共查询到20条相似文献,搜索用时 31 毫秒
1.
Roth A Buchholz A Rudolph M Schütze E Kothe E Plass W 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(5):1571-1583
A series of bimetallic zinc(II) and nickel(II) complexes based on the novel dinucleating unsymmetric double-Schiff-base ligand benzoic acid [1-(3-{[2-(bispyridin-2-ylmethylamino)ethylimino]methyl}-2-hydroxy-5-methylphenyl)methylidene]hydrazide (H(2)bpampbh) has been synthesized and structurally characterized. The metal centers reside in two entirely different binding pockets provided by the ligand H(2)bpampbh, a planar tridentate [ONO] and a pentadentate [ON(4)] compartment. The utilized ligand H(2)bpampbh has been synthesized by condensation of the single-Schiff-base proligand Hbpahmb with benzoic acid hydrazide. The reaction of H(2)bpampbh with two equivalents of either zinc(II) or nickel(II) acetate yields the homobimetallic complexes [Zn(2)(bpampbh)(mu,eta(1)-OAc)(eta(1)-OAc)] (ZnZn) and [Ni(2)(bpampbh)(mu-H(2)O)(eta(1)-OAc)(H(2)O)](OAc) (NiNi), respectively. Simultaneous presence of one equivalent zinc(II) and one equivalent nickel(II) acetate results in the directed formation of the heterobimetallic complex [NiZn(bpampbh)(mu,eta(1)-OAc)(eta(1)-OAc)] (NiZn) with a selective binding of the nickel ions in the pentadentate ligand compartment. In addition, two homobimetallic azide-bridged complexes [Ni(2)(bpampbh)(mu,eta(1)-N(3))]ClO(4) (NiNi(N(3))) and [Ni(2)(bpampbh)(mu,eta(1)-N(3))(MeOH)(2)](ClO(4))(0.5)(N(3))(0.5) (NiNi(N(3))(MeOH)(2)) were synthesized. In all complexes, the metal ions residing in the pentadentate compartment adopt a distorted octahedral coordination geometry, whereas the metal centers placed in the tridentate compartment vary in coordination number and geometry from square-planar (NiNi(N(3))) and square-pyramidal (ZnZn and NiZn), to octahedral (NiNi and NiNi(N(3))(MeOH)(2)). In the case of complex NiNi(N(3)) this leads to a mixed-spin homodinuclear nickel(II) complex. All compounds have been characterized by means of mass spectrometry as well as IR and UV/Vis spectroscopies. Magnetic susceptibility measurements show significant zero-field splitting for the nickel-containing complexes (D=2.9 for NiZn, 2.2 for NiNi(N(3)), and 0.8 cm(-1) for NiNi) and additionally a weak antiferromagnetic coupling (J=-1.4 cm(-1)) in case of NiNi. Electrochemical measurements and photometric titrations reveal a strong Lewis acidity of the metal center placed in the tridentate binding compartment towards external donor molecules. A significant superoxide dismutase reactivity against superoxide radicals was found for complex NiNi. 相似文献
2.
Ulrich J. Scheele 《Tetrahedron letters》2007,48(47):8366-8370
One or two imidazolium groups have been attached to the 3- and 6-positions of the pyridazine heterocycle, providing valuable precursors for mono- and binucleating NHC/pyridazine hybrid ligands. For N-methyl imidazole with specific backbone substituents an unexpected methyl group transfer is observed, which defines the scope of the synthetic procedure. H-Bonding patterns in the solid state are elucidated by X-ray crystallography for seven chloride or salts of the new compounds. 相似文献
3.
Kawai H Takeda T Fujiwara K Suzuki T 《Journal of the American Chemical Society》2005,127(35):12172-12173
The intramolecular triarylmethane-methylium complex with an averaged C2v-symmetry was successfully generated by N-methylation of the acridine-acridan hybrid. Theoretical calculation and VT-NMR analyses in solution indicate the unsymmetric geometry for the three-center bond, which was finally confirmed crystallographically. Significant degree of CT interaction is induced through the very short C-H...C+ contact. 相似文献
4.
Michaud G Bulliard M Ricard L Genêt JP Marinetti A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(15):3327-3330
MeO-NAPhePHOS represents the first example of a new series of atropisomeric diphosphines bearing heterotopic biaryl moieties. The key step of its synthesis is the diastereoselective, intramolecular, Cu(I)-promoted coupling of 1-iodonaphthol and 2-iodo-3-methoxyphenol connected by a chiral tether. (R,R)-2,4-Pentanediol is used as the chiral auxiliary in this highly selective reaction that leads to a single enantiomer of the title diphosphine. In the Ru-promoted hydrogenations of carbonyl derivatives, NAPhePHOS affords enantioselectivity levels fully comparable to those of the C(2)-symmetrical analogues, BINAP and MeO-BIPHEP respectively, thus showing that the lack of C(2) symmetry is not detrimental to the catalytic properties of atropisomeric ligands in these hydrogenation reactions. 相似文献
5.
Arzu Özel Kaan Karaoğlu Nihan Gürcan Mustafa Emirik Ufuk Çoruh 《Journal of Coordination Chemistry》2016,69(10):1587-1601
Ferrocenyl-substituted unsymmetrical azine and its Cu(II) complex were prepared. The redox active ferrocene-based azine was obtained by condensation of 1-[(E)-hydrazono]-5-bromo-2-hydroxybenzene with ferrocene carboxaldehyde. The ferrocenyl ligand and its Cu(II) complex were characterized by IR, UV–vis, NMR, X-ray, magnetic susceptibility, molar electrical conductivity measurements, and TG techniques. The redox behaviors of the ferrocene compounds were investigated by cyclic voltammetry. Structural parameters and spectroscopic properties of the ligand and the Cu(II) complex were calculated by employing density functional theory (DFT) and time-dependent DFT and compared with available experimental data. We found slightly stronger binding ability for Cu(II) complex than the free ligand. DNA binding abilities for ferrocenyl-substituted unsymmetrical azine ligand and its Cu(II) complex are higher than some reported ferrocene compounds. We also studied DNA cleavage, superoxide and DPPH radical scavenging abilities of the compounds. Furthermore, the synthesized organometallic compounds can be bound to DNA through an intercalative mode. 相似文献
6.
Photochromic and luminescence switching properties of a versatile diarylethene-containing 1,10-phenanthroline ligand and its rhenium(I) complex 总被引:1,自引:0,他引:1
A versatile bis(2,5-dimethyl-3-thienyl)-1,10-phenanthroline photochromic ligand has been successfully synthesized via a Suzuki cross-coupling reaction. The excitation wavelength for photochromic reaction of the dithienylphenanthroline could be extended from lambda = 340 nm in the UV region to ca. 480 nm in the visible region, corresponding to the MLCT excitation, through the incorporation into the rhenium(I) tricarbonyl system. Reversible switching of the emissive state by the photochromic reaction has also been demonstrated. 相似文献
7.
Qiu L Kwong FY Wu J Lam WH Chan S Yu WY Li YM Guo R Zhou Z Chan AS 《Journal of the American Chemical Society》2006,128(17):5955-5965
A series of chiral diphosphine ligands denoted as PQ-Phos was prepared by atropdiastereoselective Ullmann coupling and ring-closure reactions. The Ullmann coupling reaction of the biaryl diphosphine dioxides is featured by highly efficient central-to-axial chirality transfer with diastereomeric excess >99%. This substrate-directed diastereomeric biaryl coupling reaction is unprecedented for the preparation of chiral diphosphine dioxides, and our method precludes the tedious resolution procedures usually required for preparing enantiomerically pure diphosphine ligands. The effect of chiral recognition was also revealed in a relevant asymmetric ring-closure reaction. The chiral tether bridging the two aryl units creates a conformationally rigid scaffold essential for enantiofacial differentiation; fine-tuning of the ligand scaffold (e.g., dihedral angles) can be achieved by varying the chain length of the chiral tether. The enantiomerically pure Ru- and Ir-PQ-Phos complexes have been prepared and applied to the catalytic enantioselective hydrogenations of alpha- and beta-ketoesters (C=O bond reduction), 2-(6'-methoxy-2'-naphthyl)propenoic acid, alkyl-substituted beta-dehydroamino acids (C=C bond reduction), and N-heteroaromatic compounds (C=N bond reduction). An excellent level of enantioselection (up to 99.9% ee) has been attained for the catalytic reactions. In addition, the significant ligand dihedral angle effects on the Ir-catalyzed asymmetric hydrogenation of N-heteroaromatic compounds were also revealed. 相似文献
8.
Two new inorganic–organic coordination networks based on a versatile and unsymmetric building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) and inorganic CoII and CdII salts have been synthesized in mixed solvent media and structurally characterized by single-crystal X-ray diffraction analysis. Crystal Hpot (1) was obtained from methanol solution. Reaction of Co(NO3)2 · 6H2O with Hpot afforded a neutral two-dimensional (2-D) porous coordination polymer {[Co(pot)2] · 6H2O}n (2) with a (4,4) network, which shows a 3-D supramolecular network through O–H?O weak interactions. While substituting the transition metal ions used in 2 with Cd(NO3)2 · 6H2O, a neutral 2-D coordination polymer [Cd2(pot)4]n (3) with a (6,3) network which further extended to a 3-D supramolecular structure through versatile hydrogen bonds C–H?X (X = O, N and S) was obtained. It is remarkable that the building block “pot” anion exhibits versatile coordination modes in complexes 2 and 3. These results indicate that the versatile nature of this rigid unsymmetric ligand, together with the coordination preferences of the metal centers, plays a critical role in construction of novel coordination polymers. The properties of gas absorption, magnetism and luminescence of 2 and 3 have been investigated and discussed in detail. 相似文献
9.
Chung KH So CM Wong SM Luk CH Zhou Z Lau CP Kwong FY 《Chemical communications (Cambridge, England)》2012,48(14):1967-1969
A new class of easily accessible hemilabile benzimidazolyl phosphine ligands has been developed. The ligand skeleton is prepared from commercially available and inexpensive o-phenylenediamine and 2-bromobenzoic acid. With catalyst loading down to 0.5 mol% palladium, excellent catalytic activity towards the Suzuki-Miyaura coupling of aryl mesylates is still observed. This represents the lowest catalyst loading achieved so far for this reaction in general. X-Ray crystallography shows that new ligand L2 is coordinated with Pd in a κ(2)-P,N fashion. 相似文献
10.
Two new thiosemicarbazone-pyridylhydrazine (THYNIC) hybrid ligands have been synthesized. Copper(II) and copper(I) complexes of the ligands have been prepared and characterized by X-ray crystallography. Cyclic voltammetry measurements show that the copper(II) complexes undergo quasi-reversible reductions at biologically accessible potentials. One of the ligands, bearing a pendant carboxylate arm, has been conjugated to N-alpha-(tert-butoxycarbonyl)-L-lysine. 相似文献
11.
Y. G. Li X. W. Dong R. Ai X. L. Xu H. L. Zhu 《Russian Journal of Coordination Chemistry》2011,37(7):523-527
The crystal structures of cobalt(II) Schiff base complex (CoIIL2 · H2O) and Schiff base ligand 3,5-dichlorosalicylidene-2-chlorophenylmethylamine (HL) have been determined by single-crystal X-ray analysis. The geometry around cobalt in CoIIL2 · H2O is distorted tetrahedral. CoIIL2 · H2O crystallizes in the monoclinic system, in space group C2/c, with crystallographic parameters: a = 12.9143(16) Å, b = 8.8326(16) Å, c = 25.115(3) Å, β = 92.791(10)°, V = 2861.4(7) Å3, Z = 4, F(000) = 1420, and the final R indices (I > 2σ(I)) are R 1 = 0.0440, wR 2 = 0.1272. HL crystallizes in the monoclinic system, in space group P21/c, with crystallographic parameters: a = 11.9764(15), b = 8.2331(10), c = 14.2211(17) Å, β = 98.723(6)°, V = 1386.0(3) Å3, Z = 4, F(000) = 640, and the final R indices (I > 2σ(I)) are R 1 = 0.0397, wR 2 = 0.1018. 相似文献
12.
The Schiff base ligands 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (L1, monoclinic, P2(1)/c, a = 3.856(1) A, b = 11.032(2) A, c = 12.738(3) A, beta = 92.21(3) degrees, Z = 2) and 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (L2, monoclinic, P2(1)/c, a = 10.885(2) A, b = 4.613(1) A, c = 14.978(3) A, beta = 92.827(4) degrees, Z = 2) were used in the synthesis of four new organic-inorganic coordination polymers, each of them adopting a different structural motif. Synthesis, X-ray structural determinations, and spectroscopic and thermogravimetric analyses are presented. The reaction between Co(NO(3))(2).6H(2)O and L1 afforded a two-dimensional noninterpenetrating brick-wall structure, [Co(C(12)N(4)H(10))(1.5)(NO(3))(2)(H(2)O)(CH(2)Cl(2))(2)](n)() (1, triclinic, P1; a = 10.242(7) A, b = 10.802(7) A, c = 15.100(1) A, alpha = 70.031(1), beta = 75.168(11), gamma = 76.155(11), Z = 2), while Ni(NO(3))(2).6H(2)O combined with L1 yielded an interpenetrating three-dimensional rhombus-grid polymer, [Ni(C(12)N(4)H(10))(2)(NO(3))(2)(OC(4)H(8))(1.66)(H(2)O)(0.33)](n) (2, monoclinic, C2/c; a = 20.815(8) A, b = 23.427(8) A, c = 17.291(6) A, beta = 116.148(6), Z = 8). The reaction of Co(NO(3))(2).6H(2)O and L2 was found to be solvent-sensitive and resulted in the formation of two different noninterpenetrating compounds: [Co(C(14)N(4)H(14))(2)(NO(3))(2)(C(6)H(6))(1.5)](n)() (3, monoclinic, C2/c; a = 22.760(2) A, b = 21.010(3) A, c = 25.521(2) A, beta = 97.151(2), Z = 8), which adopts a two-dimensional square-grid motif formed by propeller-type modules, and [Co(C(14)N(4)H(14))(1.5)(NO(3))(2)(CH(2)Cl(2))(2)](n)() (4, monoclinic, P2(1)/n; a = 14.432(2) A, b = 14.543(8) A, c = 15.448(4) A, beta = 96.968(0), Z = 4), consisting of T-shaped building blocks assembled into a one-dimensional ladder-type structure. These four coordination polymers all exhibit impressive thermal stability. Thermogravimetric studies showed that after complete removal of the solvents, the frameworks are stable to temperatures between 234 degrees C and 260 degrees C. 相似文献
13.
Tahir AA Molloy KC Mazhar M Kociok-Köhn G Hamid M Dastgir S 《Inorganic chemistry》2005,44(25):9207-9212
Ba(dmae)2 (dmaeH=N,N-dimethylaminoethanol, C4H11NO) reacts with Co(acac)2 (acac=2,4-pentanedionate) to produce the trinuclear coordination complex [Ba2Co(acac)4(dmae)3(dmaeH)] in an 85% yield. Spectroscopic and single-crystal X-ray diffraction experiments indicate that the complex possesses a structure in which two barium atoms and a cobalt atom are bridged by acac and dmae groups. The barium centers are eight and nine coordinate with BaO7N and BaO7N2 coordination spheres while the cobalt is a more regular CoO5N octahedron. This 2:1 heterobimetallic molecular complex was investigated as precursor for the deposition of thin film by AACVD. The film was characterized by SEM and XRD. TGA shows that the complex starts thermal decomposition upon heating in nitrogen atmosphere at 105 degrees C to produce barium cobalt oxide material of a Ba2CoO3 composition with an orthorhombic structure. The synthetic approach detailed here represents a unique route to the formation of a heterobimetallic barium cobalt coordination complex. 相似文献
14.
Clentsmith GK Gibson VC Hitchcock PB Kimberley BS Rees CW 《Chemical communications (Cambridge, England)》2002,(14):1498-1499
Addition of MeLi to bis(imino)pyridines results in an unprecedented nucleophilic attack at pyridine nitrogen to afford novel mono-anionic [N,N,N] ligands: their treatment with FeCl3, followed by MAO activation, affords highly active ethylene polymerisation catalysts. 相似文献
15.
A palladium-catalyzed oxidative C-H bond functionalization/ortho-acylation of acetanilides using easily accessible aldehyde as the acyl source is described. In the presence of a Pd(TFA)(2) catalyst and tert-butylhydroperoxide at 90 °C in general, an array of ortho-acylacetanilides can be afforded in good yields. 相似文献
16.
The reactivity of 1,5-bis(trimethylsilyl)propargylic ethers 3 toward bases and electrophiles was investigated. Bispropargylic ethers 4, substituted allenyne ethers 6-8, and alpha-substituted bispropargylic ethers 9 were prepared in good yields, respectively, by protodesilylation, isomerization, or metalation/alkylation of bispropargylic protected alcohol 3. The ambident behavior of metalated synthon 3 was discussed and rationalized. Removal of the protecting groups of 9 easily afforded useful alpha-substituted bispropargylic alcohol. 相似文献
17.
Ismail Yilmaz 《Transition Metal Chemistry》2008,33(2):259-265
The new asymmetric, fluorescent Schiff-base ligand, N-(pyrene)-salicylaldimine (L), and its copper complex having an ONNO donor set, [Cu(L)
2
], were synthesized and characterized using elemental analysis, IR, UV-vis, 1H and 13C-NMR spectroscopies. Their electrochemical and spectroelectrochemical behaviors were investigated in a detail by using cyclic
voltammetry (CV), square wave voltammetry (SWV), in-situ UV-vis, and fluorescence spectroelectrochemistry. The formation of
the complex was monitored by the in-situ fluorescence technique based on the quenching of the fluorescence-probe ligand. Electrochemical
studies showed that L exhibits a single irreversible reduction process. However, the SWV indicated that this process was not totally irreversible
in the time scale of the measurement. The cathodic peak potential of the reduction process occurred at E
pc = −1.35 V vs Ag/AgCl (scan rate: 0.025 Vs−1). On the other hand, [Cu(L)
2
] showed one quasi-reversible one-electron reduction process in the scan rates of 0.025–0.50 Vs−1, which was assigned to metal-based one-electron process; [Cu(2+)(L)2] + e− → [Cu(+)(L)2]−. The value of half-wave potential (E
1/2) of the reduction process was −0.54 V vs Ag/AgCl (scan rate: 0.025 Vs−1). The time-resolved spectra showed, when the potential (E
app = −1.60 V) was applied in a thin-layer cell, that the main and shoulder bands of (L) at 385, 336, and 407 nm almost disappeared and a new band at 443 nm with a shoulder formed during the reduction process. No
change was observed on the final spectrum of the totally reduced ligand for long period under nitrogen atmosphere, which indicated
that the singly reduced species remained stable and was not accompanied by a chemical reaction in the time scale of the spectroelectrochemical
measurement. The spectral changes during the reduction process of [Cu(L)
2
] confirmed the metal-centered reduction process. The fluorescence intensity of L decreased during the reduction process in the thin-layer cell, as result of the perturbation of the conjugated system of
the reduced species. 相似文献
18.
The preparation of porous polymer monoliths with dodecyl and zwitterionic functionalities via the "thiol-ene" click chemistry of thiol-containing monoliths with both hydrophobic and polar methacrylate "ene" monomers has been demonstrated. Selected separations confirmed the excellent potential of these monoliths in chromatography. 相似文献
19.
Noel R. Russell Mary McNamara 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(4):455-460
Changes occurring in the FT-IR and Raman spectra of-CD when complexed to Mn(III), in a compound formulated as Mn2(OH)2CD, may be taken as indicating the formation of a complex in which-CD is acting simultaneously as a first and second sphere ligand. 相似文献
20.
《Journal of organometallic chemistry》2005,690(24-25):5576-5580
The new bis(imidazolylidene) tripodal ligand precursor (2-pyridine)bis(3-methylimidazolium-1-yl)methane diiodide, [H2PYBIMMe]I2, has been obtained by a simple method. The molecular structure of this new ligand precursor has been determined by means of X-ray diffraction. The coordination of this ligand to Rh, provides a Rh(III) complex with very low solubility in most solvents, which we attributed to the polymeric nature of the species. Solution of this polymer in DMSO provided a biscarbene Rh(III) complex in which the pyridine fragment remained unbound. 相似文献