Synthesis,characterization and antimicrobial activities of transition metal complexes of N,N -dialkyl- N′ -(2-chlorobenzoyl)thiourea derivatives

N,N-di-n-propyl-N′-(2-chlorobenzoyl)thiourea (HL¹) (1), N,N-diphenyl-N′-(2-chlorobenzoyl)thiourea (HL²) (2), and their Ni^II, Co^II, Cu^II, Zn^II, Pt^II, Cd^II and Pd^II complexes have been synthesized and characterized. HL¹ and its copper complex were characterized by single-crystal X-ray diffraction methods. The ligands coordinate as bidentates yielding essentially neutral complexes of the type [ML₂]. The complexes were screened for their in vitro antibacterial, antifungal activities and toxicity. All compounds showed antimicrobial activity, but antibacterial efficacy is greater than antifungal activity.     

Thermal decomposition of metal complexes—VI some ammine cobalt (II) complexes

The thermal dissociation of a number of cobalt (II) ammine complexes of the type, [Co(NH₃)₆]X₂ (X = Cl, Br, I, and NO₃), and [Co(NH₃)₆]SO₄, were studied by thermogravimetry, differential thermal analysis, and gas evolution analysis. The thermal dissociation of these complexes involved intermediate ammine complexes containing lower ammonia to cobalt ratios. For the chloride and bromide complexes, the dissociation sequence was: [Co(NH₃)₆]X₂ → [Co(NH₃)₂]X₂ → [Co(NH₃)]X₂ → CoX₂. The stoichiometry of the dissociation of [Co(NH₃)₆](NO₃)₂ was: 9[Co(NH₃)₆ (NO₃)₂ → 3Co₃O₄ + 30NH₃ + 36H₂O + 17N₂ + 4NO + 2N₂O.     

Studies on platinum(II) and palladium(II) complexes of some N,N′-disubstituted thiourea derivatives

Summary A series of new Pt^II and Pd^II complexes of N,N-disubstituted thiourea derivatives of general formulae [MLCl₂]₂, [ML₂Cl₂] and [ML₄]Cl₂ have been prepared and characterised by physicochemical and spectroscopic methods. The reaction of these ligands with [M(DMSO)₂Cl₂], M = Pt, cis- or Pd, trans-, in CHCl₃ and EtOH at ambient temperature or under reflux, is described.     

A calorimetric study of N,N-diethyl-N′-furoylthiourea and N,N-diisobutyl-N′-furoylthiourea

The standard ( p^o =  0.1 MPa) molar enthalpies of combustion in oxygen, at T =  298.15 K, were measured by rotative bomb calorimetry for crystalline N, N -diethyl- N^′-furoylthiourea, (2-C₄H₃O)CONHCSN(C₂H₅)₂, HFET, and N, N -diisobutyl- N^′-furoylthiourea, (2-C₄H₃O)CONHCSN(iso-C₄H₉)₂, HFIB. The standard molar enthalpies of sublimation of both HFET and HFIB were measured by high-temperature Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the compounds, in their crystalline and gaseous phases.     

Some group VB chloride complexes with thiourea and N,N′-diethyl-dithiooxamide

The following complexes of thiourea(tu) and N,N′-diethyl-dithioxamide (Et₂DH₂) with phosphorous (III), arsenic(III), antimony(III) and bismuth(III) have been prepared and characterises: PCl₃(tu) (DMF)₂; AsCl₃(tu)₃(DMSO)₃: MCl₃(tu)₃ (M = As, Bi); SbCl₃(tu)₂(DMF) and SbCl₃(Et₂DH₂)_1.5 (C₂H₄Cl₂). IR and NMR (¹H, ¹³C and ³¹P) spectral data provides evidence for ligand attachment exclusively by sulphur coordination in all complexes excepting PCl₃(tu) (DMF)₂. For the latter additional metal-nitrogen bonding is proposed.     

Polymeric complexes of cobalt (II) thiocyanate with thiourea,N-methylthiourea and N,N′-ethylenethiourea

The syntheses and properties of complexes of the type Co(NCS)₂2L (L = thiourea, N-methylthiourea, N,N′-ethylenethiourea, N-ethylthiourea) have been investigated.The thiourea and N-methylthiourea derivatives are octahedral involving polymerization via the sulphur atom of the respective thioureas. These complexes are soluble in various non-aqueous solvents yielding tetrahedral species.The N,N′-ethylenethiourea complex can exist at room temperature both as a blue tetrahedral form and also as a brown-red octahedal modifiication. The octahedral isomer is believed to contain thiocyanato bridging groups.The N-ethylthiourea derivative is unstable and only a blue form-probably tetrahedral-can be isolated.The factors determining the stereochemical arrangements in these complexes are discussed.     

Divalent metal complexes of meso- and dl-2,3-diaminobutane-N,N,N′,N′-tetra-acetic acid

Stability constants of complexes of Mn, Cu(II), Zn, Cd and Hg(II) with meso- and dl- 2,3-diaminobutane-N,N,N′,N′-tetra acetic acid (DIMEDTA) valid for 20·0°C and μ = 0·1 M (KNO₃) have been obtained potentiometrically by a modification of Schwarzenbach's mercury-drop procedure adapted to continuous titration.In view of a discrepancy between the value thus found for the stability of the cadmium complex with the meso-isomer and that recently reported by Czech authors, a redetermination was made by the method of corresponding solutions using the cupric complex of meso-DIMEDTA as the coloured species. This procedure was first tested with the EDTA system and led to the value log K_CdY = 16·76 ± 0·08 in fair agreement with the literature value.Differences in the stability of complexes with a particular metal and meso- or dl-DIMEDTA are explained on conformational grounds and discussed in relation to the stability of complexes with analogous ligands such as EDTA, PDTA and DCTA.     

Preparation and molecular structures of N,N-2,2′-dipicolyl- and N,N-3,3′-dipicolyldithiocarbamato metal complexes

New iron(III) and cobalt(III) complexes, [Fe(2,2′-dpdtc)₃], [Fe(3,3′-dpdtc)₃], [Co(2,2′-dpdtc)₃], and [Co(3,3′-dpdtc)₃] (dpdtc?=?dipicolyldithiocarbamate) have been synthesized and their molecular structures and spectroscopic properties determined. The 2,2′- and 3,3′-dpdtc ligands have four donors, S, S′, N, and N′. These complexes are insoluble in water, but soluble in acidic solution. Crystal structures of these metal complexes reveal that the central metal ions have MS₆ (M?=?Fe and Co) octahedral structures and all dipicolyl groups do not coordinate.     

Metalation of dibenzenechromium by N,N,N′N′-tetramethylethylenediamine complexes of n-butyllithium and phenyllithium

Dibenzenechromium is metalated by n-butyllithium in presence of TMEDA. The extent and orientation of metalation were investigated by mass spectrometric analysis of the products after quenching with D₂O. A lithium substituent on dibenzenechromium strongly activates the molecule for further metalation. Competition metalation of dibenzenechromium/benzene mixtures demonstrated the enhanced rate of metalation and therefore increased kinetic CH acidity of the benzene molecule bound to chromium in a π-complex.     

Thermal and FTIR spectral studies of N,N′-diphenylguanidine

Thermal decomposition of N,N??-diphenylguanidine (DPG) was investigated by simultaneous TG/DSC-FTIR techniques under nonisothermal conditions. Online FTIR measurements illustrate that aniline is a major product of DPG decomposition. The observation that the activation energy depends on the extent of conversion indicates that the DPG decomposition kinetics features multiple processes. The initial elimination of aniline from DPG involves two pathways because of the isomerization of DPG. Mass spectrometry and thin film chromatography suggest that there are two major intermediate products with the major one of C₂₁N₃H₁₇. The most probable kinetic model deduced through multivariate nonlinear regression method agrees well with the experimental data with a correlation coefficient of 0.9998. The temperature-independent function of conversion f(??), activation energy E and the pre-exponential factor A of DPG decomposition was also established through model-fitting method in this research.     

Stabilities of some complexes of 2-hydroxy-1,3-diaminopropane-N,N,N′,n′,-tetra-acetic acid with divalent metal ions

The solution stabilities of the complexes of 2-dydroxy-1,3-diaminopropane-N,N,N′,N′-tetra-acetic acid with Ca²⁺, Sr²⁺, Ba²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ have been determined at 25°C and μ = 0·1 (KNO₃). It is shown that both normal and protonated species exist and that the neglect of the latter has contributed to the widely discordant results which have previously been published for the alkaline earths. The values obtained are compared to those for trimethylene-diaminetetra-acetic acid and it is concluded that in theses complexes, with the possible exception of the strontium and barium complexes, there is no participation of the —OH group in the bonding to the metal ion.     

Copper(II) complexes of N,N′-dibenzylethylenediamine

The following complexes of N,N′-dibenzylethylenediamine (DBEn) of copper(II) have been prepared: CuDBEn₂Cl₂,H₂O; CuDBEn₂X₂ (X = Cl, Br, I, and NO₃); CuDBEn₂SO₄,2H₂O; CuDBEn₂(ClO₄)₂,H₂O and CuDBEnX₂ (X = Cl, Br). They have normal magnetic moments, almost invariant with temperature. From the low temperature reflectance spectra of the mono(amine) complexes, evidence for the three ²B_1g → ²A_1g; ²B_1g → ²B_2g; and ²B_1g → ²E_g transitions expected for a tetragonally-distorted complex has been obtained. The coordination of anions in the tetragonal positions of the bis(amine) complexes is established from their reflectance, solution and infrared spectra, and molar conductances except for the perchlorate, which is considered to have a highly distorted, virtually planar structure. The compound CuDBEn₂Br₂ can also be obtained in a form which from its reflectance spectrum may be five-coordinate.     

Synthesis, spectral and thermal studies of N,N − -pyridine-2,6-diyl bis[N −-phenyl(thiourea)] and its metal complexes

Four new metal complexes with the general formula, [ML·mH₂O]nH₂O (where, M = Cu(I), Co(II), Ni(II) or Zn(II); L = N,N ^?-pyridine–2,6-diyl bis[N ^?-phenyl (thiourea)] (PDPT); m = 1 or 3 and n = 0.5 or 4.0), have been synthesized and characterized by elemental analyses, spectral analyses (IR, UV–Vis., ¹H-NMR and MS), thermal analyses (TGA), conductivity and magnetic measurements. The results showed that the ligand (PDPT) acts in a mononegative tridentate manner towards Cu(I) ion coordinating via the two thiol sulfurs and pyridyl nitrogen groups with displacement of only one hydrogen atom from the thiol group, while the ligand behaves in a binegative tridentate manner towards the Co(II), Ni(II) and Zn(II) ions with displacement of two hydrogen atoms from the two thiol groups. The value of magnetic measurements showed a diamagnetic character of the copper complex indicating the reduction of Cu(II) to Cu(I). Semi-empirical calculations of the ligand and its metal complexes have been used to study the molecular geometry using ZINDO/1, PM3 and AM1. Also, the harmonic vibration spectra of the ligand and its metal complexes have been investigated with the purpose to assist the experimental assignment of metal complexes. The results of the optical absorption studies reveal that the optical transition is direct with band gaps energy (E_g) values 2.62, 1.98 and 1.85 eV for Cu, Co and Ni complexes, respectively, indicating that these complexes can behave as semi-conductors.     

The characterization of some square planar Ni(II) complexes of N,N′-ethylenebis (isonitrosoacetylacetoneimine)

The ligand (H₂L) is prepared by the condensation of 2 molecules of isonitrosoacetylacetone with 1 molecule of ethylenediamine. The dimeric nature of the ligand is compatible with the types of the square planar Ni(II) complexes it produces with NiX₂(X  Cl, NO₃, CH₃CO₂). The 1:1 up to 5:1 molar ratio reaction of nickel chloride with the ligand produced the same complex H₂LNiCl₂ · HLNiCI(I) which did not react with pyridine, while the 1:2 and 1:3 molar ratio reaction afforded the complexes LNi · HLNiCl(II) and (LNi)₂(III) respectively. The reaction of nickel nitrate with (H₂L)₂ led to the formation of the complex LNi · HLNiNO₃(IV). The Ni(II) complex LNi(V) of the monomeric ligand was obtained by either the reaction of nickel acetate with (H₂L)₂ (1:1 or 5:1) or by reacting nickel chloride with the neutral solution of the ligand (1:1 or 2:1). The two anions of the ligand are linked together through either (a) hydrogen bonding formation that involves the oxime groups (H₂L and complex I), (b) coordination of one on the oximato group of a ligand's anion with the chelated metal ion to another ligand's anion (complex III), or (c) by both types of linkages (complexes II and IV). The suggested molecular formulations are based on analytical, spectral and magnetic moment evidence.     

Production and thermal decomposition of polycondensates containing N,N′-disubstituted thiourea derivatives

Polycondensates containing N,N-ethylenethiourea or N,N-diisopropylthiourea units and titanium or silicon-derived coupling agent molecules were prepared. Their structures were confirmed through FTIR spectroscopy. The thermal decomposition of these polycondensates was studied by means of TG and DTA methods and FTIR and ESR spectroscopy.

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Zusammenfassung Es wurden Polykondensate mit einem Gehalt an N,N-Ethylenthiokarbamidoder N,N-Diisopropylthiokarbamideinheiten und mit Titan oder Silizium abgeleiteten Koppelreagenzmolekülen hergestellt. Ihre Struktur wurde mittels FTIR Spektroskopie bestätigt. Die thermische Zersetzung dieser Polykondensate wurde mittels TG und DTA Verfahren sowie mit Hilfe von FTIR und ESR Spektroskopie untersucht.

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The author thanks Professor P. I. Premovic for valuable discussions. This reseach was supported by the Research Fund of Macedonia, contract 10/1.