Co(II) and Cu(II) Schiff base complexes of bis(N-(4-diethylamino-2-methylphenyl)-3,5-di-tert-butylsalicylaldimine): Electrochemical and X-ray structural study (original) (raw)
Related papers
Polyhedron, 1989
Neutral copper(I1) complexes of Schiff bases derived from substituted salicylaldehydes and 2-aminopyridine methyl derivatives have been synthesized by an electrochemical procedure. The crystal and molecular structure of bis(N-[2-(3_methylpyridyl)]-5-methoxysalicylideneiminato}copper (II) and of bis{N-[2-(6-methylpyridyl)]-salicylide-neiminato}copper(II) have been determined by X-ray diffraction. The former compound crystallizes in the monoclinic space group C2/c with four molecules in the unit cell and cell constants a = 16.784(2), b = 16.344(2) and c = 11.21 l(2) A, and j? = 124.08(l)", while the other complex crystallizes in the monoclinic space group P2 ,/c with two molecules in a cell of dimensions a = 12.456(l), b = 7.812(2) and c = 12.047(2) A, and j? = 110.48(l)". In both structures, the metals adopt square-planar coordination geometries and the pyridyl nitrogen atoms are not coordinated. The electronic and IR spectra of the complexes are discussed and related to the structure.
Polyhedron, 2003
The structures of six N ,N ?-polymethylene-bis(salicylaldiminato)copper(II) Schiff base complexes with alkyl backbones ranging from two to eight carbons have been determined by X-ray crystallography. The complexes are monomeric when the alkyl chain length is relatively short (two, three, and four CH 2 groups) but are dimers when the chain length becomes longer (five, six, and eight CH 2 groups). There is a regular increase in the distortion about the copper center as the alkyl chain length approaches four and five carbons, followed by a decrease as the chains become longer. Previously noted trends in electronic spectral, magnetic susceptibility, and microwave dielectric loss data can be accounted for based on this structural information. #
The complexes of general formula Cu(H 2 L) (II); [CuLn(L)(NO 3)(H 2 O) n ] (where H 4 L=N,N I-bis[2-hydroxy(3-carboxynaphtalidene)]ethylenediamine; Ln: Nd, n=6 (III); Eu, n=4 (IV); Gd, n=6 (V) have been synthesized and investigated by different methods (IR spectroscopy, TG analysis and magnetochemistry). The coordination set of complex generators are Cu(N 2 O 2) and Ln(O 8-9). The effective magnetic moment values, µ eff, at 300 K are: 1.78 (II), 3.22 (III), 6.44 (V) B.M. The temperature dependence (300-2 K) of magnetic susceptibility of [CuNd(L)(NO 3)(H 2 O) 6 ] indicates the antiferromagnetic interaction between metal ions.
Polyhedron, 2006
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Synthesis, Spectral Studies and DFT Calculation of Copper(II) Complexes with Mixed Ligands
Asian Journal of Chemistry, 2018
Mixed ligand metal complexes of Schiff base derived from salicylaldehyde with aromatic amines have received significant attention in the recent years [1] because of their interesting physico-chemical properties [2], varied structural features [3] and biologically activities [4]. The high affinity for the chelation of the Schiff bases toward the copper metal ions is employed in synthesis of their important biologically potent coordination complexes. Therefore, significant work has been devoted to the synthesis and characterization of mixed ligand copper(II) complexes with several Schiff base ligands [5]. Electrochemical studies of some copper (II) complexes show that the complexes with lower reduction potential are more biologically active [6]. Copper complexes show significant antibacterial and antifungal activities [7]. Due to the presence of nitrogen and oxygen donor sites in the ligands in their backbones they form stable and intensely coloured coordination complexes of copper [8,9]. The occurrence of an amine group in the alkanolamine offers further possibilities of inter molecular hydrogen bond [10] formation with Schiff bases, which may lead to metal complexes with three-dimensional network structures. Survey of literature reveals that there is no report of synthesis and structural studies of complexes of copper with mixed ligand such as salicylidine-1-aminobenzene (sabH), salicylidene-4chloro-1-aminobenzene (scabH), salicylidene-4-methyl-1
Inorganica Chimica Acta, 2008
The following Schiff bases were employed as ligands in synthesizing copper(II) and zinc(II) complexes: N- Hsaldmen), and N-[(2-pyridyl)-methyl]-3-methoxy-salicylimine (Hvalampy). The first two ligands were obtained by reacting salicylaldehyde with 2-aminomethyl-pyridyne and N,N-dimethylethylene diamine, respectively, while the third one results from the condensation of 3-methoxysalicylaldehyde with 2-aminomethyl-pyridine. Four new coordination compounds were synthesized and structurally characterized: [Cu(salampy)(H 2 O)(ClO 4 )] 1, [Cu 2 (salampy) 2 (H 2 trim) 2 ] 2 (H 2 trim À = the monoanion of the trimescic acid), [Cu 4 (valampy) 4 ](ClO 4 ) 4 Á 2CH 3 CN 3, and [Zn 3 (saldmen) 3 (OH)](ClO 4 ) 2 Á 0.25H 2 O 4. The crystal structure of 1 consists of supramolecular dimers resulted from hydrogen bond interactions established between mononuclear [Cu(salampy)(H 2 O)(ClO 4 )] complexes. Compound 2 is a binuclear complex with the copper ions connected by two monoatomic carboxylato bridges arising from two molecules of monodeprotonated trimesic acid. The crystal structure of 3 consists of tetranuclear cations with a heterocubane {Cu 4 O 4 } core, and perchlorate ions. Compound 4 is a trinuclear complex with a defective heterocubane structure. The magnetic properties of complexes 1-3 have been investigated. Compound 4 exhibits solid-state photoluminescence at room temperature.
Inorganica Chimica Acta, 2018
The hexadentate ligand, 2,2′-bis(salicylideneamino)azobenzene, 1 has been synthesized from 2,2'diaminoazobenzene and salicylaldehyde in refluxing diethyl ether. Reaction of ligand 1 with Cu(II) acetate and Cu(II) perchlorate separately in methanol afforded tetradentate (N,N,N,O) Cu(II) complexes, Cu(L) & [Cu(HL)]ClO 4 respectively [where H 2 L represent the one imine moiety cleavage product of ligand 1 (H represents the dissociable amino and phenolic protons)]. These were characterized by microanalytical data and spectroscopic studies. In addition, the crystal structures of the ligand 1 and complexes Cu(L) & [Cu(HL)]ClO 4 were determined by X-ray diffraction analysis. The diffraction analysis revealed that the ligand (H 2 L) binds Cu(II) centers in (N,N,N,O) tetra dentate fashion in distorted square planer geometry. In complex [Cu(HL)]ClO 4 the apical position of copper center is weakly coordinated with one perchlorate ion. The dimeric structure of the molecule [Cu(HL)]ClO 4 is stabilized through NH 2 •••O hydrogen bonds. The fluorescence and redox property of ligand 1 and complexes Cu(L) & [Cu(HL)]ClO 4 were studied. Preliminary DFT calculations were carried out using crystallographic coordinates to understand the electronic spectra and redox properties of the ligand and complexes. The complex Cu(L) shows very good catalytic activities towards oxidation of benzyl alcohol to benzaldeyhde (under solventfree condition) and organic thioethers to sulfoxide and sulfones using H 2 O 2 as the oxidant.
Synthesis and Reactivity in Inorganic and Metal-organic Chemistry, 2003
Cu(II), Co(II), Ni(II) and Zn(II) metal complexes of a new heterocylic Schiff base derived from 1-amino-5-benzoyl-4-phenyl-1H-pyrimidine-2one with 3-hydroxy-salicylaldehyde have been synthesized and characterized on the basis of elemental analyses, electronic, IR and 1 H NMR spectra, molar conductivity measurements, magnetic moment measurements and thermogravimetric analyses (TGA). It has been found that the Schiff base behaves as a neutral bidentate (NO) or tridentate (ONO) ligand forming chelates with 1:2 (metal:ligand) stoichiometry and
Polyhedron, 2006
Four new copper(II) complexes, [(CuL 1 N 3) 2 ](ClO 4) 2 (1), [(CuL 2 N 3) 2 ](ClO 4) 2 (2), [CuL 3 (N 3)(ClO 4)] n (3) and [CuL 4 (l-1,1-N 3)-(l-1,3-N 3)(ClO 4)] n (4) where L 1 = N 1-pyridin-2-yl-methylene-propane-1,3-diamine, L 2 = N 1-(1-pyridin-2-yl-ethylidene)propane-1,3-diamine, L 3 = N 1-(1-pyridin-2-yl-ethylidene)ethane-1,2-diamine and L 4 = N 1-(1-pyridin-2-yl-ethylidene)propane-1,2-diamine are four tridentate N,N,N donor Schiff base ligands, have been derived and structurally characterized by X-ray crystallography. Compounds 1 and 2 consist of double basal-apical end-on (EO) azide bridged dinuclear Cu II complexes with square-pyramidal geometry. In complex 3 the square planar mononuclear [CuL 3 (N 3)] units are linked by weakly coordinated perchlorate ions in the axial positions of Cu II to form a one-dimensional chain. Two such chains are connected by hydrogen bonds involving perchlorate ions and azide groups. Compound 4 consists of 1-D chains in which the Cu II ions with a square-pyramidal geometry are alternately bridged by single EO and end-toend (EE) azido ligands, both adopting a basal-apical disposition. Variable temperature (300-2 K) magnetic susceptibility measurements and magnetization measurements at 2 K have been performed. The results reveal that complexes 1 and 2 are antiferromagnetically coupled through azido bridges (J = À12.18 ± 0.09 and À4.43 ± 0.1 cm À1 for 1 and 2, respectively). Complex 3 shows two different magnetic interactions through the two kinds of hydrogen bonds; one is antiferromagnetic (J 1 = À9.69 ± 0.03 cm À1) and the other is ferromagnetic (J 2 = 1.00 ± 0.01 cm À1). From a magnetic point of view complex 4 is a ferromagnetic dinuclear complex (J = 1.91 ± 0.01 cm À1) coupled through the EO bridge only. The coupling through the EE bridge is practically nil as the N(azido)-Cu II (axial) distance (2.643 Å) is too long.
Complexes formulated as {[Co(L) 2 ]. [Co(HL) 2 ]. 4H 2 O} (1), [Ni 2 (HL) 2 (Cl) 2 (H 2 O) 2 ] 2 (2), {[Cu 2 (HL) 2 (Cl) 2 ]. [Cu 2 (HL) 2 (Cl) 2 ]. (H 2 O)} (3) and [Cu 2 (HL) 2 (Cl) 2 ] (4) were synthesized by mixing an equimolar amount of methanol or ethanol solution containing CoCl 2. 6H 2 O, NiCl 2. 6H 2 O or CuCl 2. 2H 2 O and methanol or ethanol solution containing the ligand H 2 L [2-((2-hydroxyethylimino)methyl)phenol]. Complex 1 is composed of two mononuclear ionic units, anionic [Co(L) 2 ]and cationic [Co(HL) 2 ] + and two uncoordinated water molecules. In the cationic unit, the cobalt(III) is coordinated by two monodeprotonated ligand molecules. In the anionic unit the cobalt(III) is coordinated by two dideprotonated ligand molecules. In both molecules the Co(III) ion is coordinated through three set donors per ligand molecule, yielding a distorted octahedral environment N 2 O 4 around the metal center. In the dinuclear nickel(II) complex 2, each of the two metal ions is coordinated by one monodeprotonated ligand molecule through three set donors. Each of the phenolate oxygen anion of the ligand molecules acts as bridge to connect the two metal centers yielding a dinuclear unit. Each of the nickel ion is also coordinated by a terminal chloride ion and a water molecule resulting in an octahedral environment NO 4 Cl around the metal center. In the complex 3, two independent dinuclear molecules are present in the asymmetric unit. Each copper(II) ion is coordinated by one monodeprotonated organic molecule and two chloride ions which act as bridges between two copper ions. All the copper cations are pentacoordinated and display a distorted square-pyramidal geometry for the NO 2 Cl 2 donor set in which one chloride occupies the apical position and the other remains in the basal plane. In the complex 4, the two copper ions are situated in NO 3 Cl and NO 2 Cl 2 inners respectively and are bridged by one chlorine ion and one phenolate oxygen ion. For all the complexes intramolecular and intermolecular hydrogen bonds stabilize the structure.