Square planar complexes of nickel(II), palladium(II) and platinum(II) with 1-(2-hydroxyphenyl)-3,5-diphenylformazan

Summary A novel series of formazan complexes of general formula FoML [H₂Fo = 1-(2-hydroxyphenyl)-3,5-diphenylformazan; M = Ni^II, Pd^II or Pt^II; L = NH₃, py and Ph₃P] are described. The formazan nickel(II) system shows linkage isomerism; one isomer, A, contains an unusual five-membered formazan chelate ring, whereas the other, isomer B, has the usual six-membered ring.¹³C n.m.r., u.v. and i.r. spectra are presented and interpreted. From these the palladium and platinum complexes appear to contain the six-membered ring of the B type isomer.     

Copper(II), nickel(II), palladium(II) and iron(III) complexes of 2-(3-phthalhydrazidylazo)-1,3-diketones

Neutral complexes of three phthalhydrazidylazo-1,3-diketones [phthalhydrazidylazo-acetylacetone (H₂PAA),-benzoylacetone (H₂PBA) and-dibenzoylmethane (H₂PDM)] with Cu(II), Ni(II), Pd(II) and Fe(III) have been synthesised and characterized on the basis of their analytical data, magnetic moment, molar conductance and IR and¹H NMR spectral data. Dibasic tridentate coordination of the ligands is brought out by the above spectral data. Half-wave potentials and far IR spectral data of the Cu(II) complexes indicate that the H₂PAA complex is the most stable. M?ssbauer spectra of the Fe(III) complexes reveal that delocalisation of the metald electrons with the chelate ring decreases with increasing capability of the pendant groups of the ring for cross conjugation.     

Chromium(III), manganese(II), cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a 12-membered tetraaza [N4] macrocyclic ligand

Cr^III, Mn^II, Co^II, Ni^II, Cu^II and Pd^II complexes of the macrocyclic ligand, 2,3,5,8,9,11 hexamethyl-1,4,7,10 tetraaza- cyclododeca-1,3,7,9 tetraene (DADAP), have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, i.r., electronic and e.p.r. spectral studies. These spectral studies suggest an octahedral geometry for the Cr^III, Mn^II and Co^II, square planar geometry for Ni^II and Pd^II and tetragonal geometry for Cu^II complexes.     

Synthesis,spectroscopy and thermal analysis of nickel(II), palladium(II) and copper(II) complexes with N,N′-bis(2-hydroxyethyl)-oxamide

Summary The new complexes K₂[Ni(H₂heo)₂]·3H₂O, K₂[Pd-(H₂heo)₂], K₂[Cu(heo)]·3H₂O and [Cu₂(heo)·2H₂O] {heo = [(CONCH₂CH₂O)₂]^4-} were prepared and characterized by chemical analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and i.r. and u.v. spectroscopy.Monomeric square planar structures with MN₄ coordination spheres are found for the nickel and palladium complex anions.For copper, two different complexes were identified. In slightly alkaline media, a green insoluble nonelectrolyte [Cu₂(heo)·2H₂O] was prepared; the two copper(II) centres are bridged by the tetra-deprotonated ligand in a trans-planar configuration with the H₂O molecules strongly coordinated to the copper(II). The copper(II) monomer has been prepared in strong alkaline media, this anion also contains the tetra-deprotonated ligand in a planar trans form.     

N 1,N 4-diarylidene-S-ethylthiosemicarbazone iron(III) and nickel(II) complexes

Template reactions of salicyl-, 5-bromosalicyl- and 2-hydroxy-1-naphth-aldehyde with S-ethylthiosemicarbazones, in the presence of FeCl₃ and NiCl₂, yielded the corresponding N ¹,N ⁴-di(same/different)arylidene-S-ethylthiosemicarbazone complexes, which were characterized by elemental analysis, magnetic measurements, i.r. and ¹H-n.m.r. spectra.     

New complexes of iron(III), cobalt(II), nickel(II) and copper(II) with Schiff bases derived from 2-aminocyclopent-1-ene-1-dithiocarboxylic acid

Summary Fe^III, Co^II, Ni^II and Cu^II, complexes of a new Schiff base ligand, prepared by condensing 2-aminocyclopent-1-ene-1-dithiocarboxylic acid with benzaldehyde (ACB), and also Cu^II and Ni^II complexes of a second Schiff base ligand prepared by condensing 2-aminocyclopent-1-ene-1-dithiocarboxylic acid with salicylaldehyde (ACS), have been prepared and characterized by elemental analyses, conductivity measurements, magnetic and spectral (electronic, i.r. and e.p.r.) studies. The i.r. spectra suggest that both ACB and ACS are acting as bidentate ligands, coordinating through one of the sulphur atoms and through the azomethine nitrogen atom. The magnetic moment of the Fe^III complex indicates spin crossover behaviour. Square planar structures have been assigned to the Cu^II and Ni^II complexes and a tetrahedral structure to the Co^II complex. The e.p.r. spectra of the Cu^II complexes suggest a square planar environment with rhombic distortion around the Cu^II ion.     

Cobalt(II), nickel(II), and copper(II) complexes with Schiff bases, derivatives of 1-amino-8-hydroxynaphthalene-2,4-disulfonic acid

Five new cobalt(II), nickel(II), and copper(II) complexes with Schiff bases have been synthesized. The Schiff bases have been prepared by the condensation of monopotassium 1-amino-8-hydroxynaphthalene-2,4-disulfonate with benzoin (L¹) or 2-hydroxy-1-naphthaldehyde (L²). The compounds have been identified and studied by elemental analysis, X-ray diffraction, thermogravimetry, measurements of magnetic susceptibility and electrical conductivity, and IR, ESR, and diffuse reflectance spectroscopy. The dimeric (with oxo bridges) structure of the Co(II) complex with L¹ has been additionally confirmed by the EXAFS method.     

Synthesis, structural, spectral, thermal and antimicrobial studies of palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes derived from N,N,N,N-tetradentate macrocyclic ligand

Palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes of general stoichiometry [PdL]Cl(2), [PtL]Cl(2), [Ru(L)Cl(2)]Cl and [Ir(L)Cl(2)]Cl are synthesized with a tetradentate macrocyclic ligand, derived from 2,6-diaminopyridine with 3-ethyl 2,4-pentanedione. Ligand was characterized on the basis of elemental analyses, IR, mass, and (1)H NMR and (13)C NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, mass, electronic spectral techniques and thermal studies. The value of magnetic moments indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moments corresponding its one unpaired electron. The macrocyclic ligand and all its metal complexes were also evaluated in vitro against some plant pathogenic fungi and bacteria to assess their biocidal properties.     

Synthesis,characterization, and anticancer activity of some azole‐heterocyclic complexes with gold(III), palladium(II), nickel(II), and copper(II) metal ions

Four new complexes of Au(III), Pd(II), Ni(II), and Cu(II) ions were synthesized, derived from a novel heterocyclic ligand (L) that has both triazole and tetrazole rings. The ligand synthesis was through successive steps to achieve both heterocyclic rings. The synthesized compounds were characterized using conventional techniques like infrared, ultra violet—visible and proton/carbon nuclear magnetic resonance spectroscopy, metal and thermal analyses, and molar conductivity. All complexes were suggested to have square planar geometry, gold, nickel, and palladium complexes were salts while copper neutral complexes have the chemical formulas; [AuL₂]Cl.2H₂O, [PdL₂]Cl₂.2H₂O, [NiL₂]Cl₂.2H₂O, and [CuL₂]. The cytotoxic effect was studied on breast cancer cell line (MCF‐7 cell line) at different concentrations by using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay method, for the ligand (L) and complexes. The results showed that gold(III) and nickel(II) complexes have the highest cytotoxicity among all compounds against cancer cell lines.     

Novel N,N-diacetyloximo-1,3-phenylenediamine copper(II) complexes

Transition Metal Chemistry -     

Synthesis,magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 2–formylpyridine N(4)-antipyrinylthiosemicarbazone

2–Formylpyridine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.e., i.r., electronic, n.m.r. and e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands either in the thione or thiolato form. Ligand field parameters have been calculated and the proposed stereochemistries are based on the various physical and spectral methods.     

Synthesis,magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 4–formylantipyrine N(4)-antipyrinylthiosemicarbazone

4–Formylantipyrine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic, n.m.r., e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate (NS) or tridentate ligands (ONS), either in the thione or thiolato form. Stereochemistries are proposed for the complexes on the basis of both spectral and magnetic studies.     

Synthesis,structures, and characterization of copper(II), nickel(II), and cobalt(III) metal complexes derived from an asymmetric bidentate Schiff-base ligand

An asymmetric bidentate Schiff-base ligand (2-hydroxybenzyl-2-furylmethyl)imine (L–OH) was prepared. Three complexes derived from L–OH were synthesized by treating an ethanolic solution of the appropriate ligand with an equimolar amount of metallic salt. Three complexes, Cu₂(L–O^?)₂Cl₂ (1), Ni(L–O^?)₂ (2) and Co(L–O^?)₃ (3), have been structurally characterized through elemental analysis, IR, UV spectra and thermogravimetric analysis. Single crystal X-ray diffraction shows metal ions and ligands reacted with different proportions 1?:?1, 1?:?2 and 1?:?3, respectively, so copper(II), nickel(II), and cobalt(III) have different geometries.     

Synthesis,spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of oxalyldihydrazide

Summary The new complexes K₂[ML₂]·2H₂O (M=Ni, Cu), K₂[PdL₂]·H₂O, K₂[CuL₂(H₂O)₂]·H₂O, [Ni(LH₂)Cl₂]_x ·xH₂O and [Ni(LH₂)Br₂]_x·1,5xH₂O, where LH₂= oxalyldihydrazide, have been prepared. Emphasis has been put on determining the conditions for the synthesis of both deprotonated and non-deprotonated Ni^II complexes. They were characterized by analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and spectroscopic methods like i.r. and far-i.r., diffuse reflectance u.v. vis, and e.s.r. Monomeric square planar and distorted octahedral structures were found for the deprotonated complexes in the solid state while the non-deprotonated Ni^II complexes appeared to be pseudo-tetrahedral polymers. The doubly deprotonated L²-ion exhibits a bidentate N(amide), N(amide)-coordination, while the neutral LH₂ molecule behaves as a N(amino), N(amino)-bidentate ligand forming polymeric structures. Vibrational analysis of the complexes was carried out, using hydrogen and metal isotopic substitution.     

Salen-type nickel(II), palladium(II) and copper(II) complexes having chiral and racemic camphoric diamine components

Chiral and racemic Salen-type Schiff-base ligands (H₂L¹, H₂L² and H₂L³), condensed between D-(+)- and D,L-camphoric diamine (also known as (1R,3S)-1,2,2-trimethylcyclopentane-1,3-diamine) and 2-hydroxybenzaldehyde or 3,5-dibromo-2-hydroxybenzaldehyde with a 1:2 molar ratio, have been synthesized and characterized. A series of new nickel(II), palladium(II) and copper(II) complexes of these chiral and racemic ligands exhibiting different coordination number (4, 5 and 6) have been characterized with the formulae [NiL¹]·CH₃OH (3), [NiL¹]·H₂O (4), [NiL²] (5), [PdL²] (6), [Cu₂(L²)₂(H₂O)] (7) and [NiL³(DMF)(H₂O)] (8). Different solvent molecules in 3 and 4 (methanol and water molecules) as well as different apical ligands in 7 and 8 (water and DMF molecules) are involved in different O–H···O hydrogen bonding interactions to further stabilize the structures. UV–Vis (UV–Vis), circular dichroism (CD) spectra and thermogravimetric (TG) analyses for the metal complexes have also been carried out.     

Pyrrole-appended derivatives of O-confused oxaporphyrins and their complexes with nickel(II), palladium(II), and silver(III)

Condensation of 2,4-bis(phenylhydroxymethyl)furan with pyrrole and p-toluylaldehyde formed, instead of the expected 5,20-diphenyl-10,15-di(p-tolyl)-2-oxa-21-carbaporphyrin, a pyrrole addition product [(H,pyr)OCPH]H(2); this product can formally be considered as an effect of hydrogenation of 3-(2'-pyrrolyl)-5,20-diphenyl-10,15-di(p-tolyl)-2-oxa-21-carbaporphyrin ([(pyr)OCPH]H). The new oxacarbaporphyrinoid presents the (1)H NMR spectroscopy features of an aromatic molecule, including the upfield shift of the inner H21 atom. Insertion of NiCl(2) or PdCl(2) into [(H,pyr)OCPH]H(2) gave two structurally related organometallic complexes, [(pyr)OCP]Ni(II)] and [(pyr)OCP]Pd(II)], in which the metal ions are bound by three pyrrolic nitrogens and the trigonally hybridized C21 atom of the inverted furan. The reaction of [(H,pyr)OCPH]H(2) with silver(I) acetate yields a stable Ag(III) complex [(C(2)H(5)O,pyr)OCP]Ag(III)] substituted at the C3 position by the ethoxy and pyrrole moieties. The macrocyclic frame of [(H,pyr)OCPH]H(2) is conserved. Addition of trifluoroacetic acid to [(C(2)H(5)O,pyr)OCP]Ag(III)] yielded a new aromatic complex [(pyr)OCP]Ag(III)](+). The structures of [(pyr)OCP]Ni(II)] and [(C(2)H(5)O,pyr)OCP]Ag(III)] have been determined by X-ray crystallography. In both molecules the macrocycles are only slightly distorted from planarity and the nickel(II) and silver(III) are located in the NNNC plane. The dihedral angle between the macrocyclic and appended-pyrrole planes of [(pyr)OCP]Ni(II)] reflects the biphenyl-like arrangement with the NH group pointing out toward the adjacent phenyl ring on the C5 position. Tetrahedral geometry around the C3 atom was detected for [(C(2)H(5)O,pyr)OCP]Ag(III)]. The Ni[bond]C and Ag[bond]C bond lengths are similar to other nickel(II) or silver(III) carbaporphyrinoids where the trigonal carbon atom coordinates the metal ion. The trend detected in the (13)C chemical shifts for the appended-pyrrole resonances has been rationalized by the extent of effective conjugation between the macrocycle and the appended pyrrole moiety controlled by the hybridization of the C3 atom and the metal ion oxidation state. The dianionic or trianionic macrocyclic core of the pyrrole-appended derivatives is favored to match the oxidation state of nickel(II), palladium(II), or silver(III), respectively.     

Cimetidine complexes derived from cobalt(II), nickel(II) and copper(II) salts of polyatomic anions

Summary Cobalt(II), nickel(II) and copper(II) complexes [M(CM)₂]X₂ (X = BF₄ or NO₃) have been prepared with cimetidine (CM). Powder data, molar conductivities, magnetic moments, i.r. and electronic spectra support apseudo-octahedral stereochemistry with MN₂N ₂ S₂ chromophore and tentative structures are proposed for the complexes. Their properties are compared with these of previously prepared complexes.     

New nickel(II), copper(II), platinum(II) and palladium(II) complexes of a multidentate sulfur–nitrogen chelating agent

A new, potentially polydentate sulfur–nitrogen chelating agent, 2,6–bis(N-methyl-S-methyldithiocarbazato)pyridine (L) has been synthesized and characterized. With nickel(II) salts, the ligand yields complexes of empirical formula NiLX2·nH2O (X=Cl−, NCS− or NO3−; n=0 or 1) in which it behaves as a quadridentate NSSN chelating agent, coordinating to the nickel(II) ion via the two amino nitrogen atoms and the two sulfur atoms. Magnetic and spectral evidence support a distorted octahedral structure for these complexes. The ligand reacts with copper(II), platinum(II) and palladium(II) salts to yield homo-binuclear complexes of general formula [M2LX4]·nSol (M=CuII, PtII or PdII; X=Cl− or Br−; n=0.5, 1 or 2; Sol=H2O, MeOH or MeCOMe), in which each of the metal ions is in a square-planar environment. These complexes have been characterized by a variety of physicochemical techniques. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis and characterization of biacetyldihydrazone complexes of cobalt(II), copper(II), nickel(II) and iron(III)

Summary Biacetyldihydrazone (BdH) complexes [M(BdH)₃](ClO₄)₂ (M=Co^IIor Cu^II) and [M(BdH)₃](NO₃)_2,3 (M = Ni^IIor Fe^III) have been prepared and characterized by chemical analysis, conductance measurements, electronic, i.r. and e.p.r. spectral studies and magnetic subsceptibilities measurements. A mononuclear octahedral configuration is proposed for all complexes studied.