Samir S. Kandil

Cobalt(II, III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine

A new series of cobalt(II, III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine (L) having formulae LMIIX2, L2MIIX2 and LCoIIIX3, (X = Cl, OAc or ClO4; MII = CoII or CuII) were isolated and characterized by elemental analyses, molar conductances, magnetic moments and i.r., electronic and e.s.r. spectral measurements. The i.r. spectra indicated that the ligand, L, behaves as a neutral bidentate towards divalent metal ions via a triazine-N, and azomethine-N, and acts as a tridentate towards cobalt(III) via the same two nitrogen atoms and the furan-O. The magnetic moments and electronic spectral data suggest a pseudo-tetrahedral geometry for [L2Co]Cl2, a diamagnetic tetragonally distorted octahedral geometry for [LCoCl3], [LCo(OAc)3] · 4H2O and [LCo(H2O)3](ClO4)3 and a dimeric square pyramidal geometry for both [LCuCl2] and [LCu(OAc)2] · 2H2O through bridged chloro and acetato ligands, respectively. The ligand field parameters (B′, 10Dq and β) were evaluated from the electronic spectral data and magnetic moments and related to the bonding of the complexes. The X-band e.s.r. spectra showed three g values with large magnetic anisotropy for [L2Co]Cl2 in accordance with pseudo-tetrahedral CoII complexes; axial pattern for [LCuCl2], [LCu(OAc)2] · 2H2O and [L2Cu(H2O)2](ClO4)2 with two g values and a signal due to ΔMs = ±2 transition for both chloro and acetato copper(II) complexes.

Cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin

A new series of hexacoordinate cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin HL having formulae [LM(OAc)(H2O)2] · nH2O (M = CoII, CuII and NiII), [LM′Cl(H2O)2] · nH2O (M′ = CoII and NiII), [LCuCl(H2O)]2 · 2H2O, [LCu(H2O)3](ClO4) and [LCu(HSO4)(H2O)2] were isolated and characterized by elemental analyses, molar conductivities and magnetic susceptibilities, and by i.r., electronic and e.s.r. spectral measurements, as well as by thermal (t.g. and d.t.g.) analyses. The i.r. spectra indicate that the ligand HL behaves as a monobasic tridentate towards the three divalent metal ions via an azo-N, carboxylate-O and thiohydantoin-O atom. The magnetic moments and electronic spectral data suggest an octahedral geometry for CoII complexes, distorted octahedral geometry for both NiII and CuII complexes with a dimeric structure for [LCuCl(H2O)]2 · 2H2O through bridged chloro ligands. The X-band e.s.r. spectra reveal an axial symmetry for the copper(II) complexes with unsymmetrical ΔMs = ± 1 signal and G-parameter less than four for the dimeric [LCuCl(H2O)]2 · 2H2O. The thermogravimetry (t.g. and d.t.g.) of some complexes were studied; the order and kinetic parameters of their thermal degradation were determined by applying Coats–Redfern method and discussed.

Cobalt(II), nickel(II) and copper(II) complexes of 4-(sulfonylazido)phenylazopyrazolones

Transition metal complexes of CoII, NiII and CuII with 4-(4-azidosulfophenylazo)-5-phenyl-3,4-dihydro-2H-pyrazol-3-oneHL1, 4-(4-azidosulfophenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL2 and 4-(3-azidosulfo-6-methoxyphenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL3 were prepared and characterized by elemental analyses, molar conductances and magnetic susceptibilities and by i.r., electronic and e.s.r. spectral measurements as well as thermal (d.t.a and t.g.a.) analysis. The i.r. spectra indicate that HL acts as a bidentate ligand coordinating via the azo and enolic-oxygen linkages. The electronic spectral data and magnetic moments suggest a tetragonally distorted octahedral geometry for the complexes having the formula ML2·2H2O, (M = CoII, NiII and CuII), square pyramidal geometry for CuL23H2O and tetrahedral geometry for CoL23. The X-band e.s.r. spectra of the copper(II) complexes reveal anaxial symmetry for both CuL222H2O and CuL23H2O while CuL21O is isotropic in the solid state at room temperature. The d.t.a. curves show two exothermic peaks for all three complexes CoL23,NiL232H2O and CuL23H2O and one endothermic peak for the latter two aqua complexes.

Cobalt(II) and Copper(II) Complexes of (2-Acetylpyridine)-(5,6-Diphenyl-[1,2,4]Triazin-3-YL) Hydrazone

A series of cobalt(II) and copper(II) complexes of (2-acetylpyridine)-(5,6-diphenyl-[1,2,4]triazin-3-yl) hydrazone, APyTHy, L, having the formulae [LMCl2]·nH2O, [L2Cu(H2O)2](ClO4)2 and [L2M]X2·nH2O (X = ClO4 or OAc; M = Co or Cu and n = 0, 2 or 4) were isolated and characterized by elemental analysis, molar conductance, magnetic moment and IR, electronic and ESR spectral measurements. The IR spectra indicate that APyTHy behaves as a neutral tridentate ligand, coordinating via a triazine-N, azomethine-N and pyridine-N, except for [LCuCl2] and [L2Cu]X2·nH2O (X = OAc or ClO4), where it acts as a bidentate, not using the triazine-N in complexation. The magnetic moment and electronic spectral data suggest a distorted octahedral structure for 1 : 2 Co(II) complexes, a tetrahedral geometry for 1 : 2 Cu(II) complexes and a trigonal bipyramidal structure for [LCu(H2O)2](ClO4)2 and [LMCl2]·nH2O (M = CoII or CuII; n = 0 or 2) complexes. Upon heating the green [LCuCl2]·2H2O, brown square planar [LCuCl2] was produced. The mixing coefficients and covalency factors for the copper(II) complexes estimated from the combined X-band ESR g-values and electronic d–d transitions using Reinens method imply that the CuN3X2 chromophore is considerably distorted towards square pyramidal.

Cobalt(II) and copper(II) complexes of (2-thiophene)-(5,6-diphenyl-[1,2,4]-triazin-3-yl)hydrazone

New complexes having the formulae [L2CoX2] and [LCuCl2], [LCuCl] and [LCu](ClO4)2 where L = (2-thiophene)-(5,6-diphenyl-[1,2,4]-triazin-3-yl)hydrazone TDPTH; X = Cl, OAc or ClO4 have been synthesized and characterized on the basis of elemental analyses, conductance, magnetic moments and infrared, electronic and ESR spectral data. The IR spectra indicate that TDPTH is a neutral bidentate ligand, coordinating via a triazine-N and azomethine-N in [L2CoX2] and [LCuCl2] with the thiophene-S not coordinated but is tridentate in [LCuCl] and [LCu](ClO4)2 through the same two nitrogen atoms and thiophene-S. The magnetic moment and electronic spectral data suggest a distorted octahedral structure for Co(II) complexes, a dimeric square pyramidal geometry for [LCuCl2] through chloride bridges and a dimeric diamagnetic, four-coordinate copper in [LCu](ClO4)2 through thiophene-S bridges. The X-band ESR spectra of Co(II) complexes, in the solid state, are rhombic with three g values consistent with a high-spin distorted octahedral structure. The X-band ESR spectrum of the powdered sample of both [LCuCl2]·2H2O and [LCu](ClO4)2 at room temperature and at 77 K showed only one broad signal due to ΔM s = ± 1 transition and a weak signal due to the forbidden ΔM s = ± 2 transition, indicating an antiferromagnetic interaction between copper(II) centers whereas [LCuCl] is ESR silent, indicating a monovalent copper ion in this complex.

Synthesis and Characterization of 2,2-Biimidazole Complexes of Oxocations of Molybdenum (VI, V) and Uranium(VI)

Abstract 2,2′-Biimidazole complexes of MoO2 +2, MoO2 + and UO2 +2 have been prepared and characterized by elemental analysis, conductance; and 1H NMR, IR and electronic spectra. Two types of complexes have been identified. Those obtained from slightly acidic solutions have the formulae MoO2 (H2bim)Cl2.2H2O 1, UO2(H2bim) (Ac)2 2 and UO2(H2bim)Cl2.2H2O 3; whereas those from alkaline solutions have the formulae Mo2O4(Hbim)2.2H2O 4, and MO2(Hbim)2 (M = Mo(VI) 5, U(VI) 6). The infrared spectra of these complexes show characteristic biimidazole frequencies in the 3200–2500, 1550–1000 and 750 cm−1 regions as well as metal oxygen double bonds in the 900 cm−1 region. The stoichiometries of the acetate complex has been confirmed from 1H NMR signal ratios of bimidazole to acetate protons at 7.3 and 2.3 ppm, respectively. The electronic spectrum of molybdenum(V) complex showed d-d transition band at ≃13,500 cm−1 in accord with that reported for copper (d9) imidazole complexes; as well as peaks due to charge transfer ...

Synthesis and Characterization of Manganese(II), Nickel(II) and Copper(II) Complexes of 4-(Arylideneamino)-3-Mercapto-6-Methyl-1,2,4-Triazin-5(4H)-Ones

Abstract Manganese(II), nickel(II) and copper(II) complexes of 4-(2,6-dichlorobenzylidene-amino)-3-mercapto-6-methyl-1,2,4-triazin-5(4H)-one (HL1) and 4-(cinnamylideneamino)-3-mercaptc-6-inethyl-1,2,4-triazin-5(4H)-one (HL2) have been synthesized and characterized. The IR spectra indicate that both HL1 and HL2 act as neutral or monobasic bidentate ligands, coordinating to metal ions via azomethine-N and either carbony]-O or (thiolo or thiono)-S, depending on the metal ion. The magnetic and spectroscopic data suggest a distorted-octahedral geometry for the Ni(II) complexes, a square-planar geometry for [L1CuCl(H2O)] a dimeric distorted octahedral geometry for both [(L2)2Cu(H2O)]2 and [(HL)Mn(SO4)(H2O)2]2. Such dimeric structures have been revealed by the subnormally low μoff values for the Mn(II) complexes, due to antifenomagnetic coupling between the two Nm(II) centers, and the diamagnetism of [(L2 2Cu(H2O)]2 is due to a quenching mechanism. ESR parameters support the structures of the Mn(II) and Cu(II) complexes and that the two azomethine nitrogens are coordinated to the Cu(II) ion in the [(L2)2Cu(H2O)]2 complex. DTA studies of the maganese(II) and copper(II) complexes are also reported.

Coordination of cobalt(III), nickel(II), copper(II), palladium(II) and platinum(II) with N-ethyl-N′-(4′-methylthiazol-2′-yl)thiourea (HL)

Coordination complexes of formula [ML2], [CoL3], [Pd(HL)Cl2], [CuLCl(H2O)] and [CuL2(H2O)2] {L=anion of N-ethyl-N′-(4′-methylthiazol-2′-yl)thiourea; M=PtII, PdII or NiII} were prepared and characterized by elemental analyses, magnetic susceptibilities, and by IR, NMR, electronic and mass spectral measurements. GRAPHICAL ABSTRACT

Structural Investigations of 2-(P-Substituted Benzeneazo)-1,5-dihydroxy Naphthalene and Their Cobalt(II), Nickel(II) and Copper(II) Complexes

Abstract The acid-base properties of 2-(P-substituted benzene-azo)-1, 5-dihydroxynaphthalene have been investigated spectro-photoraetrically. The influence of p-substituents on the ionisation of the O-OH group is discussed. Mesomerically electron repelling substituents prevent ionisation of O-OH by increasing negative centers. Infrared and electronic spectral studies provide proof of the existence of a tautomeric equilibrium between azo and quinone-hydrazone forms in the solid and solution states. Additionally, a number of cobalt(II), nickel(II) and copper(II) complexes of these ligands have been characterized in the solid state. On the basis of elemental analyses, magnetic and spectral data, a distorted octahedral geometry is proposed for all the complexes.

Novel aspects of the thenno-kinetic properties of cobalt(II), nickel(II) and copper(II) complexes of 2-(benzeneazo)-1,5-dihydroxynaphthalene

Abstract The compound 2-(benzeneazo)-1,5-dihydroxynaphthalene has been isolated and combined with some of the first-row transition metal ions, namely Co(II), Ni(II) and Cu(II). The complexes have been characterised in the solid state by elemental analyses, and infrared and electronic absorption spectral measurements. The thermal behaviour of the complexes has been studied by a combination of thermogravimetric analysis (TGA) and differential thermal analysis (DTA) from ambient temperature up to approximately 550 ° C in air. Two thermal processes have been identified: dehydration and decomposition, which interfered with structural rearrangements. The thermal stability of the complexes follows the order Ni(II) > Co(II) > Cu(II). In addition, kinetic data extracted from the DTA thermograms demonstrated that the dehydration process ML 2 · 2H 2 O → ML 2 is simple, whereas the second stage decomposition is complicated and metal-ion dependent.