Copper(ii), cobalt(ii), manganese(ii) and nickel(ii) bis(hexafluoroacetylacetonate) complexes with N-vinylimidazole

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Homo- and heterometallic trinuclear nickel(ii) and cobalt(ii) pivalate complexes

The reaction of the dinuclear complex Co₂(bpy)₂(OOCBu^t)₄ with the tetranuclear complex Ni₄(₃-OH)₂(OOCBu^t)₆(EtOH)₆ afforded the trinuclear heterometallic complex M₃(bpy)₂(₃-OH)(-OOCBu^t)₄(OOCBu^t) (6) (M = Ni, Co; Ni : Co = 1.2 : 1) in which two metal atoms are in an octahedral environment and one metal atom is in a tetrahedral environment. The reaction of 2,2"-bipyridine with Co₄(₃-OH)₂(OOCBu^t)₆(HOEt)₆ (reagent ratio was 2 : 1) or the reaction of bpy with Co₈(₄-O)₂( _n -OOCBu^t)₁₂ (reagent ratio was 4 : 1) produced a homometallic analog of 6, viz., the trinuclear cluster Co₃(bpy)₂(₃-OH)(-OOCBu^t)₄(OOCBu^t) (8). The reaction of 1,10-phenanthroline (phen) with the [Co(OH) _n (OOCBu^t)_2–n ] _x polymer gave the analogous trinuclear cluster (phen)₂Co₃(₃-OH)(₂-OOCBu^t)₄(¹-OOCBu^t). Compounds 6 and 8 exhibit antiferromagnetic spin-spin exchange interactions.     

Studies on nickel(II) complexes of N-aryl thioureas

The preparation and properties of the crystalline compounds of the type NiL ₄Cl₂, NiL ₂Cl₂ and NiLCl₂ (L=N-aryl thioureas) are described. Analytical, conductometric, magnetic and spectral data (infrared and electronic)_show that complexes of the type NiL ₄Cl₂ possess octahedral structure and those of NiL ₂Cl₂ and NiLCl₂ are characterised as distorted octahedral in solid state. The ligand field parametersD _q ,B and calculated from electronic spectral data, suggest a weak field for all the ligands. Metal sulphur bonding for all ligands is adduced from infrared and far infrared spectral studies.

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Untersuchungen an Nickel(II) Komplexen von N-Aryl-thioharnstoff Derivaten

Zusammenfassung Darstellung und Eigenschaften der kristallinen Verbindungen vom Typ NiL ₄Cl₂, NiL ₂Cl₂ und NiLCl₂ (L=N-Arylthioharnstoff) werden beschrieben. Magnetische Eigenschaften, Leitfähigkeitsmessungen, analytische und spektroskopische Daten beweisen, daß die Komplexe vom Typ NiL ₄Cl₂ oktaedrische Struktur besitzen; die Komplexe vom Typ NiL ₂Cl₂ und NiLCL₂ weisen eine verzerrt oktaedrische Geometrie auf. Die Ligandenfeld-ParameterD _q ,B und , die aus Elektronenanregungsspektren berechnet wurden, zeigen ein schwaches Feld für alle untersuchten Liganden an Aus Untersuchungen der Spektren des IR und fernen IR folgt, daß die Komplexe eine Metall—Schwefel-Bindung aufweisen.

     

4-carboxy-1,2-cyclohexanedionedioxime complexes of nickel(ii) in alkaline media

The reactions of 4-carboxy-1,2-cyclohexanedionedioxime and nickel(II) were studied in alkaline media. Spectrophotometric studies indicate the presence of a 1:1 complex ion, NiD^-. Magnetic susceptibility measurements on a series of solutions of varying ratios of vic-dioxime and nickel(II) showed that the 1:1 complex ion was diamagnetic and that two paramagnetic complexes, probably NiD₂^4- and NiD₃^7-, are present in solution. The stability constants for the three complexes were calculated from spectrophotometric and magnetic susceptibility data. The log K values were found to be log K₁ = 28.74 ± 0.60, log K₂ = 0.76 ± 0.15, and log K₃ = 3.67 ± 0.73, respectively.     

Polynuclear and mixed-ligand mononuclear Cu(I) complexes with N-thiophosphorylated thioureas and 1,10-phenanthroline or PPh3

Deprotonation of the N-thiophosphorylated thioureas RC(S)NHP(S)(OiPr)(2) (R = Me(2)N, HL(I); iPrNH, HL(II); 2,6-Me(2)C(6)H(3)NH, HL(III), 2,4,6-Me(3)C(6)H(2)NH, HL(IV), aza-15-crown-5, HL(V)) and reaction with CuI or Cu(NO(3))(2) in aqueous EtOH leads to the polynuclear complexes [Cu(4)(L(I)-S,S')(4)], [Cu(8)(L(II)-S,S')(8)], and [Cu(3)(L(III-V)-S,S')(3)]. The structures of these compounds were investigated by IR, (1)H, (31)P{(1)H} NMR, UV-vis spectroscopy and elemental analyses. The crystal structures of [Cu(4)L(I)(4)], [Cu(8)L(II)(8)], [Cu(3)L(III,IV)(3)] were determined by single-crystal X-ray diffraction. Reaction of the deprotonated ligands (L(I-V))(-) with a mixture of CuI and 1,10-phenanthroline (phen) or PPh(3) leads to the mixed-ligand mononuclear complexes [Cu(phen)L(I-V)], [Cu(PPh(3))L(I-V)] or [Cu(PPh(3))(2)L(I-V)]. The same mixed-ligand complexes were obtained from the reaction of [Cu(4)L(I)(4)], [Cu(8)L(II)(8)], [Cu(3)L(III-V)(3)] with phen or PPh(3).     

Coordination behaviour of 2-halo-1,3,4-thiadiazoles towards cobalt(ii) and nickel(ii)

Summary A series of cobalt(II) and nickel(II) 2-X-1,3,4-thiadiazole complexes (X=Cl or Br) were investigated by electronic, n.m.r., Raman and i.r. spectroscopy, and by thermogravimetric analyses, magnetic moments and conductivity measurements.The complexes havepseudo-tetrahedral or pseudo-octa-hedral stereochemistries with MN₂X₂ (X=Cl or Br), MN₄X₂ (X=Cl, Br or O) or MN₃O₃ chromophores.The ligands are mono- or bi-dentate without involving the sulphur atom. Surprisingly, the chloro-derivative ligand seems to be more nucleophilic than the bromo-analogue.The computed (CNDO/2) molecular orbital indices for the uncomplexed ligands indicate that the coordination sites are the nitrogen atoms.In connection with our previous work⁽¹⁾ on the coordination ability of heterocyclic ligands with interesting biological^(2,3) and pharmaceutical⁽⁴⁾ properties and containing endocyclic nitrogen and sulphur donor atoms, we have considered the 1,3,4-thiadiazole ring, which is the main framework of a very important class of diuretic drugs, the sulphonamide inhibitors⁽⁵⁾ of the zinc m tallo-enzyme carbonic anhydrase.In this study we have investigated the coordination behaviour of the 2-chloro-1,3,4-thiadiazole(ctz) and the 2-bromo-1,3,4-thiadiazole (btz).     

Complexes of nickel(ii) and copper(ii) chlorides with a nitroxide radical derivative of 4-tetrazolyl-3-imidazolme-3-oxide

NiCl₂ and CuCl₂ complexes with a new stable nitroxyl radical, 2,2,5,5-tetramethyl-4-(tetrazol-5-yl)-3-imidazoline-3-oxide-1-oxyl (L), NiLCl₂· H₂O and CuLCl₂, have been synthesized. The _eff values attest to a weak exchange interaction between the paramagnetic centers in the temperature interval of 78–300 K.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 932–934, May, 1994.The authors are grateful to E. G. Boguslavskii for the registration and interpretation of the ESR spectrum, to V. A. Shipachev for the measurement of SDR, and to V. I. Lisoivan for the X-ray analysis.     

CXCR4 chemokine receptor antagonists: nickel(ii) complexes of configurationally restricted macrocycles

Tetraazamacrocyclic complexes of transition metals provide useful units for incorporating multiple coordination interactions into a single protein binding molecule. They can be designed with available sites for protein interactions via donor atom-containing amino acid side chains or labile ligands, such as H(2)O, allowing facile exchange. Three configurationally restricted nickel(ii) cyclam complexes with either one or two macrocyclic rings were synthesised and their ability to abrogate the CXCR4 chemokine receptor signalling process was assessed (IC(50) = 8320, 194 and 14 nM). Analogues were characterised crystallographically to determine the geometric parameters of the acetate binding as a model for aspartate. The most active nickel(ii) compound was tested in several anti-HIV assays against representative viral strains showing highly potent EC(50) values down to 13 nM against CXCR4 using viruses, with no observed cytotoxicity (CC(50) > 125 μM).     

Spectrophotometric determination of nickel(ii) with molybdophosphoric acid

A sensitive spectrophotometric method for the determination of nickel, based on the reduction of a complex formed between molybdophosphoric acid and Ni(II) at pH 4.3 has been developed. Excess of molybdophosphoric acid is eliminated by complexation with sodium citrate. The method is rapid and the system obeys Beer's law up to 5 ppm of Ni(II). The molar absorptivity is 1.30 x 10(3) 1.mole(-1).mm(-1). The technique compares favourably with existing photometric methods for nickel in sensitivity and is reasonably selective.     

Adsorption characteristics of radionuclides on nickel hexacyanoferrate(ii)

The composition of nickel hexacyanoferrate(II) complexes depends on the ratios of sodium hexacyanoferrate(II) and nickel nitrate solutions mixed. The adsorption behavior of nickel hexacyanoferrate(II) is described; acid treatment of Ni₂Fe(CN)₆ accelerates the adsorption rate of cesium, but does not increase the adsorption capacity. The Ni—Cs exchange ratios of Ni₂Fe(CN)₆ are discussed. In concentrated salt solutions, the distribution coefficients of ⁵⁹Fe, ⁶⁰Co, ⁶⁵Zn. ¹³⁷Cs, ⁹⁵Zr and ¹⁴⁴Ce are determined together with those of ⁸⁵Sr and ¹⁰⁶Ru. A simple determination of ¹³⁷Cs in sea water containing ⁵⁹Fe, ⁶⁰Co, ⁶⁵Zn, ⁹⁵Zr, ¹⁴⁴Ce, ⁸⁵Sr and ¹⁰⁶Ru is described.     

Synthesis and properties of new binuclear nickel(ii) phthalocyanines

New binuclear nickel(ii) phthalonitrile complexes, viz., Ni^II 2,2",9(10),9"(10"),17(18),17"(18"),24(25),24"(25")-tetra(phenylene-1,2-dioxy)bisphthalocyanine and Ni^II 2,2",9(10),9"(10"),17(18),17"(18"),24(25),24"(25")-tetra(4-tert-butylphenylene-1,2-dioxy)bisphthalocyanine, were synthesized. The complexes were characterized by electronic spectroscopy and MALDI—TOF mass spectrometry and studied as active components for membranes of ion-selective electrodes in solutions of dicarboxylic acids.     

Ru(ii)-cornered coordination cage that senses guest inclusion by color change

Upon guest recognition, a self-assembled hexa-ruthenium coordination cage shows a chromic shift resulting from the slight conformational change in the panel ligand.     

Hydrothermal synthesis of a nano-rod mercury(ii) metal-ligand coordination compound

A novel nano-rod mercury(II) coordination compound [Hg (BINH)I₂] (1), (BINH is the abbreviation of benzylideneisonicotinohydrazide) is synthesized by a hydrothermal method that produces the coordination compound at a nanosize level. The new nanostructure is characterized by scanning electron microscopy, powder X-ray diffraction, elemental analysis, and IR spectroscopy. Compound 1 was structurally characterized by single crystal X-ray diffraction and the single-crystal structure of this complex shows that each mercury(II) center is four-coordinated with two N-donor atoms from tow BINH ligands and tow iodo anions. Self-assembly of this complexes is pereformed by CH?I and π-π stacking interactions. The supramolecular features in these complexes are controlled by weak directional intermolecular interactions.     

First examples of two ferromagnetic end-to-end cyanate bridged 1D linear coordination polymers of nickel(ii) containing an unsymmetrical diamine

Two new end-to-end (EE) cyanate bridged 1D coordination polymers of Ni(II) are isolated which contain linear (180°) Ni-N-C and Ni-O-C angles in Ni-NCO-Ni bridges and show ferromagnetic (F) coupling in agreement with the reported theoretical model for linear EE bridges.     

The alcoholysis and phenolysis of isosteric isobutyl(isopropoxy)silanethiols catalyzed by 4-dimethylaminopyridine or triethylamine

The reaction rates of alcoholysis of isosteric silanethiols ⁱBu_n(ⁱPrO)_3−nSiSH, n = 0–3, in the presence of the tertiary amines, 4-dimethylaminopyridine (DMAP) or triethylamine (NEt₃), were measured in benzene and in acetonitrile solutions under pseudo-first-order conditions. The catalytic activity of NEt₃ is low. The alcoholysis catalyzed by DMAP shows features of a nucleophilic catalysis. The protonation of the catalyst (DMAP or NEt₃) by silanethiols causes substantial deviations from pseudo-first-order kinetics. Phenolysis of silanethiols is effectively catalyzed by both DMAP and NEt₃. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 245–251, 1997.     

Role of metal center in reactions of polynuclear nickel(ii) and cobalt(ii) trimethylacetates with 8-amino-2,4-dimethylquinoline

The reactions of 8-amino-2,4-dimethylquinoline (L) (1) with polynuclear nickel(ii) and cobalt(ii) hydroxotrimethylacetato complexes under anaerobic conditions were studied. The nonanuclear cluster Ni₉(₄-OH)₃(₃-OH)₃(_n-OOCCMe₃)₁₂(HOOCCMe₃)₄ gave the mononuclear complex Ni(²-L)(²-OOCCMe₃)₂ (2). The tetranuclear complex Ni₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ produced the mononuclear complex Ni(²-L)(²-OOCCMe₃)(OOCCMe₃)L (3). At room temperature, the cobalt-containing polynuclear trimethylacetates, viz., the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x and the tetranuclear complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆, were transformed into the trinuclear cobalt(ii) complex Co₃(₃-OH)(-OOCCMe₃)₄(²-L)₂(OOCCMe₃) (4). Meanwhile, at 80 °C these compounds generated the binuclear cobalt(iii) complex Co₂(₂²-(HN)C₉NMe₂)₂(-OOCCMe₃)(L)(OOCCMe₃)₃ (5). The structures of the resulting compounds were established by X-ray diffraction analysis. Compounds 2—4 exhibit the antiferromagnetic spin-spin exchange coupling, whereas compound 5 is diamagnetic.     

Synthesis, structure and luminescence properties of Cu(ii), Zn(ii) and Cd(ii) complexes with 4'-terphenylterpyridine

The complexes [M(tptpy)(2)](ClO(4))(2) (M = Zn(ii) (1), Cd(ii) (2), and Cu(ii) (3)); tptpy = 4'-[1,1':4',1']terphenyl-4'-yl-[2,2':6',2']terpyridine = 4'-terphenylterpyridine) have been synthesized, structurally characterized by X-ray crystallography and subjected to preliminary luminescence studies. In the crystalline state, all the metal ions have an N(6) coordination sphere of distorted octahedral geometry and the structures of the Zn(ii) and Cd(ii) complexes are isomorphous but differ from that of the Cu(ii) complex, which also differs from the other two in that it is non-emissive. The structure determinations show that aromatic-aromatic interactions involving both the terpyridine heads and the terphenyl tails are important factors influencing the crystalline array. The emission spectra of the Zn(ii) and Cd(ii) complexes are very similar and show a considerable red-shift of the emission maximum compared to that of the free ligand.     

Thermal properties of solid nickel(II) coordination compounds

The paper deals with the chemical and physical factors influencing the thermal octahedral square planar changes of nickel(II) complexes in the solid phase. The relationship between these transformations and the tetragonal distortion of the octahedral ligand field is discussed. Depending on the coordination of the ligands, these transformations can be divided into two groups: octahedral monomer square planar monomer, and octahedral polymer square planar monomer changes. Attention is directed only to octahedral and square planat Ni(II) complexes (square planar complexes with chromophores [NiN₄], [NiN₂O₂] and [NiO₄]), which can be isolated in the solid state before and after heating. The possibility of such a configurational change seems to be dependent upon the thermal stabilities of the initial and final complexes, the electronic and steric properties of the ligands, the complexing ability of the central atom, and particularly the equatorial-axial interactions of the ligands via the central atom.

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Zusammenfassung Vorliegende Arbeit befasst sich mit den chemischen und physikalischen Faktoren, die den thermischen Übergang oktaedrisch-rechteckig planar der Festkörperphase von Nickel(II) komplexen beeinflussen. Es werden die Beziehungen zwischen dieser Transformation und der tetragonalen Verzerrung oktaedrischer Ligandenfelder besprochen. Entsprechend der Koordinierung der Liganden können diese Transformationen in zwei Gruppen eingeteilt werden: monomer oktaedrisch-monomer rechteckig planar sowie polymer oktaedrisch-monomer rechteckig planare. Hier werden nur solche oktaedrische und rechteckig planare Ni(II)komplexe (rechteckig planare Komplexe mit (NiN₄)-, (NiN₂O₂)- und (NiO₄)-Chromophoren) betrachtet, die sowohl vor als auch nach dem Erhitzen in fester Form isoliert werden können. Die Möglichkeit solcher Konfigurationsübergange scheint von der thermischen Stabilität der Ausgangs- und Produktekomplexe, von elektronischen und sterischen Eigenschaften der Liganden, von der Komplexbildungsstärke des Zentralatomes und hauptsächlich von den äquatorial-axialen Wechselwirkungen der Liganden gegenüber dem Zentralatom abzuhängen.

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, . . , : . - ( [NiN₄], [NiN₂O₂] [NiO₂]), . , , , , , — .

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Part A: J. Thermal Anal., 16 (1979) 213.