Studies on the thermal decomposition of salicylhydroxamic acid and its metal complexes with Ni(II), Co(II), Fe(II), Mn(II) and Zn(II)

The thermal decomposition of salicylhydroxamic acid and its metal complexes with Ni(II), Co(II), Fe(II), Mn(II) and Zn(II) has been studied by TG, DTG, DTA and IR spectroscopy. All the compounds investigated decompose to yield intermediate N-hydroxylactams.Decomposition schemes have been proposed and reaction enthalpies and kinetic parameters have been calculated.     

Zinc(II), cadmium(II) and mercury(II) complexes of 4,6-dimethyl-pyrimidine-2(1H)-one

The following zinc(II), cadmium(II) and mercury(II) complexes of 4,6-dimethylpyrimidine-2(1H)-one (L) have been prepared and investigated by conductometric,IR and Raman methods: MX₂L₂ (M = Zn, X = Cl, Br(CHCl₃, I(CHCl₃, CF₃COO; M = Cd, X = Cl, Br CF₃COO; M = Hg, X = Cl, CF₃COO), Cd₂I₄L₃, Hg₃X₆L₂ (X = Cl, Br), Hg₃X₆L₄(X = Br, I), MX₂L₄·6H₂O (M = Zn, Cd, X = CIO₄, BF₄; M = Hg, X = CIO₄. The ligand is principally bonded through the unprotonated nitrogen atom and in some complexes also through the carbonylic oxygen atom. The zinc halide complexes are tetrahedrally coordinated, the trifluoroacetate ion is coordinated as a monodentate ligand.     

Complexes of vitamin B6—XV quaternary complexes involving pyridoxamine,glycine and ethylenediamine with Co(II), Ni(II), Cu(II) and Zn

The formation constants of quaternary Co(II), Ni(II), Cu(II) and Zn complexes comprising pyridoxamine as a first, glycine as a second and ethylenediamine as a third ligand were determined by pH-metric titration at I = 0.5 M NaNO₃ and 30°. The complexes are generally protonated in which the ligands may act as bidentate as well as monodentate. The formation of the quaternary species is discussed in relation to pertinent binary and ternary species. The validity of the Van Panthaleon van Eck equation was also tested.     

Synthesis and characterization of two Ni(II) complexes with furfural s-methylthiosemicarbazone

Synthesis of two Ni(II) complexes with furfural S-methylthiosemicarbazone (HL) of the formula [Ni(HL)₂(H₂O)₂](ClO₄)₂ (A) and [Ni(HL)₂(ClO₄)₂] (B) are reported. Compound A was obtained from an ethanolic solution of Ni(ClO₄)₂·6H₂O and HL, whilst compound B was produced by heating compound A to 378 K. An X-ray analysis of the complex A showed that it has a trans(H₂O)-trans(HL) octahedral configuration in which HL behaves as a bidentate (NN) ligand. On the basis of the IR and electronic spectra as well as the magnetism, it was found that the compound B has also an octahedral configuration in which, HL and ClO₄ groups, are coordinated.     

On the tri-n-octylammonium chloro complexes of Cu(II), Zn(II) and Co(II) in benzene solution

Extracts with tri-n-octylammonium chloro complexes of Cu(II), Zn(II) and Co(II) of various compositions, including the N-deuterated compounds, were prepared and investigated by IR spectroscopy and conductivity measurements. Besides the well-known 2:1-complexes (TOAH⁺)₂MCl₄^2?, for which new assignments of νNH frequencies are given, complexes with a stoichiometric ratio TOA:M > 2 were found. Their cations contain the groups (TOAH …Cl…HTOA)⁺ and TOAH⁺ and they are supposed to be 3:1-complexes (TOAH…Cl…HTOA)⁺TOAH⁺MCl₄^2?. The IR spectrum of the 1:1-complex TOAH⁺CuCl_3? is given. The occurrence of the analogous 1:1-complex TOAH⁺ZnCl_3? could not be detected under the preparative conditions used.     

Synthesis,X-ray structure and spectroscopy of Cu(II) complexes derived from diacetylazine dioxime

Complexes of Cu(II) with the polydentate diacetylazine dioxime ligand C₈H₁₄N₄O₂ have been synthesized by template and non-template reactions. The crystal structure of [Cu(C₈H₁₃N₄O₂)]₂[ClO₄]₂(C₂H₅OH)₂ has been determined to establish the conformation of the ligand and the coordination of the oxime function. The structural analysis shows that the nearly planar [C₈H₁₃N₄O₂]^? group behaves as a bridging tetradentate ligand. The distorted square-pyramidal coordination about each Cu atom includes three N donors from two oxime and azine and one O donor from the other oxime, the ethanol molecule occupying the apical position. A perchlorate anion is loosely bonded to Cu. The intramolecular Cu…Cu separation is 3.725(2) Å. The compound crystallizes in the centrosymmetric space group P$\text{1}$ triclinic lattice with refined lattice parameters of a = 11.963(8) Å, b = 9.784(7) Å, c = 7.501(6) Å, α = 90.69(4)°, β = 104.53(4)°, γ = 90.83(4)°, V = 849.7 ų and Z = 2. Full-matrix least-squares refinement of 1490 independent reflexions led to final discrepancy indices, R = 0.059, and R_w = 0.065. The Cu centres are highly coupled as indicated by the ESR spectrum. There is no evidence that the C₈H₁₄N₄O₂ ligand stabilizes unusual oxidation states of Cu.     

Synthesis of tert-butyl mercapto complexes of titanium(IV). X-ray crystal structure of Ti(diars)Cl2 (tBuS)2

The new class of tert-butyl mercapto compounds, Ti(L)Cl₂(^tBuS)₂ (L = diars, dmpe, dppe), has been synthesized and characterized. The X-ray crystal structure of Ti(diars)Cl₂(^tBuS)₂ (1) shows that the Ti(IV) atom has a distorted octahedral geometry with trans chlorides and cis tert-butyl mercapto units. The structures of the other complexes are similar based on spectroscopic (NMR, IR) evidence. Crystal data for (1): C₁₈H₃₄As₂Cl₂S₂Ti, M = 583.24, trigonal space group P3₁21 (No. 152), a = b = 16.892(5) Å, c = 8.492(2) Å, U = 2098.4 ų, Z = 3, D_c = 1.389 gcm^?3, μ = 29.841 cm^?1, λ(MoK_α) = 0.71069 Å (graphite monochromator). Refinement of 948 observed (1371 unique measured; I > 3σ(I) reflections gave a final R = 0.0462 and R_w = 0.0597.     

An NMR study of the complexes of Zn(II) and Cd(II) ions with tris(dimethylamino)phosphine sulphide: Ligand exchange kinetics

The preparation of the complex species [Cd(TDPS)₄](ClO₄)₂ and [Zn(TDPS)₄](ClO₄)₂ (TDPS = tris(dimethylamino)phosphine sulphide)     

The isolation and X-ray structure of a complex between lithium picrate and dibenzo-36-crown-12

The crystal structure of 2Li picrate.dibenzo-36-crown-12.2H₂O was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystalli     

Ni(II) complexes with 8-aminoquinoline derivatives

Some Ni(II) complexes with 5,7-dicloro-8-aminoquinoline (dcaq), 5,7-dibromo-8-aminoquinoline(dbaq) and 5,7-diiodo-8-aminoquinoline(diaq) are described. The compounds are of stoichiometry NiL₂X₂(L= dcaq, dbaq, diaq; X= NO^?₃ and L= dbaq; X= Cl^?, Br^?, I^?, NCS^?) and NiLX₂·H₂O(L= dcaq, diaq; X= Cl^?). The electronic spectra and magnetic susceptibility data at room temperature, are consistent with octahedral geometry for the Ni(II) in each compound. I.r. spectra show the presence of ionic and bridging nitrate groups in the compounds NiL₂(NO₃)₂(L= dcaq, dbaq, diaq) and we assign them polymeric structures. Polymeric structures with bridging chloride are proposed for the compounds NiLCl₂·H₂O(L= dcaq, diaq) and monomeric octahedral structures for NiL₂X₂(L= dbaq; X= Cl, Br, I, NCS).     

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.     

Metal complexes of anti-inflammatory drugs—I. Complexes of iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) with 4-hydroxy-3-(5-methyl-3-is

The preparation, spectroscopic and magnetic properties are reported for complexes of iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) with th     

Complexes of 1-methyl-4-mercaptopiperidine with zinc(II), cadmium(II) and mercury(II) halides

The preparation of a series of complexes formed by 1-methyl-4-mercaptopiperidine (AH) and divalent zinc, cadmium and mercury halides is reported together with some spectral and physical properties. The results of a crystallographic study allows to establish the structure of those of formula [M₂(AH)₂X₄]H₂O (M = Zn, Cd, Hg; X = Br, I) consisting of dimers and involving tetrahedral environment with sulphur-bridges for the metal atoms. Polymeric structures are proposed for the complexes of formulae Cd(AH)Cl₂ and Hg₂Cl₄(AH).     

Synthesis and characterisation of ReOCl3(DTO)2 and ReOCl3(MBT)2 complexes

New complexes of Re(V) with dithiooxamide and 2-mercaptobenzothiazole with the general formula ReOCl₃L₂, were prepared starting from potassium perrhenate. The compounds were characterised by chemical analysis, optical spectra and magnetic susceptibilities.     

Tridentate chelate π-bonded complexes of rhodium(I), iridium(I), and iridium(III) and chelate σ-bonded complexes of nickel(II), palladium(II), and platinum(II) formed by intramolecular hydrogen abstraction reactions

2,2′-Bis(o-diphenylphosphino)bibenzyl, o-Ph₂PC₆H₄CH₂CH₂C₆H₄PPh₂-o (bdpbz), is dehydrogenated by various rhodium complexes to give the planar rhodium(I) complex

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, from which the ligand, 2,2′-bis(o-diphenylphosphino)-trans-stilbene (bdpps) can be displaced by treatment with sodium cyanide. The stilbene forms stable chelate olefin complexes with planar rhodium(I) and iridium(I) and with octahedral iridium(III). On reaction with halide complexes of nickel(II), palladium(II) or platinum(II), the stilbene ligands

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(R = Ph or o-CH₃C₆H₄) lose a vinyl proton in the form of hydrogen chloride to give chelate, planar σ-vinyls of general formula =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; X = Cl, Br, I) of high thermal stability; analogous methyl derivatives =CHC₆H₄PR₂-o) are obtained from Pt(CH₃)₂(COD) (COD = 1,5-cyclooctadiene) and the stilbene ligands. The bibenzyl also forms chelate σ-benzyls HCH₂C₆H₄PPh₂-o) (M = Pd, Pt; X = Cl, Br, I). The ¹H NMR spectra of the o-tolyl methyl groups in the compounds =CHC₆H₄PR₂-o) (M = Ni, Pd, Pt; R = o-CH₃C₆H₄) vary with temperature, probably as a consequence of interconversion of enantiomers arising from restricted rotation about the M---P and M---C bonds. Possible mechanisms for the dehydrogenation reactions are briefly discussed.     

Photochemistry of planar four-co-ordinate palladium(II) complexes—III. Photosynthesis and crystal structure of [Pd2(PPr3n2(NCS)(SCN)2(μ-CN)]

U.V. irradiation of MeOH and CH₃CN solutions of trans-[Pd(PPr₃ⁿ)₂(NCS)₂] causes a stepwise photochemical reaction. When the solvent is CH₃CN the photoproduct can be conveniently isolated in a crystalline form. This compound has been shown, by X-ray analysis, to be a cyano bridged palladium(II) complex.     

Synthesis and 31P NMR spectra of some platinum(II) complexes of the phospha-alkene, (mesityl)P=CPh2: Crystal and molecular structure of cis-[PtCl2(PEt3)(C6H2Me3P=CPh2)]·CHCl3

Syntheses of the phospha-alkene complexes cis- and trans-[PtCl₂(PEt₃)(mesityl)P=CPh₂], and cis- [PtX₂{(Mesityl)P=CPh₂}₂](X=Cl, I, Me) complexes are reported. ³¹P NMR spectra indicate that bonding of the phospha-alkene to the metal is via the phosphorus lone pair and this is confirmed by a single crystal X-ray diffraction study of cis-[PtCl₂(PEt₃){(mesityl)P=CPh₂}]CHCl₃.     

Electrochemical reductions of substituted pyridinium 2-pyridylcarbonylmethylides,their Pt(II) complexes,and substituted n-(2-pyridylcarbonyl)methylpyridinium perchlorates

The title pyridinium salts and pyridinium ylide-platinum(II) complexes have been reduced through a one-electron process at more positive potentials by 0.3 $\text{\$}\text{?}$0.6 V than the corresponding ylides. Both the reduced pyridinium salts and Pt(II)-ylide complexes reacted with dioxygen, followed by elimination of the N-methylene and ylide protons to form pyridinium ylides and Pt(II)-pyridinium ylide complexes containing the three-coordinate ylide carbon atom, respectively.     

Ethylphosphinediacetic acid: synthesis,characterization and coordinating behaviour towards Ca(II), Ni(II) and Hg(II) ions in solution

The new ligand, ethylphosphinediacetic acid, H₂Z, was synthesized and characterized by spectral methods. The Z^2? anion is protonated in three steps with the pK values of 6.10 (phosphorus atom), 2.75 and 0.9 (carboxyl groups). The ligand is highly selective for soft metal ions as demonstrated by the stability constants of the water-soluble complexes CaHZ-(logβ_CaHZ^HZ 0.73), NiZ₂^2? (log β₂ 9.06) and HgZ₄^6? (log β₄ 40.9). The di in behaviour compared to related phosphineacetic acids are mainly consequences of the high basicity of the phosphorus atom.     

Stability and thermodynamic parameters of thiopyrimidines, 2-thioxanthine and their complexes with Zn(II) and Cd(II)

The thermodynamic protonation constants of 4-amino-1,6-dihydro-2-methylthio-5-nitroso-6-oxo-pyrimidine (MTH), 4-amino-5-nitroso-6-oxo-1,2,3,6,-tetrahydro-2-thiopyrimidine (TANH) and 2-thioxanthine (TXH) in aqueous media at 25, 30, 40 and 50 ± 0.1°C, have been determined potentiometrically by Bjerrum and Robinson's methods. The ionic strength was maintained constant by using 0.1 M NaNO₃ as the supporting electrolyte.The stability constants and thermodynamic functions for Zn(II) and Cd(II) complexes of MTH and TXH, at different ionic strengths and temperatures, have been calculated.