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1.
Biswarup Chakraborty 《Inorganica chimica acta》2011,378(1):231-238
The syntheses and structural characterization of four cobalt(II)-salicylate complexes, [(TPA)CoII(HSA)](ClO4) (1), [(isoBPMEN)CoII(HSA)](BPh4) (2), [(TPzA)CoII(HSA)](ClO4) (3) and [(6Me3TPA)CoII(HSA)](BPh4) (4) [TPA = tris(2-pyridylmethyl)amine, isoBPMEN = N1,N1-dimethyl-N2,N2-bis(2-pyridylmethyl)ethane-1,2-diamine, TPzA = tris((3,5-dimethyl-1H-pyrazole-1-yl)methyl)amine and 6Me3TPA = tris(6-methyl-2-pyridylmethyl)amine] are described. While 2, 3 and 4 are unreactive towards dioxygen, 1 reacts slowly with molecular oxygen to a cobalt(III)-salicylate complex, [(TPA)CoIII(SA)](ClO4) (1a). Two different crystalline forms, 1a and 1a·4H2O were isolated depending upon the condition of oxidation and crystallization. The solid-state structures of cobalt(III)-salicylate unit in both 1a and 1a·4H2O show a six-coordinate distorted octahedral coordination geometry at the cobalt(III) center ligated by the tetradentate ligand (TPA) where the dianionic salicylate (SA) binds in a bidentate fashion through one carboxylate and one phenolate oxygen. The hydrated form 1a·4H2O reveals a hexameric water cluster formation in the inorganic lattice host. The complex cation and the perchlorate counterion are involved in stabilizing the (H2O)6 cluster in a rare ‘pentamer planar+1’ conformation. A one-dimensional water tape consisting of edge-shared water hexamers is observed. The water tape represents a subunit of ice structure. 相似文献
2.
By applying the hydrothermal in situ acylation reactions between alkyl-substituted pyridine-2,3-dicarboxylic acids and hydrazine hydrate, six pyridine-monoacylhydrazidate-coordinated transition-metal complexes [Mn(MPDH)2] 1, [M(MPDH)2(H2O)2]·2H2O (M2+ = Co2+2, Zn2+3), [Mn(EPDH)2(H2O)2] 4 and [M(EPDH)2(H2O)2] (M2+ = Zn2+5, Co2+6) (MPDH = 6-methylpyridine-2,3-dicarboxylhydrazidate; EPDH = 5-ethylpyridine-2,3-dicarboxylhydrazidate) were obtained. Although only compound 1 is a 1-D chained coordination polymer and the others are the mononuclear molecular entities, they all further self-assemble into the interesting supramolecular networks via hydrogen-bonded interactions between pyridine-monoacylhydrazidate ligands. Two Zn2+ compounds 3 and 5 possess the fluorescence properties with maximum emissions at 517 nm for 3 and 530 nm for 5 upon excitation, respectively. The magnetic analysis for compound 1 indicates there exists the antiferromagnetic interactions between the Mn(II) ions. 相似文献
3.
Reactions of FeII, CoII, NiII, and ZnII salts with 6-quinolinecarboxylic acid (HL) under the hydrothermal conditions afford three monomeric complexes [M(L)2(H2O)4] (M = FeII for 1, CoII for 2, and NiII for 3) and a 1-D polymeric species {[Zn(L)2(H2O)] · H2O}n (4). The crystal structures of the ligand HL and these four complexes have been determined by using the X-ray single-crystal diffraction technique. The results suggest that complexes 1-3 are isostructural, displaying novel 3-D pillar-layered networks through multiple intermolecular hydrogen bonds, whereas in coordination polymer 4, the 1-D comb-like coordination chains are extended to generate a hydrogen-bonded layer, which is further reinforced via aromatic stacking interactions. Solid-state properties such as thermal stability and fluorescence emission of the polymeric ZnII complex 4 have also been investigated. 相似文献
4.
Masahiro Ebihara 《Inorganica chimica acta》2004,357(4):1236-1242
Reactions of a benzylidyne-capped tricobalt cluster, [Co3Cp3(μ3-CPh)2] (1), with halogens (X2 = Cl2, Br2, and I2) in CH2Cl2 afforded halogen-adducts of 1. The structure of four isolated salts [Co3Cp3(μ3-CPh)2(μ-Cl)]PF6 · MeCN (2PF6 · MeCN), [Co3Cp3(μ3-CPh)2(μ-Br)]SbF6 (3SbF6), [Co3Cp3(μ3-CPh)2(μ-I)]SbF6 · CH2Cl2 (4SbF6 · CH2Cl2), and [Co3Cp3(μ3-CPh)2(μ-I)]I3 (4I3) determined by X-ray diffraction can be regarded formally as halide-adducts of 12+. The halogen atom in each structure lies in the Co3 plane. The halogen-bridged Co-Co edge was elongated (in 2PF6 · MeCN = 2.6072(4), in 3SbF6 = 2.6106(7), in 4SbF6 · CH2Cl2 = 2.622(2), and in 4I3=2.6718(9) Å), and the Co-Co distances that had no halogen-bridge remained unchanged from the Co-Co distance of 1 (2.382(8) Å), (in 2PF6=2.4037(8) and 2.3948(7), in 3SbF6=2.3888(6) and 2.4017(7), in 4SbF6 · CH2Cl2 = 2.393(2) and 2.388(1), and in 4I3 = 2.397(1) and 2.3868(9) Å). The UV-Vis absorption spectra of 2+, 3+, and 4+ had characteristic absorption peaks at 796, 819, and 844 nm, respectively. Cyclic voltammograms of 2PF6 in CH2Cl2 with 0.1 M nBu4NPF6 as the supporting electrolyte showed a chemically reversible oxidation (at a potential of 0.75 V versus Fc/Fc+), and an irreversible reduction wave at −0.57 V. The irreversible reduction resulted in the recovery of 1. The redox properties of 3+ and 4+ are very similar to that of 2+. Cyclic voltammetry of 1 in 0.1 M nBu4NCl/MeCN indicates that the formation of 2+ is a multi-step reaction. Initially, 1 is oxidized to 1+, and then, 1+ is coordinated by Cl− followed by immediate oxidation to 2+. 相似文献
5.
The trinuclear [{RuII(bpy)2(bpy-terpy)}2CoII]6+ complex (16+) in which a Co(II)-bis-terpyridine-like centre is covalently linked to two Ru(II)-tris-bipyridine-like moieties by a bridging bipyridine-terpyridine ligand has been synthesised and characterised. Its electrochemical, photophysical and photochemical properties have been investigated in CH3CN. The cyclic voltammetry exhibits two successive reversible oxidation processes, corresponding to the CoIII/CoII and RuIII/RuII redox couples at E1/2 = −0.06 and 0.91 V vs Ag/Ag+ 10 mM, respectively. The one-electron oxidized form of the complex, [{RuII(bpy)2(bpy-terpy)}2CoIII]7+ (17+) obtained after exhaustive electrolysis carried out at 0.2 V is fully stable. 16+ and 17+ are only poorly luminescent, indicating that the covalent linkage of the Ru(II)-tris-bipyridine centre to the cobalt subunit leads to a strong quenching of the RuII excited state by an intramolecular process. Luminescence lifetime experiments carried out at different temperatures indicate that the transfer is more efficient for 17+ compare to 16+ due to lower activation energy. Continuous irradiation of 17+ performed at 405 nm in the presence of P(Ph)3 acting as sacrificial electron donor leads to its quantitative reduction into 16+, whereas similar experiment starting from 16+ with a sulfonium salt as sacrificial electron acceptor converts 16+ into 17+ with a slower rate and a maximum yield of 80%. These photoinduced electron transfers were followed by UV-Visible spectroscopy and compared with those obtained with a simple mixture of both mononuclear parent complexes i.e. [RuII(bpy)3]2+ and [CoII(tolyl-terpy)2]2+ or [CoIII(tolyl-terpy)2]3+ (tolyl-terpy = 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine). 相似文献
6.
Wilson Jacob 《Inorganica chimica acta》2008,361(5):1231-1238
Synthesis and crystal structure of two coordination polymers of composition [MnII(H2bpbn)1.5][ClO4]2 · 2MeOH · 2H2O (1) and [CoII(H2bpbn)(H2O)2]Cl2 · H2O (2) [H2bpbn = N,N′-bis(2-pyridinecarboxamido)-1,4-butane], formed from the reaction between [Mn(H2O)6][ClO4]2/CoCl2 · 4H2O with H2bpbn in MeCN, are described. In 1 each MnII ion is surrounded by three pyridine amide units, providing three pyridine nitrogen and three amide oxygen donors. Each MnII center in 1 has distorted MnN3O3 coordination. In 2 each CoII ion is coordinated by two pyridine amide moieties in the equatorial plane and two water molecules provide coordination in the axial positions. Thus, the metal center in 2 has trans-octahedral geometry. In both 1 and 2, the existence of 1D zigzag network structure has been revealed. Owing to π-π stacking of pyridine rings from adjacent layers 1 forms 2D network; 2 forms 2D and 3D network assemblies via N-H?Cl and O-H?Cl secondary interactions. Both the metal centers are high-spin. 相似文献
7.
A series of tris-[2-(1-methylimidazolyl)phosphine] sandwich complexes with Co2+ (1), Ni2+ (2), Cu2+ (3) and Zn2+ (4) have been synthesized and characterized with the intent of using these complexes as templates for building polymetallic species. X-ray analysis reveals that each metal is six-coordinate with octahedral geometry. Compound 3 exhibits a tetragonal distortion resulting from a Jahn-Teller distortion of a Cu2+ (d9) complex. Electrochemistry of 1-4 displayed peaks assigned to both ligand-based oxidation at 1.45-1.56 V and a perchlorate-based reduction at −2.36 to −2.78 V versus FcH+/FcH. Metal-based reduction was also observed for 2, with a reversible Ni2+/3+ oxidation at 0.89 V, consistent with the relatively poor donor ability of the imidazolyl nitrogen bases; and 3, with a irreversible Cu2+/1+ reduction at −1.29 V versus FcH+/FcH, consistent with the decomposition of the complex upon reduction. X-ray structures indicate large steric crowding around the phosphorus atom resulting from the orientation of the methyl substituent on the imidazoles. This crowding may prohibit the formation of polymetallic species through phosphorus-metal bonding. 相似文献
8.
Marina V. Kirillova 《Inorganica chimica acta》2007,360(2):506-512
The heteronuclear water-soluble and air-stable compounds [M(H2O)5M′(dipic)2] · mH2O (M/M′ = CuII/CoII (1), CuII/NiII (2), CuII/ZnII (3), ZnII/CoII (4), NiII/CoII (5), m = 2-3; H2dipic = dipicolinic acid) have been prepared by self-assembly synthesis in aqueous solution at room temperature, and characterized by IR, UV-Vis and atomic absorption spectroscopies, elemental and X-ray diffraction single crystal (for 1 and 2) analyses. 1-5 represent the first examples of heteronuclear dipicolinate compounds with 3d metals. Extensive H-bonding interactions involving all aqua ligands, dipicolinate oxygens and lattice water molecules further stabilize the dimetallic units by linking them to form three-dimensional polymeric networks. 相似文献
9.
Silvia Melnic Charles Simmons Tatiana Chiriac Valeriu Rudic 《Inorganica chimica acta》2011,373(1):167-172
New trinuclear iron(III) furoates with the general formula [Fe3O(α-fur)6(R-OH)3]X, where α-fur C4H3OCOO, R = CH3 (1), C2H5 (2), n-C3H7 (3), n-C4H9 (4), X = NO3− (1-4); [Fe3O(α-Fur)6(DMF)(CH3OH)2]NO3 (5); [Fe3O(α-Fur)6(H2O)(CH3OH)2]Cl (6); [Fe2MO(α-Fur)6(L)(H2O)2], where L = THF (7-9), DMF (10-12), M = Mn2+ (7, 10), Co2+ (8, 11), Ni2+ (9, 12) and [Fe2MO(α-Fur)6(3Cl-Py)3], where M = Mn2+ (13), Co2+ (14), Ni2+ (15); have been prepared and investigated by Mössbauer and IR spectroscopy. The X-ray crystal structure for the 1·2CH3OH complex indicates that it crystallizes in the monoclinic crystal system (P21/n) and has a structure typical of μ3-O-bridged trinuclear iron(III) compounds. Coordination compounds 1, 4, 7, 8 can be used as regulators of the biochemical composition of cyanobacterium Spirulina platensis biomass. The supplementation of these compounds, in concentrations exceeding 5-10 mg/l, increases the content of iron, amino acids, peptides and carbohydrates in Spirulina. 相似文献
10.
The synthesis of iron(II), cobalt(II) and nickel(II) complexes supported by chelating borate ligands containing one pyrazole and two thioethers, phenyl(pyrazolyl)bis((alkylthio)methyl)borates, [Ph(pz)BtR], is described. The six-coordinate complexes [Ph(pz)Bt]2M, M = Fe (1Fe), Co (1Co) and Ni (1Ni), form exclusively the cis isomers as confirmed by X-ray diffraction analyses. Whereas 1Co and 1Ni are high spin, 1Fe exhibits a room temperature magnetic moment, μeff = 4.1 μB, consistent with spin-crossover behavior. Quantitative analysis of the electronic spectrum of 2Ni leads to a value of Dq = 1086 cm−1, reflective of a ligand field strength somewhat weaker than those imposed by the related tridentate borate ligands Tp or PhTt. Replacement of the methylthioether substituent with the sterically more demanding tert-butylthioether leads to the isolation of [Ph(pz)BttBu]MX, M = Co, X = Cl (2Co); M = Ni, X = Cl (2Ni) or acac (3). The solid state structures of 2Co and 2Ni are chloride-bridged dimers. Additional high-spin cobalt(II) complexes, accessible under distinct preparative conditions, [κ2-Ph(pzH)BttBu] CoCl2·THF (4) and [κ2-Ph(pz)BttBu]2Co (5), have been fully characterized. 相似文献
11.
Hydrothermal reactions between H4ODPA (2,2′,3,3′-oxydiphthalic acid) and metal ion salts of Ba2+, Cu2+, Zn2+ and Gd3+ afford four novel coordination polymers [Ba(H2ODPA)(H2O)4] · H2O (1), [Cu2(ODPA)(H2O)3] · H2O (2), Zn2(ODPA)(H2O)2 (3) and [Gd(HODPA)(H2O)3.5] · H2O (4), accordingly. These polymers show great differences in regard to their structures and properties originated from the variation of size and coordination geometry of the metal ions. Compound 1 presents puckered achiral layer structure with (4.82) topology with helices, 2 has a 63 topology with copper tetramer as SBUs, 3 has chiral layer with two kinds of helices built up from Zn-binuclear “paddle-wheel” like SBUs, and 4 features a simple 1D helix with opposite chirality. Compound 3 shows obvious fluorescent emissions upon excitation. Compound 2 shows ferromagnetic interactions between CuII centers bridged by carboxylate groups, whereas compound 4 presents weak ferromagnetic interaction between GdIII ions. 相似文献
12.
Anna G. Matveeva Pavel S. Lemport Larissa A. Leites Rinat R. Aysin Anna V. Vologzhanina Zoya A. Starikova Margarita P. Passechnik Edward E. Nifant’ev 《Inorganica chimica acta》2009,362(9):3187-3195
The complexes of 2-[2-(diphenylphosphoryl)prop-2-yl]-1,8-naphthyridine (L) with lanthanide nitrates Ln(NO3)3 (Ln = Nd, Eu, Lu) were investigated to elucidate the coordination ability of a novel type of potentially tridentate ligands - phosphorylalkyl substituted naphthyridines. The X-ray crystal structures of [NdL3]3+ · 3(NO3)− · MeCN (1), [EuL3]3+ · 3(NO3)− · [Eu(NO3)3 · 4H2O] · MeCN (2), and [LuL3]3+ · 3(NO3)− · [Lu(NO3)3 · 3H2O] · 2 MeCN · 0.5 H2O (3) are reported together with their IR and Raman spectra. All the compounds studied contain isostructural [LnL3]3+ cations and three NO3− counterions. Coordination of each L appears to be O,N,N tridentate-cyclic and coordination number of Ln is nine. Vibrational spectra of 1-3 are also compared with that of free ligand and model compounds. 相似文献
13.
Hydrothermal synthesis has afforded a family of three structurally related metal phthalate (pht) 1-D coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine (dpa), with a general formulation of [L2M(dpa)2M(H2O)4] · H2O (L = pht, M = Co, 1, M = Ni, 2; L = 4-methylphthalate (4-mpht), M = Co, 3). Single crystal X-ray diffraction of 1 and 2 revealed the presence of one-dimensional (1-D) polymeric chains consisting of [M(H2O)4]2+ and [M(pht)2]2− subunits linked through dpa tethers. These chains in turn conjoin into pseudo 2-D layers and 3-D networks via extensive supramolecular hydrogen bonding pathways. An extremely similar structure is observed for 3 despite the presence of the bulkier methyl group substituent. 1-3 were further characterized via infrared spectroscopy and elemental and thermogravimetric analysis. 1-3 represent the first dicarboxylate coordination polymers incorporating dpa tethering ligands. 相似文献
14.
Xian-Ming Zhang Jie-Sheng Chen Cai-Rong Ding Xiao-Ming Chen 《Inorganica chimica acta》2004,357(5):1389-1396
Three cluster-based coordination polymers, namely [Zn3(bpy)3(hip)2] · 5H2O (1), [Co3(bpy)3(hip)2] · 5H2O (2) and [Cd3(bpy)3(hip)2] (3) (bpy=2,2′-bipyridine, hip=4-hydroxyl-isophthalate) were synthesized and structurally characterized. X-ray single-crystal structural analyses revealed that both 1 and 2 crystallize in the chiral space group P21, while 3 crystallizes in the centric space group Pccn. Compounds 1 and 2 are isomorphous and both have (4,4) topological layered structures constructed from trinuclear metal clusters. Compound 3 also shows layered structure of (4,4) topology constructed from trinulear Cd(II) cores. The layers are stacked in a staggered ?ABAB? fashion in 1 and 2 but in an overlapped ?AAA? fashion in 3. There are two types of coordination modes of hip ligand in 1 and 2 but only one in 3. The structural difference between 1 (or 2) and 3 may be attributed to the difference of metal ion nature such as the ionic radius and coordination preference, resulting in the different orientation fashions of the auxiliary bpy ligands, stacking fashions of the layers, as well as chirality of the crystals. The chiral structures of 1 and 2 were also confirmed by measurements of powder second-harmonic-generation (SHG) measurements, which show that 1 and 2 have SHG intensity of 0.50 and 0.02 relative to that of urea, respectively. 相似文献
15.
Silvio Quici Marco Cavazzini Mauro Botta Giovanni Battista Giovenzana Gianluca Accorsi Francesco Barigelletti 《Inorganica chimica acta》2007,360(8):2549-2557
The two-component ligand systems 1 and 2 which contain 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) as the hosting unit for the lanthanide cations, and naphthalene (which is devoid of any chelating ability) or quinoline units, respectively, as chromophores, were synthesized. The 1:1 complexes with Gd3+, Eu3+ and Tb3+ have been studied in aqueous solution. Relaxometric properties for Gd · 1 indicate that two water molecules (q = 2) are in the first coordination sphere of the metal ion whereas for Gd · 2, q < 2 is found. For Gd · 1, these results indicate that the naphthalene unit is not coordinated to the metal centre; for the case of quinoline, reasons for the lower hydration state are discussed. In case of Eu · 1, Tb · 1, Eu · 2, and Tb · 2 the absorption and luminescence spectra, the overall luminescence efficiencies, and the metal-centred lifetimes, were obtained both in water and deuterated water. The coordination features of these complexes were explored by comparing their luminescence properties, resulting in hydration state q = 2 and 1.4 for the cases of the complexes of 1 and 2, respectively. Use of the photophysical parameters in air-equilibrated water allowed the determination of the ligand-to-cation energy transfer efficiency, ΦEnT, leading to the overall emission sensitization process. For Eu · 1, and Eu · 2, we found ΦEnT = 0.034 and 0.078, respectively, supporting that also a non-coordinating chromophore like naphthalene, case of ligand 1, can transfer excitation energy to the metal centre. 相似文献
16.
The synthesis of an unsymmetrical phenanthroline-based ligand, 2-methyl-9-(3,5-dimethylpyrazolylmethyl)-1,10-phenanthroline (L), and its cupric [Cu(II)] (1) and cuprous [Cu(I)] (2) complexes, are reported. The X-ray structures of each of these Cu complexes show distinct changes in coordination environments consistent with the geometrical preferences of the two oxidation states. In the solid-state, the Cu(II) complex (1) adopts a geometry best described as trigonal bipyramidal, while the Cu(I) complex (2) consists of a single dicationic dimer in which the ligand bridges between two copper ions, separated by 4.26 Å. The two Cu(I) coordination sites differ in 2 with one copper center complexed in a trigonal planar geometry and the other copper in a distorted tetrahedral environment; the latter coordination results from an additional CH3CN ligand. Complex 1 exhibits a reversible redox process at −0.34 V versus Fc/Fc+ in CH3CN, attributable to the Cu2+/Cu+ couple, while the dimeric Cu(I) complex (2) does not display this redox couple on the CV timescale. Over minutes however, complex 1 does oxidize in the presence of dioxygen to 2 in CH3CN. 相似文献
17.
Ruo-Jie Tao Chong-Zhen Mei Qing-Lun Wang Dai-Zheng Liao 《Inorganica chimica acta》2004,357(7):1985-1990
A dissymmetrical double Schiff base Cu(II) mononuclear complex: CuHL (1) (where H3L is N-3-carboxylsalicylidene-N′-salicylaldehyde-1,2-diaminoethane) and two trinuclear complexes: [CuL(H2O)CoCuL] · H2O · CH3OH (2) and [(CuL)2Ni] · 2H2O (3) have been synthesized and characterized by means of elemental analyses, IR and electronic spectra. The crystal structures of two heterotrinucler complexes were determined by X-ray analysis. Each dissymmetrical cell unit of the complex 2 contains two heterotrinucler neutral molecules. In each neutral molecule, the central Co2+ ion is located at the site of O6 with a distorted octahedral geometry and one terminal Cu2+ ion at the four-coordination site of N2O2, but the other one at the square-pyramidal environment of N2O3. Each dissymmetrical unit of the complex 3 contains a heterotrinucler neutral molecule, whose structure is similar to that of 2 except two terminal Cu2+ ions both at the inner site of N2O2. The magnetic properties of two heterotrinucler complexes have been determined in the temperature range of 5-300 K, which indicate that the interaction between the central Co2+ ion or Ni2+ ion and the outer Cu2+ ions is antiferromagnetic. The exchange integrals are equal to −26.2 cm−1 for 2 and −50.6 cm−1 for 3. 相似文献
18.
Gregory A. Farnum 《Inorganica chimica acta》2009,362(11):3955-4227
Slow diffusion of aqueous solutions of metal perchlorates with alcoholic solutions of bis(4-pyridylmethyl)piperazine (4-bpmp) or bis(3-pyridylmethyl)piperazine (3-bpmp) afforded crystalline coordination polymer phases whose dimensionality and topology is determined largely by the pyridyl nitrogen donor disposition within the imine components. {[M(H2O)4(4-bpmp)](ClO4)2·4-bpmp·4H2O}n (M = Co, 1-Co; M = Zn, 1-Zn) are isostructural, displaying cationic [M(H2O)4(4-bpmp)]n2n+ 1-D coordination polymer chains connected through extensive hydrogen-bonding pathways involving unligated species. In contrast, use of the 3-bpmp isomer generated compounds with formulation of {[M(H2O)2(3-bpmp)2](ClO4)2·8H2O}n (M = Co, 2-Co; M = Zn, 2-Zn), which manifest achiral 3-fold interpenetrated 66 diamondoid lattices. The zinc derivatives undergo modest blue-violet luminescence on exposure to ultraviolet light. 相似文献
19.
Fabrice Thomas 《Inorganica chimica acta》2010,363(12):3122-11468
The three complexes [CoIIIL1Cl] (1), [CoIIIL2]+·ClO4− (2+·ClO4−), and [CuIIH2L2]2+·2ClO4− (H232+·2ClO4−) [where H2L1 = N,N′-dimethyl-N,N′-bis(2-hydroxy-3,5-di-tert-butylbenzyl)ethylenediamine, H2L2 = N,N′-bis(2-pyridylmethyl)-N,N′-bis(2-hydroxy-3,5-di-tert-butylbenzyl)ethylenediamine] have been prepared. The bis-phenolate and bis-phenol complexes, 2+ and H232+ respectively, have been characterized by X-ray diffraction, showing a metal ion within an elongated octahedral geometry. 1-2 exhibit in their cyclic voltammetry curves two anodic reversible waves attributed to the successive oxidation of the phenolates into phenoxyl radicals. The cobalt radical species (1)+, (2)2+, and (2)3+ have been characterized by combined UV-Vis and EPR spectroscopies. In the presence of one equivalent of base, one phenolic arm of H232+ is deprotonated and coordinates the metal. The resulting complex (H3+) exhibits a single reversible redox wave at ca. 0.3 V. The electrochemically generated oxidized species is EPR silent and exhibits the typical features of a radical compound, with absorption bands at 411 and 650 nm. The fully deprotonated complex 3 is obtained by addition of two equivalents of nBu4N+OH− to H232+. It exhibits a new redox wave at a lower potential (−0.16 V), in addition to the wave at ca. 0.3 V. We assigned the former to the one-electron oxidation of the uncoordinated phenolate into an unstable phenoxyl radical. 相似文献
20.
Three complexes of composition [Co2IICo2III(H2hbhpd)2(H4hbhpd)2(H2O)2]Cl2(CH3OH)4 (1), [Co2IICo2III(H2hbhpd)2(H4hbhpd)2(H2O)2](NO3)2(CH3OH)4 (2) and [Ni2(H4hbhpd)2(NO3)](NO3)(CH3OH)1.5 (3) (H5hbhpd = 2-(2-hydroxy-benzylamino)-2-hydroxymethyl-propane-1,3-diol) have been synthesized and their structures have been characterized. Complexes 1 and 2 are mixed-valence cobalt clusters and display face-sharing monovacant dicubane structures. In the complexes 1 and 2, one of the three alkyl hydroxyl groups of H5hbhpd ligand is deprotonated instead of deprotonation of phenyl hydroxyl group; thus monoanionic H4hbhpd− ligand displays novel η3, η1, η1, μ3 coordination mode. Complex 3 is binuclear, and the two metal centers of 3 are bridged by two deprotonated phenyl hydroxyl oxygen atoms and iso-orthogonalized by a nitrato group in η1η1-O,O′ coordination fashion. Variable-temperature solid-state dc magnetization studies have been performed in the temperature range 2-300 K for compounds 1 and 3. Antiferromagnetic interactions were determined for 1 and ferromagnetic couplings were found for 3. 相似文献