IRON(II, III) COMPLEXES WITHN, N'-DI(2-)PYRIDYL THIOUREA. MÖSSBAUER AND OTHER SPECTROSCOPIC STUDIES

Devi K.R., Sathyanarayana D.N.

The infrared spectra of symmetric N,N′-dimethylthiourea (s-DMTU) and its N-deuterated (s-DMTU-d2) species have been measured. The fundamental frequencies have been assigned by comparison with the assignments in structurally related molecules and the infrared band shifts on N-deuteration, S-methylation, available Raman data and with the aid of theoretical band assignments from normal coordinate treatments for s-DMTU-d0 and -d2. A force field is derived for s-DMTU by transferring the force constants chiefly from N-methylthiourea and the subsequent refinement of the force constants by a least squares procedure.

Dockum B.W., Reiff W.M.

The temperature dependence of the zero field Mossbauer spectrum and magnetic susceptibility of Fe(2,9-di-CH3-phenanthroline)2(NCS)2 over the range 1.8 to 300 K shows that the complex contains spin quintet iron(II) at all temperatures. The ligand is apparently to the weak field side of the ‘crossover point’ and contrary to the results of a previous study there is no evidence of a transition to a lower multiplicity (triplet or singlet) ground state. The observed decrease of the magnetic moment (4.81 μβ at 302 K to 3.48 μβ at 1.82 K) is consistent with zero field splitting (|D|≈ 5 cm−1) of the ground spin manifold.

Ortego J.D., Upalawanna S., Amanollahi S.

Little B.F., Long G.J.

Ainscough E.

Galabov B., Vassilev G., Neykova N., Galabov A.

The conformation of the —NH—CS—NH— grouping in a series of N,N'-diarylthioureas some of which possess a marked anti-viral activity is studied using IR spectral data. The results indicate that in organic solvents (CCl4, CHCl3, C2C14, CH2C12) the compounds studied participate in an equilibrium between several isomeric forms arising from the possibility of a cis or trans structure of the —CS—NH— groups. The increased solvent polarity favours the cis conformation.

Galabov A.S., Velichkova E.H., Vassilev G.N.

The effect of 12 derivatives of N-phenyl-N'-aryl- or alkylthiourea, inhibitors of human enteroviruses and foot-and-mouth disease virus, on reproduction of some rhinoviruses (H-17, B-632) in HeLa Bristol cells was studied. As screening methods both the multicylce growth test in roller tube cultures and two variants of plaque inhibition tests were employed. The compounds selected were tested in one-step growth cycle set-up. We established that N-phenyl-N'-4-hydroxyphenylthiourea (V-24) and N-phenyl-N'-2-carboxyphenylthiourea (V-17) have a distinct inhibitory effect on the growth of rhinovirus H-17, and N-phenyl-N'-2-hydroxy-5-nitrophenylthiourea (V-25) inhibited strongly the multiplication of rhinovirus B-632.

Goodwin H.A.

Birchall T., Khin Mar Tun

Prasad C.S., Banerji S.K.

Bachechi F., Zambonelli L., Marcotrigiano G.

The crystal structure of tetrakis(N-ethylthiourea)platinum(II) iodide, [Pt(CS(NH2)(NHC2H5))4]I2, has been determined from three-dimensional X-ray diffraction data. The triclinic crystals belong to the P 1 space group: a = 8.096(8), b = 13.165(12), c = 14.248 (12) A, α = 101.7(1), β = 108.5(1), γ = 102.1(1)°. The observed and calculated (Z = 2) densities are 2.13(1) and 2.127 g cm−3 respectively. 5306 independent reflections with Fo2 > 3σ(Fo2) were collected by counter methods. Least-squares refinement gave a final discrepancy factor of 0.038. The stereochemistry around the platinum is almost square-planar with the sulphur atom of each thiourea group bound to the metal. Pt-S distances range from 2.309(3) to 2.335 (3) A. The thiourea groups have quite regular geometry and dimensions. The structure is stabilized in the solid state by a network of NH … I−1 hydrogen bonds.

Bigotto A., Galasso V., Pappalardo G.C., Scarlata G.

The electric dipole moments and u.v. and i.r. spectra of di-2-pyridyl sulphone and of its p-nitro- and p,p′-dinitroderivatives have been measured and analysed. Dipole moment data, in conjunction with theoretical calculations of conformational energy (CNDO/2 and EHT), show that these molecules prefer a single conformation in which the pyridine ring planes are perpendicular to the CSC plane and the nitrogen atoms are located anti to each other. The main features of the u.v. and i.r. spectra of the compounds examined, together with those of diphenyl sulphone, have been surveyed. The electronic transitions have been interpreted in terms of CNDO/S-Cl calculations for the most favoured conformation. Vibrational assignments for the characteristic SO2 group frequencies are also presented.

Maeda Y., Sasaki Y., Takashima Y.

Visible, infrared and Mossbauer spectra of 4-substituted pyridine N-oxide complexes of the formula [Fe(4-ZC 5 H 4 NO) 6 ](ClO 4 ) 2 , where Z = OCH 3 , CH 3 , H, Cl and NO 2 are reported. Spectral data indicate that the six coordinated complexes are of high-spin octahedral structure distorted from O h symmetry. From infrared spectral measurements metal-oxygen stretching vibrations are found to be correlated with the σ pyNO values of the ligand. Crystal field parameters are evaluated from diffuse reflectance spectra and the trend of parameter was discussed in terms of spectrochemical series.

Taylor I.F., Weininger M.S., Amma E.L.

Saleh R.Y., Straub D.K.

Ramadan A.A., El-Behairy M.A., Ismail A.I., Mahmoud M.M.

Proton-ligand formation constants ofDCPT and metal-ligand formation constants of its complexes with Fe(II) and Fe(III) have been determined potentiometrically at 10, 20, 30, and 40°C in 75% (v/v) dioxane-water at 0.10M ionic strength (KNO3). The thermodynamic parameters ΔG, ΔH, and ΔS have also been evaluated. The possibility of formingM(HL),M(HL)2, andM(HL)3 species was substantiated from potentiometric and electronic absorption measurements. The values of the stability constants logK M(HL), log $$K_{M(HL)_2 } $$ , and log $$K_{M(HL)_3 } $$ derived from the spectrophotometric method are in good agreement with those obtained from potentiometric data. The use ofDCPT as an analytical reagent for the spectrophotometric determination of iron is discussed. The solid complexes have been characterized by chemical analysis and magnetic susceptibility, IR, NMR, and electronic spectral data.

Venugopal P., Ravinder V., Lingaiah P.

Complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Pd(II) with di-N-phenyl pyromellitic diimide (PhPMDI) and di-N-pyridyl pyromellitic diimide (PyPMDI) were prepared and characterized based on analytical, molar conductance, magnetic, IR, PMR, electronic and ESR data. Based on analytical and molar conductance, the complexes have been formulated as [M(PhPMDA)(H2O)2]n (M = Mn, Fe, Co, Ni), [Cu(PhPMDA)]n [Pd2(PhPMDA)Cl2(H2O)2], [M(PyPMDA)]n (M = Mn, Fe, Co, Ni and Cu) and [Pd2(PyPMDA)Cl2] In all these complexes PhPMDA acts as a mononegative bidentate ligand whereas PyPMDA acts as a mononegative tridentate one in the form of amide rather than imide. The geometries of the complexes have been proposed based on the electronic spectra. The various bonding parameters have been calculated from the ESR spectra of Cu(II) complexes.

Ibrahim K.M., Bekheit M.M., El-Reash G.M.

The complexes of MnII, CoII, NiII, CuII, ZnII, CdII, HgII, CoIII and UO 2 2+ ions with 2-hydroxyimino-3-(2′-hydrazonopyridyl)-butane (HL) have been synthesised and characterized by elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., visible, n.m.r.) studies. I.r. spectra show that HL behaves as a neutral or mononegative ligand and binds in a bidentate and/or tridentate manner. Also, HL behaves as oxidizing agent towards CoII forming diamagnetic CoIII complexes depending on the preparative conditions. Different stereochemistries are proposed for MnII, CoIII, CoII, NiII and CuII on the basis of spectral and magnetic studies.

Gade D., Gubba B., Vadde R., Puri L.

Iron(II) complexes of the type [FeL2X2] (L=bidentate ligand, X=H2O, Cl, or SCN) and [FeL2] (L=tridentate ligand) with polydentate ligands derived from 2-(acetylamino)benzoic acid, 2-(benzoylamino)benzoic acid,2-[2-aminobenzoylamino]benzoic acid, 2-[amino-carbonyl]benzoic acid, 2-[(phenylamino)carbonyl]-benzoic acid, 2-[aminobenzoyl]benzoic acid and 2-aminobenzanilide have been synthesized and characterized by elemental analyses, conductivity, magnetic susceptibility and i.r., electronic, n.m.r., and Mossbauer spectral studies. The different modes of ligand chelation and the stereochemistry around the metal ion are discussed. The small range of isomer shift values for iron(II) complexes confirms the similar geometry for all the complexes.

Jain S.K., Garg B.S., Bhoon Y.K.

Copper(II) complexes of 2-acetylpyridine 4,4-dimethyl-3-thiosemicarbazone (L′H) and 2-acetylpyridine 4-(4-methylpiperidinyl)-3-thiosemicarbazone (LH) of the general formula CuLX (where L is a deprotonated ligand and X = F−, Cl−, Br−, I−, OAc− and NO−3) have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements between 93 and 298 K in the polycrystalline state, i.r. spectra, electronic spectra, conductivity measurements and ESR spectra recorded in the polycrystalline state, in chloroform and dimethylformamide solution at room temperature and at 77K. The molar conductivities measured in dimethylformamide for all complexes show them to be non-electrolytes. The terdentate character of the ligands in all the complexes is inferred from i.r. spectral studies. The i.r. spectra also confirm the monodentate nature of the polyatomic anions such as nitrate and acetate. The electronic spectra in Nujol mulls, chloroform or dimethylformamide solution suggest planar geometry for all of the complexes. The calculated ESR parameters show an axial dx2−y2 ground state and suggest coordination through sulphur in agreement with the i.r. results. Little change in the value of g with temperature indicates no significant change in planarity of these four coordinated species. ESR spectra in solution at room temperature and 77 K also suggest a strong covalent environment with strong in-plane sigma and pi bonds provided by the ligands.

Jain S.K., Garg B.S., Bhoon Y.K., Klayman D.L., Scovill J.P.

Sudha L.V., Sathyanarayana D.N.

The Cu(II). Zn(II) and Cd(II) chloride and bromide complexes of N-2(2-pyridyl)thioacetamide and N-(2-pyridyl)thiobenzamide have been prepared. The infrared and 1H and 13C NMR spectra of the complexes and the free ligands have been analysed to determine the coordination sites. It was concluded that N-(2-pyridyl)thioacetamide behaves as a bidentate ligand, chelating to the metal via pyridine nitrogen and thionamide sulfur atoms while the other ligand, N-(2-pyridyl)thiobenzamide coordinates to the metal atom as a unidentate through the pyridine nitrogen atom. Conformations of the free ligands are discussed.