Self-assembled dinuclear,trinuclear, tetranuclear,pentanuclear, and octanuclear Ni(II) complexes of a series of polytopic diazine based ligands: structural and magnetic properties

The nickel coordination chemistry of a series of polytopic diazine (N-N) based ligands has been examined. Self-assembly reactions lead to examples of dinuclear, trinuclear, tetranuclear, pentanuclear, and octanuclear complexes, all of which exhibit magnetic exchange coupling, with antiferromagnetic and ferromagnetic examples. Structural details are presented for [(L1)(2)Ni(2)(H(2)O)(2)](NO(3))(4).3H(2)O (1), [(L2)(2)Ni(3)(H(2)O)(2)](NO(3))(6).8H(2)O (2), [(L3)(4)Ni(4)(H(2)O)(8)] (NO(3))(4).8H(2)O (3), [(L4)(2)Ni(5)(H(2)O)(10)(NO(3))](NO(3))(7).8H(2)O (4), and [(L5)(4)Ni(8)(H(2)O)(8)](BF(4))(8).16H(2)O (5). Compound 1 crystallizes in the monoclinic system, space group P2(1)/c, with a = 14.937(1) A, b = 18.612(2) A, c = 20.583(2) A, beta = 108.862(2) degrees, Z = 4. Compound 2 crystallizes in the orthorhombic system, space group P2(1)2(1)2, with a = 21.771(4) A, b = 13.700(2) A, c = 20.017(3) A, Z = 4. Compound 3 crystallizes in the tetragonal system, space group P4(3), with a = 12.9483(7) A, c = 33.416(3) A, Z = 4. Compound 4 crystallizes in the triclinic system, space group P(-)1, with a = 12.6677(8) A, b = 18.110(1) A, c = 19.998(1) A, alpha = 100.395(1) degrees, beta = 109.514(1) degrees, gamma = 109.686(1) degrees, Z = 2. Compound 5 crystallizes in the monoclinic system, space group P2(1)/n, with a = 21.153(5) A, b = 35.778(9) A, c = 21.823(5) A, beta = 97.757(6) degrees, Z = 4. The linear trinuclear Ni(II) complex (2) has a cis-N-N single bond bridge, and a water bridge linking the central Ni(II) to each external Ni(II) center in each of two similar trinuclear subunits, and exhibits intramolecular ferromagnetic exchange (J = 5.0 cm(-1)). A novel octanuclear metallacyclic ring structure exists in 5, with trans-N-N single bond bridges linking adjacent Ni(II) centers, leading to quite strong intramolecular antiferromagnetic exchange (J = -30.4 cm(-1)).     

Structural, spectroscopic, and electrochemical studies of the complexes [Ni2(mu-CNR)(CNR)2(mu-dppm)2](n+) (n = 0, 1, 2): unusual examples of nickel(0)-nickel(I) and nickel(0)-nickel(II) mixed valency

Reaction of Ni(COD)(2) (COD = cyclooctadiene) with dppm (dppm = bis(diphenylphosphino) methane) followed by addition of alkyl or aryl isocyanides yields the class of nickel(0) dimers Ni(2)(mu-CNR)(CNR)(2)(mu-dppm)(2) (R = CH(3) (1), n-C(4)H(9) (2), CH(2)C(6)H(5) (3), i-C(3)H(7) (4), C(6)H(11) (5), t-C(4)H(9) (6), p-IC(6)H(4) (7), 2,6-(CH(3))(2)C(6)H(3) (8)). The cyclic voltammograms of the dimers exhibit two sequential single electron oxidations to the +1 and +2 forms. Specular reflectance infrared spectroelectrochemical (IRSEC) measurements demonstrate reversible interconversions between the neutral Ni(0) dimers and their +1 and +2 forms. Bulk samples of the +2 forms are prepared by chemical oxidation using [FeCp(2)][PF(6)], while the +1 forms are prepared by the comproportionation of neutral and +2 forms. The neutral complexes 6 and 8 were characterized by X-ray diffraction as symmetric, locally tetrahedral binuclear Ni(0) complexes. The +2 forms of these complexes, 6(2+) and 8(2+), have asymmetric structures with one locally square planar and one locally tetrahedral metal center, evidence for a Ni(II)-Ni(0) mixed valence state. The X-ray structural characterization of 6(+) is symmetrical and qualitatively similar to that of the neutral complex 6. The +1 forms all exhibit intense near IR electronic absorptions that are assigned as intervalence charge transfer (IVCT) bands. On the basis of structural, spectroscopic, and electrochemical data, the +1 forms of the complexes, 1(+)-8(+), are assigned as Robin-Day class III, fully delocalized Ni(+0.5)-Ni(+0.5) mixed valence complexes.     

N,N''''-(2-苯并咪唑基甲基)亚氨基甲基膦酸的双核镍化合物Ni2(bbimp)2(4,4''''-bipy)(H2O)2·2H2O和Ni2(bbimp)2(H2O)2][Ni(bbimp)(H2O)2]2·4H2O的晶体结构和磁学性质

该文报道了N,N′-(2-苯并咪唑基甲基)亚氨基甲基膦酸{bbimpH_2,[(C7H5N2)CH2]2NCH2PO3H2}的2个镍化合物Ni2(bbimp)2(4,4′-bipy)(H2O)2·2H2O(1)和[Ni2(bbimp)2(H2O)2][Ni(bbimp)(H2O)2]2·4H2O(2)。化合物1是4,4′-联吡啶作为桥连配体的中性双核结构。化合物2含有1个中性的[Ni2(bbimp)2(H2O)2]双核分子与2个中性的[Ni(bbimp)(H2O)2]单核分子。双核分子单元中的2个Ni!离子被2个膦酸氧桥连。在化合物2中,膦酸氧桥连的2个Ni!离子之间存在铁磁性相互作用。     

Nickel(II) macrocyclic complexes with long alkyl pendant chain: synthesis,x-ray structure,and anion exchange property in the solid state

A nickel(II) pentaaza macrocyclic complex containing a 1-hexadecyl pendant chain, [Ni(C(25)H(55)N(5))](ClO(4))(2).H(2)O (1), was synthesized by a one-pot metal-template condensation reaction. Crystal data for 1: triclinic, Ponemacr;, a = 8.333(4) A, b = 8.356(3) A, c = 28.374(9) A, alpha = 81.865(19) degrees, beta = 86.242(18) degrees, gamma = 63.871(17) degrees, Z = 2. Solid 1 forms hydrophobic layers that are constructed by the long alkyl chains of the macrocycles. Solid 1 exchanges ClO(4)(-) with NCS(-), PF(6)(-), C(2)O(4)(2-), NO(3)(-), and CF(3)SO(3)(-) that are dissolved in water. From the reaction of [Ni(C(25)H(55)N(5))Cl(2)] with Et(3)NH(TCNQ)(2) in EtOH/DMF/acetone solution, [Ni(C(25)H(55)N(5))(TCNQ)(2)](TCNQ).(CH(3)COCH(3)) (2) (TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) was prepared. Crystal data for 2: triclinic, Ponemacr;, a = 8.459(0) A, b = 13.945 (1) A, c = 26.833(2) A, alpha = 88.744(2) degrees, beta = 84.536(2) degrees, gamma = 80.089(4) degrees, Z = 2. In 2, TCNQ anions coordinate nickel(II) at the axial sites, which form pi-stacked TCNQ(-) dimers to give rise to 1-D chains. The neutral TCNQ molecules are included between the dimerized TCNQ(-) species, which construct a pi-stacked group of six TCNQ units as blocked by the long alkyl chains. Compound 2 is an electric insulator. It shows a weak signal in the EPR spectrum. The magnetic susceptibility data of 2 measured at 5-300 K exhibit a simple paramagnetism at low temperatures (<100 K) but an increase in the magnetic moment at higher temperatures due to the contribution of a thermally accessible triplet state for the antiferromagnetically coupled [TCNQ](2)(2-).     

Cyano-bridged homometallic 1-D and bimetallic 2-D assemblies: synthesis,structures, and magnetic properties of [Ni(baepn)(CN)]n(ClO4)n and [Ni(baepn)]2n[Fe(CN)(6)]n(H2O)8n

Cyano-bridged homometallic complex [Ni(baepn)(CN)](n)(ClO(4))(n)(1) and bimetallic complex [Ni(baepn)](2)(n)[Fe(CN)(6)](n)(H(2)O)(8)(n)(2) [baepn = N,N'-bis(2-aminoethyl)-1,3-propanediamine] were synthesized and characterized. 1 crystallizes in the monoclinic space group P2(1)/n with a = 9.560(3) A, b = 10.700(3) A, c = 14.138(9) A, beta = 90.18(6) degrees, and Z = 4; 2 crystallizes in the monoclinic space group P2(1)/c with a = 8.951(2) A, b = 13.672(3) A, c = 14.392(3) A, beta = 98.906(4) degrees, and Z = 4. The complex 1 has one-dimensional structure whose chain vector runs along the b axis with baepn ligands and perchlorate anions alternately arranged up and down in the c direction. The antiferromagnetic nature of 1 was explained in terms of the infinite chain model and Haldane gap, giving g = 2.33, J = -29.4 cm(-1), and the magnitude of Haldane gap E(g) = 5.22 K. The complex 2 that constitutes the first example of 2-D bimetallic assembly of Ni(II) ion and ferrocyanide anion is composed of the neutral layers based on the [Ni(4)Fe(4)] square grid spanning in the bc plane. For 2, the analysis with the Curie-Weiss law in 2-300 K range results in THETA = 0.200 K and the magnetism was explained in terms of the ability of ferrocyanide in the -Ni-NC-Fe-CN-Ni unit to promote ferromagnetic Ni-Ni interaction.     

Deprotonation sites of acetohydroxamic acid isomers. A theoretical and experimental study

Theoretical (ab initio calculations) and experimental (NMR, spectrophotometric, and potentiometric measurements) investigations of the isomers of acetohydroxamic acid (AHA) and their deprotonation processes have been performed. Calculations with the Gaussian 98 package, refined at the MP2(FC)/AUG-cc-pVDZ level considering the molecule isolated, indicate that the Z(cis) amide is the most stable form of the neutral molecule. This species and the less stable (Z)-imide form undergo deprotonation, giving rise to two stable anions. Upon deprotonation, the E(trans) forms give three stable anions. The ab initio calculations were performed in solution as well, regarding water as a continuous dielectric; on the basis of the relative energies of the most stable anion and neutral forms, calculated with MP2/PCM/AUG-cc-pVDZ, N-deprotonation of the amide (Z or E) structure appeared to be the most likely process in solution. NMR measurements provided evidence for the existence of (Z)- and (E)-isomers of both the neutral and anion forms in solution. Comparisons of the dynamic NMR and NOESY (one-dimensional) results obtained for the neutral species and their anions were consistent with N-deprotonation, which occurred preferentially to O-deprotonation. The (microscopic) acid dissociation constants of the two isomers determined at 25 degrees C from the pH dependence of the relevant chemical shifts, pK(E) = 9.01 and pK(Z) = 9.35, were consistent with the spectrophotometric and potentiometric evaluations (pK(HA) = 9.31).     

Metal complexes of tetrapodal ligands: synthesis, spectroscopic and thermal studies, and X-ray crystal structure studies of Na(I), Ca(II), Sr(II), and Ba(II) complexes of tetrapodal ligands N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine and N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine

Twelve complexes 1-12 of general category [M(ligand)(anion)(x)(water)(y)], where ligand = N,N,N',N'-tetrakis(2-hydroxypropyl/ethyl)ethylenediamine (HPEN/HEEN), anion = anions of picric acid (PIC), 3,5-dinitrobenzoic acid (DNB), 2,4-dinitrophenol (DNP), and o-nitrobenzoic acid (ONB), M = Ca(2+), Sr(2+), Ba(2+), or Na(+), x = 1 and 2, and y = 0-4, were synthesized. All of these complexes were characterized by elemental analysis, IR, (1)H and (13)C NMR, and thermal studies. X-ray crystal studies of these complexes 1-12, [Ca(HPEN)(H(2)O)(2)](PIC)(2).H(2)O (1), [Ca(HEEN)(PIC)](PIC) (2), Ba(HPEN)(PIC)(2) (3), [Na(HPEN)(PIC)](2) (4), Ca(HPEN)(H(2)O)(2)](DNB)(2).H(2)O (5),Ca(HEEN)(H(2)O)](DNB)(2).H(2)O (6), [Sr(HPEN)(H(2)O)(3)](DNB)(2) (7), [Ba(HPEN)(H(2)O)(2)](DNB)(2).H(2)O](2) (8), [[Ba(HEEN)(H(2)O)(2)](ONB)(2)](2) (9), [[Sr(HPEN)(H(2)O)(2)](DNP)(2)](2) (10), [[Ba(HPEN)(H(2)O)(2)](DNP)(2)](2) (11), and [Ca(HEEN)(DNP)](DNP) (H(2)O) (12), have been carried out at room temperature. Factors which influence the stability and the type of complex formed have been recognized as H-bonding interactions, presence/absence of solvent, nature of the anion, and nature of the cation. Both the ligands coordinate the metal ion through all the six available donor atoms. The complexes 1 and 5-11 have water molecules in the coordination sphere, and their crystal structures show that water is playing a dual character. It coordinates to the metal ion on one hand and strongly hydrogen bonds to the anion on the other. These strong hydrogen bonds stabilize the anion and decrease the cation-anion interactions by many times to an extent that the anions are completely excluded out of the coordination sphere and produce totally charge-separated complexes. In the absence of water molecules as in 2 and 3 the number of hydrogen bonds is reduced considerably. In both the complexes the anions case interact more strongly with the metal ion to give rise to a partially charge-separated 2 or tightly ion-paired 3 complex. High charge density Ca(2+) forms only monomeric complexes. It has more affinity toward stronger nucleophiles such as DNP and PIC with which it gives partially charge-separated eight-coordinated complexes. But with relatively weaker nucleophile like DNB, water replaces the anion and produces a seven coordinated totally charge-separated complex. Sr(2+) with lesser charge/radius ratio forms only charge-separated monomeric as well as dimeric complexes. Higher coordination number of Sr(2+) is achieved with coordinated water molecules which may be bridging or nonbridging in nature. All charge-separated complexes of the largest Ba(2+) are dimeric with bridging water molecules. Only one monomeric ion-paired complex was obtained with Ba(PIC)(2). Na(+) forms a unique dinuclear cryptand-like complex with HPEN behaving as a heptadentate chelating-cum-bridging ligand.     

X-ray crystal structures, electron paramagnetic resonance, and magnetic studies on strongly antiferromagnetically coupled mixed mu-hydroxide-mu-N(1),N(2)-triazole-bridged one dimensional linear chain copper(II) complexes

Four new metal-organic polymeric complexes, {[Cu(mu-OH)(mu-ClPhtrz)][(H 2O)(BF 4)]} n ( 1), {[Cu(mu-OH)(mu-BrPhtrz)][(H 2O)(BF 4)]} n ( 2), {[Cu(mu-OH)(mu-ClPhtrz)(H 2O)](NO 3)} n ( 3), and {[Cu(mu-OH)(mu-BrPhtrz)(H 2O)](NO 3)} n ( 4) (ClPhtrz = N-[( E)-(4-chlorophenyl)methylidene]-4 H-1,2,4-triazol-4-amine; BrPhtrz = N-[( E)-(4-bromophenyl)methylidene]-4 H-1,2,4-triazol-4-amine), were synthesized in a reaction of substituted 1,2,4-triazole and various copper(II) salts in water/acetonitrile solutions. The structures of 1- 4 were characterized by single-crystal X-ray diffraction analysis. The Cu(II) ions are linked both by single N (1), N (2)-1,2,4-triazole and hydroxide bridges yielding one dimensional (1D) linear chain polymers. The tetragonally distorted octahedral geometry of copper atoms is completed alternately by two water and two BF 4 (-) anion molecules in 1 and 2 but solely by two water molecules in 3 and 4. Magnetic properties of all complexes were studied by variable temperature magnetic susceptibility measurements. The Cu(II) ions are strongly antiferromagnetically coupled with J = -419(1) cm (-1) ( 1), -412(2) cm (-1) ( 2), -391(3) cm (-1) ( 3), and -608(2) cm (-1) ( 4) (based on the Hamiltonian H = - J[ summation operator S i . S i+ 1]). The nature and the magnitude of the antiferromagnetic exchange were discussed on the basis of complementarity/countercomplementarity of the two competing bridges.     

Structure,magnetism, and electrochemistry of the multinickel polyoxoanions [Ni6As3W24O94(H2O)2]17-, [Ni3Na(H2O)2(AsW9O34)2]11-, and [Ni4Mn2P3W24O94(H2O)2]17-

The three novel, multi-nickel-substituted heteropolytungstates [Ni(6)As(3)W(24)O(94)(H(2)O)(2)](17)(-) (1), [Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)](11)(-) (2), and [Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)](17)(-) (3) have been synthesized and characterized by IR, elemental analysis, electrochemistry, and magnetic studies. Single-crystal X-ray analysis was carried out on Na(16.5)Ni(0.25)[Ni(6)As(3)W(24)O(94)(H(2)O)(2)].54H(2)O, which crystallizes in the triclinic system, space group P1, with a = 17.450(4) A, b = 17.476(4) A, c = 22.232(4) A, alpha = 85.73(3) degrees, beta = 89.74(3) degrees, gamma = 84.33(3) degrees, and Z = 2, Na(11)[Ni(3)Na(H(2)O)(2)(AsW(9)O(34))(2)].30.5H(2)O, which crystallizes in the triclinic system, space group P1, with a = 12.228(2) A, b = 16.743(3) A, c = 23.342(5) A, alpha = 78.50(3) degrees, beta = 80.69(3) degrees, gamma = 78.66(3) degrees, and Z = 2, and Na(17)[Ni(4)Mn(2)P(3)W(24)O(94)(H(2)O)(2)].50.5H(2)O, which crystallizes in the monoclinic system, space group P2(1)/c, with a = 17.540(4) A, b = 22.303(5) A, c = 35.067(7) A, beta = 95.87(3) A, and Z = 4. Polyanion 1 consists of two B-alpha-(Ni(3)AsW(9)O(40)) Keggin moieties linked via a unique AsW(6)O(16) fragment, leading to a banana-shaped structure with C(2)(v)() symmetry. The mixed-metal tungstophosphate 3 is isostructural with 1. Polyanion 2 consists of two lacunary B-alpha-[AsW(9)O(34)](9)(-) Keggin moieties linked via three nickel(II) centers and a sodium ion. Electrochemical studies show that 1-3 exhibit a unique and reproducible voltammetric pattern and that all three compounds are stable in a large pH range. An investigation of the magnetic properties of 1-3 indicates that the exchange interactions within the trimetal clusters are ferromagnetic. However, for 1 and 3 intra- and intermolecular interactions between different trinuclear clusters are also present.     

Ni(bpy)(H2O)(V2O6)和[Ni(bpy)2]2(V6O17)的水热合成与晶体结构

用NiCl2·6H2O,2,2＇-联吡啶（bpy）,NH4VO3,WO3在443K下通过水热反应法得到了两种多钒酸镍配合物Ni（bpy）（H2O）（V2O6）（1）和[Ni（bpy）2]2（V6O17）（2）．单晶X射线衍射结果表明化合物（1）属于正交晶系,空间群为Pcα2（1）,晶胞参数为0=0．91704（18）nm,b=1．0519（2）nm,c=1．4336（3）nm,V=1．3830（5）nm^3,Z=4;化合物（2）属于单斜晶系,空间群为P2（1）／c,晶胞参数为α=1．5467（3）nm,b=1．4740（3）nm,c=1．0457（2）nm,β=91．99（3）°,V=2．3826（8）nm^3,Z=4．化合物（1）由2,2’-联吡啶修饰的二维[Ni（V2O6）（H2O）]∞电中性层构成,而化合物（2）则由2,2＇-联吡啶修饰的、呈正弦波浪状的[Ni：（V6O17）]∞二维电中性层构成．     

Re(V) complexes with an open-chain quadridentate ligand containing two amine and two amido donors. Synthesis, characterization, and solution equilibria of Re2O3(dioxo-tetH4)2 and [ReO(H2O)(dioxo-tetH4)]Cl (dioxo-tetH6 = 1,4,8,11-tetraazaundecane-5,7-dione)

We are interested in identifying mononuclear cationic [M(V)=O]3+ (M = Tc, Re) complexes for radiopharmaceutical applications. The open-chain ligand, 1,4,8,11-tetraazaundecane-5,7-dione-(dioxo-tetH6) with two amine and two amide donors, was selected for investigation since the literature led us to expect that a five-coordinate [Re(V)=O(dioxo-tetH4)]+ cation would dominate. Instead, the neutral mu-oxo bridged dinuclear complex, Re2O3(dioxo-tetH4)2 (1), and a salt of the six-coordinate mononuclear cation, [ReO(H2O)(dioxo-tetH4)]+ (2), were isolated; the structure of each was determined by X-ray crystallography. The cation (2) is unusual because it has a trans-oxo/aqua core. Such aqua compounds are rarely isolated, and the Re-OH2 distance is relatively short (2.185 A). The cation has two pKa values, 4.1 and 8.7, determined with visible spectroscopy. Since the Re-OH2 bond is short, the coordinated water is likely to be acidic. Thus the two pKa's are assigned to the stepwise deprotonation of the water ligand to give a trans-oxo/hydroxo neutral form and a trans-dioxo anion. Although 1 was the first product isolated following ligand exchange of ReOCl3(Me2S)(OPPh3) with dioxo-tetH6 under neutral conditions, it probably formed from the hydroxo mononuclear complex. Under concentrated conditions (approximately 300 mM) the dinuclear complex deposited from solution, but the 1H NMR spectra of 2 (approximately 20 mM) were consistent with the presence of only monomeric forms in D2O, pH 3-12. 1H NMR experiments demonstrated that in DMSO-d6 2 converts to 1 upon addition of base, consistent with the proposal that two units of the hydroxo monomer condense to give the dinuclear form. In addition, all spectra of pure 1 dissolved in DMSO-d6 included extra low intensity signals that were characteristic of the monomer. Thus, although 1 is favored over the neutral monomer in DMSO-d6, the two complexes exist as a mixture of equilibrating forms. Our results do not support the previous findings for the Re(V) complex with a macrocyclic diamine-diamide ligand related to dioxo-tetH6. The data indicate that the ability of an amido group to donate electron density to a Re(V) center is moderately greater than the donating ability of a neutral amine group.     

Hydrothermal preparation of nickel(II)/uranium(IV) fluorides with one-, two-, and three-dimensional topologies

A modified compositional diagram for the reactions of Ni(C(2)H(3)O(2))(2).4H(2)O with UO(2)(C(2)H(3)O(2))(2).2H(2)O and HF in aqueous media under mild hydrothermal conditions (200 degrees C) has been completed to yield three Ni(II)/U(IV) fluorides, Ni(H(2)O)(4)UF(6).1.5H(2)O (1), Ni(2)(H(2)O)(6)U(3)F(16).3H(2)O (2), and Ni(H(2)O)(2)UF(6)(H(2)O) (3). The structure of 1 consists of one-dimensional columns constructed from two parallel chains of edge-sharing dodecahedral [UF(8)] units. The sides of the columns are terminated by octahedral Ni(II) units that occur as cis-[Ni(H(2)O)(4)F(2)] polyhedra. In contrast, the crystal structure of 2 reveals a two-dimensional Ni(II)/U(IV) architecture built from edge-sharing tricapped trigonal prismatic [UF(9)] units. The top and bottom of the sheets are capped by fac-[Ni(H(2)O)(3)F(3)] octahedra. The structure of 3 is formed from [UF(8)(H(2)O)] tricapped trigonal prisms that edge share with one another to form one-dimensional chains. These chains are then joined together into a three-dimensional network by corner sharing with trans-[Ni(H(2)O)(2)F(4)] octahedra. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 14.3383(8) A, b = 15.6867(8) A, c = 8.0282(4) A, Z = 8; 2, hexagonal, space group P6(3)/mmc, a = 7.9863(5) A, c = 16.566(1) A, Z = 2; 3, monoclinic, space group C2/c, a = 12.059(1) A, b = 6.8895(6) A, c = 7.9351(7) A, beta = 92.833(2) degrees, Z = 4.     

Synthesis, characterization, and DNA-binding studies of nitro(oligopyridine)ruthenium(II) complexes

The complexes of general formulas [RuII(terpy)(4-CO2H-4'-Mebpy)(X)]n+ (X = NO (n = 3) and NO2 (n = 1); 1, 2) and [RuII(terpy)(4-COGHK-4'-Mebpy)(X)] (X = NO (n = 3) and NO2 (n = 1); 3, 4) were synthesized and characterized. The complex [RuII(terpy)(4-CO2-4'-Mebpy)(NO2)]_7.5H2O has also been characterized by X-ray crystallographic studies. It crystallizes in the triclinic system: a = 9.4982(1) A, b = 13.1330(1) A, c = 14.2498(2) A; alpha = 110.5870(6) x bc, beta = 98.4048(5) x bc, gamma = 106.4353(5), P1, Z = 2. The crystal structure reveals an extended hydrogen-bonding network. Two water molecules form strong hydrogen bonds with the nitro and the carboxylic oxygen atoms of two separate units of the complex, resulting in a dimeric unit. The dimers are bridged by a (H2O)15 cluster, consisting of two cyclo-(H2O)6 species, while an exo-H2O(8) connects them. Two more exo-H2O molecules are joined together and connect the cyclo-(H2O)6 units with the H2O(1) of the dimeric unit. It was found that complexes 1 and 3 can be transformed into their nitro derivatives in aqueous media at neutral pH. Photorelease of NO in dry MeCN solutions was observed for complexes 1 and 3. Also, complex 2 partially releases (NO2)- in MeCN upon visible light irradiation. Complex 2 interacts with short fragments (70-300 bp) of calf thymus DNA shortening slightly the apparent polynucleotide length, while the conjugation of the peptide GHK to it (2) affects its DNA-binding mode. The peptide moiety of complex 4 was found to interact with the DNA helix in a synergistic way with the whole complex. Preliminary results of photocleavage of DNA by complex 2 are also reported.     

Dinuclear calcium complex with weakly NH...O hydrogen-bonded sulfonate ligands

The novel intramolecularly NH...O hydrogen-bonded Ca(II)-aryl sulfonate complex, [Ca2(SO3-2-t-BuCONHC6H4)2(H2O)4]n(2-t-BuCONHC6H4SO3)2n (1), sulfonate anion, (HNEt3)(SO3-2-t-BuCONHC6H4) (2a), (PPh4)(SO3-2-t-BuCONHC6H4) (2b), (n-Bu4N)(SO3-2-t-BuCONHC6H4) (2c), and sulfonic acid, 2-t-BuCONHC6H4SO3H (3), were synthesized. The structures of 1, 2a, and 2b depict the presence of the formation of NH...O hydrogen bonds between the amide NH and S-O oxygen for a series of compounds as determined by IR and 1H NMR analyses both in the solid state and in the solution state. Thus, the NH...O hydrogen bonds with neutral amide groups are available for investigation of the electronic state of the O- anion. The combined data from the IR and 1H NMR spectra indicate that the sulfonic acid, sulfonate anion, and Ca(II) complex have a substantially weak intramolecular NH...O hydrogen bond between the SO3 oxygen and amide NH. In the detailed comparison with the intense NH...O hydrogen bonds for the carboxylate, weak NH...O hydrogen bonds for sulfonate is due to the strong conjugation of the SO3- group with the lower nucleophilicity.     

18-冠-6与Na2[M(mnt)2](M=Cu,Ni)配合物的合成与结构

研究了18-冠-6分别与Na2[M(mnt)2][M=Cu,Ni;mnt=丁二腈烯二硫醇阴离子,C2S2(CN)^2^-~2]的反应,得到的配合物{[Na(18-C-6)][Na(18-C-6)(H2O)]}[Cu(mnt)2](1),[Na(18-C-6)(H2O)]2[Ni(mnt)2].(18-C-6)(2)通过元素分析、红外光谱、X射线单晶衍射进行了表征。两个配合物均为三斜晶系,空间群P1。1的晶体学结构数据：a=1.22697(19)nm,b=1.22780(19)nm,c=1.5665(3)nm,α=95.083(3)°,β=101.534(3)°,Υ=91.007(3)°,V=2.3016(6)nm^3,Z=2,Dcalcd=1.350g/cm^3,F(000)=976,R1=0.0726,wR2=0.1843.2的晶体学结构数据：a=1.11620(17)nm,b=1.22054(18)nm,c=1.27939(18)nm,α=111.647(2)°,β=29.792(3)°,Υ=103.201(2)°,V=2.5461(4)nm^3,Z=1,Dcalcd=1.304g/cm^3,F(000)=642,R1=0.0459,wR2=0.1003.1中的[Cu(mnt)2]^2^-通过mnt的氮原子与[Na(18-C-6)]^+中的钠原子成键,形成了一维链状结构;[Na(18-C-6)(H2O)]^+只起平衡电荷的作用。2中的[Ni(mnt)2]^2^-也通过配体的mnt氮原子与两个[Na(18-C-6)(H2O)]^+中的钠原子成键,形成稳定的中性配合物。     

Synthesis and complexation properties of DTPA-N,N''-bis[bis(n-butyl)]-N'-methyl-tris(amide). Kinetic stability and water exchange of its Gd3+ complex

A novel DTPA-tris(amide) derivative ligand, DTPA-N,N'-bis[bis(n-butyl)]-N'-methyl-tris(amide)(H2L3) was synthesized. With Gd3+, it forms a positively charged [Gd(L3)]+ complex, whereas with Cu2+ and Zn2+ [ML3], [MHL3]+ and [M2L3]2+ species are formed. The protonation constants of H2L3 and the stability constants of the complexes were determined by pH potentiometry. The stability constants are lower than those for DTPA-N,N'-bis[bis(n-butyl)amide)](H3L2), due to the lower negative charge and reduced basicity of the amine nitrogens in (L3)2-. The kinetic stability of [Gd(L3)]+ was characterised by the rates of metal exchange reactions with Eu3+, Cu2+ and Zn2+. The exchange reactions, which occur via proton and metal ion assisted dissociation of [Gd(L3)]+, are significantly slower than for [Gd(DTPA)]2-, since the amide groups cannot be protonated and interact only weakly with the attacking metal ions. The relaxivities of [Gd(L2)] and [Gd(L3)]+ are constant between 10-20 degrees C, indicating a relatively slow water exchange. Above 25 degrees C, the relaxivities decrease, similarly to other Gd3+ DTPA-bis(amide) complexes. The pH dependence of the relaxivities for [Gd(L3)]+ shows a minimum at pH approximately 9, thus differs from the behaviour of Gd3+-DTPA-bis(amides) which have constant relaxivities at pH 3-8 and an increase below and above. The water exchange rates for [Gd(L2)(H2O)] and [Gd(L3)(H2O)]+, determined from a variable temperature (17)O NMR study, are lower than that for [Gd(DTPA)(H2O)]2-. This is a consequence of the lower negative charge and decreased steric crowding at the water binding site in amides as compared to carboxylate analogues. Substitution of the third acetate of DTPA5- with an amide, however, results in a less pronounced decrease in kex than substitution of the first two acetates. The activation volumes derived from a variable pressure (17)O NMR study prove a dissociative interchange and a limiting dissociative mechanism for [Gd(L2)(H2O)] and [Gd(L3)(H2O)]+, respectively.     

Octa-membered Water Ring Chain Based on Sulfonic Group in Ni(Ⅱ) Complex with 2-[(E)-(2-Oxidophenyl)methyleneamino]Ethanesulfonato and 2,2''-Bipyridinyl

The title compound, [Ni(tssb)(2,2-bipy)2]·5(H2O) 1 (tssbH2 =2-[(E)-(2-oxido-phenyl)methyleneamino]ethanesulfonato, 2,2-bipy = 2,2'-bipyridinyl), belongs to orthorhombic,space group Pbcn with a = 20.3983(18), b = 17.6929(15), c = 17.0897(15) nm, V = 6167.8(9) nm3,Mr= 688.38, Z = 8, Dc = 1.481 g·cm-3, F(000) = 2880, μ = 0.758 mm-1 and S =1.099. Each NiⅡ atom is six-coordinated by one N and one O atoms from one tssb2- anion and four N atoms from two 2,2-bipy ligands to give a distorted octahedral geometry. Noticeably, there exists a rare octa-membered water ring which presents a 1D chain by sulfonic group.     

Addition of water to Al5O4- determined by anion photoelectron spectroscopy and quantum chemical calculations

The anion photoelectron spectra of Al5O4- and Al5O5H2- are presented and interpreted within the context of quantum chemical calculations on these species. Experimentally, the electron affinities of these two molecules are determined to be 3.50(5) eV and 3.10(10) eV for the bare and hydrated cluster, respectively. The spectra show at least three electronic transitions crowded into a 1 eV energy window. Calculations on Al5O4- predict a highly symmetric near-planar structure with a singlet ground state. The neutral structure calculated to be most structurally similar to the ground state structure of the anion is predicted to lie 0.15 eV above the ground state structure of the neutral. The lowest energy neutral isomer does not have significant Franck-Condon overlap with the ground state of the anion. Dissociative addition of water to Al5O4- is energetically favored over physisorption. The ground state structure for the Al5O4- +H(2)O product forms when water adds to the central Al atom in Al5O4- with -H migration to one of the neighboring O atoms. Again, the ground state structures for the anion and neutral are very different, and the PE spectrum represents transitions to a higher-lying neutral structure from the ground state anion structure.     

Lead tetrakis(imidazolyl)borate solids: anion exchange, solvent intercalation, and self assembly of an organic anion

The coordination polymer Pb[B(Im)(4)](NO(3))(xH(2)O), constructed by using sodium tetrakis(imidazolyl)borate and lead(II) nitrate solutions, is a layered material with the metal centers facing the interlayer spacing. As in naturally occurring layered minerals, this compound can readily undergo anion exchange and reversible intercalation of solvent water in the solid state with retention of crystallinity. We observed changes in solvent intercalation by (207)Pb solid state NMR (SSNMR) and thermogravimetric analysis (TGA). Stoichiometric exchange of (15)N nitrate for nitrate and iodide for nitrate is monitored by (15)N and (207)Pb SSNMR, and single crystals of the iodide-exchanged material Pb[B(Im)(4)]I were isolated. While the iodide compound can be obtained through facile exchange from the nitrate parent compound, the organic anion benzoate is placed in the interlayer spacing for nitrate under self-assembly conditions and forms an alternating monolayer in Pb[B(Im)(4)](C(6)H(5)COO)(0.5H(2)O). The ion exchange versus self-assembly behavior correlates with the structural differences in the three compounds. In both Pb[B(Im)(4)]I and Pb[B(Im)(4)](C(6)H(5)COO)(0.5H(2)O), the lead sites act as Lewis acids for the iodide and benzoate, respectively.     

Comparison of nickel-group metal cyanides and acetylides and their anions using anion photoelectron spectroscopy and density functional theory calculations

The photoelectron spectra of NiCN-, PdCN-, PtCN-, HNiC2H-, Ni(C2H)2(-), PdC2H-, and PtC2H- are presented along with density functional theory calculations. Linear structures are predicted for all anions and neutrals. NiCN- and NiCN are predicted to have 3delta and 2delta ground states, respectively. HNiC2H- and Ni(C2H)2(-) are predicted to have 2delta and 2delta(g) anion and 3delta and 3pi(g) neutral ground states, respectively. The palladium and platinum cyanide and acetylides have 1sigma+ anion and 2sigma+ neutral ground states. Simulations generated from the calculated parameters are compared to observed spectra, and molecular orbital diagrams are presented to compare the bonding in these species.