共查询到20条相似文献,搜索用时 31 毫秒
1.
Bodini Mario E. Valle M. Angélica del Copia Georgina Francisco M Jara 《Transition Metal Chemistry》1999,24(4):474-477
The monoanion of pyrazincarboxylic acid (PcA–), the dianion of quinizarine (Qz=) and manganese(II) yield a soluble deep-blue complex in dimethylsulphoxide whose MnII:Qz=:PcA– stoichiometry has been established as 1:1:1. This mixed-ligand complex is oxidized in two steps, each involving one equivalent of charge per complex present, as indicated by controlled-potential electrolyses done at +0.30V versus s.c.e. and +0.50 V versus s.c.e.. The association between the metal ion and the ligands prevail and the oxidations finally produce a dark-red complex which possesses the same stoichiometry as the original deep-blue species. In the latter the metal ion is present in oxidation state +3 with the quinizarine dianion as the corresponding semiquinone of the oxidized quinizarine. The monoanion of pyrazincarboxylic acid remains unchanged. Controlled-potential electrolysis at –0.20 V versus s.c.e. of a solution of the mixed-ligand complex indicates that it is binuclear, generating a MnII-MnIIImixed-valence species. The latter is, in turn, reduced at –1.60 V versus s.c.e. producing probably a mononuclear of manganese(II) species. If manganese(II) is combined with the semiquinone of quinizarine the metal ion exhibits themagnetic characteristic of manganese(III) and thesemiquinone is reduced to the quinizarine dianion, indicating that the mixed-ligand formed exhibits intramolecular charge-transfer. This is a good example of a binuclear species accumulating four oxidation equivalents after oxidation of both metal centers and the quinizarine ligands. 相似文献
2.
Shi Jing-Min Liao Dai-Zheng Cheng Peng Jiang Zong-Hui Wang Geng-Lin 《Transition Metal Chemistry》1997,22(3):209-210
The heterobinuclear complex, [CuMn(L)(phen)2](ClO4)2· H2O, [L = N,N-bis(N-hydroxyethyleneamine)oxamido, phen=1,10-phenanthroline], has been synthesized with N,N-bis(N-hydroxyethylaminoethyl)oxamido as the bridging ligand. The electronic reflectance spectrum indicates the presence of exchange-coupling interaction between bridging MnII and CuII ions. The variable-temperature magnetic susceptibility of the complex was measured over the 4–300K range. The magnetic coupling parameter is consistent with an antiferromagnetic exchange between the MnII ion and CuII ion and fits the data for a heterobinuclear CuII–MnII magnetic exchange model based on the Hamiltonian operator (H= –2JS1S2, S1=1/2, S2=5/2), giving the antiferromagnetic coupling parameter of 2J=–74.0cm–1. 相似文献
3.
Mikata Y Wakamatsu M So H Abe Y Mikuriya M Fukui K Yano S 《Inorganic chemistry》2005,44(21):7268-7270
A new heptadentate N6-O1 ligand, N,N,N',N'-tetrakis(2-quinolylmethyl)-2-hydroxy-1,3-propanediamine (Htqhpn), was synthesized and used to generate compounds with linearly ordered MnIIMnIIIMnIIIMnII tetranuclear cores. This is the lowest valent tetranuclear manganese complex that exhibits a (mu2-O)2Mn2 core in the molecule. The electron paramagnetic resonance and magnetic measurements of these tetranuclear complexes suggest moderately strong antiferromagnetic coupling for the central MnIII2 core, with weak coupling between the MnII and MnIII centers. 相似文献
4.
The preparation and characterization of MnII, FeIII and CuII complexes of three tridentate pyridyl hydrazones are reported.
The ligands were prepared via Schiff base condensation of 6-chloro-2-hydrazopyridine with alpha-formyl-(L1), alpha-acetyl-(L2),
or alpha-benzoyl-(L3) pyridine. The structural characterization of the compounds prepared was based on elemental analyses,
electrical conductance and magnetic moment measurements, 1H-n.m.r., i.r., u.v.-vis. and e.s.r spectroscopic methods. The overall
structure and reactivity of the metal chelates critically depend on the ligand substituents within the carbonyl moiety. Octahedral
and tetrahedral monomeric species were proposed for MnII complexes, and an octahedral environment for the FeIII complexes.
Regarding the copper(II) complexes, a monomeric square-planar and a dimeric structure with a chloride bridge in square-pyramidal
geometry were suggested. In the presence of molecular oxygen, MnII and CuII complexes catalyse the oxidative transformation
of catechol (benzene-1,2-diol) to the corresponding o-benzoquinone. Iron(III) complexes catalyse the aerobic oxidation of
catechol to the intradiol cleavage product. The catalytic activity has been correlated with the Lewis acidity of the metal
centres created according to the nature of the ligand substituents. The probable mechanistic implications of the catalysed
oxidation reactions are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Shaikh N Goswami S Panja A Wang XY Gao S Butcher RJ Banerjee P 《Inorganic chemistry》2004,43(19):5908-5918
The semiquinone-catecholate based mixed valence complex, [FeIII(bispicen)(Cl4Cat)(Cl4SQ)] x DMF (1), and catecholate based (H2bispictn)[Mn2III(Cl4Cat)4(DMF)2] (2) (bispicen = N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine, bispictn = N,N'-bis(2-pyridylmethyl)-1,3-propanediamine, Cl4Cat = tetrachlorocatecholate dianion, and Cl4SQ = tetrachlorosemiquinone radical anion) were synthesized directly utilizing a facile route. Both the complexes have been characterized by single crystal X-ray diffraction study. The electronic structures have been elucidated by UV-vis-NIR absorption spectroscopy, cyclic voltammetry, EPR, and magnetic properties. The structural as well as spectroscopic features support the mixed valence tetrachlorosemiquinone-tetrachlorocatecholate charge distribution in 1. The ligand based mixed valence state was further confirmed by the presence of an intervalence charge transfer (IVCT) band in the 1900 nm region both in solution and in the solid. The intramolecular electron transfer, a phenomenon known as valence tautomerism (VT), has been followed by electronic absorption spectroscopy. For 1, the isomeric form [FeIII(bispicen)(Cl4Cat)(Cl4SQ)] is favored at low temperature, while at an elevated temperature, the [FeII(bispicen)(Cl4SQ)2] redox isomer dominates. Infrared as well as UV-vis-NIR spectral characterization for 2 suggest that the MnIII(Cat)2- moiety is admixed with its mixed valence semiquinone-catecholate isomer MnII(SQ)(Cat)-, and the electronic absorption spectrum is dominated by the mixed charged species. The origin of the intervalence charge transfer band in the 1900 nm range is associated with the mixed valence form, MnII(Cl4Cat)(Cl4SQ)-. The observation of VT in complex 1 is the first example where a mixed valence semiquinone-catecholate iron(III) complex undergoes intramolecular electron transfer similar to manganese and cobalt complexes. 相似文献
6.
Synthesis of six hydroxo-bridged binuclear manganese(III) complexes of formulae [MnL-X-MnL](ClO4) [X = OH (1–6)] along with a mononuclear manganese(III) complex (7) [Mn(L)(L′)(MeOH)2] [HL′ = 2-(2-hydroxy-phen-yl)benzimidazole] and two carboxylate-bridged binuclear manganese(III) complexes (8) and (9) are described. The complexes have been characterized by the combination of i.r., u.v.-vis spectroscopy, magnetic moments and by their redox properties. The electronic spectra of all the complexes exhibit almost identical features consisting of two d–d bands at ca. 550 and 600 nm, one MLCT band at ca.400 nm, together with two π–π* intra-ligand transitions at ca. 250 nm and ca.300 nm. Room temperature magnetic data range from μ = 2.7–3.0 BM indicates some super-exchange between the binuclear metal centers via bridging hydroxo/carboxylato groups. The X-ray crystal structure of the binuclear complex (5) revealed that it has a symmetric MnIIIN2O2 core bridged by a hydroxyl group. The X-ray analysis of the mononuclear complex (7) showed that the manganese-center possesses a distorted octahedral geometry. Electrochemical properties of hydroxo-bridged manganese(III) complexes (1–6) show identical features consisting of an irreversible and a quasi-reversible reduction corresponding to the Mn2III → MnIIMnIII → MnIIMnII couples in the voltammogram. It was found that electron withdrawing substituents on the ligand result in easier reduction. Complex (7) displays an irreversible reduction at 0.08 V and a reversible oxidation at 0.45V assignable to the MnIII → MnII reduction and MnIII → MnIV oxidation, respectively. The carboxylate-bridged compound (8) exhibits two irreversible oxidations at 0.4 and 0.6 V, probably due to Mn2III → MnIIIMnIV → MnIVMnIV oxidations and shows a quasi-reversible reductive wave at −0.85 V, tentatively assigned to Mn2III → MnIIMnIII reduction. 相似文献
7.
A family of Mn3+ and Fe3+ complexes of 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (1) and 4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (2) has been prepared by the chemical oxidation of the divalent manganese and iron analogues. The ligands are ethylene cross-bridged tetraazamacrocycles derived from cylam and cyclen, respectively. The synthesis and characterization of these complexes, including X-ray crystal structure determinations, are described. The structural evidence demonstrates that the tetradentate ligands enforce distorted octahedral geometries on the metal ions, with two cis sites occupied by labile ligands. Magnetic measurements reveal that the complexes are high spin with typical magnetic moments. Cyclic voltammetry shows reversible redox processes for the Fe3+/Fe2+ couples of the iron(III) complexes, while Mn3+/Mn2+ and Mn4+/Mn3+ couples were observed for the complexes with manganese(III). The manganese chemistry of 1 was studied in depth. The dichloro manganese(III) cation of 1 undergoes facile ligand substitution reactions at the labile, monodentate sites, for example substituting azide for chloride ligands. Air oxidation of the dichloro complex of Mn (1)2+ in basic solution does not give the expected mu-oxo dimeric product common to manganese. Instead, an unusual manganese(III)-OH complex has been isolated from this reaction and structurally characterized. A similar reaction under slightly different conditions gives a putative MnIII(OH)2 complex that metathesizes to MnIII(OMe)2 upon recrystallization from methanol. 相似文献
8.
Verónica Arancibia M. Angélica del Valle Mario Bodini 《Transition Metal Chemistry》1995,20(2):179-184
Summary MnII forms a yellow mononuclear species with the title ligand having a 12 stoichiometry and whose conditional stability constant is 8.9 × 1010
m
–2. The c.v. of this complex shows an oxidation at +0.78V versus s.c.e. Controlled-potential electrolysis at +0.80V versus s.c.e. yields a binuclear species of MnIII with a 12 metal:ligand stoichiometry.The addition of MnIII(urea)6(ClO4)3 to a solution of the ligand produces a mononuclear complex of MnIII if the concentration of the metal ion is less than 1 mM. At higher concentrations a binuclear species is obtained. The latter is reduced in two steps, at +0.24 and –0.58 V versus s.c.e. Controlled-potential electrolysis at 0.0 V produces a dark green complex after the transfer of 0.5 equivalents of charge per mole of Mn. This binuclear L2MnII-MnIIIL2 mixed-valence complex can be obtained only by electrolysis of the binuclear L2MnIIIMnIIIL2 species. Attempts to prepare the complex chemically were unsuccessful - the binuclear MnIII species was obtained in every case.Author to whom all correspondence should be directed. 相似文献
9.
High-valent metal-oxo complexes are postulated as key intermediates for a wide range of enzymatic and synthetic processes. To gain an understanding of these processes, the reactivity of an isolated, well-characterized Mn(V)-oxo complex, (TBP8Cz)MnVO (1), (TBP8Cz = octakis(para-tert-butylphenyl)corrolazinato(3-)) has been examined. This complex has been shown to oxidize a series of substituted phenols (4-X-2,6-t-Bu2C6H2OH, X = C(CH3)3 (3), H, Me, OMe, CN), resulting in the production of phenoxyl radicals and the MnIII complex [(TBP8Cz)MnIII] (2). Kinetic studies have led to the determination of second-order rate constants for the phenol substrates, which give a Hammett correlation ((log k'x/k'H) vs sigmap+) with rho = -1.26. A plot of log k versus BDE(O-H) also reveals a linear correlation. These data, combined with a KIE of 5.9 for 3-OD, provide strong evidence for a concerted hydrogen-atom-abstraction mechanism. Substrates with C-H bonds (1,4-cyclohexadiene and 9,10-dihydroanthracene) are also oxidized via H-atom abstraction by 1, although at a much slower rate. Given the stability of 1, and in particular its low redox potential, (-0.05 V vs SCE), the observed H atom abstraction ability is surprising. These findings support a hypothesis regarding how certain heme enzymes can perform difficult H-atom abstractions while avoiding the generation of high-valent metal-oxo intermediates with oxidation potentials that would lead to the destruction of the surrounding protein environment. 相似文献
10.
Brudenell SJ Spiccia L Bond AM Fallon GD Hockless DC Lazarev G Mahon PJ Tiekink ER 《Inorganic chemistry》2000,39(5):881-892
Structural, electrochemical, ESR, and H2O2 reactivity studies are reported for [Mn(dmptacn)Cl]ClO4 (1, dmptacn = 1,4-bis(2-pyridylmethyl)-1,4,7-triazacyclononane) and binuclear complexes of bis(pentadentate) ligands, generated by attaching 2-pyridylmethyl arms to each secondary nitrogen in bis(1,4,7-triazacyclononane) macrocycles and linked by ethyl (tmpdtne, [Mn2(tmpdtne)Cl2](ClO4)2.2DMF, 2), propyl (tmpdtnp, [Mn2(tmpdtnp)Cl2](ClO4)2.3H2O, 3), butyl (tmpdtnb, [Mn2(tmpdtnb)Cl2](ClO4)2.DMF.2H2O, 4), m-xylyl (tmpdtn-m-X, [Mn2(tmpdtn-m-X)-Cl2](ClO4)2, 5) and 2-propanol (tmpdtnp-OH, [Mn2(tmpdtnp-OH)Cl2](ClO4)2, 6) groups. 1 crystallizes in the orthorhombic space group P2(1)2(1)2(1) (No. 19) with a = 7.959(7) A, b = 12.30(1) A, and c = 21.72(2) A; 2, in the monoclinic space group P2(1)/c (No. 14) with a = 11.455(4) A, b = 15.037(6) A, c = 15.887(4) A, and beta = 96.48(2) degrees; 3, in the monoclinic space group P2(1)/c (No. 14) with a = 13.334(2) A, b = 19.926(2) A, c = 18.799(1) A, and beta = 104.328(8) degrees; and [Mn2(tmpdtnb)Cl2](ClO4)2.4DMF.3H2O (4'), in the monoclinic space group P2(1)/n (No. 14) with a = 13.361(3) A, b = 16.807(5) A, c = 14.339(4) A, and beta = 111.14(2) degrees. Significant distortion of the Mn(II) geometry is evident from the angle subtended by the five-membered chelate (ca. 75 degrees) and the angles spanned by trans donor atoms (< 160 degrees). The Mn geometry is intermediate between octahedral and trigonal prismatic, and for complexes 2-4, there is a systematic increase in M...M distance with the length of the alkyl chain. Cyclic and square-wave voltammetric studies indicate that 1 undergoes a 1e- oxidation from Mn(II) to Mn(III) followed by a further oxidation to MnIV at a significantly more positive potential. The binuclear Mn(II) complexes 2-5 are oxidized to the Mn(III) state in two unresolved 1e- processes [MnII2-->MnIIMnIII-->MnIII2] and then to the MnIV state [MnIII2-->MnIIIMnIV-->MnIV2]. For 2, the second oxidation process was partially resolved into two 1e- oxidation processes under the conditions of square-wave voltammetry. In the case of 6, initial oxidation to the MnIII2 state occurs in two overlapping 1e- processes as was found for 2-5, but this complex then undergoes two further clearly separated 1e- oxidation processes to the MnIIIMnIV state at +0.89 V and the MnIV2 state at +1.33 V (vs Fc/Fc+). This behavior is attributed to formation of an alkoxo-bridged complex. Complexes 1-6 were found to catalyze the disproportionation of H2O2. Addition of H2O2 to 2 generated an oxo-bridged mixed-valent MnIIIMnIV intermediate with a characteristic 16-line ESR signal. 相似文献
11.
Hatzipanayioti Despina Karaliota Alexandra Kamariotaki Mary Veneris Antony Falaras Polykarpos 《Transition Metal Chemistry》1998,23(4):407-416
The electrochemical and spectroscopic behaviour of 2,3-dihydroxybenzoic acid (2,3-DHBA) and its oxidized forms have been studied in dimethyl sulfoxide solutions under aerobic and anaerobic conditions. The products resulting from the reaction with manganese(II) (in dimethyl sulfoxide) are also studied by cyclic voltammetry, u.v–vis., n.m.r. and e.s.r. spectroscopies. Under anaerobic conditions the anions of the ligand form stable complexes with manganese(II) and (III) of MnL2 type, while in the presence of air the oxidized forms of the ligand react with manganese(II) to give mixed-valence species. The chemical stability of the semiquinone and its manganese complexes in addition to its photosensitivity is noteworthy. Calculations show that the electrogenerated manganese(III)–(2,3-DHB–semiquinone) system is stable, but redox-active and can undergo a two-electron exchange (per monomer). The dimeric (or oligomeric) species should be good candidates for water oxidation studies. 相似文献
12.
采用溶剂扩散法获得了锰(III)的两个单核配合物 [Mn(Miao)2(H2O)2]ClO4(1)和[Mn(Miao)2(DMF)2]ClO4(2)(HMiao = 1-甲基-2-咪唑醛肟,DMF = N,N-二甲基甲酰胺)的晶体。X-射线衍射单晶结构表明:两种配合物均属三斜晶系,空间群Pī,锰与配位原子形成稳定的八面体结构。采用Gaussian03W程序计算了HMiao配体的电荷密度,理论计算与实际配位形式完全吻合。通过循环伏安法测定了两种锰配合物在DMF 溶液中的电化学性质。 相似文献
13.
Linkage isomers of bis(bipyridine)(1,2-dihydroxy-9,10-anthraquinonato)ruthenium(II), 1,2- and 1,9-coordinated complexes, and several of their oxidation products have been prepared chemically and/or electrochemically. For the 1,2-coordinated complex, the one- and two-electron oxidized species have been characterized, and for the 1,9-coordinated complex, the one-electron oxidized species has been characterized. The rich redox activity of these complexes leads to ambiguity in assessing the electronic structure. This paper reports EPR spectra of odd-electron species and detailed analyses of electronic spectra and structure of the complexes, based on INDO molecular orbital calculations. Results of calculations on the related 1-hydroxyanthraquinone complex and the free ligands,1,2-dihydroxy-9,10-anthraquinone (alizarin) and 1-hydroxyanthraquinone, are also briefly discussed. 相似文献
14.
Hureau C Sabater L Anxolabéhère-Mallart E Nierlich M Charlot MF Gonnet F Rivière E Blondin G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(8):1998-2010
The dinuclear phenolato-bridged complex [(mL)Mn(II)Mn(II)(mL)](ClO(4))(2) (1(ClO(4))(2)) has been obtained with the new [N(4)O] pentadentate ligand mL(-) (mLH=N,N'-bis-(2-pyridylmethyl)-N-(2-hydroxybenzyl)-N'-methyl-ethane-1,2-diamine) and has been characterised by X-ray crystallography. X- and Q-band EPR spectra were recorded and their variation with temperature was examined. All spectra exhibit features extending over 0-800 mT at the X band and over 100-1450 mT at the Q band, features that are usually observed for dinuclear Mn(II) complexes. Cyclic voltammetry of 1 exhibits two irreversible oxidation waves at E(1)(p)=0.89 V and E(2)(p)=1.02 V, accompanied on the reverse scan by an ill-defined cathodic wave at E(1')(p)=0.56 V (all measured versus the saturated calomel electrode (SCE)). Upon chemical oxidation with tBuOOH (10 equiv) at 20 degrees C, 1 is transformed into the mono-mu-oxo species [(mL)Mn(III)-(mu-O)-Mn(III)(mL)](2+) (2), which eventually partially evolves into the di-mu-oxo species [(mL)Mn(III)-(mu-O)(2)-Mn(IV)(mL)](n+) (3) in which one of the aromatic rings of the ligand is decoordinated. The UV/Vis spectrum of 2 displays a large absorption band at 507 nm, which is attributed to a phenolate-->Mn(III) charge-transfer transition. The cyclovoltammogram of 2 exhibits two reversible oxidation waves, at 0.65 and 1.16 V versus the SCE, corresponding to the Mn(III)Mn(III)/Mn(III)Mn(IV) and Mn(III)Mn(IV)/Mn(IV)Mn(IV) oxidation processes, respectively. The one-electron electrochemical oxidation of 2 leads to the mono-mu-oxo mixed-valent species [(mL)Mn(III)-(mu-O)-Mn(IV)(mL)](3+) (2 ox). The UV/Vis spectrum of 2 ox exhibits one large band at 643 nm, which is attributed to the phenolate-->Mn(IV) charge-transfer transition. 2 ox can also be obtained by the direct electrochemical oxidation of 1 in the presence of an external base. The 2 ox and 3 species exhibit a 16-line EPR signal with first peak to last trough widths of 125 and 111 mT, respectively. Both spectra have been simulated by using colinear rhombic Mn-hyperfine tensors. Mechanisms for the chemical formation of 2 and the electrochemical oxidation of 1 into 2 ox are proposed. 相似文献
15.
Mononuclear, binuclear NiII and heterobinuclear ZnIINiII complexes have been derived from lateral macrobicyclic tricompartmental ligands embracing three different donor sets: (i) O2N2-donor set, derived from ether oxygens and tertiary amine nitrogens; (ii) N2O2-donor set, derived from tertiary amine nitrogens and phenolic oxygens; (iii) O2N2-donor set, derived from phenolic oxygens and azomethine nitrogens. Cyclic voltammograms of the mononuclear NiII complexes showed irreversible one-electron reduction processes in the –1.2 to –1.3 V region and an irreversible oxidation process in the range +0.8 V potential region. The binuclear complexes showed quasireversible two-step single electron reduction processes around the –1.3 and –1.7 V potential regions. The anodic potential region showed an irreversible oxidation process at +1.0 V. The heterobinuclear ZnIINiII complex showed an irreversible reduction of the NiII species at –1.55 V. The catalytic hydrolysis towards 4-nitrophenyl phosphate by the mononuclear, binuclear NiII complexes and the heterobinuclear complex were found to be appreciable. The pseudo-first order rate constant for the catalytic hydrolysis catalyzed by the binuclear and heterobinuclear complexes were found to be higher (9.8 × 10–4 s–1) than that of the corresponding mononuclear complexes (1.3 × 10–5 s–1), which ascertain the requirement of two metal ions in close proximity for the binding of the nucleophilic OH and the phosphate group. 相似文献
16.
The oxidation of n-Bu2S by t-BuOOH in the presence ofthe catalysts [Mn2L2(MeCO2)2 (-O)] (ClO4)2 (L= Me3tacn=1,4,7–trimethyl-1,4,7–triazacyclononane) and VO(acac)2 has been studied using microemulsion media (BRIJ 97 and SD2 microemulsions). In the presence of the MnIII complex oxidation to the sulfone occurs, while in the presence of the VIV complex the sulfide is oxidised to the sulfoxide. The oxidation of mustard gas, (ClCH2CH2)2S, has also been studied. The reactions have been monitored by total internal reflectance i.r. spectroscopy. The use of optically transparent microemulsions provides a useful method for carrying out oxidations involving inorganic reagents and water-insoluble substrates. 相似文献
17.
Andrey I. Poddelsky Ivan V. Smolyaninov Aleksandra I. Shataeva Evgenii V. Baranov Georgy K. Fukin 《Molecules (Basel, Switzerland)》2022,27(19)
A series of binuclear triphenylantimony(V) bis-catecholato complexes 1–11 of the type (Cat)Ph3Sb-linker-SbPh3(Cat) was prepared by a reaction of the corresponding mononuclear catecholates (Cat)SbPh3 with a neutral bidentate donor linker ligands pyrazine (Pyr), 4,4′-dipyridyl (Bipy), bis-(pyridine-4-yl)-disulfide (PySSPy), and diazobicyclo[2,2,2]octane (DABCO) in a dry toluene: Cat = 3,6-di-tert-butyl-catecholate (3,6-DBCat), linker = Pyr (1); PySSPy (2); Bipy (3); DABCO (4); Cat = 3,5-di-tert-butyl-catecholate (3,5-DBCat), linker = Bipy (5); DABCO (9); Cat = 4,5-(piperazine-1,4-diyl)-3,6-di-tert-butylcatecholate (pip-3,6-DBCat), linker = Bipy (6); DABCO (10); Cat = 4,5-dichloro-3,6-di-tert-butylcatecholate (4,5-Cl2-3,6-DBCat), linker = Bipy (7); DABCO (11); and Cat = 4,5-dimethoxy-3,6-di-tert-butylcatecholate (4,5-(MeO)2-3,6-DBCat), linker = Bipy (8). The same reaction of (4,5-Cl2-3,6-DBCat)SbPh3 with DABCO in an open atmosphere results in a formation of 1D coordination polymer {[(4,5-Cl2-3,6-DBCat)SbPh3·H2O]·DABCO}n (12). Bis-catecholate complex Ph3Sb(Cat-Spiro-Cat)SbPh3 reacts with Bipy as 1:1 yielding a rare macrocyclic tetranuclear compound {Ph3Sb(Cat-Spiro-Cat)SbPh3∙(Bipy)}2 (13). The molecular structures of 1, 3, 4, 5, 8, 10, 12, and 13 in crystal state were established by single-crystal X-ray analysis. Complexes demonstrate different types of relative spatial positions of mononuclear moieties. The nature of chemical bonds, charges distribution, and the energy of Sb...N interaction were investigated in the example of complex 5. The electrochemical behavior of the complexes depends on the coordinated N-donor ligand. The coordination of pyrazine, Bipy, and PySSPy at the antimony atom changes their mechanism of electrooxidation: instead of two successive redox stages Cat/SQ and SQ/Cat, one multielectron stage was observed. The coordination of the DABCO ligand is accompanied by a significant shift in the oxidation potentials of the catecholate ligand to the cathodic region (by 0.4 V), compared to the initial complex. 相似文献
18.
The syntheses, spectroscopic and electrochemical properties of manganese (3), nickel (4) and iron (5) phthalocyanine complexes, octa-substituted at the peripheral positions with diethlyaminoethanethiol substituent, are reported. The electrochemistry of these complexes and the corresponding cobalt complex (6) are reported. Complex 3 showed two reversible reduction couples attributed to the MnIIIPc−2/MnIIPc−2 (E½ = −0.12 V versus Ag|AgCl) and MnIIPc−2/MnIIPc−3 (E½ = −0.82 V versus Ag|AgCl) species. Two ring-based reduction couples were also observed for complex 4. Two reduction couples, assigned to the FeIIPc−2/FeIPc−2 (E½ = −0.35 V versus Ag|AgCl) and FeIPc−2/FeIPc−3 (E½ = −0.96 V versus Ag|AgCl) species, and an oxidation couple, attributed to FeIIIPc−2/FeIIPc−2 (E½ = 0.26 V versus Ag|AgCl) species, were observed. For complex 6, two reductions and one oxidation were also observed with the potential range of 1.2 to −1.8 V versus Ag|AgCl Spectroelectrochemical studies were used to confirm some of the assigned processes. 相似文献
19.
Summary 2-Pyridylphenylacetonitrile (ppa) is oxidized by iron(III) chloride in dry ethanol to 1,2-dicyano-1,2-di(phenyl)-1,2-(2-pyridyl)ethane (dcppe). When 1,2-dichloroethane or ether are used as solvents, a 31 complex of dcppe with iron trichloride, [(FeCl3)3(dcppe)] is obtained.Titanium(IV), vanadium(IV) and chromium(III) chlorides react with ppa and dcppe, giving complexes of general formulae [MCl4(ppa)] (M = Ti or V), [CrCl3(ppa)n] (n = 2 or 3), [(MCl4)2(dcppe)] (M = Ti or V) and [CrCl3(dcppe)]. 相似文献
20.
Sugimoto H Tano H Miyake H Itoh S 《Dalton transactions (Cambridge, England : 2003)》2011,40(10):2358-2365
Electron transfer oxidation reaction of bis(dithiolene)monooxomolybdenum(iv) (Mo(IV)OL(x)) complexes is studied as a model of oxidative-half reaction of arsenite oxidase molybdenum enzymes. The reactions are revealed to involve proton-coupled electron transfer. Electrochemical oxidation of Mo(IV)OL(x) yields the corresponding bis(dithiolene)dioxomolybdenum(vi) complexes in basic solution, where the conversion of Mo(IV)OL(dmed) supported by a smaller electron donating dithiolene ligand (1,2-dicarbomethoxyethylene-1,2-dithiolate, L(dmed)) to Mo(VI)O(2)L(dmed) is faster than that of Mo(IV)OL(bdt) with a larger electron donating dithiolene ligand (1,2-benzenedithiolate, L(bdt)) under the same conditions. Titration experiments for the electrochemical oxidation reveal that the reaction involves two-electron oxidation and two equivalents of OH(-) consumption per Mo(IV)OL(x). In the conversion process of Mo(IV)OL(x) to Mo(VI)O(2)L(x), the five-coordinate bis(dithiolene)monooxomolybdenum(v) complex (Mo(V)OL(x)) being a one-electron oxidized species of Mo(IV)OL(x) is suggested to react with OH(-). Mo(V)OL(x) reacts with OH(-) in CH(3)CN or C(2)H(5)CN in a 2?:?2 ratio to give one equivalent Mo(IV)OL(x) and one equivalent Mo(VI)O(2)L(x), which is confirmed by the UV-vis and IR spectroscopies. The low temperature stopped-flow analysis allows investigations of the mechanism for the reaction of Mo(V)OL(x) with OH(-). The kinetic study for the reaction of Mo(V)OL(dmed) with OH(-) suggests that Mo(V)OL(dmed) reacts with OH(-) to give a six-coordinate oxo-hydroxo-molybdenum(v) species, Mo(V)O(OH), and, then, the resulting species undergoes successive deprotonation by another OH(-) and oxidation by a remaining Mo(V)OL(dmed) to yield the final products Mo(IV)OL(dmed) and Mo(VI)O(2)L(dmed) complexes in a 1?:?1 ratio. In this case, the Mo(V)O(2) species are involved as an intermediate in the reaction. On the other hand, in the reaction of Mo(V)OL(bdt) with OH(-), coordination of OH(-) to the Mo(V) centre to give a six-coordinate Mo(V)O(OH)L(bdt) species becomes the rate limiting step and other intermediates are not suggested. On the basis of these results, the ligand effects of the dithiolene ligands on the reactivity of the bis(dithiolene)molybdenum complexes are discussed. 相似文献