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1.
A series of binuclear CuII complexes [Cu2XL] n+ having two copper(II) ions bridged by different motifs (X = OH, MeCO2 , or Cl) have been prepared using the ligands: H2L1 = 4-methyl-2-[N-(2-{dimethylamino}ethyl-N-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H2L2 = 4-nitro-2-[N-(2-{dimethylamino}ethyl-N-methyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol, H2L3 = 4-methyl-2-[N-(2-{diethylamino}ethyl-N-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol and H2L4 = 4-nitro-2-[N-(2-{diethylamino}ethyl-N-ethyl)aminomethyl]-6-[(prolin-1-yl)methyl]phenol. The complexes have been characterized by spectroscopic, analytical, magnetic and electrochemical measurements. Cryomagnetic investigations (80–300 K) revealed anti-ferromagnetic exchange between the CuII ions (–2J in the range –50 to –182 cm–1). The strength of anti-ferromagnetic coupling lies in the order: OAc > OH > Cl. Cyclic voltammetry revealed the presence of two redox couples, assigned to CuII/CuII/CuII/CuI/CuI/CuI. The first reduction potential is sensitive to electronic effects from the aromatic ring substituents and steric effect on the donor nitrogens (side arm) of the ligand systems.  相似文献   

2.
Binuclear CuII complexes having new flexible heptadentate ligands 2,6-bis{[bis(3,3-N,N-dimethylaminopropyl)amino]methyl}-4-bromophenol [HL1], 2,6-bis(3,3-N,N-dimethylaminopropyl)amino]methyl}-4-methylphenol [HL2], and 2,6-bis{[bis(3,3-N,N-dimethylaminopropyl)amino]methyl}-4-methoxyphenol [HL3], capable of assembling two copper ions in close proximity have been synthesized. Comparisons of the charge-transfer (CT) features, observed in electronic spectra of these complexes, are correlated with the electronic effect on the aromatic ring of the ligand systems. Cyclic voltammetry has revealed the existence of two reduction couples,
The first is sensitive to the electronic effects of aromatic ring substituents of the ligand system, shifting to more positive potentials when more electrophilic groups replace the existing substituents. The conproportionation constants (k con) for the mixed valent CuICuII complexes have been determined electrochemically. The magnetic susceptibilities of the complexes have been measured over the 70–300 K range and the exchange coupling parameter (–2J) determined by a least squares fit of the data which indicates an antiferromagnetic spin exchange (–2J = 94–172 cm–1) between the CuII ions with bridging units in the order: N3 NO2 > OAc > OH.  相似文献   

3.
Preparation of pentadentate ligands L1, L2, L3 and L4, where L1 = 4-chloro-3-methyl-2[(prolin-1-yl)methyl]-6-[N-phenyl piperazin-1-yl)methyl]phenol, L2 = 4-ethyl-2-[(prolin-1-yl)methyl]-6-[(N-phenyl piperazin-1-yl)methyl]phenol, L3 = 4-chloro-3-methyl-2-[(prolin-1-yl)methyl]-6-[N-methyl piperazin-1-yl]methyl phenol, L4 = 4-methoxy-2-[(prolin-1-yl)methyl]-6-[(N-phenyl piperazin-1-yl)methyl]phenol is described together with that of the corresponding Cu(II) complexes with various bridging motifs like OH, OAc and NO2. The complexes are characterized by elemental analysis, electrochemical and electron paramagnetic spectral studies. Redox properties of the complexes in acetonitrile are highly quasireversible due to the chemical or/and stereochemical changes subsequent to electron transfer. The complexes show resolved copper hyperfine EPR at room temperature, indicating the presence of weak antiferromagnetic coupling between the copper atoms. Strengths of the antiferromagnetic interactions are in the order NO2>OAc>OH.  相似文献   

4.
The synthesis, reduction, optical and e.p.r. spectral properties of a series of new binuclear copper(II) complexes, containing bridging moieties (OH, MeCO2 , NO2 , and N3 ), with new proline-based binuclear pentadentate Mannich base ligands is described. The ligands are: 2,6-bis[(prolin-1-yl)methyl]4-bromophenol [H3L1], 2,6-bis[(prolin-1-yl)methyl]4-t-butylphenol [H3L2] and 2,6-bis[(prolin-1-yl)methyl]4-methoxyphenol [H3L3]. The exogenous bridging complexes thus prepared were hydroxo: [Cu2L1(OH)(H2O)2] · H2O (1a), [Cu2L2(OH)(H2O)2] · H2O (1b), [Cu2L3(OH)(H2O)2] · H2O (1c), acetato [Cu2L1(OAc)] · H2O (2a), [Cu2L2(OAc)] · H2O (2b), [Cu2L3(OAc)] · H2O (2c), nitrito [Cu2L1(NO2)(H2O)2] · H2O (3a), [Cu2L2(NO2)(H2O)2] · H2O (3b), [Cu2L3(NO2)(H2O)2] · H2O (3c) and azido [Cu2L1(N3)(H2O)2] · H2O (4a), [Cu2L2(N3)(H2O)2] · H2O (4b) and [Cu2L3(N3)(H2O)2] · H2O (4c). The complexes were characterized by elemental analysis and by spectroscopy. They exhibit resolved copper hyperfine e.p.r. spectra at room temperature, indicating the presence of weak antiferromagnetic coupling between the copper atoms. The strength of the antiferromagnetic coupling lies in the order: NO2 N3 OH OAc. Cyclic voltammetry revealed the presence of two redox couples CuIICuII CuIICuI CuICuI. The conproportionality constant K con for the mixed valent CuIICuI species for all the complexes have been determined electrochemically.  相似文献   

5.
Hong  Xian-Lan  Chao  Hui  Wang  Xiang-Li  ji  Liang-Nian  li  Hong 《Transition Metal Chemistry》2004,29(5):561-565
Two novel RuII complexes [Ru(dppt)(bpy)Cl]ClO4 (1) and [Ru(pta)(bpy)Cl]ClO4 (2)[dppt, pta and bpy = 3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazine, 3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]acenaphthylene and 2,2-bipyridine, respectively] were synthesized and characterized by elemental analysis and electrospray mass spectrometry, 1H-n.m.r., and u.v.–vis spectroscopy. The redox properties of the complexes were examined using cyclic voltammetry. Due to the strong -accepting character of asymmetric ligands, the MLCT bands of (1) and (2) are shifted significantly to lower energies by comparison with [Ru(tpy)(bpy)Cl]+.  相似文献   

6.
Two cyano-bridged assemblies, [FeIII(salpn)]2[FeII(CN)5NO] (1) and [FeIII (salpn)]2[NiII(CN)4] (2) [salpn = N, N-1,2-propylenebis(salicylideneiminato)dianion], have been prepared and structurally and magnetically characterized. In each complex, [Fe(CN)5NO]2– or [Ni(CN)4]2– coordinates with four [Fe(salpn)]+ cations using four co-planar CN ligands, whereas each [Fe(salpn)]+ links two [Fe(CN)5NO]2– or [Ni(CN)4]2– ions in the trans form, which results in a two-dimensional (2D) network consisting of pillow-like octanuclear [—MII—CN—FeIII—NC—]4 units (M = Fe or Ni). In complex (1), the NO group of [Fe(CN)5NO]2– remains monodentate and the bond angle of FeII—N—O is 180.0°. The variable temperature magnetic susceptibilities, measured in the 5–300 K range, show weak intralayer antiferromagnetic interactions in both complexes with the intramolecular iron(III)iron(III) exchange integrals of –0.017 cm–1 for (1) and –0.020 cm–1 for (2), respectively.  相似文献   

7.
New picoline adducts with carbamic acid [(furan-2-yl)methylene]hydrazide–CuII (CFMH) (1); thiocarbamic acid [(furan-2-yl)methylene]hydrazide–CuII (TFMH) (2); carbamic acid [(furan-2-yl)ethylidene]hydrazide–CuII (CFEH) (3), thiocarbamic acid [(furan-2-yl)ethylidene]hydrazide–CuII (TFEH) (4); carbamic acid [(thiophene-2-yl) methylene]hydrazide–CuII (CTMH) (5), thiocarbamic acid [(thiophene-2-yl)methylene]hydrazide–CuII (TTMH) (6), carbamic acid [(thiophene-2-yl)ethylidene]hydrazide–CuII (CTEH) (7), thiocarbamic acid [(thiophene-2-yl)ethylidene]hydrazide–CuII (TTEH) (8) have been prepared and characterized by analytical, i.r., electronic, e.s.r. and c.v. spectral data. The electronic spectra suggest distorted octahedral geometry for all the picoline adducts. E.s.r. g values lie between 2.251–2.286 at l.n.t. All the adducts undergo a quasi-reversible one-electron reduction in the range +0.47 to +0.51 V versus s.c.e., attributable to the CuIII/CuII redox couple. The electron transfer is much faster in the semicarbazone complexes than in the thiosemicarbazone complexes. All adducts showed increased nuclease activity in the presence of oxidant; the nuclease activity is compared with that of the parent copper(II) complexes.  相似文献   

8.
The condensation of the potassium salt of thiazolidine-2,4-dione with bis(-chloro-ethyl) sulfide leads to bis[-(thiazolidine-2,4-dion-3-yl)ethyl]sulfide, which is readily oxidized by H2O2 to bis[-(thiazolidine-2,4-dion-3-yl)ethyl]sulfoxide. Products of condensation of the latter with oxo compounds were obtained. The structures of the synthesized compounds were proved by their UV and IR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 48–50, January, 1981.  相似文献   

9.
A chiral Schiff base ligand (H2L) was obtained by condensing 2-hydroxynaphthalene-1-carbaldehyde with substituted (1R,2R)-(–)-diaminocyclohexane. Chiral Schiff base complexes [CuL], [NiL], [ZnL] and [MnLOH] have been synthesized and characterized by elemental analyses, M, i.r., u.v.–vis. and 1H-n.m.r. and magnetic measurements.  相似文献   

10.
Two new diamines — [1,3-bis(5-phenyl-1,2,4-triazol-3-yl)-4,6-diamino]benzene and [1,3-di-(2-benzimldazolyl)-4,6-diamino]benzene — were synthesized from 4,6-dinitroisophthalic acid. Newheterocyclic systems — 3,5,9,11-tetraphenyl[benzo[1,2-a; 4,5-a]bis(1,2,4-triazolo[4,3-c]pyrimidine)] and 2,16-diphenyl[benzo[1,2-a;4,5-a']bis(pyrimido[1,6-a]benzimidazole)]—were obtained by reaction of the diamines with benzoyl chloride and subsequent cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1274–1277, September, 1977.  相似文献   

11.
1:1 and 2:1 palladium(II) complexes of egta4– (egta4– = glycine, N,N-(1,2-ethanediylbis)(oxy-2,1-ethanediyl)bis[N-carboxymethyl]) were prepared by 1:1 and 2:1 addition of K2PdCl4 to K4egta, and examined by 1H-, 13C- and 15N-n.m.r. methods. The 1:1 complex, [Pd(egta)]2– in solution, utilizes a square-planar coordination comprised of two nitrogen and two glycinato carboxylate donors of egta4–, leaving two glycinato carboxylates pendant. The complex has a cis-(R,S) stereochemistry which places both pendant carboxylates below the PdN2O2 square plane and the tether backbone of egta4– in the up, up sense above the same plane. The cis-(R,S) assignment was assisted by computer simulations of the 13C-n.m.r. spectrum for four possible isomers. Only cis-(R,S) and trans-(R,R) calculated 13C-spectra were compatible with the observed 13C-n.m.r. pattern. The HH NOESY spectrum of [Pd(egta)]2– detects long range coupling of the backbone –OCH2CH2O– linkage with both coordinated and pendant glycinato CH2 moieties. The cis-(R,S) isomer's tortional movements allow such contacts whereas a trans-(R,R) isomer does not. The 2:1 complex, [Pd2(egta)(H2O)2] in solution has an extended-chain structure with each palladium(II) center coordinated in the mer-iminodiacetate-like coordination with two bound glycinato-functionalities.  相似文献   

12.
Summary The copper(III)-imine-oxime complexes [CuIII(Enio)]+ and [CuIII(Pre)]+ {EnioH2 =N,N-ethylene bis(isonitrosoacetylacetoneimine) and PreH2 = N,N-propylene bis (isonitrosoacetylacetoneimine)} react very rapidly with iodide. The rate law under fixed conditions for the reaction is given by the equation: –d[CuIII]/dt = (2k2[I] + 2k3[I]2)[CuIII] The [CuIII(Enio)]+ reaction was pH-independent whereas the [Cu (Pre)]+ reaction rate increased with increasing pH. Both the k2 and the k3 pathways are believed to involve one-electron transfer. An inner-sphere mechanism may operate in the pathway, first-order in [I].  相似文献   

13.
Two complexes [PyH][Ni(Mnt)2] (I) and [QlH][Ni(Mnt)2] (II) (Mnt2– = maleonitriledithiolate, [PyH]+ = pyridinium, [QlH]+ = quinolinium) were synthesized and characterized by elemental analysis and IR spectra. ESR spectra of polycrystalline samples collected at room temperature are isotropic with g = 2.039 for Iand anisotropic with g z = 1.997, g y g x = 2.102 (g av = 2.068) for II. The magnetic susceptibility data of I and II have been measured in the temperature range of 2–300 K. The results obtained suggest the antiferromagnetic coupling interactions between neighboring Ni3+ ions for I and ferromagnetic coupling interactions for II, respectively. Based on the crystal structure analysis of I, the magnetic properties of two complexes were discussed.  相似文献   

14.
Summary The synthesis and principle properties of several novel tris[1-(4-X-phenyl)-4,4-dimethylpenta-1, 3-dionato]-iron(III) and manganese(III) complexes, where X=MeO, Me, H, F, Cl and NO2, are described. Magnetic susceptibility measurements in the 4.2–295 K range show a near Curie behaviour and a constant magnetic moment for manganese(III) complexes and for iron complexes, with X=F, Cl or NO2. Iron complexes with ligands having substituents: X=MeO, Me and H, show weak antiferromagnetic interaction (J=ca.–8 cm–1 for the two former compounds) and a decrease in magnetic moment with decreasing temperature. In both manganese(III) and iron(III) complexes the diketonate ligand can be easily replaced by chlorine. Equilibrium constants could be evaluated only for substitution of the third diketonate ligand by chloride in the iron complexes on the basis of spectrophotometric measurements. For manganese chelates, the replacement of the second diketonate by chloride is accompanied by reduction of manganese(III) manganese(II) and free organic radical formation is observed.  相似文献   

15.
A series of homoleptic complexes of hexacoordinate cobalt(II) and copper(II) complexes with 3,5-disubstituted homo- and heteroscorpionate tris(pyrazolyl)borate anionic ligands (Tp′) were synthesized, i.e. bis[hydrotris(3-phenyl,5-methylpyrazol-1-yl)borato]cobalt(II), bis[hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3-methyl,5-phenylpyrazol-1-yl)borato]cobalt(II) and bis[hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3-methyl,5-phenylpyrazol-1-yl)borato]copper(II) and their structures were elucidated crystallographically. The complexes were also formed spontaneously during attempted metathesis of the corresponding Tp′M(NCS) complexes into Tp′M(OOCCH(OH)CH3) complexes. In the case of the analogous conversion applied for the thiocyanato [hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3,5-dimethylpyrazol-1-yl)boratocobalt(II) complex with sodium carboxylates (lactate, pyruvate and 2-hydroxybutyrate), the cross-transfer of pyrazolyl residues between starting anionic ligands was observed resulting in formation of bis-ligand homo- and heteroleptic Tp′CoTp″ complexes, where Tp′, Tp″ were tris(pyrazolyl)borates composed of n 3(5)-phenyl,5(3)-methylpyrazolyl and (3−n) 3,5-dimethylpyrazolyl residues (n=0–3) identified by mass spectrometry. Metathesis of thiocyanate in thiocyanato hydrotris(3-phenyl,5-methylpyrazol-1-yl)boratocobalt(II) into pyruvate led to the isolation of stable the pyruvato hydrotris(3-phenyl,5-methylpyrazol-1-yl)boratocobalt(II) complex, the structure of which was determined crystallographically. The Tp′ ligands are η3 coordinated to metal ions in every case, whereas the pyruvate anion is coordinated through carboxylate and carbonyl oxygen atoms to the cobalt center. Two rotational isomers distinguishable by 1H NMR spectroscopy for the hexacoordinate bis[hydrobis(3-phenyl,5-methylpyrazol-1-yl)(3-methyl,5-phenylpyrazol-1-yl)borato]cobalt(II) complex were detected in solution.  相似文献   

16.
Two 2-terephthalate (tp) bridged complexes, [Cu2(tp)(pren)4](ClO4)2 (pren = 1,3-diaminopropane) (1) and [Ni2(tp)(pren)4(Him)2](ClO4)2 (Him = imidazole) (2), have been synthesized and characterized by X-ray single-crystal structural analysis. In the discrete dinuclear [Cu2(tp)(pren)4]2+ cation of complex (1), each CuII atom has a square-pyramidal geometry, being coordinated by four nitrogen atoms (avg. 2.031 Å) from two pren ligands at the basal plane and one oxygen atom [2.259(3) Å] from a bis-monodentate tp group at the axial position. In the discrete dinuclear [Ni2(tp)(pren)4(Him)2]2+ cation of complex (2), each NiII center is coordinated by five nitrogen atoms [Ni—N 2.069(3)–2.109(2) Å] from one Him group and two pren groups, and completed by one oxygen atom [Ni—O 2.138(3) Å] from a bis-monodentate tp group to furnish a distorted octahedron. Magnetic susceptibility studies show that the pair of metal atoms, although being separated by >11.5 Å, exhibit weak intramolecular antiferromagnetic interactions in complexes (1) (g = 2.07 and J = –3.4 cm–1) and (2) (g = 2.10 and J = –0.7 cm–1). The electrochemical behaviors of the complexes have also been studied by cyclic voltammogram processes.  相似文献   

17.
Summary Novel mixed-ligand copper(I) complexes of general formula [TPP–Cu–(L)Cl] or [TPPhos–Cu–(L)Cl], where TPP=triphenylphosphine, TPPhos=triphenylphosphate and L=imidazolidine-2-thione [Imt],N-propylimidazolidice-2-thione [PrImt],N-i-propylimidazolidine-2-thione [iPrImt], and 1,3-diazinine-2-thione [Diaz] and bis coniplexes of formula [(L)2CuCl] where L=[PrImt] and [iPrImt] have been prepared and characterized by electronic, vibrational and n.m.r. spectroscopy. The spectral data are consistent with S-donation of thiones. The magnitude of upfield shift in13Cn.m.r. of the thionreide carbon on complexation has been interpreted in terms of coordination geometry around the metal stoms. X-ray structure analysis agrees with the conclusions from the spectroscopic measurements. The structure of [(PrImt)2CuCl] revealed three-coordinated copper(I) with crystal data:a=14.106(4),b=14.380(2),c=19.024(3) A, =108.8(2)°,z=8 and space group P2/c.  相似文献   

18.
    
Zusammenfassung Probleme der schnellen Flüssigkeits-Chromatographie mit Eingangsdrucken bis 300 at werden diskutiert. Eine Näherungsformel für die Abschätzung der Permeabilität gepackter Säulen (Teilchengröße 30 bis 200 m) wird vorgeschlagen. Vor- und Nachteile verschiedenartiger Hochdruckpumpen werden zusammengefaßt. Eine einfache Regelanordnung zur Glättung der Pumpenpulsation, ein Regelsystem für Druckprogrammierung und ein System für das Einspritzen der Proben unter hohem Druck werden beschrieben. Eine blasenfreie Förderung der Flüssigkeit ohne Entgasen derselben konnte erreicht werden. Die Bandenverbreiterung innerhalb und außerhalb der Kolonne wird besprochen. Die Detektoren werden nach der Art der Anzeige und der Empfindlichkeit klassifiziert.
Summary Problems of speedy liquid chromatography with inlet pressures up to 300 at are discussed. An approximation formula is given for the estimation of the permeability of packed columns with particle sizes between 30–200 m. Advantages and disadvantages of different types of high pressure pumps are summarized. Simple controlling equipments for smoothing the pulsation of high pressure pumps, a device for pressure program and a sample injection system are described. A gas-bubble free flow was achieved without degassing the liquid. Peak broadening effects inside and outside the column are calculated. The detectors are classified due to the kind of their recording and that of their sensitivity.

Symbolverzeichnis at 1 Kilopond/cm2 Druck - c Konzentration - d p Teilchengröße des Trägermaterials [cm] - h Bandenverbreiterung in der Kolonne, HETP [cm] - h gem. L(w/4t R)2 = gemessene Bandenverbreiterung, [cm] - h z r 224DL = Bandenverbreiterung in der Zuleitung, bezogen auf die Kolonnenlänge [cm] - f Pumpfrequenz [sec–1] - l Länge der Zuleitung [cm] - m Masse - p Druckabfall an der Kolonne [1 at = 9,81 · 105 dyn/cm2] - r Radius [cm] - t Zeit - t R Retentionszeit [sec] - u lineare Geschwindigkeit der mobilen Phase [cm] - w Bandenbreite, Achsenschnitt der Wendetangenten an der Basislinie [sec] - C pneumatische Kapazität [cm/dyn oder cm3/at] - D Interdiffusionskoeffizient [cm2sec–1] - F Volumengeschwindigkeit der mobilen Phase [cm3sec–1] - K Permeabilitätskonstante oder Permeabilität [cm2] - L Kolonnenlänge [cm] - V Volumen - Porosität - Viscosität der beweglichen Phase [poise] - 2 Varianz der Bande in Längeneinheiten [cm] Die Autoren möchten der Deutschen Forschungsgemeinschaft, Bad Godesberg, für finanzielle Unterstützung danken, mit der diese Arbeit durchgeführt werden konnte.  相似文献   

19.
A series of mononuclear MnII and MnIV complexes of general formulae [MnL2(NCS)2] (1a1d) and [Mn(L)2(NCS)2] (2a2c) have been prepared where L are Schiff bases obtained by the condensation of pyridine-2-aldehyde with para-alkyl-substituted aniline, and L are the corresponding amide ligands. The room temperature magnetic susceptibility data of (1a–1d) indicate that MnII is in a high spin state. The cyclic voltammograms of (1a–1d) exhibit a one-electron quasi-reversible MnIIMnIII oxidation. A linear correlation has been found when E0[MnIII/MnII] is plotted against Hammett p parameters. X-ray crystallographic data of (1b) shows that the central MnII ion adopts a distorted octahedral geometry with six different Mn–N distances. Upon oxidation of MnII complexes (1b–1d) by H2O2, the corresponding MnIV complexes (2a–2c) were obtained, and the Schiff base ligands were oxidized to the corresponding amides. The lowest energy LMCT bands of these MnIV complexes correlate linearly with Hammett p parameters. The redox behavior of the MnIV complexes has been investigated by cyclic voltammetry. E.p.r. spectra of the MnII and MnIV complexes are also reported.  相似文献   

20.
Cobalt(II) complexes of the Schiff bases 1,2-(diimino-4-antipyrinyl)ethane (GA) and 4-N-(4-antipyrylmethylidene)aminoantipyrine (AA) have been prepared and characterised by elemental analysis, electrical conductance in non-aqueous solvents, i.r. and electronic spectra, as well as by magnetic susceptibility measurements. The complexes have the general formulae [Co(GA)X]X (X = ClO 4 or NO3 ), [Co(GA)X2] (X = Cl, Br or I), [Co(AA)2]X2 (X = ClO4 , NO3 , Br or I) and [Co(AA)Cl2]. GA acts as a neutral tetradentate ligand, coordinating through both carbonyl oxygens and both azomethine nitrogens. In the perchlorate and nitrate complexes of GA one anion is coordinated in a bidentate fashion, whereas in the halide complexes both anions are coordinated to the metal, generating an octahedral geometry around the Co ion. AA acts as a neutral bidentate ligand, coordinating through the carbonyl oxygen derived from the aldehydic moiety and the azomethine nitrogen. Both anions remain ionic in the perchlorate, nitrate, bromide and iodide complexes of AA, whereas both anions are coordinated to the metal ion in the chloride complex, resulting tetrahedral geometry around the Co ion.  相似文献   

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