Polymer complexes XXXVII novel models and structural of symmetrical poly-Schiff base on heterobinuclear complexes of dioxouranium(VI)

Some binary and ternary novel complexes of dioxouranium(VI) with 5-vinylsalicylaldehyde (VSH) have been prepared and characterized by various physico-chemical techniques. The amine exchange reactions of coordinated poly-Schiff bases in these complexes have been also carried out which give symmetrical tetradentate poly-Schiff base complexes. Metal exchange reaction of these dioxouranium(VI) complexes with copper(II) gives the corresponding Cu(II) complexes. Reaction of tetradentate poly-Schiff base complexes of Cu(II) so obtained with ZrCl4 gives heterobinuclear polymer complexes. Magnetic, electronic and IR spectral information commensurate that configurations of square planar copper(II) polymer complexes. All the polymer complexes are coloured and appear to be nonelectrolytes in DMF. The ligands behave as bi-(O, O) and tetradentate (N2, O2) donors. El-Sonbati equation was used to evaluate the symmetric stretching frequency from which the fU-O and fUO, UO- were calculated.     

Novel supramolecular assembly of symmetrical mixed-metal-ligand complexes of dioxouranium(VI)

Some binary and ternary novel complexes of dioxouranium(VI) with 8-hydroxy-7-quinolinecarboxaldehyde (OXH) have been prepared and characterized by elemental analyses, magnetic susceptibility measurements and spectral studies. Coordination effects on the vibrational spectra of the ligands have been investigated. The amine exchange reactions of coordinated Schiff bases in these complexes have been also studied, which reveal symmetrical tetradentate Schiff base complexes. Metal exchange reaction of dioxouranium(VI) complexes was obtained when reacted with tetradentate Schiff base complexes of Cu(II) with ZrCl(4)/UO(2)(CH(3)COO)(2) giving heterobinuclear complexes. Magnetic, electronic and IR spectral data suggest the configurations of distorted square planar ligand field copper(II) complexes. The ligands behave as bi-(O,O) and tetradentate (N(2),O(2)) donors. El-Sonbati equation has been used to evaluate the symmetric stretching frequency from which the F(U-O) and F(UO,UO)(-) were calculated. The bond distances of these complexes were also investigated.     

Versatile Synthesis of Luminescent Tetradentate Cyclometalated Alkynylgold(III) Complexes and Their Application in Solution‐Processable Organic Light‐Emitting Devices

A new class of cyclometalated tetradentate alkynylgold(III) complexes has been successfully synthesized by post‐synthetic modification. Through the judicious design and choice of pincer ligands, post‐synthetic cyclization could be achieved to produce the robust and structurally rigid class of tetradentate gold(III) C^N^C^C complexes with high photoluminescence quantum yields of up to 0.49 in solution and 0.78 in doped thin films at room temperature, at least an order of magnitude higher than those of the structurally related uncyclized tridentate alkynylgold(III) analogues. High‐performance yellow to orange‐red emitting solution‐processable organic light‐emitting devices have also been achieved with external quantum efficiency of 11.1 %. This work describes for the first time of the use of post‐synthetic ligand modification approach to overcome the synthetic challenge for tetradentate alkynylgold(III) complexes.     

Tetradentate Gold(III) Complexes as Thermally Activated Delayed Fluorescence (TADF) Emitters: Microwave-Assisted Synthesis and High-Performance OLEDs with Long Operational Lifetime

Structurally robust tetradentate gold(III)-emitters have potent material applications but are rare and unprecedented for those displaying thermally activated delayed fluorescence (TADF). Herein, a novel synthetic route leading to the preparation of highly emissive, charge-neutral tetradentate [C^C^N^C] gold(III) complexes with 5-5-6-membered chelate rings has been developed through microwave-assisted C−H bond activation. These complexes show high thermal stability and with emission origin (³IL, ³ILCT, and TADF) tuned by varying the substituents of the C^C^N^C ligand. With phenoxazine/diphenylamine substituent, we prepared the first tetradentate gold(III) complexes that are TADF emitters with emission quantum yields of up to 94 % and emission lifetimes of down to 0.62 μs in deoxygenated toluene. These tetradentate Au^III TADF emitters showed good performance in vacuum-deposited OLEDs with maximum EQEs of up to 25 % and LT₉₅ of up to 5280 h at 100 cd m⁻².     

Synthesis and characterization of nitro-Schiff bases derived from 5-nitro-salicylaldehyde and various diamines and their complexes of Co(II)

Some neutral tetradentate N₂O₂ type complexes of Co(II) have been synthesized using Schiff bases formed by condensation of 5-nitro-salicylaldehyde with various diamines in alcohol. The nature of the ligands and complexes was established by spectroscopic techniques. The Schiff bases are bivalent anions with tetradentate ONNO donors derived from phenolic oxygen and azomethine nitrogen. IR and UV-Vis spectral data suggest that all the complexes are square-planar.     

Transition metal complexes of 3-cyano- and 3-nitroformazans

The synthesis and characterization of six transition metal complexes of 3-cyano- and 3-nitroformazans are described. Three different formazans were reacted with nickel(II) to produce complexes with bidentate formazan ligands. Mononuclear NiL2 (L = deprotonated formazan) or binuclear hydroxo-bridged (LNi)2(mu-OH) 2 species were produced depending on the steric bulk on the formazan N-aromatic substituents. 1,5-Bis(2-methoxyphenyl)-3-cyanoformazan acts as a tetradentate monoanionic ligand in a copper(II) complex, whereas the analogous 1,5-bis(2-hydroxyphenyl)-3-cyanoformazan binds as a trianion in a tetradentate manner to Fe(III) and Co(III). Crystal structures-the first examples of metal complexes of cyano- or nitroformazans-as well as the electronic spectra of the complexes are discussed in relation to each other as well as that of the uncoordinated formazans.     

Tetradentate Gold(III) Complexes as Thermally Activated Delayed Fluorescence (TADF) Emitters: Microwave‐Assisted Synthesis and High‐Performance OLEDs with Long Operational Lifetime

Structurally robust tetradentate gold(III)‐emitters have potent material applications but are rare and unprecedented for those displaying thermally activated delayed fluorescence (TADF). Herein, a novel synthetic route leading to the preparation of highly emissive, charge‐neutral tetradentate [C^C^N^C] gold(III) complexes with 5‐5‐6‐membered chelate rings has been developed through microwave‐assisted C?H bond activation. These complexes show high thermal stability and with emission origin (³IL, ³ILCT, and TADF) tuned by varying the substituents of the C^C^N^C ligand. With phenoxazine/diphenylamine substituent, we prepared the first tetradentate gold(III) complexes that are TADF emitters with emission quantum yields of up to 94 % and emission lifetimes of down to 0.62 μs in deoxygenated toluene. These tetradentate Au^III TADF emitters showed good performance in vacuum‐deposited OLEDs with maximum EQEs of up to 25 % and LT₉₅ of up to 5280 h at 100 cd m^?2.     

Rhodium complexes bearing tetradentate diamine-bis(phenolate) ligands

Using tetradentate, dianionic ligands, several new rhodium complexes have been prepared. Some of these diamine-bis(phenolate) compounds, are active for C-H activation of benzene. These complexes are air and thermally stable. All four complexes were characterized by X-ray diffraction.     

Synthesis,Characterization, and Reaction Studies of Pd(II) Tripeptide Complexes

The aqueous synthesis of Pd(II) complexes with alkylated tripeptides led to the hydrolysis of the peptides at low pH values and mixtures of complexed peptides were formed. A non-aqueous synthetic route allowed the formation and isolation of single products and their characterization. Pd(II) complexes with α-Asp(OR)AlaGly(OR), β-Asp(OR)AlaGly(OR), and TrpAlaGly(OR) (R = H or alkyl) as tri and tetradentate chelates were characterized. The tridentate coordination mode was accompanied by a fourth monodentate ligand that was shown to participate in both ligand exchange reactions and a direct removal to form the tetradentate coordination mode. The tetradentate coordination revealed a rare a hemi labile carbonyl goup coordination mode to Pd(II). Reactivity with small molecules such as ethylene, acids, formate, and episulfide was investigated. Under acidic conditions and in the presence of ethylene; acetaldehyde was formed. The Pd(II) is a soft Lewis acid and thiophilic and the complexes abstract sulfur from episulfide at apparent modest catalytic rates. The complexes adopt a square planar geometry according to a spectroscopic analysis and DFT calculations that were employed to evaluate the most energetically favorable coordination geometry and compared with the observed infrared and NMR data.     

Trialkyl borate assisted amination of fluorinated 1,3-diketones for synthesis of N,N′-1,2-phenylen-bis(β-aminoenones) and their Ni(II), Cu(II) and Pd(II) complexes

An effecient synthetic method for fluorinated tridentate β-aminoenones and tetradentate bis(β-aminoenones) via amination of fluorinated 1,3-diketones with o-phenylenediamine in the presence of trialkyl borates was developed. Ni(II), Cu(II) and Pd(II) complexes with tetradentate bis(β-aminoenones) were obtained. Their gaschromatographic behaviour and main fragmentation paths in the electron ionization mass spectra were described.     

Investigation of the oxygen affinity of manganese(II), cobalt(II) and nickel(II) complexes with some tetradentate Schiff bases

Oxygen absorption–desorption processes for square planar Mn(II), Co(II) and Mn(II) complexes of tetradentate Schiff base ligands in DMF and chloroform solvents were investigated. The tetradentate Schiff base ligands were obtained by condensation reaction of ethylenediamine with salcyldehyde, o-hydroxyacetophenone or acetylacetone in the molar ratio 1:2. The square planar complexes were prepared by the reaction of the Schiff base ligands with Mn(II) acetate, Co(II) nitrate and Ni(II) nitrate in dry ethanol under nitrogen atmosphere. The sorption processes were undertaken in the presence and absence of (pyridine) axial-base in 1:1 M ratio of (pyridine:metal(II) complexes). Complexes in DMF indicate significant oxygen affinity than in chloroform solvent. Cobalt(II) complexes showed significant sorption processes compared to Mn(II) and Ni(II) complexes. The presence of pyridine axial base clearly increases oxygen affinity.     

Divalent nickel,cobalt and copper complexes of a tetradentate N6 macrocyclic ligand

Summary Divalent nickel, cobalt and copper salts react with 2,6-diaminopyridine and acetylacetone to form complexes containing a 16-membered N₆ tetradentate macrocyclic ligand. The complexes are characterised as distorted octahedra of the M(TML)X₂ type where M=nickel(II), cobalt(II) and copper(II); TML=tetradentate macrocyclic ligand and X=Cl, Br, NO₃ or NCS. The ligand coordinates through all the four azomethine nitrogen atoms which are bridged by acetylacetone moieties. Pyridine nitrogen does not participate in coordination, a fact supported by far i.r. studies. The magnetic, electronic and i.r. spectral studies indicate that the complexes have lower symmetries and the amounts of distortion calculated in terms of DT/DQ applying normalised spherical harmonic Hamiltonian theory indicate that these complexes are moderately distored.     

Template syntheses of iron(II) complexes containing chiral P-N-N-P and P-N-N ligands

A multicomponent template reaction utilizing an air-stable phosphonium precursor leads initially to the first enantiopure bis-tridentate iron complexes mer-[Fe(P-N-N) 2] (2+) in high yield and then to new tetradentate iron complexes trans-[Fe(MeCN) 2(P-N-N-P)] (2+).     

New Ruthenium Complexes Based on Tetradentate Bipyridine Ligands for Catalytic Hydrogenation of Esters

New bipyridinemethanamine‐containing tetradentate ligands and their corresponding ruthenium complexes have been synthesized. The synthesized complexes performed well in the hydrogenation of a variety of esters with high efficiency (TON up to 9700) giving alcohols in good yields.     

Rod-like phases formed by Ni(II) and VO(II) complexes of tetradentate enaminoketone ligands

Most of the nickel(II) complexes of tetradentate enaminoketone ligands obtained, although not strictly calamitic and with a rather low length to width ratio, form enantiotropic rod-like nematic and smectic A phases. Corresponding vanadyl(II) complexes exhibit only monotropic mesophases. The vanadyl complexes, due to their non-planar structure, are chiral with an asymmetry centre placed at the metal ion.     

The two spin states of an end-on copper(II)-superoxide mimic

The reaction of nitrosobenzene with copper(I) complexes of a tetradentate ligand led to two novel species that are best described as copper(II) complexes of an O-bonded nitrosobenzyl radical anion, in either the singlet or the triplet spin-state. Both states were characterized by crystal structures, magnetic measurements and DFT calculations.     

Synthesis and spectroscopic studies of mixed-ligand and polymeric dinuclear transition metal complexes with bis-acylhydrazone tetradentate ligands and 1,10-phenanthroline

Two types of dinuclear copper(II) and nickel(II) complexes with two tetradentate N2O2 donor ligands 1,4-bis(1-anthranoylhydrazonoethyl)benzene (L1), 1,4-bis(1-salicyloylhydrazonoethyl)benzene (L2) and N,N'-bidentate heterocyclic base [1,10-phenonthroline (phen)] have been synthesized and characterized by elemental analysis, infrared spectra, UV-vis electronic absorption spectra and magnetic susceptibility measurements. The reaction of metal(II) acetates with the solution containing ligand and 1,10-phenonthroline in methanol gives mixed-ligand dinuclear metal(II) complexes with general formula [M2L(phen)2]Cl2 (L=L1 or L2), whereas, the ligands react with metal(II) acetates to form polymeric dinuclear complexes with general formula [(M2L2)n] (L=L1 or L2). In the complexes, the ligands act as dianionic tetradentate and coordination takes place in the enol tautomeric form with the enolic oxygen and azomethine nitrogen atoms while the phenolic hydroxyl and amino groups of aroylhydrazone moiety do not participate in coordination. The effect of varying pH and solvent on the absorption behavior of both ligands and complexes has been investigated.     

Microwave assisted synthesis and characterization of unsymmetrical tetradentate Schiff base complexes of VO(IV) and MoO(V)

Microwave synthesis, is green chemical method, simple, sensitive, reducing solvent amount and reaction time. The attempt was made to synthesize the unsymmetrical tetradentate N(2)O(2) ligands and their VO(IV) and MoO(V) unsymmetrical tetradentate Schiff base complexes by classical and microwave techniques using domestic microwave oven. The resulting unsymmetrical Schiff base ligands L(1)-L(3) characterized by different spectral methods. Their complexes with oxocations of VO(IV) and MoO(V) have been synthesized and characterized by elemental analyses, conductometric measurements, infrared and electronic absorption, (1)H NMR spectra, mass spectrometry, ESR spectra, magnetic susceptibility measurement and thermal study. The study suggests that the oxo metal ion is bonded to the ligand through the oxygen and imino nitrogen and the geometry around metal ion is distorted octahedral.     

Homogeneous Oxidation of Water by Iron Complexes with Macrocyclic Ligands

The activity of eleven separated iron complexes and nine in situ‐generated iron complexes towards catalytic water oxidation have been examined in aqueous solutions with Ce(NH₄)₂(NO₃)₆ as the oxidant. Two iron complexes bearing tridentate and tetradentate macrocyclic ligands were found to be novel water oxidation catalysts. The one with tetradentate ligand exhibited a promising activity with a turnover number of 65 for oxygen evolution.     

Synthesis and structure of iron(iii) diamine-bis(phenolate) complexes

The structures and properties of six new iron(iii) diamine-bis(phenolate) complexes are reported. Reaction of anhydrous FeX(3) salts (where X = Cl or Br) with the diprotonated tripodal tetradentate ligands 2-pyridylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H(2)[L(1)], and N,N-dimethyl-N',N'-bis(2-methylene-4-methyl-6-tert-butylphenol)ethylenediamine, H(2)[L(2)], produces the trigonal bipyramidal iron(iii) complexes, [L(1)]FeCl , [L(1)]FeBr , [L(2)]FeCl and [L(2)]FeBr . Reaction of FeX(3) with the related linear tetradentate ligand N,N'-bis(4,6-tert-butyl-2-methylphenol)-N,N'-bismethyl-1,2-diaminoethane, H(2)[L(3)], generates square pyramidal iron(iii) complexes, [L(3)]FeCl and [L(3)]FeBr . Complexes have been characterized using electronic absorption spectroscopy and magnetometry. Single crystal X-ray molecular structures have been determined for complexes 1, 3, 5 and 6.