共查询到20条相似文献,搜索用时 207 毫秒
1.
The crystal and molecular structures of the [Pr III(nta)(H 2O) 2]·H 2O (nta = nitrilotriacetic acids), K 3[Gd III(nta) 2(H 2O)]·6H 2O, and K 3[Yb III(nta) 2]·5H 2O complexes have been determined by single-crystal X-ray structure analyses. In [Pr III(nta)(H 2O) 2]·H 2O, the Pr IIINO 8 part forms a nine-coordinate pseudo-monocapped square antiprismatic structure in which one N and three O atoms are from one nta ligand in the same molecule, three O atoms from another nta ligand in the neighboring molecule and two O atoms from two coordinate water molecules. In K 3[Gd III(nta) 2(H 2O)]·6H 2O, the [Gd III(nta) 2(H 2O) 3- complex anion has a nine-coordinate pseudo-monocapped square antiprismatic structure in which each nta acts as a tetradentate ligand with one N atom of the amino group and three O atoms of the carboxylic groups. In K 3[Yb III(nta) 2]·5H 2O, each nta also acts as a tetradentate ligand with one N atom of amino group and three O atoms of the carboxylic groups, but the [Yb III(nta) 2
3- complex anion has an eight-coordinate structure with a distorted square antiprismatic prism. All the results including those for [Tm III(nta)(H 2O) 2]·2H 2O confirm the inferences on the coordinate structures and coordination numbers of rare earth metal complexes with the nta ligand. 相似文献
2.
The oxidation of [Co II(nta)(ox)(H 2O) 2] 3− and [Co II(nta)(ph)(H 2O) 2] 3− (nta = nitrilotriacetate, ox = oxalic acid and ph = phthalic acid) by periodate have been studied kinetically in aqueous
solution over 20–40 °C and a variety of pH ranges. The rate of oxidation of [Co II(nta)(ox)(H 2O) 2] 3− by periodate, obeys the following equation: d[Co III]/dt = [Co II(nta)(ox)(H 2O) 23−][H 5IO 6] { k
4
K
5 + ( k
5
K
6
K
2/[H +]} while the reaction of [Co II(nta)(ph)(H 2O) 2] 3− with periodate in aqueous acidic medium obeys the following rate law: d[Co III]/dt = k
6
K
8[Co II] T [I VII] T/{1 + [H +]/ K
7 + K
8[I VII]
T
}. Initial cobalt(III) products were formed and slowly converted to final products, fitting an inner-sphere mechanism. Thermodynamic
activation parameters have been calculated. A common mechanism for the oxidation of ternary nitrilotriacetatocobalt(II) complexes
by periodate is proposed and supported by an excellent isokinetic relationship between Δ H* and Δ S* values for these reactions. 相似文献
3.
The mechanism of oxidation of ternary complexes, [Co II(nta)(S)(H 2O) 2] 3? and [Co II(nta)(M)(H 2O)] 3? (nta = nitrilotriacetate acid, S = succinate dianion, and M = malonate dianion), by periodate in aqueous medium has been studied spectrophotometrically over the (20.0–40.0) ± 0.1°C range. The reaction is first order with respect to both [IO 4?] and the complex, and the rate decreases over the [H +] range (2.69–56.20) × 10 ?6 mol dm ?3 in both cases. The experimental rate law is consistent with a mechanism in which both the hydroxy complexes [Co II(nta)(S)(H 2O)(OH)] 4? and [Co II(nta)(M)(OH)] 4? are significantly more reactive than their conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of the [Co II(nta)(S)(H 2O) 2] 3?, k1 (3.60 × 10 ?3 s ?1), is greater than the value of k6 (1.54 × 10 ?3 s ?1) for the oxidation of [Co II(nta)(M)(H 2O)] 3? at 30.0 ± 0.1°C and I = 0.20 mol dm ?3. The thermodynamic activation parameters have been calculated. It is assumed that electron transfer takes place via an inner‐sphere mechanism. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 103–113, 2008 相似文献
4.
The interaction of BSA and Fe III complexes ([Fe III(gly)(H 2O) 4] 2+, [Fe III(ida)(H 2O) 3] +, and [Fe III(nta)(H 2O) 2], gly—glyane, ida—iminodiacetic acid, nta—triglycolamic acid) as well as the sonocatalytic damage to BSA was studied by UV-vis
and fluorescence spectra. In addition, the influences of ultrasonic irradiation time and Fe III complex concentration were also examined on the sonocatalytic damage to BSA. The results showed that the fluorescence quenching
of BSA solution caused by the Fe III complexes belonged to the static quenching process. The BSA and Fe III complexes interacted with each other mainly through weak interaction and coordinate actions. The binding association constants
( K) and binding site numbers ( n) were calculated. The results were as follows: K
1 = 0.5353 × 10 4 l mol −1 and n
1 = 0.9812 for [Fe III(gly)(H 2O) 4] 2+, K
2 = 1.4285 × 10 4 l mol −1 and n
2 = 1.0899 for [Fe III(ida)(H 2O) 3, and K
3 = 0.4411 × 10 4 l mol −1 and n
3 = 0.9471 for [Fe III(nta)(H 2O) 2]. Otherwise, under ultrasonic irradiation the BSA were obviously damaged by the Fe III complexes. The damage degree rose up with the increase of ultrasonic irradiation time and Fe III complex concentration. And that, [Fe III(nta)(H 2O) 2] exhibited in a way higher sonocatalytic activity than [Fe III(gly)(H 2O) 4] 2+ and [Fe III(ida)(H 2O) 3] +. 相似文献
5.
Reactions of singly-bonded dinuclear complexes [(η 5-CH 3O 2CC 5H 4) 2M 2(CO) 6] ( I, M?=?Mo; II, M?=?W) with the diarenylditelluride [4-CH 3C 6H 4Te] 2 in refluxing toluene for 4–6?h afforded dinuclear complexes 1 and 2 trans/ae-[(η 5-RC 5H 4) 2M 2(CO) 4(μ-ArTe) 2] (Ar?=?4-CH 3C 6H 4Te). Complexes 1 and 2 were also synthesized by reactions of triply-bonded dinuclear complexes [(η 5-CH 3O 2CC 5H 4) 2M 2(CO) 4] ( III, M?=?Mo; IV, M?=?W) with [4-CH 3C 6H 4Te] 2 in refluxing toluene for 1?h. Both complexes have been characterized by elemental analysis, 1H NMR, 13C NMR and IR spectroscopy and X-ray diffraction. Preliminary low-temperature NMR experiments on complexes 1 and 2 have revealed that in solution each complex goes through a rapid inversion of the butterfly four-membered ring M 2Te 2. 相似文献
6.
Details of the reaction sequence used for the fluorimetric detection of phosphates by disassembly of transition metal Schiff base complexes were investigated for [Fe III(salen)(H 2O)] +, [Zn II(salen)], [Mn II(salen)(H 2O) 2], and [Mn III(salen)(H 2O)] +. The reactivity of these compounds towards phosphorus oxoanions of differing charge, number of donor atoms and steric hindrance was detected by UV/Vis and fluorescence spectroscopy in both aprotic organic and aqueous media. Selectivity of [Fe III(salen)(H 2O)] + towards pyrophosphate over all other tested phosphorus-containing analytes was strongly supported. [Zn II(salen)] showed a faster reactivity but was much less selective. In contrast, [Mn III(salen)(H 2O)] + proved to be more stable than the iron complex but generally showed little reactivity towards phosphorus oxoanions. The influence of the charge of the central atom was investigated using the Mn II analogue [Mn II(salen)(H 2O) 2]. As expected, the reduced charge resulted in a reactivity comparable to the Zn II complex in organic solution but lead to hydrolysis of the complex in water. Finally, the reaction products of [Fe III(salen)(H 2O)] + with phosphates were characterized by IR spectroscopy and mass spectrometry, providing further insights into the reaction mechanism of the disassembly process. 相似文献
7.
Three complexes, Na 4[Dy III(dtpa)(H 2O)] 2?·?16H 2O, Na[Dy III(edta)(H 2O) 3]?·?3.25H 2O and Na 3[Dy III (nta) 2(H 2O)]?·?5.5H 2O, have been synthesized in aqueous solution and characterized by FT–IR, elemental analyses, TG–DTA and single-crystal X-ray diffraction. Na 4[Dy III(dtpa)(H 2O)] 2?·?16H 2O crystallizes in the monoclinic system with P2 1/ n space group, a?=?18.158(10)?Å, b?=?14.968(9)?Å, c?=?20.769(12)?Å, β?=?108.552(9)°, V?=?5351(5)?Å 3, Z?=?4, M?=?1517.87?g?mol ?1, D c?=?1.879?g?cm ?3, μ?=?2.914?mm ?1, F(000)?=?3032, and its structure is refined to R 1( F)?=?0.0500 for 9384 observed reflections [ I?>?2σ( I)]. Na[Dy III(edta)(H 2O) 3]?·?3.25H 2O crystallizes in the orthorhombic system with Fdd2 space group, a?=?19.338(7)?Å, b?=?35.378(13)?Å, c?=?12.137(5)?Å, β?=?90°, V?=?8303(5)?Å 3, Z?=?16, M?=?586.31?g?mol ?1, D c?=?1.876?g?cm ?3, μ?=?3.690?mm ?1, F(000)?=?4632, and its structure is refined to R 1( F)?=?0.0307 for 4027 observed reflections [ I?>?2σ( I)]. Na 3[Dy III(nta) 2(H 2O)]?·?5.5H 2O crystallizes in the orthorhombic system with Pccn space group, a?=?15.964(12)?Å, b?=?19.665(15)?Å, c?=?14.552(11)?Å, β?=?90°, V?=?4568(6)?Å 3, Z?=?8, M?=?724.81?g?mol ?1, D c?=?2.102?g?cm ?3, μ?=?3.422?mm ?1, F(000)?=?2848, and its structure is refined to R 1( F)?=?0.0449 for 4033 observed reflections [ I?>?2?σ( I)]. The coordination polyhedra are tricapped trigonal prism for Na 4[Dy III(dtpa)(H 2O)] 2?·?16H 2O and Na 3[Dy III(nta) 2(H 2O)]?·?5.5H 2O, but monocapped square antiprism for Na[Dy III(edta)(H 2O) 3]?·?3.25H 2O. The crystal structures of these three complexes are completely different from one another. The three-dimensional geometries of three polymers are 3-D layer-shaped structure for Na 4[Dy III(dtpa)(H 2O)] 2?·?16H 2O, 1-D zigzag type structure for Na[Dy III(edta)(H 2O) 3]?·?3.25H 2O and a 2-D parallelogram for Na 3[Dy III(nta) 2(H 2O)]?·?5.5H 2O. According to thermal analyses, the collapsing temperatures are 356°C for Na 4[Dy III(dtpa)(H 2O)] 2?·?16H 2O, 371°C for Na[Dy III(edta)(H 2O) 3]?·?3.25H 2O and 387°C for Na 3[Dy III(nta) 2(H 2O)]?·?5.5H 2O, which indicates that their crystal structures are very stable. 相似文献
8.
Three new Cd(II) complexes consisting of phenanthroline derivative and organic acid ligands, formulated as [Cd 3(3-PIP) 2(L 1) 6] ( I), [Cd(3-PIP)(L 2)] · H 2O ( II), and [Cd(3-PIP)(L 3)] ( III) (3-PIP = 2-(3-pyridyl)imidazo[4,5- f]-1,10-phenanthroline, HL 1 = 3,5-dinitrobenzoic acid, H 2L 2 = oxalic acid, H 2L 3 = benzene-1,3-dicarboxylic acid), have been synthesized via the hydrothermal reaction and characterized by single-crystal
X-ray diffraction, elemental analyses and FT-IR spectra. Complex I is a trinuclear structure. Complex II features a 1D zigzag chain. Complex III shows a twisted double chain of binuclear units sustained by double carboxylate bridges. Three complexes are further extended
into 3D supramolecular frameworks by hydrogen bonding and π-π-stacking interactions. The structural differences among I–III show that the organic carboxylates have important effects on the structures. Furthermore, the supramolecular interactions
are the critical factors in determining the final structures of the complexes. In addition, the thermal stabilities and luminescent
properties of complexes I and II are also investigated. 相似文献
9.
A new series of transition metal complexes K[M II(s-bqdi) 2][Fe III(s-bqdi) 2(CN) 2]?·?10H 2O (s-bqdi?=?semibenzoquinonediiminate, M II?=?Co ( 2), Ni ( 3), and Cu ( 4)) have been synthesized. These complexes have been characterized by elemental analyses, FT IR, Far IR, FAB mass, UV-Vis, TGA, CV measurements, and powder XRD. The powder XRD patterns of 2, 3, and 4 show that they are isostructural with hexagonal primitive lattice structures. The coordination polymers display 1-D chain networks. Magnetic properties of the Co IIFe III complex studied by a SQUID magnetometer reveal low-temperature antiferromagnetic interaction. 相似文献
10.
Four metal complexes of N, N′-bis(salicyl)-2,6-pyridine-dicarbohydrazide ligand (H 6L), [Co II(H 4L)(H 2O) 2]·2DMF ( 1), [Zn II(H 4L)(H 2O) 2]·2DMF ( 2), [Cd II(H 4L)(Py) 2]·DMF·Py ( 3), and [Co IICo 2III(H 4L) 4(H 2O) 4]·DMF·H 2O ( 4), were synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction analysis. Structural
studies revealed that complexes 1– 3 present discrete mononuclear structures and complex 4 displays a centrosymmetric mixed-valence trinuclear structure. All four complexes are further extended into interesting two-
or three-dimensional supramolecular frameworks. The luminescent properties of 2 and 3 were studied, which show emissions with maxima at 485 nm upon excitation at 396 nm for 2 and 476 nm upon excitation at 397 nm for 3, respectively. 相似文献
11.
New mixed ligand complexes of benzoyldithiocarbazate (H 2BDT) have been synthesized and characterized by elemental analyses, spectral studies (i.r., u.v.–vis., mass), thermal analysis and electrical conductivity measurements. The complexes have the general formulae: [M 2(BDT)(OX) 2] · xH 2O; [Co 2(BDT)(OX) 2(H 2O) 4]; [M(HBDT)(OX)-(H 2O)], [Ni(BDT)(py) 2]
n
and [Ni(BDT)(L)]
n
where M = Mn II, Ni II and Cu II; BDT = dithiocarbazate dianion; OX = 8-hydroxyquinolinate; x = 1 or 2; M = Zn II or Cd II; HBDT = dithiocarbazate anion and L = 2,2-bipyridyl or 1,10- o-phenanthroline. For the [M 2(BDT)(OX) 2] · xH 2O, [Co 2(BDT)(OX) 2(H 2O) 4], [Ni(BDT)(py) 2]
n
and [Ni(BDT)(L)]
n
complexes, benzoyldithiocarbazate acts as a dibasic-tetradentate ligand in the enol form via the enolic oxygen, the hydrazide nitrogens and the thiolate sulphur, while it acts as a monobasic-tridentate ligand in the keto form in the [M(HBDT)(OX)(H 2O)] complexes. The thermal behaviour of the complexes has been studied by t.g.–d.t.g. techniques. Kinetic parameters of the thermal decomposition process have been computed by Coats–Redfern and Horowitz–Metzger methods. It is obvious that the thermal decomposition in the complexes occurs directly at the metal–ligand bonds except for the Zn II and Cd II complexes in which decomposition seems to be at a point in the benzoyldithiocarbazate moiety. From the calculated kinetic data it can be concluded that the dehydration processes in all complexes have been described as phase-boundary controlled reactions. The activation energy values reveal that the thermal stabilities of the homobimetallic complexes lie in the order: Mn II < Ni II < Co II, while the monomeric Cd II complex has more enhanced thermal stability than the Zn II complex. 相似文献
12.
Summary This paper deals with the preparation and investigation of thermal and spectral properties of the complexes Cu(5-ClSal) 2·2H 2O ( I), Cu(5-BrSal) 2·2H 2O ( II), Cu(5-ClSal) 2(nia)(H 2O) ( III), Cu(5-BrSal) 2(nia)(H 2O) ( IV), and Cu(5-ISal) 2(nia)(H 2O) ( V) (where Sal=salicylate, and nia=nicotinamide). TG, DTG, DTA, EPR, IR and electronic spectra have been used to study thermal and spectral properties of the complexes. The chemical composition of the complexes, the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. Schemes of the decomposition of the complexes are suggested. Heating of the compounds first resulted in the release of water molecules. The thermal stability of these complexes can be ordered in the sequence: I < II < IV= V< III. The final product of the thermal decomposition was CuO in all cases. IR data suggested a bidentate coordination of carboxylates to Cu(II) in complexes I- II and bridging ones for complexes III- V. 相似文献
13.
Four biradical-Ln complexes with different transition metal ions, namely [LnM(hfac) 5(NITPh-PyPzbis)] (M II=Mn II and Ln III=Gd 1 , Dy 2 ; M II=Ni II and Ln III=Tb 3 , Dy 4 ), were prepared by the reaction of Ln(hfac) 3 ⋅ 2H 2O, Mn(hfac) 2 ⋅ 2H 2O or Ni(hfac) 2 ⋅ 2H 2O with NITPh-PyPzbis biradical (hfac=hexafluoroacetylacetonate, NITPh-PyPzbis=5-(3-(2-pyridinyl)-1 H-pyrazol-1-yl)-1,3-bis(1’-oxyl-3’-oxido- 4’,4’,5’,5’-tetramethyl-4,5-hydro-1 H-imidazol-2-yl)benzene). In complexes 1 – 4 , the NITPh-PyPzbis biradical chelates one Ln III ion by means of its aminoxyl moieties and the transition metal ion is introduced through the two N donors from the pyridyl pyrazolyl moiety. Magnetic investigations indicate that complex 4 displays visible maxima in frequency/temperature-dependent χ′′ signals with two-step relaxation processes, but complex 2 exhibits no slow magnetization relaxation. The comparison of structure parameters of both Dy complexes indicates that the symmetries of coordination spheres of two Dy ions are D2d for 2 and C2v for 4 , which thus probably results in different magnetic relaxation behaviors. This work provides new insight for improving properties of Ln-biradical based SMMs. 相似文献
14.
Heteronuclear cationic complexes, [LCuLn] 3+ and [(LCu) 2Ln] 3+, were employed as nodes in designing high‐nuclearity complexes and coordination polymers with a rich variety of network topologies (L is the dianion of the Schiff base resulting from the 2:1 condensation of 3‐methoxysalycilaldehyde with 1,3‐propanediamine). Two families of linkers have been chosen: the first consists of exo‐dentate ligands bearing nitrogen‐donor atoms (bipyridine (bipy), dicyanamido (dca)), whereas the second consists of exo‐dentate ligands with oxygen‐donor atoms (anions derived from the acetylenedicarboxylic (H 2acdca), fumaric (H 2fum), trimesic (H 3trim), and oxalic (H 2ox) acids). The ligands belonging to the first family prefer copper(II ) ions, whereas the ligands from the second family interact preferentially with oxophilic rare‐earth cations. The following complexes have been obtained and crystallographically characterized: [LCu II(OH 2)Gd III(NO 3) 3] ( 1 ), [{LCu IIGd III(NO 3) 3} 2(μ‐4,4′‐bipy)] ( 2 ), [LCu IIGd III(acdca) 1.5(H 2O) 2] ? 13 H 2O ( 3 ), [LCu IIGd III(fum) 1.5(H 2O) 2] ? 4 H 2O ? C 2H 5OH ( 4 ), [LCu IISm III(H 2O)(Hfum)(fum)] ( 5 ), [LCu IIEr III(H 2O) 2(fum)]NO 3 ? 3 H 2O ( 6 ), [LCu IISm III(fum) 1.5(H 2O) 2] ? 4 H 2O ? C 2H 5OH ( 7 ), [{(LCu II) 2Sm III} 2fum 2](OH) 2 ( 8 ), [LCu IIGd III(trim)(H 2O) 2] ? H 2O ( 9 ), [{(LCu II) 2Pr III}(C 2O 4) 0.5(dca)]dca ? 2 H 2O ( 10 ), [LCu IIGd III(ox)(H 2O) 3][Cr III(2,2′‐bipy)(ox) 2] ? 9 H 2O ( 11 ), and [LCuGd(H 2O) 4{Cr(CN) 6}] ? 3 H 2O ( 12 ). Compound 1 is representative of the whole family of binuclear Cu II–Ln III complexes which have been used as precursors in constructing heteropolymetallic complexes. The rich variety of the resulting structures is due to several factors: 1) the nature of the donor atoms of the linkers, 2) the preference of the copper(II ) ion for nitrogen atoms, 3) the oxophilicity of the lanthanides, 4) the degree of deprotonation of the polycarboxylic acids, 5) the various connectivity modes exhibited by the carboxylato groups, and 6) the stoichiometry of the final products, that is, the Cu II/Ln III/linker molar ratio. A unique cluster formed by 24 water molecules was found in crystal 11 . In compounds 2 , 3 , 4 , 9 , and 11 the Cu II–Gd III exchange interaction was found to be ferromagnetic, with J values in the range of 3.53–8.96 cm ?1. Compound 12 represents a new example of a polynuclear complex containing three different paramagnetic ions. The intranode Cu II–Gd III ferromagnetic interaction is overwhelmed by the antiferromagnetic interactions occurring between the cyanobridged Gd III and Cr III ions. 相似文献
15.
A one-pot synthesis, that includes CuCl 2.2H 2O, Na 2mnt, H 2salph and Mn(CH 3COO) 3.H 2O, leads to the isolation of a trinuclear heterometallic compound [Mn III(salph)(H 2O) 2Cu II(mnt) 2].4DMF (1) formed by Mn…S-Cu-S…Mn supramolecular interactions. Compound 1 crystallizes in the monoclinic space group P21/c with a = 13.433(4), b = 16.283(5), c = 15.072(4) ?, Β = 107.785(4)‡, Z = 2. In the crystal structure, the complex anion [Cu II(mnt) 2] 2- bridges two [Mn III(salph)(H 2O)] 1+ cations through Mn…S contacts. The non-covalent hydrogen bonding and π-π interactions among the trinuclear [Mn III (salph)(H 2O) 2Cu II(mnt) 2)] complexes lead to an extended chain-like arrangement of [Mn III(salph) (H 2O)] 1+ cations with [Cu II(mnt) 2] 2- anions embedded in between these chains. 相似文献
16.
Summary The kinetics of oxidation of [Cr III(nta)(H 2O) 2] (nta is nitrilotriacetate) by periodate obey the rate law d[Cr VI]/dt=(k 2[IO
4
–
]+k 3[IO
4
–
] 2)[Cr III(nta)(H 2O) 2] under fixed conditions. The activation parameters are reported and we propose that electron-transfer proceeds via an inner-sphere mechanism. 相似文献
17.
The reaction of [M(L)]Cl 2 · 2H 2O (M = Ni 2+ and Cu 2+, L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0 1.18,0 7.12]docosane) with 1,1-cyclobutanedicarboxylic acid (H 2-cbdc) generates 1D and 2D hydrogen-bonded infinite chains [Ni(L)(H-cbdc −) 2] ( 1) and [Cu(L)(H-cbdc −) 2] ( 2). (H-cbdc − = cyclobutane-1-carboxylic acid-1-carboxylate). These complexes have been characterized by X-ray crystallography, spectroscopy,
and cyclic voltammetry. The crystal structure of 1 shows a distorted octahedral coordination geometry around the nickel(II) ion, with four secondary amines and two oxygen atoms
of the H-cbdc − ligand at the trans position. In 2, the coordination environment around the central copper(II) ion shows a Jahn–Teller distorted octahedron with four Cu–N bonds
and two long Cu–O distances. The cyclic voltammogram of the complexes undergoes two one-electron waves corresponding to M II/M III and M II/M I processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature
of the axial H-cbdc − ligand. 相似文献
18.
The use of the [Fe III(AA)(CN) 4] ? complex anion as metalloligand towards the preformed [Cu II(valpn)Ln III] 3+ or [Ni II(valpn)Ln III] 3+ heterometallic complex cations (AA=2,2′‐bipyridine (bipy) and 1,10‐phenathroline (phen); H 2valpn=1,3‐propanediyl‐bis(2‐iminomethylene‐6‐methoxyphenol)) allowed the preparation of two families of heterotrimetallic complexes: three isostructural 1D coordination polymers of general formula {[Cu II(valpn)Ln III(H 2O) 3(μ‐NC) 2Fe III(phen)(CN) 2 {(μ‐NC)Fe III(phen)(CN) 3}]NO 3 ? 7 H 2O} n (Ln=Gd ( 1 ), Tb ( 2 ), and Dy ( 3 )) and the trinuclear complex [Cu II(valpn)La III(OH 2) 3(O 2NO)(μ‐NC)Fe III(phen)(CN) 3] ? NO 3 ? H 2O ? CH 3CN ( 4 ) were obtained with the [Cu II(valpn)Ln III] 3+ assembling unit, whereas three isostructural heterotrimetallic 2D networks, {[Ni II(valpn)Ln III(ONO 2) 2(H 2O)(μ‐NC) 3Fe III(bipy)(CN)] ? 2 H 2O ? 2 CH 3CN} n (Ln=Gd ( 5 ), Tb ( 6 ), and Dy ( 7 )) resulted with the related [Ni II(valpn)Ln III] 3+ precursor. The crystal structure of compound 4 consists of discrete heterotrimetallic complex cations, [Cu II(valpn)La III(OH 2) 3(O 2NO)(μ‐NC)Fe III(phen)(CN) 3] +, nitrate counterions, and non‐coordinate water and acetonitrile molecules. The heteroleptic {Fe III(bipy)(CN) 4} moiety in 5 – 7 acts as a tris‐monodentate ligand towards three {Ni II(valpn)Ln III} binuclear nodes leading to heterotrimetallic 2D networks. The ferromagnetic interaction through the diphenoxo bridge in the Cu II?Ln III ( 1 – 3 ) and Ni II?Ln III ( 5 – 7 ) units, as well as through the single cyanide bridge between the Fe III and either Ni II ( 5 – 7 ) or Cu II ( 4 ) account for the overall ferromagnetic behavior observed in 1 – 7 . DFT‐type calculations were performed to substantiate the magnetic interactions in 1 , 4 , and 5 . Interestingly, compound 6 exhibits slow relaxation of the magnetization with maxima of the out‐of‐phase ac signals below 4.0 K in the lack of a dc field, the values of the pre‐exponential factor ( τo) and energy barrier ( Ea) through the Arrhenius equation being 2.0×10 ?12 s and 29.1 cm ?1, respectively. In the case of 7 , the ferromagnetic interactions through the double phenoxo (Ni II–Dy III) and single cyanide (Fe III–Ni II) pathways are masked by the depopulation of the Stark levels of the Dy III ion, this feature most likely accounting for the continuous decrease of χM T upon cooling observed for this last compound. 相似文献
19.
Five acetate-diphenoxo triply-bridged Co II-Ln III complexes (Ln III = Gd, Tb, Dy, Ho, Er) of formula [Co(μ-L)(μ-Ac)Ln(NO 3) 2] and two diphenoxo doubly-bridged Co II-Ln III complexes (Ln III = Gd, Tb) of formula [Co(H 2O)(μ-L)Ln(NO 3) 3]·S (S = H 2O or MeOH), were prepared in one pot reaction from the compartmental ligand N,N′,N′′-trimethyl-N,N′′-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylene triamine (H 2L). The diphenoxo doubly-bridged Co II-Ln III complexes were used as platforms to obtain 1,5-dicyanamide-bridged tetranuclear Co II-Ln III complexes (Ln III = Gd, Tb, Dy, Ho, Er). All exhibit ferromagnetic interactions between the Co II and Ln III ions and in the case of the Gd III complexes, the JCoGd were estimated to be ∼+0.7 cm −1. Compound 3 exhibits slow relaxation of the magnetization. 相似文献
20.
Two cyanide-bridged heterometallic FeIII–MnII complexes with formula {[Mn(bipy)(H2O)]2[Fe(2-CH3im)(CN)5]2}n·nCH3OH·4nH2O (2) (bipy?=?2,2′-bipyridine) and {[Mn(MAC)][Fe(2-CH3im)(CN)5]}n·nDMF·3nH2O (3) (MAC?=?2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-1(18),2,12,14,16-pentaene) have been successfully synthesized by assembling a newly designed pentacyanoiron(III) precursor [PPh4]2[Fe(CN)5(2-CH3im)]·2CH3OH (1) and two Mn(II) compounds containing bulky ancillary organic ligands as segments, and characterized by elemental analysis, infrared (IR) spectroscopy, and X-ray structure determination. X-ray diffraction analysis revealed one-dimensional (1D) ladder-like double or linear single infinite-chain structures for complex 2 and 3, respectively, indicating the obvious steric influence of the auxiliary ligand(s) on the structural type. Experimental and theoretical investigations on the magnetic properties of the complexes showed the antiferromagnetic coupling between the cyanide-bridged low-spin Fe(III) ion and high-spin Mn(II) ion. 相似文献
|