuration in exactly equal numbers. Spectral (IR and UV–Visible) and magnetic measurements were carried out and some of the ligand-field parameters like Dq, B and β were evaluated for all the four compounds. These values suggest the presence of octahedrally coordinated nickel(II) in all the four complexes. Spectral data suggest that 3 has the two chelating dap moieties and the fumarate coordinated in η1 form through both its carboxylate moieties while 4 has one chelating dap and the oxalate moiety coordinated in η4-bis-chelating form. Though both 1 and 2 are made of the same type of [Ni(en)3]2+ units their thermograms give entirely different thermal features; 1 showing three clearly successive and step-wise dissociation of each en unit while 2 having a combined loss of two en units in the first thermal step. The relevant thermodynamic and kinetic parameters like Ea and ΔS also could be evaluated for various thermal steps for the compounds 1–4 using Coats–Redfern equation. 相似文献
Three new thiogermanates (enH)4Ge2S6 (1) and [M(en)3]2Ge2S6 (M=Mn (2), Ni (3); en=ethylenediamine) were synthesized using GeO2 and S8 as starting materials in molar ratio of 1:0.5 under solvothermal conditions. These compounds suggest that the dimeric [Ge2S6]4− anion is likely to be the main germanium-containing species in en system and it also might be preferred as counter anions by the transition metal complex cations in crystallization. The cations of [Mn(en)3]2+ and [Ni(en)3]2+ are even better mineralizers than the protonated amine of [enH]+. The crystal systems of [Ge2S6]4− compounds are related to entities of cations and intermolecular reactions between cations and [Ge2S6]4− anions. The compounds remove ethylenediamine and H2S molecules in multi steps when being heated under nitrogen stream. 相似文献
A [Cr(H2O)6]Cl3 aqueous solution, 0.25 M at T=20°C, is investigated by X-ray diffraction. The calculated radial distribution function shows, in spite of the low Cr3+ concentration, a well resolved peak centred around 1.90 A, a distance coincident with the Cr3+-H2O distance found in crystalline [Cr(H2O)6]Cl3. It can reasonably be stated that the [Cr(H2O)6]3+ ions pass relatively undisturbed into solutions where they constitute quite stable units. 相似文献
The enthalpy of the reaction: Pt(PPh3)2 (CH2CH2)(cryst.) + C(CN)2C(CN)2 (g) → Pt(PPh3)2 {C(CN)2C(CN)2}(cryst.) + CH2 CH2 (g) has been determined as ΔH298=?155.8±8.0 kJ·mol?1, from solution calorimetry. The interpretation, that the platinumethylene bond is much weaker than the platinumtetracyanoethylene bond, is contrary to conclusions drawn recently from electron emission spectroscopic studies, but in agreement with available structural data. 相似文献
The X-ray crystal structures of a series of new compounds (H3O)2[{Mn(H2O)1.5}3{Re6Se8(CN)6}2]·19H2O (1), (Me4N)2[{Co(H2O)1.5}3{Re6S8(CN)6}2]·13H2O (2), (Me4N)2[{Co(H2O)1.5}3{Re6Se8(CN)6}2]·3H2O (3), (Et4N)2[{Mn(H2O)2}3{Re6Se8(CN)6}2]·6.5H2O (4), (Et4N)2[{Ni(H2O)2}3{Re6S8(CN)6}2]·6.5H2O (5), and (Et4N)2[{Co(H2O)2}3{Re6S8(CN)6}2]·10H2O (6) are reported. All six compounds are isostructural crystallizing in cubic space group with four formulae per unit cell. For compounds 1, 3-5 the following parameters were found: (1) a=19.857(2) Å, R1=0.0283; (3 at 150 K) a=19.634(1) Å, R1=0.0572; (4) a=20.060(2) Å, R1=0.0288; (5) a=19.697(2) Å, R1=0.0224. The structures consist three-dimensional cyano-bridged framework formed by cyano cluster anions [Re6Q8(CN)6]4−, Q=S, Se and transition metal cations, M2+=Mn2+, Co2+, Ni2+. Water molecules and large organic cations Me4N+ and Et4N+ are included in cavities of this framework. Porosity of the framework, its ability to accommodate different cations and water molecules by little changes in the structure, as well as distortion of coordination framework under loss of water of crystallization is discussed. 相似文献
The FT IR and FT Raman spectra of Co(en)3Al3P4O16 · 3H2O (compound I) and [NH4]3[Co(NH3)6]3[Al2(PO4)4]2 · 2H2O (compound II) are recorded and analysed based on the vibrations of Co(en)33+, Co(NH3)63+, NH4+, Al---O---P, PO3, PO2 and H2O. The observed splitting of bands indicate that the site symmetry and correlation field effects are appreciable in both the compounds. In compound I, the overtone of CH2 deformation Fermi resonates with its symmetric stretching vibration. The NH4 ion in compound II is not free to rotate in the crystalline lattice. Hydrogen bonding of different groups is also discussed. 相似文献
The electronic structure and half-metallicity of molecule-based ferromagnet Cr[N(CN)2]2 have been investigated using first-principles with generalized gradient approximation. The total energy, spin-polarized electronic band structure, density of states (DOSs) and spin mag-netic moments were all calculated. The calculations reveal that the compound Cr[N(CN)2]2 is a really half-metallic ferromagnet with a integral magnetic moment of 2.0000 μB per molecule in the optimized lattice constant. Based on the spin distribution and the DOS, it is found that the total magnetic moment is mainly from the Cr2+ with relative small contribution from C and N atoms. The sensitivity of the half-metallicity to small change in lattice constant is also discussed. 相似文献
The clectrochemical behaviour of the complexes [RuII(L)(CO)2Cl2], [RuII(L)(CO)Cl3][Me4N] and [RuII(L)(CO)2(CH3CN)2][CF3SO3]2 (L = 2,2′-bipyridine or 4,4′-isopropoxycarbonyl-2,2′-bipyridine) has been investigated in CH3CN. The oxidation of [Ru(L)(CO)2Cl2] produces new complexes [RuIII(L)(CO)(CH3CN)2Cl]2+ as a consequence of the instability of the electrogenerated transient RuIII species [RuIII(L)(CO)2Cl2]+. In contrast, the oxidation of [RuII(L)(CO)Cl3][Me4N] produces the stable [RuIII(L)(CO)Cl3] complex. In contrast [RuII(L)(CO)2(CH3CN)2][CF3SO3]2 is not oxidized in the range up to the most positive potentials achievable. The reduction of [RuII(L)(CO)2Cl2] and [RuII(L)(CO)2(CH3CN)2][CF3SO3]2 results in the formation of identical dark blue strongly adherent electroactive films. These films exhibit the characteristics of a metal-metal bond dimer structure. No films are obtained on reduction of [RuII(L)(CO)Cl3][Me4N]. The effect of the substitution of the bipyridine ligand by electron-withdrawing carboxy ester groups on the electrochemical behaviour of all these complexes has also been investigated. 相似文献
The selective in situ synthesis of trans and cis(CH3CN)-[Ru(bpy)(CO)2 (CH3CN)2]2+ isomers from the same [Ru(CO)2 (CH3CN)3]22+ dimer precursor but using either an electrochemical-chemical or chemical-electrochemical process is described. 相似文献
Potential-modulated DNA cleavage in the presence of copper–ethylenediamine (en) and –ethylenediamine tetraacetic acid (EDTA) complexes was investigated at a gold electrode in a thin layer cell. DNA can be efficiently cleaved through production of active oxygen species at −0.50 V (vs. Ag/AgCl/KCl(sat)) by reducing Cu(en)22+ to Cu(en)2+ or Cu(EDTA)2− to Cu(EDTA)3−. The extent of DNA cleavage increased as the working potential was shifted more negative and the electrolysis time was increased in air-saturated solution. When a small flow of O2 was passed through the solution during electrolysis, the extent of DNA cleavage was dramatically enhanced. In the absence of Cu(en)22+ or Cu(EDTA)2− complex, slight DNA cleavage was observed at a more negative working potential due to the reduction of oxygen at the electrode. This observation suggests that potential-modulated DNA cleavage was caused mainly by electrochemical reduction of the Cu(en)22+ or Cu(EDTA)2− complex in the presence of oxygen. The cleaved DNA fragments were separated by high performance liquid chromatography (HPLC). The experimental results proved that this method of potential-modulated DNA cleavage by Cu(en)22+ and Cu(EDTA)2− complexes is simple, mild and highly efficient. 相似文献
Electrochemical dc and ac measurements were made in the system Pt/x M [Fe(CN)6]3−, [Fe(CN)6]4− +0.5 M Na2SO4 in the range 2×10−6x 2×10−2 at T = 298 K and pH 6 using the rotating disk technique. Depending on the defined prepolarization conditions, a partial blocking of the electrode surface was observed indicated by distinct changes of the impedance spectra. Transfer function analysis based on a model of a transport controlled reaction on a partially blocked surface gave quantitative information on the degree of surface coverage. Systematic variation of the experimental conditions allowed conclusions to be drawn about the chemical nature of the blocking species. 相似文献
A simple electrochemical procedure to tailor thin polymeric films containing the [FeII(bpy)2(CH3CN)2]2+ and/or [FeII(bpy)3]2+-like cores have been described (bpy=2,2′-bipyridine). The procedure is based on the electroreductive precipitation of soluble polymers prepared in situ in CH3CN by mixing Fe3+ ions and a bis bipyridyl ligand, (chiragen: chir). In the resulting [FeII(chir)(CH3CN)2]n2+ films, the two labile S ligands can be easily replaced by a bidentate ligand. This method has been applied with success to design a modified electrode with a supramolecular structure. 相似文献
Coordination of various neutral N and O ligands causes drastic changes in 1J(31P-199Hg) (increase up to the threefold) and δ(31P) (shifts up to 30 ppm to low frequencies), which are due to the presence of the M(CO)5 groups. The complexes with DMSO, phen and bipy were isolated in the solid state. No coordination of [Hg{PCy2[Cr(CO)5]}2] with the above ligands is observed. 相似文献
By replacing Mn in YCa3(MnO)3(BO3)4 with trivalent Al and Ga, two new borates with the compositions of YCa3(MO)3(BO3)4 (M=Al, Ga) were prepared by solid-state reaction. Structure refinements from X-ray powder diffraction data revealed that both of them are isostructural to gaudefroyite with a hexagonal space group P63/m. Cell parameters of a=10.38775(13)Å, c=5.69198(10)Å for the Al-containing compound and a=10.5167(3)Å, c=5.8146(2)Å for the Ga analog were obtained from the refinements. The structure is constituted of AlO6 or GaO6 octahedral chains interconnected by BO3 groups in the ab plane to form a Kagomé-type lattice, leaving trigonal and apatite-like tunnels. It is found that most rare-earth and Cr, Mn ions can be substituted into the Y3+ and M3+ sites, respectively, and the preference of rare-earth ions to locate in the trigonal tunnel is correlated to the sizes of the M3+ ions. 相似文献
Tricarbonyl(fulvene)chromium complexes react with anionic nucleophiles to give functionally substituted cyclopentadienyl derivatives. The nucleophilic attack occurs at the exocyclic carbon atom of the fulvene ligand. Addition of PPh2− to (η6-6,6-dimethylfulvene)Cr(CO)3 (1) yields the novel anion [(η5-C5H4C(CH3)2PPh2)Cr-(CO)3]−, which can be isolated as a K+, (C2H5)4N+, (C6H5)4P+, or Tl+ derivative (2–5). The potassium salt of the uncoordinated C5H4C(CH3)2PPh2− anion (7) is obtained by treatment of 6,6-dimethylfulvene with KPPh2·2C4H8O2. Similarly, NaC5H5 reacts with 1 to give Na[(η5-C5H4C(CH3)2C5H5)Cr(CO)3] (8). The reactions of (6-dimethylaminofulvene)Cr(CO)3 (15) with nucleophiles are accompanied by elimination of dimethylamine. Addition of Ph3P=CH2 to 15 gives an unstable product, but after reaction of 6-dimethylaminofulvene with Ph3P=CH2, the free ligand C5H4=CHCH=PPh3 (17) can be isolated in moderate yields. Deeply colored anions of the type [(η5:η5-C5H4C(R)=C5H4)Cr2(CO)6]− (R = H, N(CH3)2) are synthesized by reaction of 15 or (6-dimethylamino-6-methylthiofulvene)Cr(CO)3 with NaC5H5 and subsequent complexation of the mononuclear intermediate with (CH3CN)3Cr(CO)3. In addition, the synthesis of the new fulvene complexes [C5H4=CH(CH=CH)2N(CH3)Ph]M(CO)3 (23, 24; M = Cr, Mo) is described. The investigation is extended to α-ferrocenylcarbenium ions, which are isoelectronic with (fulvene)Cr(CO)3 complexes. [(η5-C5H5)Fe(C5H4CPh2)]+ BF4− (25) adds tertiary phosphines at the exocyclic carbon atom to give phosphonium salts of the type [(η5-C5H5)Fe(C5H4CPh2PR3)]+BF4−. A CO-substititution product of a tricarbonyl (fulvene)chromium complex is obtained for the first time by irradiation of (η6-6,6-diphenylfulvene)Cr(CO)3 in the presence of PPh3. In addition, an improved synthesis of the (CH3CN)3M(CO)3 complexes (M = Cr, Mo, W) is reported. 相似文献
A novel polyoxometalate [Cu(phen)2]3{PW4VIW5VV3IVO40(VIVO)3[Cu(en)2]}4H2O 1 (en=ethylenediamine, phen=1,10-phenanthroline) has been synthesized hydrothermally and characterized by elemental analysis, IR, XPS, TG, EPR and single-crystal X-ray diffraction analysis. The crystal structure analysis shows that compound 1 contains a novel highly reduced tri-capped and mono-supported pseudo-Keggin-type heteropolyanion, {PW4VIW5VV3IVO40(VIVO)3[Cu(en)2]}6−, three [Cu(phen)2]2+ cations and four lattice water molecules. They are further linked to form three-dimensional supramolecular networks through extensive hydrogen bonding and π–π stacking interactions. Interestingly, the water dimer and terminal oxygen of the cluster polyanion constitute a beautiful supramolecular helix chain. The heteropolyanion is the first example of tri-capped and mono-supported pseudo-Keggin-type tungstovanadophosphate and the pH value is crucial for obtaining compound 1 in synthetic procedure. 相似文献
Raman and FTIR spectra of guanidinium zinc sulphate [C(NH2)3]2Zn(SO4)2 are recorded and the spectral bands assignment is carried out in terms of the fundamental modes of vibration of the guanidinium cations and sulphate anions. The analysis of the spectrum reveals distorted SO42− tetrahedra with distinct S–O bonds. The distortion of the sulphate tetrahedra is attributed to Zn–O–S–O–Zn bridging in the structure as well as hydrogen bonding. The CN3 group is planar which is expressed in the twofold symmetry along the C–N (1) vector. Spectral studies also reveal the presence of hydrogen bonds in the sample. The vibrational frequencies of [C(NH2)3]2 and HC(NH2)3 are computed using Gaussian 03 with HF/6-31G* as basis set. 相似文献
