Metal chelates of heterocyclic nitrogen containing ketones,XIII. Cobalt(II), nickel(II) and palladium(II) complexes of 2-picolyl- and 2-lutidyl-methyl ketones

Summary The preparation and characterization of a series of new coordination compounds of cobalt(II), nickel(II) and palladium(II) containing 2-picolyl- or 2-lutidyl-methyl ketone (HPMK or HLMK) and various anions, Cl^–, Br^–, NO ₃ ^– , NCS^– or BF ₄ ^– , are reported. Complexes of square planar, tetrahedral and octahedral stereochemistry as well as five-coordinate species were isolated. The reaction products were found to be dependent on the molar ratios, pH and the temperature at which the reaction takes place. Cobalt(II) thiocyanate was found to form a complex of the type [CoL₃][Co(NCS)₄] (L = HPMK or HLMK). Also complexes containing coordinated BF₄ were isolated. The ligand field parameters (Dq, B and ) for the cobalt(II) and nickel(II) complexes were calculated using the averaged-ligand-field approximation. The influence of the substituents of theses parameters and on the stereochemistry are discussed.     

Ruthenium(II/IV) complexes with potentially tridentate Schiff base chelates containing the uracil moiety

Herein we report the synthesis and characterization of trans-[Ru^IICl₂(PPh₃)₃] with potentially tridentate Schiff bases derived from 5,6-diamino-1,3-dimethyl uracil (H₂ddd) and two 2-substituted aromatic aldehydes. In the diamagnetic ruthenium(II) complexes, trans-[RuCl(PPh₃)₂(Htdp)] (1) {H₂tdp = 5-((thiophen-3-yl)methyleneamino)-6-amino-1,3-dimethyluracil} and trans-[RuCl(PPh₃)₂(Hsdp)] (2) {H₂sdp = 5-(2-(methylthio)benzylideneamino)-6-amino-1,3-dimethyluracil}, the Schiff base ligands (i.e. Htdp and Hsdp) act as mono-anionic tridentate chelators. Upon reacting 5-(2-hydroxybenzylideneamino)-6-amino-1,3-dimethyluracil (H₃hdp) with the metal precursor, the paramagnetic complex, trans-[Ru^IVCl₂(ddd)(PPh₃)₂] (3), was isolated, in which the bidentate dianionic ddd co-ligand was formed by hydrolysis. The metal complexes were fully characterized via multinuclear NMR-, IR-, and UV–Vis spectroscopy, single crystal XRD analysis and conductivity measurements. The redox properties were probed via cyclic voltammetry with all complexes exhibiting comparable electrochemical behavior with half-wave potentials (E_½) at 0.70 V (for 1), 0.725 V (for 2), and 0.68 V (for 3) versus Ag|AgCl, respectively. The presence of the paramagnetic metal center for 3 was confirmed by ESR spectroscopy.     

The high-pressure liquid chromatographic separation of copper(II) and nickel(II) schiff base chelates on microparticulate silica

The separation of neutral copper and nickel chelates of two representative Schiff base ligands, N,N'-ethylenebis(acetylacetoneimine) and N,N'-ethylene-bis(salicylaldimine) is reported on a column of 10-μm diameter silica. Both pairs of chelates are well resolved with good peak shape and efficiencies when the mobile phase is 4 : 1 methylene chloride—acetonitrile. The u.v. detector response at 254 nm is linear over approximately three orders of magnitude of quantity of chelate injected; the detection limits are in the low nanogram range. Qualitative and quantitative elution of undegraded chelates was demonstrated by u.v. spectrophotometry, mass spectrometry and electron spin resonance spectroscopy.     

Distorted pentacoordinate copper(II) complexes containing a tridentate ligand

Summary Copper(II) complexes with a tridentate chelating ligand within the general 2N, X (X = O or S) donor class, containing abis(benzimidazolyl) donor set, were prepared and characterized. X-band e.p.r. spectra of the complexes indicateg >g and the largeg and lowA have been interpreted in terms of a distorted basal plane. Superimposed on theg component are five SHF lines withA _N = 16±2G, supporting the interaction of two nitrogen atoms with the copper nucleus. Thus, the basal plane of the complex comprises 2N atoms, with the ligand hetero atom being axially coordinated.     

Metal chelates of heterocyclic containing ketones,part 2. Copper(II) complexes of hydrazones derivatives of 2-picolylphenyl; 2-lutidyl and quinaldyl phenyl ketones

Summary The reaction at room temperature of hydrazone derivatives of 2-picolyl, 2-lutidyl and 2-quinaldyl phenyl ketones with CuX₂, where X=Cl, Br, NO₃ and OAc was investigated by e.s.r., magnetic and spectral methods. A square planar was tentatively assigned for Cu(L)X chelates. The hydrazone derivatives of 2-lutidyl and 2-quinaldyl phenyl ketones reacted with copper(II) halides forming the neutral Cu(L) and Cu(L)₂ chelates whereas Cu(OAc)₂ gave the [Cu(L)]₂ dimer. The adducts formed from the reaction of the copper complexes with pyridine were also investigated.     

Synthesis and spectroscopic studies of copper(II) and nickel(II) complexes containing hydrazonic ligands and heterocyclic coligand

Two types of copper(II) and nickel(II) complexes derived from benzophenone anthranoylhydrazone (L1), 2-acetonaftanone anthranoylhydrazone (L2), 4-phenylacetonaftonone anthranoylhydrazone (L3), benzophenone salicyoylhydrazone (L4), 2-acetonaftanon salicyoylhydrazone (L5), 4-phenylacetonaftanon salicyoylhydrazone (L6) and bidentate heterocyclic base [1,10-phenanthroline (phen)] with general stoichiometry [ML2] and [ML(phen)]Cl have been synthesized and characterized by elemental analysis, infrared spectra, UV-vis electronic absorption spectra and magnetic susceptibility measurements. The effect of varying pH and solvent on the absorption behavior of both ligands and complexes have been investigated. According to the IR spectra, the ligands act as monobasic bidentate and coordination takes place in the enol tautomeric form.     

Preparation and characterization of copper(II) and nickel(II) complexes with novel tetraaza-macrocyclic schiff bases

Novel tetraaza-macrocycles with N-substituted carbamoyl groups were prepared by the reaction of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,5,7,12-tetraene with isocyanates (RNCO, R = Ch₃ and C₆H₅). Their copper(II) and nickel(II) complexes were characterized by magnetic susceptibilities, electronic absorption spectra, and electrochemical properties. The complexing abilities and extractabilities of the ligands for the metal ions were investigated.     

Copper(II) and nickel(II) complexes of schiff bases

Summary The isolation of complexes of some nickel(II) and copper(II) salts with the Schiff base derived from 2-aminobenzimidazole and 4-methylbenzaldehyde (abimbz) is reported. They are of the general type M(abimbz)₂X₂ (M=Ni or Cu; X=Cl, Br, or ClO₄). The compounds have been characterized by elemental analyses, conductivity measurements, i.r., electronic and e.p.r. spectral studies and magnetic measurements. The i.r. spectra show that the ligand is bidentate through the tertiary nitrogen of the imidazole ring and the exocyclic imine nitrogen. Possible structures for the complexes are suggested.     

Metal complexes of sulphur-nitrogen chelating agents. Part 14. Nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) complexes of the tetradentate schiff bases having ONNS donor sites

Summary Complexes of nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) with methyl-2-(-salicylaldiminoethyl)-cyclopent-1-en-dithiocarboxylate (H₂L¹) and methyl-2-(-salicylaldiminoisopropyl)cyclopent-1-en-dithiocarboxylate (H₂L²) have been prepared. They contain the donor sites ONNS. The metal(II) ions from neutral, monomeric square planar chelate complexes. The cobalt(III) complexes [CoL¹-(H₂O)₂]X (X=Cl or ClO₄) appear to betrans-diaqua-species. All compounds have been characterized by a number of physico-chemical methods.     

Ether formation on the tridentate Schiff base ligands of copper(II) complexes

A series of copper(II) complexes, CuL·imidazole, where L^2? are tridentate Schiff base ligands formed by condensation of salicylaldehyde with a series of amino acids, have been synthesized. Visible spectral data indicate that copper(II) in these complexes are five coordinate in the solid state and in solution. Electrospray mass spectrometry has been used to show how these complexes react in alcohol/NaOH solutions with and without the presence of d-galactose. In the absence of d-galactose where the amino acid in the ligand is serine, the alcohol group on the ligand is converted to its alkyl ether after sonication of the solution for up to 4?h. In the presence of d-galactose, an alkoxy group is added to the ligands except for the ligand containing serine after sonication of the solutions for up to 4?h. At the same time, d-galactose is oxidized to its aldehyde. Where the ligand contains methionine, oxygen is also added to the ligand, most likely to the thioether sulfur.     

Novel chlorotitanium complexes containing chiral tridentate schiff base ligands for ring-opening polymerization of lactide

The selective synthesis of tri- and dichlorotitanium species containing chiral tridentate Schiff base ligands, derived from (1R,2S)-(-)-1-aminoindanol, was achieved by changing the solvent. Single-crystal X-ray analyses reveal that chlorotitanium complexes are monomeric and octahedral with the meridional occupation of the Schiff base. Although the chlorotitanium complexes lack typical initiating groups such as alkoxides or amides, they are effective catalysts for the controlled ring-opening polymerization of L-lactide (L-LA) as shown by the linearity of the molecular weight vs [L-LA]/[Ti] ratio plot as well as very narrow polydispersity index values.     

New dimeric and supramolecular organotin(IV) complexes with a tridentate schiff base as potential biocidal agents

The paper describes the synthesis and structural characterization of six new diorganotin(IV) compounds 1–6, [R₂SnL] and a monoorganotin(IV) derivative, C₄H₉SnClL (7). Here L = N′-(5-bromo-2-oxidobenzylidene)-N-(oxidomethylene)hydrazine ligand with ONO tridentate chelation capability and R = CH₃ (1), C₂H₅ (2), n-C₄H₉ (3), C₆H₅ (4), C₈H₁₇ (5), tert-C₄H₉ (6), The packing diagram offers a supramolecular structure for 1 and a dimeric structure for 4 with distorted square-pyramidal and distorted trigonal geometry, respectively. The different geometry of 1 than 4 can be attributed to the presence of intermolecular non-covalent Sn---O and Sn---H interactions in the former. The antifungal, antibacterial, antiurease and antileishmanial activities of these complexes proved them to be active biologically and may be formulated as new metal-based drugs in future.     

Polymeric copper(II) and nickel(II) complexes of a tetraoxime containing a binucleating macrocycle ligand

Polymeric copper(II) and nickel(II) complexes of a binucleating tetraoxime macrocycle, 6,6-methylene-bis[1,12-di(hydroximino)- 2,3;9,10-dibenzo-1,11-diaza-4,8-dithiacyclotridecane] (H4L), have been prepared and characterised by elemental analysis, magnetic moments, i.r., uv/vis., and e.p.r. spectral studies. I.r. spectra show that the ligand acts in a tetradentate manner and coordinates via N, S and O donor atoms. The geometry of the resulting metal chelates is discussed with the help of magnetic and spectroscopic measurements. The elemental analyses, stoichiometry and the spectroscopic data of the complexes indicate that the copper(II) and nickel(II) ions are coordinated by the coordination environment of the ligand. The spectral data suggest a distorted tetragonal geometry for polymeric copper(II), and nickel(II) ions in the complexes. The stoichiometry of the metal-to- H4L ratio of complexes (2) and (3), prepared from CuCl2 and NiCl2 respectively, was 3:1, suggesting the formation of polymeric species.     

EPR, magnetic and spectral studies of copper(II) and nickel(II) complexes of schiff base macrocyclic ligand derived from thiosemicarbazide and glyoxal

A new macrocylic Schiff base 1,2,5,6,8,11-hexaazacyclododeca-7,12-dithione-2,4,8,10-tetraene(H(2)L(4)) containing thiosemicarbazone moiety is readily prepared and characterized for the first time with fairly good yield. Macrocylic ligand (H(2)L(4)) is prepared from the mesocyle 6-ethoxy-4-thio-2,3,5-triazine(H(2)L(3)) in ethanol with copper chloride acting as template using high dilution technique. The complexes of macrocylic ligand with a general composition M(H(2)L(4))X(2) [where M=Cu(II) or Ni(II); H(2)L(4)=1,2,5,6,8,11-hexaazacyclo dodeca-7,12-dithione-2,4,8,10-tetraene; X= Cl(-), NO(3)(-), (1)/(2)SO(4)(2-)] and ML(4) (where metal salt used to synthesize complex is copper acetate and nickel thiocyanate) have been synthesized. The complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility, IR, electronic, 1H NMR, mass and EPR spectral studies. The complexes from H(2)L(4) show different stoichiometry ratio and with a variable grade of deprotonation in the ligand, depending upon the salt used and working conditions.     

Chelate complexes of some NNO tridentate Schiff bases with iron(II), cobalt(II), nickel(II) and copper(II)

Summary The Schiff bases a-(C₅H₄N)CMe=NNHCOR (R = Ph, 2-thienyl or Me), prepared by condensation of 2-acetylpyridine with the acylhydrazines RCONHNH₂, coordinate in the deprotonated iminol form to yield the octahedral complexes, M[NNO]₂ M = Co or Ni; [NNOH] = Schiff base and the square-planar complexes, Pd[NNO]Cl. The Schiff bases also coordinate in the neutral keto form yielding the octahedral complexes (M[NNOH]2)Z2 (M = Ni, Co or Fe; Z = C104, BF₄ or N03) and complexes of the type M[NNOH]X2 (M = Ni, Co, Fe or Cu; X = Cl, Br or NCS). Spectral and x-ray diffraction data indicate that the complexes M[NNOH]X2 (M = Ni or Fe) are polymeric octahedral, as are the corresponding cobalt complexes having R = 2-thienyl. However, the cobalt complexes Co[NNOH]X2 (X = CI or Br; R = Ph or Me) and the copper complexes Cu[NNOH]CI₂ (R = Ph, 2-thienyl or Me) are five-coordinate, while the thiocyanato complex Co[NNOH](NCS)₂ (R = 2-thienyl) is tetrahedral.     

Complexes of cobalt(II), nickel(II), copper(II), zinc(II) and manganese(II) with tridentate Schiff base ligand

Summary A series of metal complexes with new tridentate Schiff base derived from salicylaldehyde and furfuraldehyde with o-phenyldiamine have been prepared and characterised by physical and chemical methods. Electronic spectra, room temperature magnetic moment values, e.p.r. and X-ray photoelectron spectroscopy studies suggest an octahedral geometry for all the complexes, where low molar conductance values are in accord with their non-electrolytic nature. The thermal stability of the complexes is discussed and the ligand-to-metal bonding modes discussed.     

Three heterotrinuclear Schiff base complexes of nickel(II) with cobalt(II), copper(II) and manganese(II)

The title compounds, bis­(di­methyl­form­amide)‐1κO,3κO‐bis{μ‐2,2′‐[2,2′‐di­methyl­propane‐1,3‐diyl­bis­(nitrilo­methylidyne)]­diphenolato}‐1κ⁴N,N′,O,O′:2κ²O,O′;2κ²O,O′:3κ⁴N,N′,O,O′‐di‐μ‐nitrito‐1:2κ²N:O;2:3κ²O:N‐dinickel(II)­cobalt(II), [CoNi₂(NO₂)₂(C₁₉H₂₂N₂O₂)₂(C₃H₇NO)₂], (I), ‐copper(II), [CuNi₂(NO₂)₂(C₁₉H₂₂N₂O₂)₂(C₃H₇NO)₂], (II), and ‐manganese(II), [MnNi₂(NO₂)₂(C₁₉H₂₂N₂O₂)₂(C₃H₇NO)₂], (III), consist of centrosymmetric linear heterotrinuclear metal complexes. The three complexes are isostructural. There are three bridges across the Ni–M atom pairs (M is Co²⁺, Cu²⁺ or Mn²⁺) in each complex, involving two O atoms of a μ‐N,N′‐bis­(salicyl­idene)‐2,2′di­methyl‐1,3‐propane­diaminate ligand and an N—O moiety of a μ‐nitrito group. The coordination sphere around each metal atom, whether Co²⁺, Cu²⁺, Mn²⁺ or Ni²⁺, can be described as distorted octahedral. The Ni?M distances are 2.9988 (5) Å in (I), 2.9872 (5) Å in (II) and 3.0624 (8) Å in (III).