Electrospray ionization mass spectrometry of metal complexes. Gas phase formation of a binuclear copper(II)–5-Br-PADAP complex

The complexes formed from copper(II) and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP or HL) in aqueous methanol solution was studied by electrospray ionization mass spectrometry. The solution of a 1:1 complex of Cu(II) with 5-Br-PADAP showed five peaks assignable to a binuclear complex [Cu₂L₂(AcO)]⁺ and mononuclear complexes [CuL]⁺, [CuL(H₂O)]⁺, [CuL(AcOH)]⁺ and [CuL(HL)]⁺ (AcO=acetate). Collision activated dissociation revealed the relative order of bonding strengths; Cu–L>Cu–HL>CuL–AcOH>CuL–H₂O. The peak intensities of the binuclear complex showed second-order dependency on those of the mono complex. As for the solution of Ni(II)–5-Br-PADAP, no binuclear complex was observed in the mass spectra. Thus, it was suggested that [Cu₂L₂(AcO)]⁺ was formed by the fast gas phase reaction: 2[CuL]⁺+AcO⁻[Cu₂L₂(AcO)]⁺.     

On the positronium spin conversion reactions caused by some macrocyclic Co complexes

The rate constants, k_CR, of ortho- into para-positronium (o-Ps→p-Ps) spin conversion reactions, CR, caused by the high-spin [Co^IIsep]²⁺, [Co^IIdinosar]²⁺ and [Co^IIdiamsar]²⁺ macrocyclic complexes and also by high-spin [Co^II sen]²⁺ tripod complex were measured at several temperatures. The delocalizations, β, of Co^II unpaired electrons, promoted by the mentioned ligands, were determined by using the previously established correlations between k_CR and the electron delocalization β of unpaired metal electrons. β is given by the ratio between the Racah inter-electronic repulsion parameters of complexes, B, and that of the free ions, B₀. The β values are compared with those of the Co^II complexes with en (1,2-ethanediamine), pn (1,2 propanediamine) and dien (2,2′ diamino diethylamine) ligands. The k_CR rate constants are also compared with those of the Ps oxidation reactions, OR, promoted by the corresponding Co^III complexes. It is concluded that, unlike OR's, the CR's do not occur by formation of hepta-coordinate adducts with Ps atoms.     

Neutral pyridylmethylamide ligands and their mononuclear copper(II) complexes

Mononuclear copper(II) complexes of a family of pyridylmethylamide ligands HL, HL^Me, HL^Ph, HL^Me3 and HL^Ph3, [HL = N-(2-pyridylmethyl)acetamide; HL^Me = N-(2-pyridylmethyl)propionamide; HL^Ph = 2-phenyl-N-(2-pyridylmethyl)acetamide; HL^Me3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HL^Ph3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide], were synthesized and characterized. The reaction of copper(II) salts with the pyridylmethylamide ligands yields complexes [Cu(HL)₂(OTf)₂] (1), [Cu(HL^Me)₂](ClO₄)₂ (2), [Cu(HL)₂Cl]₂[CuCl₄] (3), [Cu(HL^Me3)₂(THF)](OTf)₂ (4), [Cu(HL^Me3)₂(H₂O)](ClO₄)₂ (5a and 5b), [Cu(HL^Ph3)₂(H₂O)](ClO₄)₂ (6), [Cu(HL)(2,2′-bipy)(H₂O)](ClO₄)₂ (7), and [Cu(HL^Ph)(2,2′-bipy)(H₂O)](ClO₄)₂ (8). All complexes were fully characterized, and the X-ray structures vary from four-coordinate square-planar, to five-coordinate square-pyramidal or trigonal-bipyramidal. The neutral ligands coordinate via the pyridyl N atom and carbonyl O atom in a bidentate fashion. The spectroscopic properties are typical of mononuclear copper(II) species with similar ligand sets, and are consistent their X-ray structures.     

Optimised hydrothermal synthesis of multi-dimensional hybrid coordination polymers containing flexible organic ligands

In this paper, we summarise our recent research interest in the hydrothermal synthesis and structural characterisation of multi-dimensional coordination polymers. The use of N-(phosphonomethyl)iminodiacetic acid (also referred to as H₄pmida) in the literature as a versatile chelating organic ligand is briefly reviewed. This molecule plays an important role in the formation of centrosymmetric dimeric [V₂O₂(pmida)₂]⁴⁻ anionic units, which were first used by us as building blocks to construct novel coordination polymers. Starting with [V₂O₂(pmida)₂]⁴⁻ in solution, we have isolated [M₂V₂O₂(pmida)₂(H₂O)₁₀] species (where M²⁺ = Mn²⁺, Co²⁺ or Cd²⁺) via the hydrothermal synthetic approach, which were then employed for the construction of [CdVO(pmida)(4,4′-bpy)(H₂O)₂]·(4,4′-bpy)_0.5·(H₂O), [CoVO(pmida)(4,4′-bpy)(H₂O)₂]·(4,4′-bpy)_0.5, [Co(H₂O)₆][CoV₂O₂(pmida)₂(pyr)(H₂O)₂]·2(H₂O) and [Cd₂V₂O₂(pmida)₂(pyr)₂(H₂O)₄]·4(H₂O) by the inclusion of bridging organic ligands in the reactive mixtures, such as pyrazine (pyr) and 4,4′-bipyridine (4,4′-bpy). These materials can contain channel systems, and exhibit magnetic behaviour, not only due to the V⁴⁺ centres but also to the transition metal centres which establish the links between neighbouring dimeric [V₂O₂(pmida)₂]⁴⁻ anionic units. A closely related anionic moiety, [Ge₂(pmida)₂(OH)₂]²⁻, was engineered to allow the study of such crystalline hybrid materials using one- and two-dimensional high-resolution solid-state NMR.     

铁氰根桥联的一维链状大环配位聚合物的合成及结构

配位聚合物的合成、结构和性质研究近年来引起了人们极大的兴趣 ,已成为配位化学最活跃的研究领域之一 .由于 [Fe( CN) 6 ]3- 和 [Fe( CN) 6 ]4- 离子本身具有丰富的配位特性 ,可与金属离子及其配合物形成一维链状、二维网状和三维立体结构的配位聚合物 [1～ 5] ,铁氰根和亚铁氰根桥联的配位聚合物的研究成为其中的研究热点之一 .此外 ,铁氰根和亚铁氰根桥联的配位聚合物具有较高的铁磁相变温度[6～ 8] ,是一类具有较好应用前景的分子磁体 .但是 ,以金属大环配合物作为结构单元与 [Fe( CN) 6 ]3-和 [Fe( CN) 6 ]4-离子形成的配位聚合物…     

Synthesis, structure and nuclease activity of copper complexes of disubstituted 2,2′-bipyridine ligands bearing ammonium groups

A series of Cu(II) complexes of disubstituted 2,2′-bipyridine bearing ammonium groups [Cu(L¹⁻⁴)₂Br]⁵⁺ (1–4, L¹ = [5,5′-(Me₂NHCH₂)₂-bpy]²⁺, L² = [5,5′-(Me₃NCH₂)₂-bpy]²⁺, L³ = [4,4′-(Me₂NHCH₂)₂-bpy]²⁺, L⁴ = [4,4′-(Me₃NCH₂)₂-bpy]²⁺ and bpy = 2,2′-bipyridyl) were synthesized, of which complexes 1 and 4 were structurally characterized. Both coordination configurations of Cu(II) ions can be described as distorted trigonal bipyramid. The interaction between all complexes and CT-DNA was evaluated by thermal-denaturation experiments and CD spectroscopy. Results show that the complexes interact with CT-DNA via outside electrostatic interactions and their binding ability follows the order: 1 > 2 > 3 > 4. In the absence of any reducing agents, the cleavage of plasmid pBR322 DNA by these complexes was investigated and the hydrolysis kinetics of DNA was studied in Tris buffer (pH 7.5) at 37 °C. Obtained pseudo-Michaelis–Menten kinetic parameters: 15.0, 13.6, 2.01 and 1.69 h⁻¹ for 1, 2, 3 and 4, respectively, indicate that complexes 1 and 2 exhibit very high DNA cleavage activities. According to their crystal data, the high nuclease activity may be attributed to the strong interaction of the metal moiety and two ammonium groups with phosphate groups of DNA.     

Synthesis and structure of a novel molybdenum imido calix[6]arene

Treatment of p-tert-butylcalix[6]areneH₆ (H₆L) with [Mo(OBu^t)₂{[2,2′-(N)-C₆H₄]₂(CH₂CH₂)}] in refluxing toluene affords, after work-up, the complex [Mo(2-NC₆H₄CH₂CH₂C₆H₄NHC(Me)NH-2^/)LH₂]·4MeCN (1), which contains an 11-membered metallocyclic ring as characterised by Synchrotron X-radiation.     

Cobalt(III) complexes of ethylenediamine-N,N′-di-S-isobutylacetic acid

A new optically active ONNO-type tetradentate ligand, ethylenediamine-N,N′- di-S-isobutylacetate (SS-eniba), has been synthesized. During the preparation of diaqua cobalt(III) complexes of SS-eniba, [Co(SS-eniba)(H₂O)₂]⁺, the title ligand has coordinated stereospecifically to the cobalt(III) ion to give three isomers, Δ-s-cis, Δ-uns-cis and Λ-uns-cis, which have been isolated and characterized via electronic absorption, circular dichroism (CD), and ¹H NMR spectroscopy, along with elemental analysis data. The preparation of Δ-s-cis-[Co(SS-eniba)Cl₂]⁺ and Δ-s-cis-[Co(SS-eniba)CO₃]⁺ are also reported.     

TERNARY Cu(Ⅱ)(ATP)AND HETEROAROMATIC N BASE COMPLEXES IN SOLUTION:STABILITY CONSTANTS AND ANTITUMOR MECHANISM EXPLORATION

The stability of the complexes of four pyridine-like ligandswith Cu(ATP)~(2-) was studied and by comparing the stability constants of theternary complexes[Cu(ATP)L]~(2-) with those of the binary complexes[CuL]~(2+),astacking interaction between the pyridine ring and the purine ring of ATP isindicated.It is possible to interpret the antitumor mechanism of[Pt(NH_3)_8(N-het)Cl]Cl in terms of this stacking interaction.     

Salen型化合物的合成、表征及性质

设计合成了两种新型Salen配体H2L1(N,N?-3-二甲氧基-邻羟苯亚甲基-4,5-二甲氧基-1,2-苯二胺)、H2L2(N,N?-3-二甲氧基-邻羟苯亚甲基-4,5-二硝基-1,2-苯二胺)及相应的镍、铜、锌金属配合物ML1、ML2(M=Ni,Cu,Zn),并分别采用核磁共振(1HNMR)波谱、紫外-可见(UV-Vis)吸收光谱、红外(IR)光谱、质谱(MS)和元素分析进行了表征.探究了配体及其配合物的荧光性质.研究发现,与H2L1相比,配体H2L2由于引入强的吸电子基团―NO2,其荧光强度减弱.相对于配体,锌离子的配位则导致其配合物的荧光强度增强,而镍和铜离子的嵌入则使得配合物ML1、ML2(M=Ni,Cu)荧光猝灭.对电化学性质的研究表明,CuL1的氧化还原过程为准可逆的单电子过程;与H2L2相比,配体H2L1由于引入强的给电子基团―OCH3,其溶液的导电性降低.     

Tris-chelate complexes with chiral ligands: In search of diastereoisomeric selectivity with remote stereogenic centres

The chiral ligands, 4,4′-bis{(1S,2R,4S)-(−)-bornyloxy}-2,2′-bipyridine, (1S,2R,4S)-1, and 4,4′-bis{(1R,2S,4R)-(+)-bornyloxy}-2,2′-bipyridine, (1R,2S,4R)-1, have been prepared and characterized by spectroscopic techniques and, for (1S,2R,4S)-1, by single crystal X-ray diffraction. Despite the use of enantiomerically pure ligands, the formation of the complexes [Fe((1S,2R,4S)-1)₃]²⁺, [Ru((1S,2R,4S)-1)₃]²⁺, [Ru((1S,2R,4S)-1)(bpy)₂]²⁺ and [Ru((1R,2S,4R)-1)(bpy)₂]²⁺ proceeds without preference for either the Δ or Λ-diastereoisomers.     

溶液中杯[4]芳烃双冠-6与Cs~+配位化学研究

研究了溶液中杯[4]芳烃双冠-6(BisC₆)与Cs⁺配位行为.常温下,BisC₆/NPME(邻硝基苯甲醚)体系单级萃铯百分率达99.36%,模拟料液中,Cs⁺/Na⁺和Cs⁺/K²⁺分离系数分别为3.92×10⁴和2.21×10⁴.局域结构模型实验表明,配合物分子中可能存在水或(和)硝酸(根).ESI-MS谱表明,NPME体系中,铯离子与BisC₆同时形成1:1(单核)和2:1(双核)的配合物,并且存在[BisC₆·H₂O],[BisC₆·Cs⁺]⁺,[BisC₆·2Cs⁺·H₂O]₂+和[BisC₆·2Cs₁₀⁺·No₁₀^-3]10⁺等多种配合物分子.EXAFS实验表明,溶液中铯离子的配位数为7,形成7个氧配位的稳定结构,ADF计算验证了EXAFS实验结果.     

Intervalence electron transfer through a thiolate bridge ligand: a Fe–S–R–Fe mixed valence complex

The reaction of Cp(dppe)FeI with the ligands 2,2′- and 4,4′-dithiobispyridine (S₂(Py)₂) give the mononuclear or binuclear complexes of the type [Cp(dppe)Fe-S₂(Py)₂]PF₆, [Cp(dppe)Fe---SPy]PF₆ or [{Cp(dppe)Fe}₂-μ-SPy](PF₆)₂ depending on the reaction condition. Reaction of Cp(dppe)FeI with dithiobispyridines in presence of TlPF₆ as halide abstractor and using CH₂Cl₂ as a solvent gives the complexes [Cp(dppe)Fe-4,4′-S₂(Py)₂)₂]PF₆ (1) and [CpFe(dppe)-2,2′-S₂(Py)₂]PF₆ (2) whereas the same reaction using CH₃OH as a solvent and NH₄PF₆ as the halide abstractor leads to the formation of the Fe^III–thiolate complex [Cp(dppe)Fe-2,2′-SPy]PF₆ (3) and the mixed-valence complex [Cp(dppe)Fe^III-μSPy-Fe^II(dppe)Cp](PF₆)₂ (4). Magnetic and ESR measurements are in agreement with one unpaired electron delocalized between them. Mössbauer data indicate clearly the presence of two different iron sites, each one of the N-bonded and S-bonded iron atoms, with intermediate oxidation state Fe^II---Fe^III. An electron transfer intervalence absorption was observed for this complex at 780 nm (in CH₂Cl₂). By applying the Hush theory the intervalence parameters were obtained; =0.028, H_ab=361 cm⁻¹ which indicate Class II Robin–Day. Estimation of the rate electron transfer affords a value k_th=6.5×10⁶ s⁻¹. Solvent effect on the intervalence transition follow the Hush prediction for high dielectric constants solvents which permit the evaluation of the outer and inner-sphere reorganizational parameters, which were analyzed and discussed. The electronic interaction parameters compare well with those found for electron transfer in metalloproteins.     

Equilibrium reactions network for the cis- or trans-bis(pyrazine)tetraammineruthenium(II/III) and ruthenium(II/III)-EDTA complexes

The electrochemical and spectroelectrochemical behavior of the binuclear and trinuclear complexes generated from the association of cis- or trans-[Ru(NH₃)₄(pz)₂]^3+/2+ (where pz represents pyrazine) and [RuEDTA(H₂O)]^2−/− complexes has been investigated in aqueous solution. Based on two sets of spectrophotometrically determined equilibrium constants and on the formal redox potentials, the complex network of equilibrium reactions involving mixed valence species has been elucidated.     

A new extended structural compound based on saturated Wells-Dawson polyoxoanions

A new 3D extended structural compound,(dpdo)_2H_2{[Cu(2,2'-bipy)_2]_2(P_2W_(18)O_(62))}·5H_2O 1(dpdo = 4,4'-bipyridine-N,N'-dioxide; 2,2'-bipy = 2,2'-bipyridine),has been hydrothermally synthesized and characterized by elemental analyses,IR,TG analyses,cyclic voltammetry,and single-crystal X-ray diffraction.Compound 1 is built up of[P_2W_(18)O_(62)]~(6-) cluster as the structural motif covalently linked by[Cu(2,2'-bipy)_2]~(2+) coordination complexes to yield the 1D chains,which are further in close cont...     

配合物[Hpip] [(salen)FeⅢ(OX)]的晶体结构和异三核配合物的合成与磁性

合成了含有草酸根(OX)桥基的铁(Ⅲ)的配合物配体[Hpip] [(salen)Fe^Ⅲ(OX)](pip=哌啶;salen=N,N'-二水杨醛缩乙二胺),并解析了其晶体结构.利用这一含有草酸根桥基的配合物配体组装了3个新的异三核配合物[(salen)Fe^Ⅲ(μ-OX)]₂[M^Ⅱ(H₂O)₂]·nH₂O[M^Ⅱ=Cu^Ⅱ(1), Ni^Ⅱ(2),Fe^Ⅱ(3)],并进行了结构表征,变温磁化率(4.2~300 K)测定结果均未表现出非正规自旋态的类铁磁行为.通过计箅和分析,讨论了满足"非正规自旋态"的充分和必要条件>     

Synthetic [FeFe]-H2ase models bearing phosphino thioether chelating ligands

Through the oxidation-reduction combination procedure, the neutral tri-substituted {2Fe3S} complex 2 was synthesized by replacing the CO ligand in 1 with phosphine. This substitution leads to the Fe-Fe bonds in 1 and 2 with large Lewis basicity difference, i.e. △pK_a^MeCN~10.     

Coordination geometry of tetradentate Schiff’s base nickel complexes: the effects of donors, backbone length and hydrogenation

The X-ray crystal structures of (N,N′-bis-(o-amidobenzilidene)-1,3-diaminopropane)nickel (Niambpr), (N,N′-bis-(o-amidobenzilidene)-1,4-diaminobutane)nickel (Niambut), (N,N′-bis-(o-thiobenzilidene)-1,4-diaminobutane)nickel(II) (Nitsalbut), bis-acetonitrile-(N,N′-bis-(o-aminobenzyl)-1,2-diaminoethane) nickel(II) tetrafluoroborate [Ni(H₄amben)(MeCN)₂] [BF₄]₂, bis-O-acetato-(N,N′-bis-(o-aminobenzyl)-1,2-diaminoethane) nickel(II) [Ni(H₄amben)(OAc)₂ · H₂O] and bis-O-acetato-(N,N′-bis-(o-aminobenzyl)-1,3-diaminopropane) nickel(II) [Ni(H₄ambpr)(OAc)₂] are presented. These structures complete the structural characterisation of the simple unsubstituted Schiff’s base complexes with N₄ and N₂S₂ donor sets and allow us to assess the effects of donor groups and polymethylene chain length on the coordination geometries of nickel(II). The hydrogenated N₄ complexes offer an insight into the effects of increased flexibility and character of the internal nitrogen donors. Unlike the parent N₄ imine species the hydrogenated amine species do not deprotonate at the peripheral nitrogen donors and do not seem to be restricted to the meridial plane of the nickel.     

Preparation and characterization of [Re(bpy)(CO) 3L][SbF6] (L = phosphine, phosphite)

A series of rhenium complexes [fac-Re(bpy)(CO)₃L][SbF₆] (bpy = 2,2′-bipyridine, L = P(ⁿBu)₃, PEt₃, PPh₃, P(OMe)Ph₂, P(OⁱPr)₃, P(OEt)₃, P(OMe)₃, P(OPh)₃) has been prepared and characterized by the IR, UV-vis, ¹H NMR, ³¹P NMR, X-ray photoelectron spectroscopy and electrochemical techniques. Variations in the electronic properties, i.e. CO stretching, metal-to-ligand charge transfer transition, and ³¹P NMR chemical shifts were interpreted on the basis of the electron-acceptor strength of L. However, the redox potential corresponding to [Re(bpy)(CO)₃L]⁺/[Re(bpy⁻)(CO)₃L]showed ‘V-character type’ changes after the increase in the electron-acceptor strength of L. Variation of the P(2p) binding energy of the phosphorus atom indicated that the electronic structure of the coordinated phosphorus atom was strongly influenced by the electronic properties of the directly attached substituents.     

联咪唑镍、镉配合物的合成、晶体结构及其与DNA相互作用

分别通过水热法和室温挥发法合成了2,2'-联咪唑(H₂biim)镍、镉配合物([Ni(H₂biim)₃](phth)(phth,邻苯二甲酸根)(1)、[Cd(H₃biim)₂Cl₄](2)),并通过X射线单晶衍射、元素分析和红外等技术手段对它们进行了表征。 单晶X衍射结果表明,配合物1的配离子中心镍离子周围的配体以3个中性联咪唑分子形式分别进行二齿螯合配位,构成六配位的畸变八面体构型,邻苯二甲酸根离子在外界与配体形成丰富的氢键;而在配合物2中,两个联咪唑配体却以含有氢质子的阳离子H₃biim⁺形式与中心镉离子单齿配位,镉离子同时结合4个氯原子形成六配位配位环境。 通过紫外光谱、荧光光谱和黏度法测试结果表明配合物1和2分别与小牛胸腺DNA(ct-DNA)以经典插入和部分插入模式进行相互作用。