1INTRODUCTION Molybdenum(II)halide clusters containing[Mo6-X8]4 cores have been the subject of interest for over five decades[1].This octahedral cluster-type comple-xes comprise an important,and in a sense archetypal,class of higher nuclearity transition metal cluster com-plexes.Their high symmetry,photochemical and pho-tophysical properties as well as structural relation-ships to cluster complexes of other elements exhibit significant interest[2].In addition,there is a structural simila… 相似文献
The title compounds form an iso structural series and are isomorphic with other [MPy4X2]-2Py clathrates (XRD, KM4 diffractometer, cell parameters and space group Ccca from 17–80 reflections). In the clathrate
[NiPy4(NCO)2]-2Py studied in detail (XRD, CAD-4 diffractom eter, λCuKα, Ω/2θ scan mode, θmax = 78‡, 990 strong reflections, 104 parameters, R = 0.053), the host molecule has 222 symmetry, and the twofold axes run along
the coordination bonds. The transoctahedral environment of nickel consists of six nitrogen atoms of four pyridine and two
isocyanate ligands. The coordination polyhedron is slightly distorted due to changes in the bond lengths. The molecule has
a propeller conformation. The guest molecules lie in the cavities of the crystal structure in conformity with the van der
Waals type of packing. The host complex [NiPy4(NCO)2] (XRD, CAD-4 diffractometer, 4615 strong reflections, 560 parameters, R-0.037) crystallizes in the triclinic crystal system
(space group P1) with two independent asymmetric molecules in the unit cell. The molecular structure is analogous to that
in the ciathrate phase, but the coordination angles are severely distorted; one of the molecules acquires a distorted propeller
conformation, and the other, a centrosvmmetric conformation, which is less favorable. While being structurally identical,
the [MPy4(NCO)2]-2Py clathrates differ heavily in the properties. The first four complexes dissociate to host complexes, and their thermal
stability changes in the sequence Mn< Fe< Co< Ni; the Cu and Zn clathrates decompose in one step to dipyridine complexes with
decomposition of host complexes. Decomposition of the Cd ciathrate follows one of these patterns depending on conditions.
The results are compared with those for other known systems. Synthetic procedures are given.
Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 5, pp. 935–953, September–October, 1999. 相似文献
The results of DSC measurements in the temperature range 140–370 K on nine crystalline compounds of the type [M(H2O)6](ClO4)2, where M=Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd and Hg, are discussed. Anomalies detected in the DSC curves are related to the existence
of solid-solid phase transitions and/or to the melting points of these compounds. In consequence of two different hypothetical
structural modifications of [Fe(H2O)6](ClO4)2, two DSC curves are obtained. For the compounds with M=Fe, Cd and Hg, new phase transitions have been discovered. The transition
temperatures of the other phase transitions are in good agreement with literature data obtained by adiabatic calorimetry.
For the compounds with M=Mg, Ni and Cd, DTA measurements were also carried out and the melting points of theses compounds
were established.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Complexation of divalent cations (Mg2+, Co2+, Ni2+, Cu2+, Cd2+) by selenate ligand was studied by ACE (UV indirect detection) in 0.1 mol/L NaNO3 ionic strength solutions at various temperatures (15, 25, 35, 45 and 55°C). For each solution, a unique peak was observed as a result of a fast equilibrium between the free ion and the complex (labile systems). The migration time corresponding to this peak changed as a function of the solution composition, namely the free and complexed metal concentrations, according to the complexation reactions. The results confirmed the formation of a unique 1:1 complex for each cation. The thermodynamic parameters were fitted to the experimental data at 0.1 mol/L ionic strength: (25°C) = ?(6.5 ± 0.3), ?(7.5 ± 0.3), ?(7.7 ± 0.3), ?(7.7 ± 0.3), and –(8.1 ± 0.3) kJ/mol and = 2.5 ± 0.2, 4.7 ± 0.4, 4.5 ± 0.6, 8.4 ± 1.1, and 7.2 ± 0.6 kJ/mol for M2+ = Mg2+, Co2+, Ni2+, Cu2+, and Cd2+, respectively. Complexes with alkaline earth and transition metal cations could be distinguished by their relative stabilities. The effect of the ionic medium was treated using the specific ion interaction theory and the thermodynamic parameters at infinite dilution were compared to previously published data on metal–selenate, metal–sulfate, and metal–chromate complexes. 相似文献
The porosity and hydrogen storage properties for the dehydrated Prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn) are reported. Argon sorption isotherms measured at 87 K afford BET surface areas ranging from 560 m2/g for Ni3[Co(CN)6]2 to 870 m2/g for Mn3[Co(CN)6]2; the latter value is comparable to the highest surface area reported for any known zeolite. All six compounds show significant hydrogen sorption at 77 K and 890 Torr, varying from 1.4 wt % and 0.018 kg H2/L for Zn3[Co(CN)6]2 to 1.8 wt % and 0.025 kg H2/L for Cu3[Co(CN)6]2. Fits to the sorption data employing the Langmuir-Freundlich equation give maximum uptake quantities, resulting in a predicted storage capacity of 2.1 wt % and 0.029 kg H2/L for Cu3[Co(CN)6]2 at saturation. Enthalpies of adsorption for the frameworks were calculated from hydrogen isotherms measured at 77 and 87 K and found to increase with M varying in the order Mn < Zn < Fe < Co < Cu < Ni. In all cases, the binding enthalpies, which lie in the range of 5.3-7.4 kJ/mol, are higher than the 4.7-5.2 kJ/mol measured for Zn4O(1,4-benzenedicarboxylate)3. 相似文献
Complexation processes that occur between cadmium(II) hexacyanoferrate(II) (Cd2[Fe(CN)6]) and 3d-metal ions M(II) (M = Mn, Co, Ni, Cu, Zn) in thin gelatin layers with the immobilized cadmium(II) hexacyanoferrates when brought in contact with aqueous solutions of d-metal chlorides are studied. Cd2+ ions were found to be replaced to some extent by M2+ ions of the indicated d metals (except for Mn(II)) and form binuclear (dd)-metal hexacyanoferrates(II). A complete replacement of Cd(II) and formation of M2[Fe(CN)6] was observed in none of the cases. 相似文献
Complexing processes in MII-N-diisopropoxythiophosphorylthiobenzamide binary systems (M = Co, Ni, Cu) in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices upon contact with aqueous–alkaline (pH = 12.0 ± 0.1) solutions of organic compounds have been studied. It has been shown that, in CoII and CuII, the initial act of complexing involves destruction of the CoII and CuII hexacyanoferrates(II) by OH– ions, leading to formation of the corresponding hydroxides which react with the ligand indicated. In the both systems, successive addition of two ligand molecules per M(OH)2 fragment occurs and [MB(OH)(OH2)] and [MB2] coordination compounds are formed (B–-a singly deprotonated ligand form). In the NiII-N-diisopropoxythiophosphorylthiobenzamide system, the formation of three complexes, (Ni2BOH)2[Fe(CN)6], [NiB(OH)(OH2)] and [NiB2] occurs. 相似文献
Resonance Raman spectra of the cubic metal-halide complexes having the general formula [M(6)X(8)Y(6)](2)(-) (M = Mo or W; X, Y = Cl, Br, or I) are reported. The three totally symmetric fundamental vibrations of these complexes are identified. The extensive mixing of the symmetry coordinates that compose the symmetric normal modes expected in these systems is not observed. Instead the "group-frequency" approximation is valid. Furthermore, the force constants of both the apical and face-bridging metal-halide bonds are insensitive to the identity of either the metal or the halide. Raman spectra of related complexes with methoxy and benzenethiol groups as ligands are reported along with the structural data for [Mo(6)Cl(8)(SPh)(6)][NBu(4)](2). Crystal data for [Mo(6)Cl(8)(SPh)(6)][NBu(4)](2) at -156 degrees C: monoclinic space group P2(1)/c; a = 12.588(3), b = 17.471(5), c = 20.646(2) ?; beta = 118.53(1) degrees, V = 3223.4 ?(3); d(calcd) = 1.664 g cm(-)(3); Z = 2. 相似文献
Dithiocyanates of bis(hydrazidediphenylphosphinylacetic acid) M(II), where M is Mn, Fe, Co, Ni, Cu, and Zn were synthesized. Their magnetic properties were studied. All compounds were paramagnetic monomers with pseudooctahedral stereochemistry, except for the Zn(II) complex. 相似文献
The novel dimeric germanotungstates [M(4)(H(2)O)(2)(GeW(9)O(34))(2)](12)(-) (M = Mn(2+), Cu(2+), Zn(2+), Cd(2+)) have been synthesized and characterized by IR spectroscopy, elemental analysis, magnetic measurements, and (183)W-NMR spectroscopy. X-ray single-crystal analyses were carried out on Na(12)[Mn(4)(H(2)O)(2)(GeW(9)O(34))(2)].38H(2)O (Na(12)()-1), which crystallizes in the monoclinic system, space group P2(1)/n, with a = 13.0419(8) A, b = 17.8422(10) A, c = 21.1626(12) A, beta = 93.3120(10) degrees, and Z = 2; Na(11)Cs(2)[Cu(4)(H(2)O)(2)(GeW(9)O(34))(2)]Cl.31H(2)O (Na(11)()Cs-2) crystallizes in the triclinic system, space group P, with a = 12.2338(17) A, b = 12.3833(17) A, c = 15.449(2) A, alpha = 100.041(2) degrees, beta = 97.034(2) degrees, gamma = 101.153(2) degrees, and Z = 1; Na(12)[Zn(4)(H(2)O)(2)(GeW(9)O(34))(2)].32H(2)O (Na(12)()-3) crystallizes in the triclinic system, space group P, with a = 11.589(3) A, b = 12.811(3) A, c = 17.221(4) A, alpha = 97.828(6) degrees, beta = 106.169(6) degrees, gamma = 112.113(5) degrees, and Z = 1; Na(12)[Cd(4)(H(2)O)(2)(GeW(9)O(34))(2)].32.2H(2)O (Na(12)()-4) crystallizes also in the triclinic system, space group P, with a = 11.6923(17) A, b = 12.8464(18) A, c = 17.616(2) A, alpha = 98.149(3) degrees, beta = 105.677(3) degrees, gamma = 112.233(2) degrees, and Z = 1. The polyanions consist of two lacunary B-alpha-[GeW(9)O(34)](10)(-) Keggin moieties linked via a rhomblike M(4)O(16) (M = Mn, Cu, Zn, Cd) group leading to a sandwich-type structure. (183)W-NMR studies of the diamagnetic Zn and Cd derivatives indicate that the solid-state polyoxoanion structures are preserved in solution. EPR measurements on Na(12)()-1 at frequencies up to 188 GHz and temperatures down to 4 K yield a single, exchange-narrowed peak, at g(iso) = 1.9949, typical of Mn systems, and an upper limit of |D| = 20.0 mT; its magnetization studies still await further theoretical treatment. Detailed EPR studies on Na(11)()Cs-2 over temperatures down to 2 K and variable frequencies yield g( parallel ) = 2.4303 and g( perpendicular ) = 2.0567 and A( parallel ) = 4.4 mT (delocalized over the Cu(4) framework), with |D| = 12.1 mT. Magnetization studies in addition yield the exchange parameters J(1) = -11 and J(2) = -82 cm(-)(1), in agreement with the EPR studies. 相似文献
Hitherto unknown anhydrous GUINER patterns show that all these hexagonal compounds – except CdTiF6 (LiSbF6-structure type) – are isostructural with VF3. 相似文献
Abstract Stoichiometry and thermodynamic parameters of the title clathrates dissociation have been studied with thermoanalytical and strain method techniques. The [MPy4(NO3)2]*2Py (M = Mn, Co, Ni) clathrates dissociate with collapsing clathrate porous phase and destruction of the host complex to give the respective tripyridine complexes and gaseous pyridine. The [CuPy4(NO3)2]*2Py dissociates with collapsing clathrate phase but giving the host [CuPy4(NO3)2] complex as individual phase, with the tripyridine complex forming in further course of decomposition. The comparison of the thermodynamic dissociation parameters for the [MPy4(NO3)2]*2Py series with M = Mn, Co, Ni, Cu, Zn and Cd shows that the differences in the stability of the compounds do not correlate with structural parameters of the clathrates but depend on the nature of the metal cation in the host complex. Thermodynamic stability of these clathrate phases follows the general sequence of stabilty for complexes of the 3d transition metals known as Irwing-Williams sequence: Mn<Fe<Co<Ni<Cu>Zn. These results disclose the main issue of instability of the [MPy4(NO3)2]*2Py clathrates as instability of the respective host complexes. 相似文献
Standard enthalpies of formation of uranovanadates of 3(4)d transition metals at 298.15 K were determined. The isobaric heat capacity of Co(VUO6)2 · 4H2O was measured. The standard Gibbs functions of formation of the compounds were calculated on the basis of these data using approximate methods of absolute entropy calculation. The thermochemical characteristics of the synthesis and dehydration of uranovanadates were considered. 相似文献
Dissolution of a tetrafluoroborate or perchlorate salt of [M(OH(2))(6)](2+) (M = Co, Ni, Cu) in 1-ethyl-3-methylimidazolium tetraluforoborate ionic liquid ([emim]BF(4)) results in significant solvatochromism and increasing intensity of color. These observations arise from partial dehydration from the octahedral [M(OH(2))(6)](2+) and formation of the tetrahedral [M(OH(2))(4)](2+). This reaction was monitored by the intense absorption band due to the d-d transition in the UV-vis absorption spectrum. The EXAFS investigation clarified the coordination structures around M(2+) {[Co(OH(2))(4)](2+), R(Co-O) = 2.17 ?, N = 4.2; [Cu(OH(2))(4)](2+), R(Cu-O) = 2.09 ?, N = 3.8}. (1)H and (19)F NMR study suggested that both [emim](+) and BF(4)(-) are randomly arranged in the second-coordination sphere of [M(OH(2))(4)](2+). 相似文献
Under solvothermal conditions,two ribbon-shaped chalcogenidometalate coordination compounds(butyl-Sn)_4S_8M_2(TEPA)_2(M=Mn(1),Ni(2),TEPA=tetraethylenepentamine),have been synthesized and characterized by elemental analysis,energy dispersive X-ray,infrared/ultraviolet-visible spectroscopy,thermogravimetric analysis,single-crystal and powder X-ray diffraction.Complexes 1 and 2 crystallize in the triclinic space group P1 with a=13.999(3),b=14.658(4),c=16.150(4) A,a=68.78(3)°,β=69.12(3)°,γ=72.07(3)°,V=2825.0(14) A~3,Z=2,M_r=1448.28,μ=2.503 mm~(-1),F(000)=1444,GOOF=1.001,R=0.0629 and wR=0.1286 for 12855 observed reflections with I 2σ(I) for 1;and a=11.029(3),b=11.858(2),c=11.888(3) A,a=87.27(2)°,β=69.10(2)°,γ=83.63(2)°,V=1443.6(6) A~3,Z=1,M_r=1455.78,μ=2.660 mm~(-1),F(000)=728,GOOF=1.017,R=0.0464 and wR=0.1185 for 9267 observed reflections with I 2σ(I) for 2,respectively.Both 1 and 2 are composed of linear hexamer {Sn_4M_2}(M=Mn for 1,and Ni for 2) with 8 μ_2-S~(2-) bridges and 2 TEPA terminal ligands.Despite the quite large inter-paramagnetic-cation spacing(dMn-S-Sn-S-Sn-S-Sn-S-Sn-S-Mn=13.485 A,dNi-S-Sn-S-Sn-S-Sn-S-Sn-S-Ni=14.078 A),two samples exhibit distinct ferromagnetic-like behaviors with the intradimer coupling constant(J) and Weiss(θ) values up to 6.8 cm~(-1) and 8.5 K for 1 and 17.2 cm~(-1) and 21.1 K for 2 calculated from the temperature dependence of the magnetic susceptibility. 相似文献
The reaction of Se4[Mo2O2Cl8] with Se4[MCl6] (M = Zr, Hf) or of Se, SeCl4, MoOCl4, and MCl4 (M = Zr, Hf) at 120 °C in sealed evacuated glass ampoules gives (Se4)2[Mo2O2Cl8][MCl6] (M = Zr, Hf) in the form of dark‐green, air sensitive crystals in quantitative yield. The crystal structure analyses of both isotypic compounds (monoclinic, P21/c, Z = 2, a = 1336(2), b = 716(1), c = 1518(4) pm, β = 106.0(2)° for M = Zr; a = 1334.1(8), b = 715.03(9), c = 1518.2(3) pm, β = 106.00(2)° for M = Hf) show the presence of square‐planar Se42+, of dinuclear [Mo2O2Cl8]2—, and of almost regular octahedral [MCl6]2— ions. X‐ray crystallographic investigations on (Se4)2[Mo2O2Cl8][ZrCl6] give no hint for solid state phase transitions between —160 and 200 °C. This is in contrast to the related compounds Se4[Mo2O2Cl8] and Se4[ZrCl6] which both undergo phase transitions accompanied by reorientation of the cations and anions. (Se4)2[Mo2O2Cl8][ZrCl6] is paramagnetic and obeys the Curie‐Weiss law with a Weiss constant of —4(7) K indicating only weak interaction between the paramagnetic centres. The magnetic moment of 1.7(1) μB is consistent with the presence of MoV (d1 configuration) and supports the ionic formula. 相似文献