scispace - formally typeset
Search or ask a question

Showing papers in "Journal of Coordination Chemistry in 1983"


Journal ArticleDOI
TL;DR: The reaction of Cu(II), Zn(II, Cd(II) and Hg(II)-chlorides and bromides with imidazoline-2-thione (IZT) and its N-methyl derivative (NMIZT) yields complexes of stoichiometry ML3X2 and ML2X as mentioned in this paper.
Abstract: The reaction of Cu(II), Zn(II), Cd(II) and Hg(II) chlorides and bromides with imidazoline-2-thione (IZT) and its N-methyl derivative (NMIZT) yields complexes of stoichiometry ML3X2 and ML2X (IZT) and its N-methyl derivative (NMIZT) yields complexes of stoichiometry ML3X2 and ML2X (where M=Cu(I)); copper(II) halides yield Cu(I) complexes. On the basis of infrared and 13C n.m.r.

29 citations


Journal ArticleDOI
TL;DR: In this paper, a series of pentadentate ligand complexes with coordination sites at one pyridine nitrogen, two azomethine nitrogen and two amide oxygen atoms have been synthesized and characterized by elemental analyses, conductance measurements and infrared spectral data.
Abstract: A novel series of complexes, of the type [M(DAPCH)X2(M=Zn(II), Cd(II) or Hg(II); DAPCH =planar pentadentate ligand derived from 2,6-diacetylpyridine and carbohydrazide, X=Cl, Br, I, NO3, CH3COO) have been synthesized and characterized by elemental analyses, conductance measurements and infrared spectral data The ligand DAPCH appears to behave as a pentadentate ligand, having coordination sites at one pyridine nitrogen, two azomethine nitrogen and two amide oxygen atoms Possible structures are proposed for these complexes All the complexes contain terminal hydrazinic nitrogen atoms with an unshared electron pair and may take part in nucleophilic condensations Therefore, the reactions of these complexes (X=Cl, Br, NO3) with 2,6-diacetylpyridine have also been studied viz, ring closure and formation of macrocyclic ligand complexes Two types of cyclic products viz, mononuclear [M(L′)X2] and binuclear [M2(L′)X4] (M=Zn(II), Cd(II) or Hg(II); L=macrocyclic ligand derived from DAPCH and 2,6-diacet

27 citations


Journal ArticleDOI
TL;DR: In this article, it is suggested that the histidinate ion adopts a histamine-like bonding mode giving rise to CuN3O chromophores in the metal plane.
Abstract: Ternary copper(II) complexes of the type [Cu(His)A] (HisH=L-histidine, A=glycinato, L-valinato, L-alaninato, L-threoninato, L-serinato, or L-asparaginato) and [Cu(Glu)B]n- (GluH2=L-glutamic acid, B=glycinato, L-alaninato, L-valinato (n=1) or an amino-acid with positively charged protonated side chain such as L-asparagine, L-lysine, or L-ornithine (n=0)) have been investigated in aqueous solution by means of ESR and absorption spectra. It is suggested that in the ternary species the histidinate ion adopts a histamine-like bonding mode giving rise to CuN3O chromophores in the metal plane. Coordination in the bis-(glycine)-like mode is detected in the Glu-containing species. The spectral results have been used to postulate plausible structures for the bis-(histidinato)copper(II) complexes.

22 citations


Journal ArticleDOI
TL;DR: In the presence of a large excess of methyldiphenylphosphine in benzene, a five coordinate complex RuCl/sub 2/(PMePh/sub 3/)/sub 2)/sub 3 was obtained by the reaction of Wilkinson's green complex as mentioned in this paper.
Abstract: The complexes RuCl/sub 2/(PPh/sub 3/)/sub 3/ and RuCl/sub 3/(AsPh/sub 3/)/sub 2/(MeOH) were employed as convenient starting materials. Methods were developed to prepare cis- or trans-isomers of the type RuCl/sub 2/L/sub 4/ (L = AsMePh/sub 2/, AsMe/sub 2/Ph) starting from RuCl/sub 2/(PPh/sub 3/)/sub 3/. Meridonial complexes of the type RuCl/sub 3/L/sub 3/ (L = PPh/sub 3/, PMePh/sub 2/, PMe/sub 2/Ph, PEtPh/sub 2/) were obtained by the reaction of Wilkinson's green complex, RuCl/sub 3/(AsPh/sub 3/)/sub 2/(MeOH) with an excess of L in benzene. In the presence of a large excess of methyldiphenylphosphine in benzene, a five coordinate complex RuCl/sub 2/(PMePh/sub 2/)/sub 3/ was obtained. The temperature of the reaction and solvent decide the nature of the reaction product. Thus a polymeric complex of the composition (RuCl/sub 2/(AsPh/sub 3/)/sub 2/)/sub n/ was obtained from RuCl/sub 3/(AsPh/sub 3/)/sub 2/(MeOH) with triphenylarsine in boiling propanol. The reaction of RuCl/sub 3/.3H/sub 2/O with PPh/sub 3/ and then AsPh/sub 3/ in propanol gave mixed ligand polymers of the type (RuCl/sub 2/(PPh/sub 3/)(AsPh/sub 3/))/sub n/.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the preparation and chatacterization of dipositive metal ion complexes derived from 1-acetyltrimethylammonium chloride-4-phenyl-3-thiosemicarbazide [(ATPTS)] Cl is reported.
Abstract: The preparation and chatacterization of some dipositive metal ion complexes derived from 1-acetyltrimethylammonium chloride-4-phenyl-3-thiosemicarbazide [(ATPTS)] Cl is reported. The solid complexes with the composition [M(ATPTS)X2] Cl.nH2 O, (M=Mn(II), Cu(II), Zn(II) and Hg(II); X=Cl, Br, 1/2SO4, Ac or NO2 and n=O-3), [M(ATPTS)X2]Cl2, (M=Ni(II), Cu(II) and Cd(II); X=Cl(Br), [Co(ATPTS) Cl(H2O)]Cl2.H2O and [Cu(ATPTS)SO4 Py2]Cl, have been characterized on the basis of elemental analyses and spectra (IR, visible and NMR), as well as magnetic and conductivity measurements. IR spectral data indicate that the ligand coordinates via the carbonyl oxygen or thiocarbonyl sulphur atoms and the appropriate hydrazide nitrogen atom to give a 5-membered chelating ring.

19 citations


Journal ArticleDOI
TL;DR: In this article, the activation energies for olefin rotation in ethylene complexes of Rh(I) and Ir(I), were estimated by signal coalescence from their temperature dependent 1H nmr spectra in solution.
Abstract: The activation energies (ΔG) for olefin rotation in ethylene complexes of Rh(I) and Ir(I) have been estimated by signal coalescence from their temperature dependent 1H nmr spectra in solution. The barriers decrease with increase in the electron accepting nature of the associated ligand (η5-cyclopentadienyl, pentane-2, 4-dionate, carboxylate and substituted derivatives thereof) in accordance with the expected decrease in the importance of the π-contribution to the metal-olefin bond. Barriers are substantially higher for Ir(I) than for corresponding Rh(I) complexes. The complex temperature dependent spectra of di-μ-chlorotetrakis(4-methylpenta-1, 3-diene dirhodium(I) are interpreted in terms of both intra- and intermolecular processes. The greater ΔG values found for Ir(I) compared to Rh(I) complexes are reflected in the different mass spectral fragmentation patterns for corresponding members of the two series. Appearance potentials and heats of formation are estimated for [cpRh(C2 H4)2] and [cpRh(...

18 citations


Journal ArticleDOI
TL;DR: In this article, the products resulting from the complexation of Al[OCH(CH3)2]3 (A) and Al[ OCH(CF2)3], with ethylenediamine have been studied.
Abstract: The products resulting from the complexation of Al[OCH(CH3)2]3 (A) and Al[OCH(CF2)3], with ethylenediamine have been studied. Four complexes en. Al[OCH(CH3)2]3 (B); en.Al[OCH(CF3)2]3 (D); [en]2. Al[OCH(CF3)2]3 (E) and en. Al(OH)[OCH(CF3)2]3 (F) were isolated and identified by elemental analysis and NMR spectroscopy. The occurence of a further complex (C) en. 2Al[OCH(CH3)2]3 in solution is suggested by the NMR data. A crystal structure determination is reported for the species (F). The structure consists of en.Al(OH)[OCH(CF3)2]2 dimers with characteristic (N2O4) ligand donor sets. The Al-Al distance (2.939 A indicates that no metal-metal interaction occurs. For the other complexes, the NMR, and in particular the 27Al NMR, data are shown to be consistent with a tetracoordinated aluminium atom in an (O3N) environment (compounds B and D) or with a penta-coordinated aluminium in an (O4 N) environment (C) or in an (O3 N2) environment (E).

17 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated complex formation between copper(II) and gluconate ions (L −) in aqueous acid solutions in the range 3.5 ≤ −log[H+] ≤ 6.5 at 25° and in 1 M NaClO4, by employing copper amalgam and glass electrodes.
Abstract: Complex formation between copper(II) and gluconate ions (L −) has been investigated potentiometrically in aqueous acid solutions in the range 3.5 ≤ −log[H+] ≤ 6.5 at 25° and in 1 M NaClO4, by employing copper amalgam and glass electrodes. In the range 3.5 ≤ −log[H+] ≤ 4.5 experimental data are entirely explained by assuming the formation of the mononuclear complexes CuL + and CuL 2, while in less acidic solutions the deprotonated mononuclear complexes CuH−1 L, CuH−2 L −, CuH−1, L 2 − are also formed and evidence is given for the existence of the polynuclear deprotonated complex Cu2 H−3 L. The formation constants of the various species have been calculated.

14 citations


Journal ArticleDOI
TL;DR: The complexes of 1-isovaleryl-4-phenyl-3-thiosemicarbazide (IVPTS) with Co(II), Ni, Cu, Zn, Cd, and Hg(II) have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic moment and spectral (visible, IR, NMR) studies.
Abstract: The complexes of 1-isovaleryl-4-phenyl-3-thiosemicarbazide (IVPTS) with Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic moment and spectral (visible, IR, NMR) studies. Square-planar geometry have been proposed for Ni(II) and Cu(II) and octahedral for the Co(II) complex.

14 citations


Journal ArticleDOI
TL;DR: In this article, the coordination behavior of the aluminium(III) 8-quinolinol-5-sulfonate (hqs) and aluminium (III) nqs1 complexes with hqs in 0.1 mol dm−2 aqueous sodium chloride solution at 25° was studied.
Abstract: Studies have been made on the coordination behaviour of the aluminium(III) 8-quinolinol-5-sulfonate (hqs)1 and aluminium(III) nqs1 complexes2 with hqs in 0.1 mol dm−2 aqueous sodium chloride solution at 25°. Mixed-ligand complex formation was evidenced by electronic absorption spectral and other spectrophotometric equilibrium studies. Stopped-flow kinetic studies revealed that mixed-ligand complex formation with a mono-nqs complex proceeds via its reaction with Hhqs− and hqs2- whereas formation of the tris-hqs complex proceeds via the reaction of [Al(H2O)6]3+ with Hhqs− and hqs2- and also of [Al(OH)(H2O)5]2+ with H2 hqs and Hhqs−. Coordination mechanisms and structures for the mixed-ligand and the tris-hqs complexes are also discussed.

13 citations


Journal ArticleDOI
TL;DR: In this paper, the authors show that the rate constants for the transformation of the ion-pair to the product increase with increased proportions of the organic component in the solvent, and the dependence of k on different solvent parameters indicates significant associative character with OH− ion acting as the attacking nucleophile.
Abstract: In the base hydrolysis of the title complexes in aqueous-organic solvent media (water-ethanol and water-acetone) to the corresponding hydroxo-complexes the observed rate law is in accord with the expression: The observed K values (3.5 to 26 M−1 at 25°) and the nature of their solvent dependence suggest the formation of an ion-pair in a pre-equilibrium involving the substrate complex and OH− ion, and not of a conjugate base. Rate constants (k) for the transformation of the ion-pair to the product increase with increased proportions of the organic component in the solvent. The nature of the dependence of k on different solvent parameters indicates significant associative character with OH− ion acting as the attacking nucleophile. Activation enthalpy, ΔH≠, decreases with ethanol concentration; this along with the observed large positive slopes of the log k vs 1/D plots rule out the possibility of H2O acting as the attacking nucleophile. ΔH≠ and ΔS≠ corresponding to k in different solvent composition...

Journal ArticleDOI
TL;DR: In this article, the authors obtained and characterized by IR, electronic and EPR spectroscopy the Cu(NCS)2L2 group of complexes (L=C6H5NH2, o-CH3C4NH, m-CH 3H6H4NH2 m-NO2C 6H4 NH2, p-NO 2(o-CH-3)C6h3NH2 and p-ClC 6h4NH 2 ).
Abstract: We have obtained and characterized by IR, electronic and EPR spectroscopy the Cu(NCS)2L2 group of complexes (L=C6H5NH2, o-CH3C4NH, m-CH3C6H4NH2 p-CH3C6H4NH2 m-NO2C6H4NH2, p-NO2(o-CH3)C6H3NH2and p-ClC6H4NH2. From the IR spectra it is inferred that in all complexes, coordination of the thiocyanate groups to the metal takes place through the nitrogen atoms, these being placed in terminal and trans positions. The electronic spectra in ethanol solution indicate pseudooctahedral geometry with tetragonal distortion and with axial interaction by molecules of the solvent. From the EPR spectra in the solid and in ethanol solution it is inferred that all the complexes are monomeric.

Journal ArticleDOI
TL;DR: In this paper, a structure-reactivity relationship is presented which predicts formation constants based solely on the structure of the organic ligand and is evaluated using literature values of formation constants for Ni, Cd, Zn, and Fe.
Abstract: A structure-reactivity relationship is presented which predicts formation constants based solely on the structure of the organic ligand. This relationship has been evaluated using literature values of formation constants for Ni, Cd, Zn, and Fe. In most cases the root-mean-square deviation between observed and calculated log KML values is less than 0.8 log units. The relationship includes an adjustable parameter for each type of donor group coordinated to the metal ion, and the contribution of each donor atom is assumed to be independent of the other ligating groups. A separate term is included to account for the added stability due to the formation of chelate rings.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the kinetics of piperidine replacement by pyridine at the pentacyano(piperidine) ferrate (II) complex under pseudo-first-order condition in acetonitrile + water mixtures.
Abstract: The kinetics of piperidine replacement by pyridine at the pentacyano(piperidine) ferrate (II) complex has been investigated under pseudo-first-order condition in acetonitrile + water mixtures from a mole fraction of acetonitrile x 2=0 to x 2=0.122 at constant ionic strength (I=1 mol dm−3, NaCl). The rate constants at 25, 30 and 35° increase on addition of acetonitrile. Transition state solvation predominates over initial state solvation on account of more enhanced releasing ligand-bulk solvent interactions which occur when the mechanism is of a dissociative type. The greater hydrophobic nature of the transition state is indicated by a negative correlation between the difference in activation free energies (δ m δG#) and the excess free energy for the solvent mixture (G E ). Thus, when the aqueous mixture becomes richer in acetonitrile, the transition state is stabilized and the rate constant increases. The enthalpies and entropies of activation seem to show inflection points at x 2 ≅ 0.04, in corr...

Journal ArticleDOI
TL;DR: In this paper, the reduction and subsequent nitrosylation of ReOi using NH2OHHCI and NCS- in an alkaline medium was described, as well as the direct reductive nitro-sylation using NH 2OHHCl and N- 3 as evidenced by synthesizing the complex ion [Re(NO)(N3)3H2O]- and its 1,10-phenanthroline and 2,2′-bipyridine derivatives from an aqueous-aerobic medium.
Abstract: Reductive nitrosylation of ReO- 4 by any of the known nitrosylating agents1 and subsequent synthesis of rhenium nitrosyl derivatives have not yet been reported The known nitrosyl compounds of this metal are very few and were prepared from low valent rhenium compounds (cyano, chloro or carbonyl complexes) by the treatment with HNO3 23 or NO4,5 or NOX6 We have recently reported7 the reduction and subsequent nitrosylation of ReOi using NH2OHHCI and NCS- in alkaline medium Herein is described the direct reductive nitrosylation of ReO- 4 using NH2OHHCl and N- 3 as evidenced by synthesing the complex ion [Re(NO)(N3)3H2O]- and its 1,10-phenanthroline and 2,2′-bipyridine derivatives from an aqueous-aerobic medium It may be mentioned that azido nitrosyl complexes of any metal are extremely rare (only one is known)6

Journal ArticleDOI
TL;DR: The oxovanadium (IV) complexes of 5-chlorosalicylaldehyde, VO(5-Clsal)2, and its aliphatic diamine derivatives with a general formula, VO[OC6ClH3CH=N[sbnd]CR1R2(CH2) n-1 -N=CHC6CLH3O] have been prepared.
Abstract: The oxovanadium (IV) complexes of 5-chlorosalicylaldehyde, VO(5-Clsal)2, and its aliphatic diamine derivatives with a general formula, VO[OC6ClH3CH=N[sbnd]CR1R2(CH2) n-1 -N=CHC6ClH3O] where n=2 (R1=R2=H or CH3) and n=3–5 (R1=R2=H), have been prepared. Their spectroscopic and magnetic properties suggest that the complexes (1–3; n=2, R1=R2=H or CH3) and (6; n=5, R1=R2=H) are five-coordinate, while VO(5-Clsal)2 and complexes (4 and 5; n=3 and 4, R1=R2=H) are likely to be six-coordinate and, presumably polymeric.

Journal ArticleDOI
TL;DR: Several transition metal complexes of the cyclopentadienyl ylides (CpPPh3, CpSMe2, and CpPy) were reported in this article.
Abstract: Several new transition metal complexes of the cyclopentadienyl ylides (CpPPh3, CpSMe2, and CpPy are reported. Reactions of CpSMe2 with MnCl2, FeCl2, CoCl2 and NiX2 (where X=d or Br) leads to complexes in which the ylide:metal halide stoichiometry is 1:1. These complexes are assigned sandwich structures. Reaction of Pd(NO3)2 with CpSme2 yields a very air-sensitive compound having a unique (CpSMe2)3 Pd(NO3)2 stoichiometry. With HgX2 the CpSMe2 HgX2 (where X=Cl, Br, I) derivatives are formed; bonding of the mercury is shown for the iodide derivative to be at C-3 of the cyclopentadienyl ring. Reaction of CpPPh3 with FeCl2 produces two derivatives which appear to have stoichiometrieg unique in iron metallocene chemistry: (CpPPh3)Fe2 Cl4 and (CpPPh3)Fe2Cl4.

Journal ArticleDOI
TL;DR: In this paper, the rates of dissociation of bis-(N1-methylbiguanide)nickel(II) and bis(N 1-phenylbiguanides)-nickel (II) in aqueous acid have been studied by the stopped-flow spectrophotmetric technique.
Abstract: The rates of dissociation of bis-(N1-methylbiguanide)nickel(II) and bis-(N 1-phenylbiguanide)nickel(II) in aqueous acid have been studies by the stopped-flow spectrophotmetric technique. The reactions occur in two consecutive steps, the first being faster than the second, ultimately forming the aquometal ion and the protonated ligand. For each step the rate is acid dependent as expressed by kx=k1 x[H+], where kx is the observed rate constant. The results are consistent with a mechanism involving an assisted dissociative process involving the protonated complexes with considerable solvent participation in the transition state. The observed lability order is Ni(PhbigH)2+ 2 > Ni(MebigH)2+ 2 > Ni(BigH)2+ 2.

Journal ArticleDOI
TL;DR: In this article, the coordination behavior of aluminum(III) with 8-hydroxy-7-[(8'-hydroxy)-3 ], 6'-disulfo-1'-naphthyl)azo]quinoline-5-sulfonic acid (H5hns) was studied.
Abstract: Studies have been made on the coordination behavior of aluminum(III) with 8-hydroxy-7-[(8 ' -hydroxy-3 ', 6 ' -disulfo-1 ' -naphthyl)azo]quinoline-5-sulfonic acid (H5hns)1 which is capable of acting as a bidentate or a terdentate ligand. The ligand serves as an O-N-O terdentate one with coordination of the azo nitrogen atom to form a mono-hns complex, [Al(hns)(H2 O)3]2-, which involves two fused six-membered chelate rings. Formation of the complex proceeds through three different pathways from a kinetic viewpoint, i.e., reactions of [Al(H2O)6]3+ with Hhns4-, [Al(OH)(H2O)5]2+ with H2 hns3-, and [Al(OH)(H2 O)5]2+ with Hhns4-. The coordination mechanism is discussed.

Journal ArticleDOI
TL;DR: In this article, the depf ligand is in the tautomeric form, arising by elimination of one of the -P(OC2H5)2 ethyl groups.
Abstract: Triethyl phosphonoformate (tepf) reacts with metal chlorides at elevated temperatures to yield ethyl chloride and the corresponding M(depf)n complexes (depf=diethyl phosphonoformato ligand; Mn+=Dy3+, Ti3+, V3+, Cr3+, Fe3+, Th4+, U4+). The depf ligand is in the tautomeric form, arising by elimination of one of the -P(OC2H5)2 ethyl groups. The new metal complexes are linear chainlike polymeric species, involving bidentate bridging depf ligands coordinating through the two POO oxygens to adjacent metal ions; the COO oxygens do not participate in coordination. The ambient temperature magnetic moments of several of the paramagnetic M(depf)n complexes (M=Ti3+, V3+, Cr3+, U4+) are subnormal, as would be expected for linear chainlike polymeric metal complexes. AlCl3 .6H2O reacts with tepf to yield a different complex, namely Al(ehp)3 (ehp=ethyl hydrogenphosphonate, (C2H5O)HPOO−). Initial formation of Al(depf)3, followed by hydrolytic elimination of the -COOC2H5 ethyl group, with the P-H bond being eventu...

Journal ArticleDOI
TL;DR: In this paper, some new metal complexes of 1-amidino-2-thioureas and its S-and N-alkyl derivatives have been isolated and characterized by electronic, vibrational and pmr spectral studies, magnetic and conductance measurements and thermal analysis.
Abstract: Some new metal complexes of 1-amidino-2-thioureas† and its S- and N-alkyl derivatives have been isolated and characterized by electronic, vibrational and pmr spectral studies, magnetic and conductance measurements and thermal analysis. The ligands behave as SN or NN donors depending mainly on the pH of the medium and the nature of the metal atom. Protonation at the central nitrogen atom of the chelate ring converts the inner complexes to cationic ones and vice-versa. Electronic and pmr spectral data confirm the presence of strong ring currents in these chelates. Probable structures of the complexes have been suggested on the basis of their physicochemical properties.

Journal ArticleDOI
TL;DR: In this article, the complex bis-(benzimidazole)tetrakis-(μ-acetato)dicopper(II) has been investigated by spectroscopic and magnetic methods.
Abstract: The complex bis-(benzimidazole)tetrakis-(μ-acetato)dicopper(II) has been investigated by spectroscopic and magnetic methods. Variable-temperature (77–290K) magnetic measurements indicate a strong antiferromagnetic interaction between the copper (Cu2+) paramagnetic centres. The exchange parameter, J. was found to be −162 cm−1, by least-squares fitting to the spin Hamiltonian H=−2JS1.S2. The EPR spectrum of a polycrystalline sample of the complex revealed triplet state (S=1) transitions and the D and E zero-field splitting parameters, equal to 0.354 and 0.0032 cm−1, respectively.

Journal ArticleDOI
TL;DR: In this article, the interaction of LIX63, primarily 5,8-diethyl-7-hydroxy-6-diodecanone oxime, with copper in sulphate media has been studied by E.S.R. spectroscopy.
Abstract: The interaction of LIX63, primarily 5,8-diethyl-7-hydroxy-6-diodecanone oxime, with copper in sulphate media has been studied by E.S.R. spectroscopy. The results confirm that at a ligand to copper ratio of approximately 2:1 a monomeric complex, Cu(LIX63)2, is formed. At lower ligand to metal ratios, a polymeric, E.S.R. silent species is formed. These results confirm those obtained from equilibrium studies.

Journal ArticleDOI
TL;DR: In this paper, it was concluded that the above ligand forms low-spin complexes with palladium(II) and high-spin complex with iron(II), iron(III) and manganese(II).
Abstract: Synthetic and other studies of iron(II), iron(III), manganese(II) and palladium(II) complexes with the cycloserine derivative, N 4, N ' 4-tereftal-bis(cycloserine) or Terizidone, are reported. The methods used for the characterization of the compounds include elemental analyses, molar conductance, magnetic moments, electronic and infrared spectroscopy and thermal analyses (TG and DTG). From the magnetic properties it was concluded that the above ligand forms low-spin complexes with palladium(II) and high-spin complexes with iron(II), iron(III) and manganese(II). The wavelengths of the principal absorption bands have been accounted for quantitatively in terms of the crystal field theory for manganese(II) and tetrahedral iron(III) complexes. The values of B and C in the iron(III) derivatives are less than in the corresponding manganese(II) complexes. Far-infrared spectra have been extensively studied and the relationship between metal-halogen stretching vibrations and stereochemistry of the complex...

Journal ArticleDOI
TL;DR: In this article, the existence of the expected trans and cis structural isomers for trivalent metal oxinates was conclusively demonstrated, and the oxinates were separated by silica gel column chromatography and characterized by TLC, HPLC, elemental analyses and proton NMR.
Abstract: The oxinates of Co(III), Rh(III) and Ir(III) were prepared in relatively high cis/trans isomer ratios. These isomers were separated by silica gel column chromatography and characterized by TLC, HPLC, elemental analyses and proton NMR. The existence of the expected trans and cis structural isomers for trivalent metal oxinates was conclusively demonstrated.

Journal ArticleDOI
TL;DR: The ligating properties of 2-aminocyclopentene-1-dithiocarboxylic acid and its S-methyl esters were investigated in this article.
Abstract: The ligating properties of 2-aminocyclopentene-1-dithiocarboxylic acid and its S-methyl esters were investigated. Complexes with Zn(II), Cd(II) and Hg(II) halides were synthesized and characterized by infrared and proton and carbon-13 NMR studies. The results are concordant with a bidentate coordination of the -CS2 group to the metal ions

Journal ArticleDOI
TL;DR: In this article, the anation rate of Co(tmd)2C2O+4 by oxalic acid and bioxalate anion has been studied at 35°, 40° and 45°C.
Abstract: The kinetics of anation of cis-diaquobis(1,3-diaminopropane) cobalt(III) by oxalic acid and bioxalate anion have been studied at 35°, 40° and 45°C, I=1.0 M(NaClO4). The observed rate law for the formation of Co(tmd)2C2O+ 4, is valid in the range of [Ox]T=0.03–0.50 M, pH=0.3–2.03. The anation rate constants, k1 and k2, for cis-{Co(tmd)2(OH2)3+ 2, H2C2O4) and cis-{Co(tmd)2(OH2)3+ 2, HC2O4-] ion pairs respectively are found to be virtually the same (k1=10.7 × 10−4 sec−1 and k2=11.0 × 10−4 sec−1 at 40°C). Temperature independent oxalic acid and bioxalate ion-pair association constants (Q1 and Q2) are 1.7(±0.3)M−1 and 11.5(±0.7)M−1, respectively. The activation enthalpy and entropy for k1 and k2 paths are 122.6 kJ mol−1 89.5 JK−1 mol−1 and 103.8 kJ mol−1, 29.3 JK−1 mol−1, respectively. The anation of cis-{Co(tmd)2(OH2)3+ 2, X} ion pairs (X=H2C2O4 or HC2O− 4) is believed to involve Id mechanism. The reaction is catalysed by NO− 3.

Journal ArticleDOI
TL;DR: In this paper, the acid dissociation constants of the above ligands are reported at 30 and 60° together with the thermodynamic parameters involved in their dissociation reactions, in general the first dissociation is favourable and the stability of the 1:1 metal complexes decreases in the order Cu(II) < Ni(II), Co(III) < Mg(II).
Abstract: Formation constants of 1:1 binary complexes of Cu(II), Ni(II), Co(III) and Mg(II) with nucleic acid bases such as adenine, 8-azaadenine, cytosine and uracil are reported at 30° at an ionic strength of 0.1M (KNO3). The acid dissociation constants of the above ligands are reported at 30 and 60° together with the thermodynamic parameters involved in their dissociation reactions. In general the first dissociation is favourable and the stability of the 1:1 metal complexes decreases in the order Cu(II) < Ni(II) < Co(II) < Mg(II). There is a good correlation between the basicity of the ligands and the stability of the 1:1 metal complexes. No significant interaction is observed in the case of uracil with any of the metal ions investigated.

Journal ArticleDOI
TL;DR: For indium(III)-tetrakis-(4-sulfonato-phenyl)porphyrin, the anion effect is in the order Cl−, Br−, SCN− > ClO− 4, BF− 4 and HSO− 4.2.
Abstract: Solvolysis of several water soluble indium(III) porphyrins is catalyzed by both protons and anions. For indium(III)-tetrakis-(4-sulfonato-phenyl)porphyrin, the anion effect is in the order Cl−, Br−, SCN− > ClO− 4, BF− 4, HSO− 4. In HClO4/NaCl, Rate=k(In3+P) (Cl−)2 (ho)2.2

Journal ArticleDOI
TL;DR: In this article, an IR study of the ligands in pure D2O solution in the absence and presence of metal ion at a definite pD value was performed using a Beckman model IR-12 spectrophotometer using a KRS-5 cell with a teflon spacing of 0.1 mm.
Abstract: Studies of metal complexes of purine and pyrimidine bases and their derivatives have received considerable attention recently.1–15 The present investigation aims to elucidate the proton ionization sites and metal ion binding sites in these ligands in aqueous solution from IR spectroscopic study of these systems in D2O. The method employed consisted of the IR study of the ligands in pure D2O solution in the absence and presence of metal ion at a definite pD value. An Elico pH meter with a mini combination glass and calomel electrode was used to measure the pH of the solution. A Beckman model IR-12 spectrophotometer using a KRS-5 cell with a teflon spacing of 0.1 mm was used for all IR measurements.