Dihydrazone Ligand Research Articles

Synthesis and characterization of heterotrinuclear bis(μ2-chlorido)dicopper (II) mono zinc(II) complexes derived from succinoyldihydrazones

Three new zinc (II)–copper (II) heterometallic trinuclear complexes of the composition [ZnCu2(Ln)(μ2-Cl)2(H2O)6]⋅2H2O (H4Ln=H4L1, H4L2, H4L3) have been synthesized from substituted succinoyldihydrazones (H4Ln) in methanol medium. The composition of the complexes has been established on the basis of data obtained from analytical, mass spectral studies and molecular weight determinations in DMSO. The structure of the ligand H4L2 has been established by X-ray crystallography. The structure of the complexes has been discussed in the light of molar conductance, magnetic moment, electronic, EPR, IR and FT-IR spectral studies. The molar conductance values for the complexes fall in the region 1.2–1.7ohm−1cm2mol−1 in DMSO solution indicating that all of these are non-electrolyte. The magnetic moment values suggest weak M–M interaction in the structural unit of the complexes. The dihydrazone ligand is present in enol form in all of the complexes. Copper centre has tetragonally distorted octahedral stereochemistry. The EPR parameters of the complexes indicate that the copper centre has doublet state as the ground state. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry.

Binuclear organotin(IV) complexes with adipic dihydrazones: Synthesis, spectral characterization, crystal structures and antibacterial activity

New organotin(IV) complexes, (R2Sn)2L [L = La: R = Me (1), Ph (2); L = Lb: R = Me (3), Ph (4)] have been synthesized by reaction of dihydrazone ligands, bis(5-bromosalicylaldehyde) adipicdihydrazone (H4La) and bis(2-hydroxynaphthaldehyde) adipicdihydrazone (H4Lb) with R2SnCl2 (R = Me or Ph). The synthesized compounds have been investigated by elemental analysis and IR, 1H NMR, and 119Sn NMR spectroscopy. The structures of 1 and 4 have been also confirmed by X-ray crystallography. The results show that the dihydrazone acts as a tetrabasic ligand in the enolic form and is coordinated to two diorganotin moiety via the imine nitrogen and phenolic and enolic oxygen atoms. All complexes are binuclear and the coordination number of each tin is five. The in vitro antibacterial activity of ligands and complexes has been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and compared with standard drugs. All complexes exhibit more inhibitory effects than the parent ligands.

Hydrothermal Synthesis and Crystal Structure of a Ni(II) Complex with Diacetyl Dihydrazone Ligand

Hydrothermal Synthesis and Crystal Structure of a Ni(II) Complex with Diacetyl Dihydrazone Ligand

Characterization of heterobimetallic and mixed-valence complexes of molybdenum(V) derived from bis(2-hydroxy-1-naphthaldehyde) malonoyldihydrazone

Heterobimetallic complexes [UO2MoV(CH2L)(hzd)(H2O)2] n , [ZnMoV(CH2L)(hzd)(H2O)2] n and mixedvalence complexes [MoVIO2MoV(CH2L)(hzd)(H2O)2] n (where hzdH3 = inhH3, n = 1; slhH3, n = 2) are synthesized from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (CH2LH4) and monometallic precursor complexes [Mo(CH2LH2)(hzd)]·nH2O (n = 0, 1) in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR, and IR spectroscopic studies. All complexes have μB values in the range 1.59–1.64 B.M., slightly lower than that required for one unpaired electron. The heterobimetallic complexes show two bands, while mixed-valence complexes show only one band in the visible region assigned to the d-d transition. The g-values decrease in going from uranyl-to-molybdenyl-to-zinc complexes containing the isonicotinoyldiazenido (inh) group, however, no such regular trend is observed in the case of complexes containing the salicyloyldiazenido (slh) group in the coordination sphere. In all complexes, the principal dihydrazone ligand is present in the enol form as a bridging hexadentate ligand in the anti-cis configuration where hydrazide ligands are coordinated to the metal centre as a trinegative bidentate ligand in the diazenido form.

Synthesis and characterization of homotrimetallic copper complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

Copper (II) complexes [Cu3(nph)(μ2-X)2(H2O)6]·2H2O [X=Cl (1), (ClO4) (3)] and [Cu3(nph)(NO3)2(H2O)6] (2) have been synthesized from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone in methanol medium and characterized. The structures of the complexes have been discussed in the light of data obtained from analytical, thermoanalytical, mass spectral studies, molar conductance, magnetic moment, electronic, EPR, IR, FT-IR spectroscopic studies. The molar conductance values for the complexes fall in the region 0.5–0.9Sm2mol−1 in DMSO solution indicating that all of them are non-electrolyte. The magnetic moment values for the complexes suggest weak M-M interaction in the structural unit of the complexes. The dihydrazone ligand is present in enol form in all of the complexes. Copper centre has tetragonally distorted octahedral stereochemistry in chlorido and perchlorato complexes while in nitrato complex, copper has mixed square-pyramidal and distorted-octahedral stereochemistry. The EPR parameters of the complexes indicate that the copper centre has the doublet state as the ground state.

Synthesis and characterisation of heterometallic trinuclear copper(II) and zinc(II) complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

Abstract A new series of heterotrinuclear Cu(II) Zn(II) complexes [ZnCu2(nph)(μ2-X)2 (H2O)6] [X = Cl (1) and ClO4 (3)] and [ZnCu2(nph)(NO3)2(H2O)6]·H2O (2) have been synthesised from bis (2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone and characterised. The stoichiometry of the complexes has been established on the basis of data obtained from analytical, thermoanalytical and mass spectral studies. The structure of the complexes has been discussed in the light of scanning electron microscopy, transmission electron microscopy, molar conductance, magnetic moment, electronic, EPR, IR and FT-IR spectroscopic studies. The magnetic moment value for the chlorido complex (1) suggests weak M M interaction in the structural unit while very weak interaction in nitrato complex (2) and no interaction in the perchlorato complex (3), respectively. Copper centre has tetragonally distorted octahedral stereochemistry in chlorido and perchlorato complexes while in nitrato complex, copper has distorted square-pyramidal stereochemistry. Zinc(II) metal centre in all heterometal complexes has octahedral stereochemistry. The EPR parameters of the complexes indicate that the copper centre has d x 2 - y 2 orbital as the ground state. The IR spectral evidences are consistent with the enol form of the dihydrazone ligand in all of the complexes. TEM images showed that the nanoparticle in chlorido complex, are like one dimensional dendrimer or spherical or trigonal prismatic in shape while nitrato complex has spherical and hexagonal shape. The perchlorato complexes show no specific shape and size but the presence of metal lattice is observed. The electron transfer reactions of the complexes have been studied by cyclic voltammetry.

Crystal structure of nonadentate tricompartmental ligand derived from pyridine-2,6-dicarboxylic acid: Spectroscopic, electrochemical and thermal investigations of its transition metal(II) complexes

The coordinating behavior of a new dihydrazone ligand, 2,6-bis[(3-methoxysalicylidene)hydrazinocarbonyl]pyridine towards manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) has been described. The metal complexes were characterized by magnetic moments, conductivity measurements, spectral (IR, NMR, UV–Vis, FAB-Mass and EPR) and thermal studies. The ligand crystallizes in triclinic system, space group P-1, with α = 98.491(10)°, β = 110.820(10)° and γ = 92.228(10)°. The cell dimensions are a = 10.196(7) Å, b = 10.814(7) Å, c = 10.017(7) Å, Z = 2 and V = 1117.4(12). IR spectral studies reveal the nonadentate behavior of the ligand. All the complexes are neutral in nature and possess six-coordinate geometry around each metal center. The X-band EPR spectra of copper(II) complex at both room temperature and liquid nitrogen temperature showed unresolved broad signals with g iso = 2.106. Cyclic voltametric studies of copper(II) complex at different scan rates reveal that all the reaction occurring are irreversible.

A tetranuclear copper(II) complex with bis( o-aminobenzaldehyde)thiocarbohydrazone

Bis( o-aminobenzaldehyde)thiocarbohydrazone (HL) forms with copper(II) nitrate a tetranuclear complex [Cu 2(L)(NO 3) 3] 2·2H 2O, in which two dinuclear units are joined by nitrate bridges. The dihydrazone ligand behaves ditopically, providing NNS and NNN binding sites, with the four coppers essentially in a square-pyramidal geometry. The tetranuclear molecule displays intramolecular magnetic interactions, with the antiferromagnetic exchange (−2 J = 210(1) cm −1) between the copper(II) ions within each dinuclear moiety dominant over weak interdimer ferromagnetic coupling.

Ship-in-a-bottle synthesis, characterization and catalytic oxidation of cyclohexane by Host (nanopores of zeolite-Y)/guest (Mn(II), Co(II), Ni(II) and Cu(II) complexes of bis(salicyaldehyde)oxaloyldihydrazone) nanocomposite materials

The monomer transition metal complexes; [ML] (M = Mn(II), Co(II), Ni(II) and Cu(II)) have been synthesized from the reaction of metal acetate with bis(salicyaldehyde)oxaloyldihydrazone, H 2L; in 1:1 molar ratio in ethanol under reflux. In all of the complexes, the principal dihydrazone ligand has been suggested to coordinate to the metal centres in the anti- cis-configuration. The complexes (Co(II), Ni(II) and Cu(II)) are suggested to have four-coordinate square-planar stereochemistry while the Mn(II) complex is suggested to have tetrahedral stereochemistry. These metal complexes with tetradendate Schiff-base ligand was entrapped in the nanocavity of zeolite-Y by a two-step process in the liquid phase: (i) adsorption of [bis(salicylaldiminato)metal(II)]; [M(sal) 2]-NaY; in the supercages of the zeolite, and (ii) in situ Schiff condensation of the metal(II) precursor complex with oxaloyldihydrazone; [ML]-NaY. The new Host–Guest Nanocomposite Materials (HGNM) was characterized by several techniques: chemical analysis, spectroscopic methods (DRS, NMR, BET, FTIR and UV/vis), conductometric and magnetic measurements. The catalytic activities for oxidation of cyclohexane with HGNM and neat were reported.

Coordination “Oligomers” in Self-Assembly Reactions of Some “Tritopic” Picolinic Dihydrazone LigandsMononuclear, Dinuclear, Hexanuclear, Heptanuclear, and Nonanuclear Examples

"Tritopic" picolinic dihydrazone ligands with tridentate coordination pockets are designed to produce homoleptic [3 x 3] nonanuclear square grid complexes on reaction with transition-metal salts, and many structurally documented examples have been obtained with Mn(II), Cu(II), and Zn(II) ions. However, other oligomeric complexes with smaller nuclearities have also been discovered and identified structurally in some reactions involving Fe(II), Co(II), Ni(II), and Cu(II), with certain tritopic ligands. This illustrates the dynamic nature of the metal-ligand interaction and the conformationally flexible nature of the ligands and points to the possible involvement of some of these species as intermediates in the [3 x 3] grid formation process. Examples of mononuclear, dinuclear, hexanuclear, heptanuclear, and nonanuclear species involving Fe(II), Co(II), Ni(II), and Cu(II) salts with a series of potentially heptadentate picolinic dihydrazone ligands with pyrazine, pyrimidine, and pyridine end groups are described in the present study. Iron and cobalt complexation reactions are complicated by redox processes, which lead to mixed-oxidation-state Co(II)/Co(III) systems when starting with Co(II) salts, and reduction of Fe(III) to Fe(II) when starting with Fe(III). Magnetic exchange within the polynuclear structural frameworks is discussed and related to the structural features.

Synthesis and properties of mononuclear and binuclear molybdenum complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

The monomer molybdenum(VI) complex [MoO 2(napoxlhH 2)]·2H 2O (1) has been synthesized from the reaction of MoO 2(acac) 2 with bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone (napoxlhH 4) in 1:1 molar ratio in ethanol under reflux. This complex on reaction with pyridine/3-picoline/4-picoline yielded the dimer molybdenum(VI) complexes [Mo 2O 4(napoxlhH 2) 2(A) 2]·2H 2O (A = py (2), 3-pic (3), 4-pic (4)), whereas reaction with isonicotinoylhydrazine (inhH 3) and salicyloylhydrazine (sylshH 3) lead to the reduction of the metal centre yielding monomeric molybdenum(V) complexes [Mo(napoxlhH 2)(hzid)]·2H 2O (where hzidH 3 = inhH 3 (5) and sylshH 3 (6)). The complexes have been characterized by elemental analyses, molecular weight determinations, molar conductance data, magnetic moment data, electronic, IR, ESR and 1H NMR spectroscopic studies. The complexes (5) and (6) are paramagnetic to the extent of one unpaired electron. The electronic spectra of the complexes are dominated by strong charge transfer bands. In all of the complexes, the principal dihydrazone ligand has been suggested to coordinate to the metal centres in the anti- cis-configuration. The complexes (1), (5) and (6) are suggested to have six-coordinate octahedral stereochemistry around molybdenum(VI) and molybdenum(V) metal centres, respectively, while the complexes (2)–(4) are suggested to have eight coordinate dodecahedral stereochemistry around molybdenum(VI) metal centre.

Synthesis and Magnetic Properties of Copper(II) Complexes Derived from Dihydrazones

A series of new acyldihydrazones, H2Ln, obtained by condensation of ethylpyruvate with oxalic, malonic, succinic, glutaric and adipic dihydrazides, undergoes quantitative hydrolysis of the ‒C(O)OC2H5 group via reactions with copper(II) acetate in alcoholic medium. Dicopper(II) complexes of the general formula [Cu2(L′n) · H2O] · xH2O have been isolated, where L′n refers to the quadruply deprotonated pyruvic acid dihydrazone ligand and n refers to the number of carbon atoms of the aliphatic spacer between the two acylhydrazone units. The isolated complexes were characterized by elemental analyses, infrared spectra, mass spectra, as well as variable temperature magnetic susceptibility measurements. Magnetic susceptibility measurements in the 4.2–298 K range indicate significant antiferromagnetic coupling between copper(II) centers and suggest association of the coordinated copper(II) units Cu(ONO) via oxazine oxygen bridges. This leads to a polymeric structure where the dimeric units are connected together with aliphatic spacer. From the best fit values of the mole fraction of paramagnetic uncoupled copper(II) centers (ρ), the degree of association in these polynuclear copper(II) complexes has been estimated.

Mixed Valence Mn(II)/Mn(III) [3 × 3] Grid Complexes: Structural, Electrochemical, Spectroscopic, and Magnetic Properties

Mn(II)9 grid complexes with a [Mn9(mu-O)12] core, obtained by self-assembly of a series of tritopic picolinic dihydrazone ligands with Mn(II) salts, have been oxidized by both chemical and electrochemical methods to produce mixed oxidation state systems. Examples involving [Mn(III)3Mn(II)6] and [Mn(III)4Mn(II)5] combinations have been produced. Structures are reported for [Mn9(2poap-2H)6](NO3)6.14H2O (1), [Mn9(2poap-2H)6](ClO4)10.10H2O (3), and [Mn9(Cl2poap-2H)6](ClO4)9.14H2O.3CH3CN (10). Structural studies show distinct contraction of the corner grid sites on oxidation, with overall magnetic properties consistent with the resulting changes in electron distribution. Antiferromagnetic exchange in the outer ring of eight metal centers creates a ferrimagnetic subunit, which undergoes antiferromagnetic coupling to the central metal, leading to S=1/2 (3) and S2/2 (10) ground states. Two moderately intense absorptions are observed on oxidation of the Mn(II) grids in the visible and near-infrared (1000 nm, 700 nm), associated with charge transfer transitions (LMCT, IVCT respectively). Compound 1 crystallized in the monoclinic system, space group P2 1/n, with a=21.308(2) A, b=23.611(2) A, c=32.178(3) A, beta=93.820(2) degrees . Compound 3 crystallized in the tetragonal system, space group I, with a=b=18.44410(10) A, c = 24.9935(3) A. Compound 10 crystallized in the triclinic system, space group P, with a=19.1150(10) A, b=19.7221(10) A, c=26.8334(14) A, alpha=74.7190(10) degrees, beta=77.6970(10) degrees, gamma=64.7770(10) degrees. The facile oxidation of the Mn(II)9 grids is highlighted in terms of their potential use as molecular based platforms for switching and data storage.

Synthesis, characterisation and variable-temperature nuclear magnetic resonance of bis(bipyridine)ruthenium complexes containing dihydrazone ligands

A series of dihydrazone and substituted dihydrazone derivatives of biacetyl and of hydrazone and phenylhydrazone derivatives of 2-acetylpyridine bind to [Ru(bipy)2Cl2] to give [Ru(bipy)2(L–L)][PF6]2 complexes {bipy = 2,2′-bipyridine; L–L = biacetyl di(phenylhydrazone)1a, biacetyl di[methyl(phenyl)hydrazone]1b, biacetyl di(o-tolylhydrazone)1c, biacetyl di(dimethylhydrazone)1d, biacetyl dihydrazone 1e, biacetyl di(benzaldehyde azine)1f, 2-acetylpyridine phenylhydrazone 1g, or 2-acetylpyridine hydrazone 1h}. The structures of all complexes have been determined using IR, UV/VIS, NMR and microanalysis. The proton NMR spectra of 1a–1c show an unusual dependence on probe temperature with broadened aromatic resonances, sharpening at both high and low temperature in the case of 1b and 1c. No emission was observed for complexes with two hydrazone moieties, whereas it was observed for 1g and 1h with one hydrazone. The molecular structure of 1a has been determined and shows a hydrazone phenyl group lying over each of the bipyridyl rings: space group C2/c, a= 25.895(3), b= 10.505(1), c= 17.431(2)A, β= 106.03(2)° and Z= 4.

Reactions of the nickel(II) and copper(II) complexes of the dihydrazone ligand 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dihydrazone with pentane-2,4-dione. Crystal structures of two resultant nickel(II) complexes

Le coordinat forme (tdaa) reagit avec Ni pour donner le complexe [Ni(tdaa)ClO 4 ] + . Il est pentadente. C'est l'azote du groupement isopropylidenehydrazone qui est situe en trans d'une faible liaison Ni−O. En presence d'acetone, on isole [Ni(amba)(acac)] + , ou amba est un coordinat tetradente

Coordination compounds of hydrazine derivatives with transition metals. Part 21. Reaction of 1,5-thiocarbodihydrazones with nickel(II) and copper(II) salts

A series of 1,5-thiocarhodihydrazones (HL) were reacted with nickel(II) acetate to give neutral bisligand nickel(II) chelates, Ni(L)2. Reaction of nickel(H) chloride, however. results in partial hydrolysis of the dihydrazones to give Ni(RCH=NNHCSNHNH2)2Cl2 chelate complexes. Deprotonation of these chelates with pyridine gave the neutral chelates Ni(RCH=NN=CSNHNH2)2. Copper(H) salts are readily reduced by the dihydrazone ligands to copper(I) chelates of the type CuL, Cu(HL)2CI and Cu2(HL)3CI2.