一种镍的二胺和β-二酮混合配体配合物在不同醇中热致-溶致变色行为的可见光谱研究

用可见光谱法对一种Ni(Ⅱ)的二胺和β-二酮类混合配体配合物([Ni(Ⅱ)(Me4en)(acac)]ClO4)在四种醇类溶剂中所形成的正方半面体和变形八面体物种的平衡过程进行了研究.通过对配合物在醇中的热致-溶致变色光谱曲线的分峰拟合处理,计算出了这一过程的平衡常数,焓变△H和熵变△S等热力学甬数,同时,得到了正方平面体和变形八面体物种各自的光谱吸收曲线.△H数据表明,在醇中形成变形八面体物种是一个放热过程,放热量的大小反映了醇分子与配合物中心离子Ni(Ⅱ)配位能力的强弱.△S的绝对值与中心离子Ni(Ⅱ)配位的或释放的醇分子数相关.计算结果对深化认识Ni(Ⅱ)的二胺和β-二酮类混合配体配合物热致变色的本质有所帮助.     

吡嗪缩氨基硫脲Ni(Ⅱ)/Co(Ⅲ)配合物的合成、结构和DNA结合性质（英文）

合成并通过单晶衍射、元素分析及红外光谱表征了配合物[Ni(L)(OAc)](1)和[Co(L)_2]Cl·4CH_3OH(2)的结构(HL为2-乙酰-3-甲基吡嗪-N-(4-氟苯基)缩氨基硫脲)。单晶衍射结果表明,配合物1中,Ni(Ⅱ)离子中心与缩氨基硫脲配体中的NNS供体和1个单齿醋酸根配位,形成扭曲的平面四边形配位构型;在配合物2中,Co(Ⅲ)离子中心与2个三齿缩氨基硫脲配体配位,拥有扭曲的八面体配位构型。此外,荧光光谱表明配合物1和2与DNA的相互作用强于配体。     

含2-羟基吡啶负离子配体(hp~-)的铂(Ⅱ)配合物cis-PtCl(hp)(PPh_3)_2和cis-Pt(hp)_2(PPh_3)_2的结构

我们制得了两种含2-羟基吡啶负离子配体的铂(II)配合物:cis-PtCl(hp)(PPh_3)_2和cis-Pt(hp)_2(PPh_3)_2.其晶体结构测定的结果表明,两种配合物中的铂(II)离子呈近似平面的四边形配位.2-羟基吡啶负离子配体以酮式异构体形式通过氮原子配位于铂上.     

含2-羟基吡啶负离子配体(hp^-)的铂(II)配合物cis-PtCl(hp)(PPh3)2和cis-Pt(hp)2(PPh3)2的结构

我们制得了两种含2-羟基吡啶负离子配体的铂(II)配合物: cis-PtCl(hp)(PPh3)2和cis-Pt(hp)2(PPh3)2。其晶体结构测定的结果表明, 两种配合物中的铂(II)离子呈近似平面的四边形配位, 2-羟基吡啶负离子配体以酮式异构体形式通过氮原子配位于铂上。     

含2-羟基吡啶负离子配体(hp^-)的铂(II)配合物cis-PtCl(hp)(PPh3)2和cis-Pt(hp)2(PPh3)2的结构

我们制得了两种含2-羟基吡啶负离子配体的铂(II)配合物: cis-PtCl(hp)(PPh3)2和cis-Pt(hp)2(PPh3)2。其晶体结构测定的结果表明, 两种配合物中的铂(II)离子呈近似平面的四边形配位, 2-羟基吡啶负离子配体以酮式异构体形式通过氮原子配位于铂上。     

3-乙基-2-乙酰吡嗪缩4-甲基氨基硫脲Ni(Ⅱ)/Zn(Ⅱ)配合物的合成、结构和DNA结合性质（英文）

合成并通过单晶衍射、元素分析、红外光谱表征了配合物[Ni L(HL)](OAc)(1)和[Zn L(OAc)]n(2)的结构(HL=3-乙基-2-乙酰吡嗪缩4-甲基氨基硫脲)。单晶衍射结果表明,配合物1中的Ni髤离子与来自2个缩氨基硫脲配体的4个N原子和2个S原子配位,其中一个配体为阴离子。而配合物2中,五配位的Zn髤离子采取扭曲的四方锥配位构型,与2个μ-OCO桥联的醋酸根,一个三齿配位的缩氨基硫脲阴离子配位,形成沿a轴方向的一维链状结构。此外,荧光光谱结果表明,配合物与DNA的相互作用强于配体。     

2-乙酰吡嗪缩肼基甲酸甲酯的镍和镉配合物的晶体结构及荧光性质（英文）

合成并通过X射线单晶衍射、元素分析及红外光谱表征了配合物[Ni(L)_2](1)和[Cd(HL)(CH_3OH)(NO_3)_2](2)的结构(HL为2-乙酰吡嗪缩肼基甲酸甲酯)。单晶衍射结果表明,配合物1中,Ni(Ⅱ)离子与来自2个阴离子配体L-的N_2O电子供体配位,形成扭曲的八面体配位构型。在配合物2中,Cd(Ⅱ)离子拥有双帽三棱柱配位构型,与1个中性配体HL,2个双齿配位硝酸根和1分子甲醇配位。此外还研究了配合物1和2的荧光及热性质。     

含吡嗪的缩氨基脲配体Ni(Ⅱ)/Cd(Ⅱ)配合物的晶体结构及与DNA的相互作用（英文）

合成配合物[NiL_2]·CH_3OH·0.5H_2O(1)和[Cd(HL)Cl_2](2)(HL=3-甲基2-乙酰吡嗪缩4-苯基氨基脲)并通过单晶衍射、元素分析及红外光谱表征其结构。单晶衍射结果表明,配合物1中,Ni(Ⅱ)离子与2个拥有N_2O电子供体的阴离子配体L-配位,配位构型为扭曲的八面体。而配合物2中,Cd(Ⅱ)离子与1个中性三齿配体HL和2个氯离子配位,拥有扭曲的四方锥配位构型。荧光光谱结果表明,配合物与DNA的相互作用强于配体。     

3-乙基-2-乙酰吡嗪缩4-苯基氨基脲铜/锌配合物的晶体结构及荧光性质（英文）

合成了配合物[Cu(HL)(H_2O)(NO3)]NO3(1)和[Zn(HL)Cl2](2)(HL为3-乙基-2-乙酰吡嗪缩4-苯基氨基脲),并通过单晶X射线衍射、元素分析及红外光谱表征了结构。单晶衍射结果表明,配合物1中,中心Cu(Ⅱ)离子与1个中性三齿缩氨基脲配体,1个水分子和1个硝酸根配位,配位构型为扭曲的四方锥。配合物2中Zn(Ⅱ)离子周围的配位原子为N2OCl2,其配位构型与配合物1中Cu(Ⅱ)离子的相同。甲醇溶液中,配合物2的荧光发射峰与配体HL相似。而配合物1由于配体和金属离子之间的能量转移,最大荧光发射峰略有红移。     

金属-血清白蛋白的结构研究II. Cu(II)-BSA和Ni(II)-BSA的四 方锥-四方平面 结构

本文用紫外光谱研究Cu(II)-BSA和Ni(II)-BSA配合物的结构随BSA浓度的变化,发现当浓度增大并>2×10^-^4～3×10^-^4mol.dm^-^3时,这两种配合物从五配位的四方锥构型转变成四配位的四方平面构型,首次提供了BSA的Asp羧基氧参与同Cu(II)和Ni(II)配位的证据。计算并讨论了Cu(II),Ni(II)和有关配体轨道的光学电负性。     

Square planar vs tetrahedral coordination in diamagnetic complexes of nickel(II) containing two bidentate pi-radical monoanions

The reaction of three different 1-phenyl and 1,4-diphenyl substituted S-methylisothiosemicarbazides, H(2)[L(1-6)], with Ni(OAc)(2).4H(2)O in ethanol in the presence of air yields six four-coordinate species [Ni(L(1-6)(*))(2)] (1-6) where (L(1-6)(*))(1-) represent the monoanionic pi-radical forms. The crystal structures of the nickel complexes with 1-phenyl derivatives as in 1 reveal a square planar structure trans-[Ni(L(1)(-3)(*))(2)], whereas the corresponding 1,4-diphenyl derivatives are distorted tetrahedral as is demonstrated by X-ray crystallography of [Ni(L(5)(*))(2)] (5) and [Ni(L(6)(*))(2)] (6). Both series of mononuclear complexes possess a diamagnetic ground state. The electronic structures of both series have been elucidated experimentally (electronic spectra magnetization data). The square planar complexes 1-3 consist of a diamagnetic central Ni(II) ion and two strongly antiferromagnetically coupled ligand pi-radicals as has been deduced from correlated ab initio calculations; they are singlet diradicals. The tetrahedral complexes 4-6 consist of a paramagnetic high-spin Ni(II) ion (S(Ni) = 1), which is strongly antiferromagnetically coupled to two ligand pi-radicals. This is clearly revealed by DFT and correlated ab initio calculations. Electrochemically, complexes 1-6 can be reduced to form stable, paramagnetic monoanions [1-6](-) (S = (1)/(2)). The anions [1-3](-) are square planar Ni(II) (d,(8) S(Ni) = 0) species where the excess electron is delocalized over both ligands (class III, ligand mixed valency). In contrast, one-electron reduction of 4, 5, and 6 yields paramagnetic tetrahedral monoanions (S = (1)/(2)). X-band EPR spectroscopy shows that there are two different isomers A and B of each monoanion present in solution. In these anions, the excess electron is localized on one ligand [Ni(II)(L(4-6)(*))(L(4-6))](-) where (L(4-6))(2-) is the closed shell dianion of the ligands H(2)[L(4-6)] as was deduced from their electronic spectra and broken symmetry DFT calculations. Oxidation of 1 and 5 with excess iodine yields octahedral complexes [Ni(II)(L(1,ox))(2)I(2)] (7), [Ni(II)(L(1,ox))(3)](I(3))(2) (8), and trans-[Ni(II)(L(5,ox))(2)(I(3))(2)] (9), which have been characterized by X-ray crystallography; (L(1-)(6,ox)) represent the neutral, two-electron oxidized forms of the corresponding dianions (L(1-6))(2-). The room-temperature structures of complexes 1, 5, and 7 have been described previously in refs 1-5.     

Metal-glutathione interaction in water solution. NMR and electron spectroscopy study of Ni(II)-glutathione complexes in aqueous solution

PMR and absorption spectra have been used to establish the structure of Ni(II)-glutathione complexes in aqueous solutions at various pH values. Equilibria exist between a few octahedral and square planar complexes in solution. At pH above 11 the most stable complex is formed by the coordination of the Ni(II) ion to the residue. Ni(II) is bound to the sulphur atom and deprotonated nitrogens of the peptide A linkage form the square planar complex.     

Synthesis, spectroscopic characterization and thermal behavior of metal complexes formed with N'-(1-(4-hydroxyphenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H3OPAH)

Complexes of Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Zn(II), Hg(II) and U(IV)O(2)(2+) with N'-(1-(4-hydroxyphenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H(3)OPAH) are reported and have been characterized by various spectroscopic techniques like IR, UV-visible, (1)H NMR and ESR as well as magnetic and thermal (TG and DTA) measurements. It is found that the ligand behaves as a neutral bidentate, monoanionic tridentate or tetradentate and dianionic tetradentate. An octahedral geometry for [Mn(H(3)OPAH)(2)Cl(2)], [Co(2)(H(2)OPAH)(2)Cl(2)(H(2)O)(4)] and [(UO(2))(2)(HOPAH)(OAc)(2)(H(2)O)(2)] complexes, a square planar geometry for [Cu(2)(H(2)OPAH)Cl(3)(H(2)O)]H(2)O complex, a tetrahedral structure for [Cd(H(3)OPAH)Cl(2)], [Zn(H(3)OPAH)(OAc)(2)] and [Hg(H(3)OPAH)Cl(2)]H(2)O complexes. The binuclear [Ni(2)(HOPAH)Cl(2)(H(2)O)(2)]H(2)O complex contains a mixed geometry of both tetrahedral and square planar structures. The protonation constants of ligand and stepwise stability constants of its complexes at 298, 308 and 318 K as well as the thermodynamic parameters are being calculated. The bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated to confirm the geometry of the ligand and the investigated complexes. Also, thermal properties and decomposition kinetics of all compounds are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters (E(a), A, ΔH, ΔS and ΔG) of all thermal decomposition stages have been evaluated using Coats-Redfern and Horowitz-Metzger methods.     

Molecular and electronic structures of tetrahedral complexes of nickel and cobalt containing N,N'-disubstituted, bulky o-diiminobenzosemiquinonate(1-) pi-radical ligands

The reaction of 2 equiv of the bulky ligand N,N'-bis(3,5-di-tert-butylphenyl)-1,2-phenylenediamine, H2[3L(PDI)], excess triethylamine, and 1 equiv of M(CH3CO2)2.4H2O (M = Ni, Co) in the presence of air in CH3CN/CH2Cl2 solution yields violet-black crystals of [Ni(II)(3L(ISQ))2] CH3CN (1) or violet crystals of [Co(3L)2] (3). By using Pd(CH3CO2)2 as starting material, green-blue crystals of [Pd(II)(3L(ISQ))2].CH3CN (2) were obtained. Single-crystal X-ray crystallography revealed that 1 and 3 contain (pseudo)tetrahedral neutral molecules [M(3L)2] (M = Ni, Co) whereas in 2 nearly square planar, neutral molecules [Pd(II)(3L(ISQ))2] are present. Temperature-dependent susceptibility measurements established that 1 and 2 are diamagnetic (S = 0) whereas 3 is paramagnetic with an S = 3/2 ground state. It is shown that 1 contains two pi radical benzosemiquinonate(1-)-type monoanions, ((3L(ISQ))(1-*), S(rad) = 1/2), and a central Ni(II) ion (d8; S = 1) which are antiferromagnetically coupled yielding the observed S(t) = 0 ground state. This result has been confirmed by broken symmetry DFT calculations of 1. In contrast, the S(t) = 3/2 ground state of 3 is more difficult to understand: the two resonance structures [Co(III)(3L(ISQ))(3L(PDI))] <--> [Co(II)(3L(PDI))(3L(IBQ))] might be invoked (for tetrahedral [Co(II)(3L(ISQ))2] containing an S(Co) = 3/2 with two antiferromagnetically coupled pi-radical ligands an S(t) = 1/2 is anticipated). Complex 2 is diamagnetic (S = 0) containing a Pd(II) ion (d8, S(Pd) = 0 in an almost square planar ligand field) and two antiferromagnetically coupled ligand radicals (S(rad) = 1/2). The electrochemistry and spectroelectrochemistry of 1, 2, and 3 have been studied, and electron-transfer series comprising the species [M(L)2]z (z = 2+, 1+, 0, 1-, 2-) have been established. All oxidations and reductions are ligand centered.     

Valence Tautomerism in Octahedral and Square‐Planar Phenoxyl–Nickel(II) Complexes: Are Imino Nitrogen Atoms Good Friends?

The two tetradentate ligands H(2)L and H(2)L(Me) afford the slightly distorted square-planar low-spin Ni(II) complexes 1 and 2, which comprise two coordinated phenolate groups. Complex 1 has been electrochemically oxidized into 1(+), which contains a coordinated phenoxyl radical, with a contribution from the nickel orbital. In the presence of pyridine, 1(+) is converted into 1(Py) (+), an octahedral phenolate nickel(III) complex with two pyridines axially coordinated: An intramolecular electron transfer (valence tautomerism) is promoted by the geometrical changes, from square planar to octahedral, around the metal center. The tetradentate ligand H(2)L(Me), in the presence of pyridine, and the hexadentate ligand H(2)L(Py) in CH(2)Cl(2) afford, respectively, the octahedral high-spin Ni(II) complexes 2(Py) and 3, which involve two equatorial phenolates and two axially coordinated pyridines. At 100 K, the one-electron-oxidized product 2(Py) (+) comprises a phenoxyl radical ferromagnetically coupled to the high-spin Ni(II) ion, with large zero-field splitting parameters, while 3(+) involves a phenoxyl radical antiferromagnetically coupled to the high-spin Ni(II) ion.     

Synthesis and characterization of mixed ligand complexes of copper(II), nickel(II), cobalt(II) and zinc(II) with glycine and uracil or 2-thiouracil

Mixed ligand complexes of Cu(II), Ni(II), Co(II) and Zn(II) formed with glycine and uracil or 2-thiouracil have been synthesized and characterized by elemental analysis, conductance, spectral (IR and electronic spectra) and magnetochemical measurements. Results show that glycine is bidentate in all cases; uracil behaves as a bidentate ligand in Cu(II) complex, coordinating through its one carbonyl oxygen and nitrogen, whereas in other cases it is only monodentate, coordinating only through nitrogen. With thiouracil, coordination occurs from carbonyl oxygen and one nitrogen in Cu(II) and Ni(II) complexes, but in the Co(II) complex coordination occurs from thionyl sulphur and nitrogen. In the Zn(II) complex it shows tridentate behaviour, coordinating through oxygen, sulphur and one nitrogen. Mixed Cu(II), Co(II) and Zn(II) complexes of uracil and of Ni(II) and Zn(II) with thiouracil are octahedral, whereas the mixed Ni(II) complex with uracil shows distorted tetrahedral geometry, and the mixed Co(II)-thiouracil complex is square planar. The mixed Cu(II)-thiouracil complex has a binuclear structure, with square planar arrangement around each copper atom.     

Molecular motions in the solid state: the thermochromic nitro-nitrito Interconversion in nickel(II) bis(diamine) complexes

The NO(2)(-) ion, in the trans-octahedral [Ni(II)(N,N'-dimethylethylenediamine)(2)(NO(2))(2)](H(2)O) complex, coordinates the metal through the nitrogen atom (nitro form). On heating the solid complex, the anion rotates to give nitrito coordination (oxygen bound), according to a reversible process. The coordination mode of NO(2)(-) to Ni(II) is related to the steric interplay between the anion and the alkyl substituents on the diamine.     

Trinuclear nickel complexes with triplesalen ligands: simultaneous occurrence of mixed valence and valence tautomerism in the oxidized species

The coordination chemistries of the triple tetradentate triplesalen ligands H(6)talen, H(6)talen(t)(-)(Bu)(2), and H(6)talen(NO)(2) have been investigated with nickel(II). These triplesalen ligands provide three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone. The structures of the complexes [(talen)Ni(II)(3)], [(talen(t)(-)(Bu)(2)Ni(II)(3)], and [(talen(NO)(2)Ni(II)(3)] have been determined by single-crystal X-ray diffraction. All three compounds are composed of neutral trinuclear complexes with square-planar coordinated Ni(II) ions in a salen-like coordination environment. Whereas the overall molecular structure of [(talen(NO)(2)Ni(II)(3)] is nearly planar, the structures of [(talen)Ni(II)(3)] and [(talen(t)(-)(Bu)(2)Ni(II)(3)] are bowl-shaped as a result of ligand folding. The strongest ligand folding occurs at the central nickel-phenolate bond of [(talen(t)(-)(Bu)(2)Ni(II)(3)], resulting in the formation of a chiral hemispherical pocket. The dependence of the physical properties by the substituents on the terminal phenolates has been studied by FTIR, resonance Raman, UV-vis-NIR absorption, and electrochemistry. The three nickel-salen subunits are electronically interacting via the pi system of the bridging phloroglucinol backbone. The strength of this interaction is mediated by two opposing effects: the electron density at the terminal phenolates and the folding of the ligand at the central phenolates. The parent complex [(talen)Ni(II)(3)] is irreversibly oxidized at 0.32 V versus ferrocenium/ferrocene (Fc(+)/Fc), whereas [(talen(t)(-)(Bu)2)Ni(II)(3)] and [(talen(NO)(2)Ni(II)(3)] exhibit reversible oxidations at 0.22 V versus Fc(+)/Fc and 0.52 V versus Fc(+)/Fc, respectively. The oxidized species [(talen(t)(-)(Bu)(2)Ni(3)](+) and [(talen(NO)(2)Ni(3)](+) undergo a valence-tautomeric transformation involving a Ni(III) and a phenoxyl radical species, as observed by EPR spectroscopy. Thus, these oxidized forms exhibit the phenomena of valence tautomerism and mixed valence simultaneously. The extent of delocalization of the radical species and of the Ni(III) species is discussed.     

An unsymmetrical tripodal ligand with an N2OS donor set: coordination chemistry with nickel(II)ions and aerial oxidation to the sulfinate complex

The synthesis of the previously unknown tripodal ligand H4-1 is reported. The tetradentate ligand is equipped with a completely unsymmetrical N2OS donor set. It reacts with Ni(OAc)2. 4H2O or Ni(ClO4)2.6H2O to give the multinuclear nickel(II) complexes [Ni(H-1-Imin)(OAc)]2 (2) (which contains a coordinated Schiff base obtained by reation of the primary amine with the acetone solvent) and [Ni3(H3-1)(H2-1)2]-ClO4.H2O.3 MeCN (3), respectively. A solution of 3 in DMF is readily oxidized upon exposure to air or by aqueous H2O2 to yield [Ni(H2-1-sulfinate)]2. 2MeOH (4). The molecular structures of 2-4 have been determined by X-ray diffraction. Complex 2 exhibits a strongly distorted, octahedral coordination geometry around each nickel(II)ion. The primary amino group of the ligand in this case reacted with the solvent acetone to yield a Schiff base which is coordinated to the metal center. The molecular structure of the trinuclear complex cation in 3 consists of two subunits: a nickel atom with a square-planar N2S2 coordination geometry and two other nickel atoms with a trigonal-bipyramidal N2O2S coordination environment. The dinuclear complex 4 shows distorted octahedral geometry around each nickel(II) ion. The thiolato groups of the ligands are oxidized to sulfinato groups which are O,O-bound to the nickel center. This coordination mode is unusual for nickel sulfinate complexes.     

Interaction of Cu(II) and Ni(II) with the 63-93 fragment of histone H2B

Chromatin proteins are believed to represent reactive sites for metal ion binding. We have synthesized the 31 amino acid peptide Ac-NSFVNDIFERIAGEASRLAHYNKRSTITSRE-NH2, corresponding to the 63-93 fragment of the histone H2B and studied its interaction with Cu(II) and Ni(II). Potentiometric and spectroscopic studies (UV-vis, CD, NMR and EPR) showed that histidine 21 acts as an anchoring binding site for the metal ion. Complexation of the studied peptide with Cu(II) starts at pH 4 with the formation of the monodentate species CuH2L. At physiological pH values, the 3N complex (N(Im), 2N(-)), CuL is favoured while at basic pH values the 4N (N(Im), 3N(-)) coordination mode is preferred. Ni(II) forms several complexes with the peptide starting from the distorted octahedral NiH2L at about neutral pH, to a square planar complex where the peptide is bound through a (N(Im), 3N(-)) mode in an equatorial plane at basic pH values. These results could be important in revealing more information about the mechanism of metal induced toxicity and carcinogenesis.