Asma I. El-Said

Mixed Ligand Complexes of 5-arylazo-8-hydroxyquinoline and α-amino Acids with Co(II), Ni(II) and Cu(II)

Ten mixed ligand complexes of the type [M(X-QA)(aa)] and [Ni(X-QA)2(Haa)(H2O)],where X-HQA=5-arylazo-8-hydroxyquinoline derivatives, M=Co(II) orCu(II) and Haa=glycine (gly), alanine (ala) or methionine (met), have been prepared. The complexes have been characterized by elemental analysis, IR and electron spectra and thermal analysis. A tetrahedral structure has been proposed for the cobalt(II) and copper(II) complexes with bidentate coordination of amino acids. The nickel(II) complexes have been assigned an octahedral structure with the amino acids acting as monodentate ligands. The thermal behaviour of the complexes has been studied before and after γ-irradiation.

Complexes of tris(o-phenanthroline)nickel(II) and copper(II) bromide with dithiocarbamates derived from α-amino acids

Complexes of 1,10-o-phenanthroline (o-phen)-NiII and CuII with dithiocarbamates derived from α-amino acids (glycine, phenylalanine, alanine, methionine and tryptophan) were synthesized and characterized by chemical analysis, spectral and thermal studies and by biological screening; the complexes are non-electrolytes. The empirical formula are [Ni(o-phen)2(aadtc)] and [Cu2(o-phen)2(phaladtc)(H2O)2Br2] where, aadtc = glycinyl-, phenylalaninyl-, alaninyl-, methioninyl- and tryptophanyldithiocarbamate and phaladtc = phenylalaninyldithiocarbamate. The structure of these complexes is probably octahedral. Molecular association through hydrogen bonding between the —NH and the carboxylate groups is proposed for the NiII complexes. The CuII complex is dimeric with the phenylalaninyldithiocarbamate acting as a bridge.

Synthesis, spectral and thermal studies of monomeric, homobimetallic and polymeric complexes containing benzoyldithiocarbazate

New mixed ligand complexes of benzoyldithiocarbazate (H2BDT) have been synthesized and characterized by elemental analyses, spectral studies (i.r., u.v.–vis., mass), thermal analysis and electrical conductivity measurements. The complexes have the general formulae: [M2(BDT)(OX)2] · xH2O; [Co2(BDT)(OX)2(H2O)4]; [M′(HBDT)(OX)-(H2O)], [Ni(BDT)(py)2]n and [Ni(BDT)(L)]n where M = MnII, NiII and CuII; BDT = dithiocarbazate dianion; OX = 8-hydroxyquinolinate; x = 1 or 2; M′ = ZnII or CdII; HBDT = dithiocarbazate anion and L = 2,2′-bipyridyl or 1,10-o-phenanthroline. For the [M2(BDT)(OX)2] · xH2O, [Co2(BDT)(OX)2(H2O)4], [Ni(BDT)(py)2]n and [Ni(BDT)(L)]n complexes, benzoyldithiocarbazate acts as a dibasic-tetradentate ligand in the enol form via the enolic oxygen, the hydrazide nitrogens and the thiolate sulphur, while it acts as a monobasic-tridentate ligand in the keto form in the [M′(HBDT)(OX)(H2O)] complexes. The thermal behaviour of the complexes has been studied by t.g.–d.t.g. techniques. Kinetic parameters of the thermal decomposition process have been computed by Coats–Redfern and Horowitz–Metzger methods. It is obvious that the thermal decomposition in the complexes occurs directly at the metal–ligand bonds except for the ZnII and CdII complexes in which decomposition seems to be at a point in the benzoyldithiocarbazate moiety. From the calculated kinetic data it can be concluded that the dehydration processes in all complexes have been described as phase-boundary controlled reactions. The activation energy values reveal that the thermal stabilities of the homobimetallic complexes lie in the order: MnII < NiII < CoII, while the monomeric CdII complex has more enhanced thermal stability than the ZnII complex.

Synthesis, Spectral and Thermal Studies on Cobalt(II), Copper(II), Nickel(II) and Zinc(II) Chelates with p-tolylsalicylaldimine and Some Amino Acids

Abstract New cobalt(II), copper(II), nickel(II) and zinc(II) complexes of the p-tolyIsalicylaIdimine Schiff base (sal-TH) and some amino acids have been prepared. The complexes have the general formula [M(sal-T)(aa)].nH2O where M = Co(II), Cu(II), Ni(II) and Zn(II); sal-T = monoanion of the Schiff base p-tolylsalicylaldimine; aa = monoanion of the amino acids phenylalanine (Phala), tyrosine (tyr) or methionine (met); n = 0 for M = Co(II), Cu(II) or Ni(II) and n = 2 for M = Zn(II). The complexes have been characterized and studied by elemental analyses, conductivity, IR and UV-V1S spectroscopy as well as thermogravimetry. The Cu(II) complexes have been proposed to possess a square-planar structure while the Co(II), Ni(II) and Zn(II) complexes have an octahedral structure attained by mutual intermolecular interactions among the adjacent mixed amino acid-Schiff base molecules. The thermal decomposition reaction order and activation energy have been computed by means of the Coats-Redfern and Horowitz-Metzger methods. The biological activity of selected complexes against some bacteria and fungi have been tested.

Lewis acidity of coordinatively unsaturated bis(2-mercaptobenzothiazolato)nickel(II) towards azoles and morpholine

The reactions of bis(2-mercaptobenzothiazolato)nickel(H) with some azoles and morpholine afforded the corresponding mixed ligand complexes. The studied azoles were 2-aminothiazole, benzothiazole, benzoxazole, 2-methylbenzoxazole and 2-mercapto-benzoxazole. The formation of new compounds was confirmed from the spectral data. The thermal decompositions of the compounds together with some related compounds reported in the literature, for comparison, were studied. The activation energies and other kinetic parameters were calculated from the Coats-Redfern and Horowitz-Metzger equations.ZusammenfassungDie Reaktion von Bis(2-mercaptobenzothiazolato)nickel(II) mit einigen Azolen und Morpholin liefert die entsprechenden Mischligandenkomplexe. Die untersuchten Azole waren 2-Aminothiazol, Benzothiazol, Benzoxazol, 2-Methylbenzoxazol und 2-Mercaptobenzoxazol. Die Bildung neuer Verbindungen wurde anhand von Spektren festgestellt. Es wurde die thermische Zersetzung von einigen dieser Verbindungen sowie zum Vergleich auch von einigen in der Literatur beschriebenen verwandten Verbindungen untersucht. Anhand der Coats-Redfern- und der Horowitz-Metzger-Gleichung wurden die Aktivierungsenergien und andere kinetische Parameter errechnet.

Studies on Some Nickel(II) and Cobalt(II) Mixed Ligand Complexes of Arylsalicyl-Aldimine and Other Ligands

Several new mixed ligand complexes of Ni(II) and Co(II) of p-tolylsalicylaldimine (Sal-TH) or p-anisylsalicylaldimine (Sal-AH) with 8-hydroxyquinoline (HOx), benzohydroxamic acid (BH2) or α-picoline (α-pic) have been synthesized. The complexes have the general formulae: [M(Sal-T)L],[M(Sal-A)L]⋅H2O or [Ni(Sal-T)2(α-pic)2]⋅H2O where M=Ni(II) or Co(II), Sal-T=p-tolylsalicylaldiminate, Sal-A=p-anisylsalicylaldiminate, L=8-hydroxyquinolinate or benzohydroxamate and α-pic=α-picoline. Analytical, conductivity and spectral data support a square planar structure for Co(II) complexes and octahedral structure for Ni(II) complexes. The thermal behaviour of the complexes has been studied by TG and DTG techniques. It was proposed that the decomposition of the complexed Schiff base takes place via a radical mechanism while for 8-hydroxyquinolinate or benzohydroxamate via proton transfer. Kinetic parameters of the thermal decomposition process have been computed by means of Coats-Redfern and Horowitz-Metzger methods.

Mixed benzohydroxamato-acetylacetonato metal complexes: spectral, thermal and photochemical behaviour

SummaryBis(acetylacetonato)VOII,−CoII,−NiII,−CuII,−ZnII, −UO2II and tris(acetylacetonato)FeIII react with benzohydroxamic acid to yield the corresponding mixed ligand complexes as a result of displacement of one acetylacetone molecule. Intermolecular association may be the reason for six-coordination geometry around the metal ions. A t.g.a. study of the complexes shows, in most cases, initial loss of alcohol and water molecules associated with the complexes; subsequent decomposition steps are characterised by very sharp weight loss. The photochemical stability of the complexes has been studied. Intraligand excitation causes a decomposition in the case of FeIII and VOII-complexes but no detectable effect for CoII, NiII, CuII, ZnII, or UO2II-complexes.

Studies of mixed ligand complexes from dialkyldithiophosphate and thiosemicarbazide or thiosemicarbazones with nickel(II)

The complexes [Ni{(RO)2PS2}2Tsc], [Ni{(RO)2PS2}2ApTsc], and [Ni{(RO)2PS2}FurTsc.2H2O] where R = methyl (Me), ethyl (Et) or propyl (Prop); Tsc = thiosemicarbazide, ApTsc = 2-acetylpyridine-thiosemicarbazone, and FurTsc = furfuraldhydethiosemicarbazone have been synthesized and characterized by elemental analysis, conductance measurements, and spectral studies (IR, UV-Vis, and mass). Thermal studies of the complexes have been carried out using TG and DTG techniques. An octahedral structure has been proposed for all types of the complexes. A representative types of the complexes are tested against various pathogenic bacteria and fungi. The [Ni{(EtO)2PS2}2ApTsc] shows a high degree of activity against bacteria and fungi; this may be attributed to the pyridyl ring of the 2-acetylpyridinethiosemicarbazone ligand.

Reactivity of Mixed Ligand Complexes I. Interaction of Dithizonato-Alkylxanthato Nickel(II) with 2,2′-Bipyridyl and 1,10-o-Phenanthroline

Abstract A series of new ionic, mixed ligand complexes has been synthesized and characterized. The compounds have the general formula [Ni(Rxan)(B)2]+(HDz)−, where Rxan = methyl, ethyl, propyl, butyl and cyclohexylxanthate, B = 2,2′-bipyridyl or 1,10-o-phenanthroline and HDz− = dithizonate anion. The conductivity data of the complexes were commensurate with the ionic character of the complexes. An octahedral structure around Ni(II) is proposed. The formation of new complexes was suggested from the thermal analysis.

Thermal behaviour of heterobimetallic complexes containing bridged xanthates

SummaryHeterobimetallic complexes of the general formulae M[M′(Rxan)3]2 and Ag[M′(Buxan)3] where M=CoII, NiII or PbII; M′=NiII or PbII and Rxan=methyl- or butylxanthate have been prepared. Their thermal behaviour has been compared with the known related complexes: M[M′(Etxan)3]2 and Ag[M′(Etxan)3] where M=CoII, NiII or PbII, M′=NiII or PbII. The ethylxanthate (Etxan) complexes were also included in the investigation and a mechanism has been proposed for their thermal decomposition. Thermal elimination of aldehyde has been suggested for the bimetallic complexes containing the bridged butylxanthate. Kinetic parameters (activation energy, enthalpy and entropy) were evaluated using the Coats-Redfern and Horowitz-Metzger equations.