Carrier doping effect into quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron-correlation by Cu(II) ions, [Ni1-xCux(chxn)2Br]Br2-x

This communication will describe the electron doping effect into Ni(III) complexes by Cu(II) ions, [Ni(1-x)Cu(x)(chxn)(2)Br]Br(2-x) (x = 0.038 and 0.101) by using an electrochemical oxidation method. A drastic increase of electrical conductivity as well as a new absorption band around 0.5 eV in single crystal reflectance spectra was observed by doping Cu(II) ions, indicating the electron doping was successfully made. An ESR result shows unpaired electrons locate in the d(x2-y2) orbitals of Cu(II) and have almost no interaction with those of other ions.     

Tuning of electronic structures of quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron-correlation by doping of Co(III) ions, [Ni(1-x)Co(x)(Chxn)(2)Br]Br(2)

We have succeeded in synthesizing the Ni(III) complexes doped by Co(III) ions, [Ni(1-x)Co(x)(chxn)(2)Br]Br(2) (x = 0, 0.043, 0.093, and 0.118) by using an electrochemical oxidation method. The single-crystal reflectance spectrum of x = 0.118 shows an intense CT band about 0.5 eV, which is lower than that of [Ni(chxn)(2)Br]Br(2) (1.3 eV). The single-crystal electrical conductivities at room temperature of these compounds increase with increase of the amounts of doping of Co(III) ions. In the ESR spectra, peak-to-peak line widths DeltaH(pp) at room temperature change about 600 G in [Ni(chxn)(2)Br]Br(2) to 200 G in x = 0.118. Such a large x dependence of DeltaH(pp) seems to be ascribed to the increasing contribution from the increasing Curie spins which have smaller line width. Therefore, we have tuned the electronic structures of quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron correlations by doping of Co(III) ions.     

One-dimensional bromo-bridged Ni III complexes [Ni(S,S-bn)2Br]Br2 (S,S-bn=2S,3S-diaminobutane): synthesis, physical properties, and electrostatic carrier doping

A new bromo-bridged Ni III compound has been synthesized. This compound displayed a strong antiferromagnetic interaction between spins located on Ni III species (J=(2350+/-500) K) that result from the strong covalency of the Ni--Br bond and the spin-Peierls transition below 150 K. This was shown by the results of magnetic susceptibility and 81Br nuclear quadrupole resonance spectroscopy analysis. We succeeded in the electrostatic carrier doping of a single crystalline sample by using a field-effect transistor device. This compound also showed n-type semiconductor behavior, which can be reasonably rationalized by the existence of a small amount of Ni II impurities.     

Tuning of spin density wave strengths in quasi-one-dimensional mixed-halogen-bridged nickel(III) complexes with strong electron correlation, [Ni(III)(chxn)(2)Cl(1-x)Br(x)](NO(3))(2)

This communication describes the syntheses of the quasi-one-dimensional mixed-halogen-bridged Ni(III) complexes with strong electron correlation [Ni(chxn)(2)Cl(1-x)Br(x)](NO(3))(2) and the tuning of the spin density wave strengths of these compounds. If the Cl 3p and Br 4p make one band in the compounds, we should observe a single peak in the electronic spectra. As a result, we should observe the single peak from 1.45 to 2.00 eV depending on the mixing ratios of Cl and Br ions. Therefore, the Cl 3p and Br 4p make one band. Then, we have succeeded in tuning the spin density wave strengths of the Ni(III) complexes with the strong electron correlation by mixing the bridging halogen ions successively.     

Two new [Ni(tren)2]2+ complexes: [Ni(tren)2]Cl2 and [Ni(tren)2]WS4

Both title compounds, bis­[tris(2‐amino­ethyl)­amine]­nickel(II) dichloride, [Ni(tren)₂]Cl₂, (I), and bis­[tris(2‐amino­ethyl)­amine]­nickel(II) tetra­thio­tungstate, [Ni(tren)₂]WS₄, (II), contain the [Ni(tren)₂]²⁺ cation [tren is tris(2‐amino­ethyl)­amine, C₆H₁₈N₄]. The tren mol­ecule acts as a tridentate ligand around the central Ni atom, with the remaining primary amine group not bound to the central atom. In (I), Ni²⁺ is located on a centre of inversion surrounded by one crystallographically independent tren mol­ecule. In the [Ni(tren)₂]²⁺ cation of (II), the Ni atom is bound to two crystallographically independent tren mol­ecules. The Ni atoms in the [Ni(tren)₂]²⁺ complexes are in a distorted octahedral environment consisting of six N atoms from the chelating tren mol­ecules. The counter‐ions are chloride anions in (I) and the tetrahedral [WS₄]^2? anion in (II). Hydro­gen bonding is observed in both compounds.     

Synthesis and characterization of new Co(III) mixed-ligand complexes,containing 2-hydroxy-aryloximes and α-diimines. Crystal and molecular structure of [Co(saox)(bipy)2]Br

A series of 12 cobalt (III) complexes of 2-hydroxy-aryloximes (H₂oxime) with an α-diimine (enR), under the general formula [Co(oxime)(enR)₂]Br · 2H₂O were synthesized and characterized. The IR and H NMR spectra indicate the bidentate coordination mode of the ligands and the dianionic character of the oxime ligand in the complexes, while the electronic excitation spectra are indicative of an octahedral geometry around cobalt(III). The octahedral environment with CoN₅O chromophore was confirmed by X-ray structure analysis of the solvated [bis(2,2′-bipyridine)-(2-hydroxy-benzaldoximato)cobalt(III)]bromide, [Co(saox)(bipy)₂]Br · 0.166bipy · 0.15CH₃OH · 1.75H₂O. The phenolic oxygen as well as the oximic nitrogen plus two nitrogen atoms, each one from a different bipy molecule, build the equatorial plane. The oximic chelate ring can be described as an extentend delocalized π system. The crystal structure of one of the investigated oxime ligands, the 2-hydroxy-benzophenonoxime (H₂bpox) was also determined by X-ray analysis, verifying the strong intra-and intermolecular hydrogen bonds.     

The NQR observation of spin-Peierls transition in an antiferromagnetic MX-chain complex [NiBr(chxn)2]Br2

81Br Nuclear quadrupole resonance (NQR) measurement was performed in an S = 1/2 one-dimensional Heisenberg antiferromagnetic metal complex [NiBr(chxn)2]Br2 (chxn: 1R,2R-diaminocyclohexane), having a halogen-bridged MX chain structure -Br-Ni3+-Br-Ni3+-Br-. Two 81Br NQR signals were observed below 40 K, while a single signal was observed above 130 K, showing the presence of two nonequivalent bridging Br sites below 40 K. This NQR result together with previously reported magnetic susceptibility and X-ray results indicate the occurrence of a transition into a spin-Peierls state between 40 and 130 K. This communication reports the first spin-Peierls transition in metal complexes in which pure d electrons contribute to the magnetism. In addition, we demonstrated a new experimental method for studying a spin-Peierls system.     

Biological activity of Co(III) and Ni(II) complexes of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone: Synthesis, characterization, crystal structure of Co(III) complex of pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone1

Transition metal complexes formulated as [Co(L)₂]ClO₄ (I) and [Ni(L)₂] · H₂O (II), where HL = pyridine-2-carbaldehyde N(4)-methylthiosemicarbazone, have been synthesized. Complex I was characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction studies. In complex I, the ligand is N₂S tridentate, coordinating to the metal center through pyridine nitrogen, imine nitrogen and sulfur atoms. Hydrogen bonds link the different components to stabilize the crystal structure. Preliminary in vitro screening indicated that the free ligand was active against various bacteria and fungi and all the tested compounds showed significant antitumor activity against K562 leukaemia cell line, and can therefore be candidates for further stages of screening in vitro and/or in vivo.     

Synthesis,properties and crystal structures of R[MIII(bdt)2] complexes (M = Ni,Co, Cu)

New nickel, cobalt and copper complexes with benzene-1,2-dithiole (bdt), of general formula R[M(bdt)₂]: M = Ni, Co and Cu; R = Me₄N, Et₄N, Pr₄N, Me₃PhN, MePh₃P, Ph₄P have been synthesized and characterized by standard physico-chemical methods (elemental analyses, magnetochemical and conductivity measurements, i.r. and u.v.–;vis. spectroscopy). X-ray structural analysis of (MePh₃P)[M(bdt)₂], M = Ni, Co and Cu, confirms that the MS₄ chromophore lies in a slightly distorted square coordination arrangement around the central atom. The three complexes have also been studied by cyclic voltammetry.     

Isotype Strukturen einiger Hexaamminmetall(II)-halogenide von 3d-Metallen: [V(NH3)6]I2, [Cr(NH3)6]I2, [Mn(NH3)6]Cl2, [Fe(NH3)6]Cl2, [Fe(NH3)6]Br2, [Co(NH3)6]Br2 und [Ni(NH3)6]Cl2

The Structures of some Hexaammine Metal(II) Halides of 3 d Metals: [V(NH₃)₆]I₂, [Cr(NH₃)₆]I₂, [Mn(NH₃)₆]Cl₂, [Fe(NH₃)₆]Cl₂, [Fe(NH₃)₆]Br₂, [Co(NH₃)₆]Br₂ and [Ni(NH₃)₆]Cl₂ Crystals of yellow [V(NH₃)₆]I₂ and green [Cr(NH₃)₆]I₂ were obtained by the reaction of VI₂ and CrI₂ with liquid ammonia at room temperature. Colourless crystals of [Mn(NH₃)₆]Cl₂ were obtained from Mn and NH₄Cl in supercritical ammonia. Colourless transparent crystals of [Fe(NH₃)₆]Cl₂ and [Fe(NH₃)₆]Br₂ were obtained by the reaction of FeCl₂ and FeBr₂ with supercritical ammonia at 400°C. Under the same conditions orange crystals of [Co(NH₃)₆]Br₂ were obtained from [Co₂(NH₂)₃(NH₃)₆]Br₃. Purple crystals of [Ni(NH₃)₆]Cl₂ were obtained by the reaction of NiCl₂ · 6H₂O and NH₄Cl with aqueous NH₃ solution. The structures of the isotypic compounds (Fm3 m, Z = 4) were determined from single crystal diffractometer data (see “Inhaltsübersicht”). All compounds crystallize in the K₂[PtCl₆] structure type. In these compounds the metal ions have high-spin configuration. The orientation of the dynamically disordered hydrogen atoms of the ammonia ligands is discussed.     

Three New Thioantimonates(V): Solvothermal Syntheses and Crystal Structures of [M(chxn)3]3(SbS4)2·4H2O (M = Ni,Co) and [Co(dien)2][Co(tren)SbS4]2·4H2O

The three new thioantimonates(V) [Ni(chxn)₃]₃(SbS₄)₂·4H₂O ( I ), [Co(chxn)₃]₃(SbS₄)₂·4H₂O ( II ) (chxn is trans‐1,2‐diaminocyclohexane) and [Co(dien)₂][Co(tren)SbS₄]₂·4H₂O ( III ) (dien is diethylenetriamine and tren is tris(2‐aminoethyl)amine) were synthesized under solvothermal conditions. Compounds I and II are isostructural crystallizing in space group C2/c. The structures are composed of isolated [M(chxn)₃]²⁺ complexes (M = Ni, Co), [SbS₄]^3? anions and crystal water molecules. Short S···N/S···O/O···O separations indicate hydrogen bonding interactions between the different constituents. Compound III crystallizes in space group and is composed of [Co(dien)₂]²⁺ and [Co(tren)SbS₄]^? anions and crystal water molecules. In the cationic complex the Co²⁺ ion is in an octahedral environment of two dien ligands whereas in [Co(tren)SbS₄]^? the Co²⁺ ion is in a trigonal bipyramidal coordination of four N atoms of tren and one S atom of the [SbS₄]^3? anion, i.e., two different coordination polyhedra around Co²⁺ coexist in this compound. Like in the former compounds an extended hydrogen bonding network connects the complexes and the water molecules into a three‐dimensional network.     

Synthesis,characterization, photocleavage,antimicrobial activity and DNA binding of [Co(bpy)2MHPIP]3+, [Co(dmb)2MHPIP]3+, and [Co(phen)2MHPIP]3+ complexes

4-Methyl-2-(2-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthroline) (MHPIP) and its complexes [Co(bpy)₂MHPIP]³⁺ (1) (bpy = 2,2′-bipyridine), [Co(dmb)₂MHPIP]³⁺ (2) (dmb = 4,4′-dimethyl-2,2′-bipyridine), and [Co(phen)₂MHPIP]³⁺ (3) (phen = 1,10-phenanthroline) have been synthesized and characterized by UV/VIS, IR, EA, ¹H, ¹³C-NMR, and mass spectra. The binding of the three complexes with calf-thymus-DNA (CT-DNA) has been investigated by absorption and emission spectroscopy, DNA-melting techniques, viscosity measurements, and DNA cleavage assay. The spectroscopic data and viscosity results indicate that these complexes bind to CT-DNA via an intercalative mode. The complexes also promote photocleavage of plasmid pBR322 DNA and were screened for antimicrobial activity.     

Characterization of [Ni(Py)4]Br2 and its thermal decomposition

The stepwise thermal decomposition of [Ni(Py)₄]Br₂ was studied by means of a derivatograph. By the introduction of a larger halide atom than Cl the degradation mechanism became simpler. The solid intermediates and the starting material was also analysed with X-ray powder diffraction methods and the unit-cell dimensions were calculated.

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Zusammenfassung Mittels eines Derivatographen wurde die stufenweise thermische Zersetzung von [Ni(Py)₄]Br₂ untersucht. Mit Einbringung eines größeren Halogenidatomes als Cl gestaltet sich der Abbaumechanismus einfacherer. Feste Zwischenprodukte und Ausgangsmaterialien wurden ebenfalls mittels Röntgenpulverdiffraktionsmethoden untersucht und die Gitterzellenkonstanten berechnet.

     

Synthesis, crystal structure and properties of the semiconducting salts (TTF)2[Ni(dtcr)2] and (ET)2[Ni(dtcr)2] based on [Ni(dtcr)2] dianions (dtcr = dithiocroconate)

The first examples of CT salts based on [Ni(dtcr)2] dianions (1) (dtcr = dithiocroconate = 4,5-disulfanylcyclopent-4-ene-1,2,3-trionate), (TTF)2[Ni(dtcr)2] (TTF = tetrathiafulvalene) (2) and (ET)2[Ni(dtcr)2] [ET = bis(ethylenedithio)tetrathiafulvalene] (3) are reported. The redox-active dianion 1, containing oxo-groups in the periphery of the molecule, has been selected to investigate the role of the oxo-groups in promoting intermolecular interactions and hopefully their conducting properties. The salts 2 and 3 have been prepared by electrocrystallisation methods and 3 shows a semi-metallic behaviour: sigma = 1 x 10(-3) omega(-1) cm(-1) at room temperature, with a low activation energy 60 meV, while crystals of 2 were unsuitable for conductivity measurements. The X-ray structural characterisation shows an alternate dianion-(cation)2 stacking and the capability of the oxo-groups to promote interstack contacts. In 2, the TTF donors are present as face-to-face dimers of monocations (D2)2+. The stacking arrangement is different in 3, where ET monocations stack along two directions ([110] and [110]) in the same manner, with the repeating sequence (ET)-(ET)-[Ni(dtcr)2]-(ET)-(ET) and are almost parallel to each other, with interplanar distances of 3.575 angstroms. Both structures are built on a dianion and two donor molecules, each one with a charge of +1. Diffuse reflectance combined with vibrational spectra complement structural results well. Crystal data: both 2 and 3 crystallise in the monoclinic space group P2(1)/c with a = 8.6340(8) angstroms, b = 21.586(2) angstroms, c = 7.5960(8) angstroms, beta = 95.625(11) degrees and V = 1408.9(2) angstroms3 for 2 and with a = 9.3700(7), b = 7.4410(6), c = 28.278(2) angstroms, beta = 99.039(6) degrees, V = 1947.1(3) angstroms3 for 3.     

Mixed-valent selenidoantimonates(III,V) with transition-metal complexes as counterions: solvothermal syntheses and characterization of [M(dien)2]2Sb4Se9 (M = Mn, Fe), [Co(dien)2]2Sb2Se6, and [Ni(dien)2]2Sb2Se5

Novel selenidoantimonate compounds [M(dien)2]2Sb4Se9 [M = Mn (1), Fe (2)], [Co(dien)2]2Sb2Se6 (3), and [Ni(dien)2]2Sb2Se5 (4) (dien = diethylenetriamine) were solvothermally synthesized and characterized. The unique features of compounds 1-3 are the mixed-valent anionic structures constructed by the Sb(III)Se3 trigonal pyramid and Sb(V)Se4 tetrahedron. Three Sb(III)Se3 pyramids share common corners, forming a heterocyclic Sb3Se6 moiety, and the Sb3Se6 moieties are further connected with Sb(V)Se4 tetrahedra to form the novel one-dimensional [Sb4Se9(4-)]n anionic chain in 1 and 2. The discrete [Sb2Se6]4- anion in 3 is formed by an Sb(III)Se3 trigonal pyramid and an Sb(V)Se4 tetrahedron sharing a common corner. The [Sb2Se5]4- anion in 4 is composed of two Sb(III)Se3 trigonal pyramids connected in the same manner as the [Sb2Se6]4- anion. The mixed-valent [Sb4Se9(4-)]n and [Sb2Se6]4- anions were not observed before. The synthesis and solid-state structural studies of the title compounds show that the transition-metal complexes exhibit different structure-directing effects on the formation of selenidoantimonates in dien. Extensive N-H...Se hydrogen bonds are observed between cations and anions in compounds 1-4, resulting in three-dimensional network structures. Optical and thermal properties of the compounds are reported.     

An octanuclear [Co(II)2-Co(III)2]2 interlocked grid--example of an inorganic [2]catenane

An oxalic dihydrazide based flexible polydentate amidrazone ligand undergoes spontaneous [2 x 2] grid assembly, followed by partial disassembly, and then reassembly in the presence of Co(NO3)2.6H2O and NH4(NCS) to form a unique octanuclear [Co(II)2-Co(III)2]2 interlocked, single braided 4 + 4 [2]catenane.