Showing papers in "Transition Metal Chemistry in 1990"

Transition metal complexes of porphyrins and phthalocyanines as electrocatalysts for dioxygen reduction

Abstract: Article de synthese sur l'utilisation d'electrocatalyseurs comme les porphyrines metalliques, les phtalocyanines et d'autres macrocycliques lors de la reduction de l'oxygene moleculaire

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 7. Chemical and antifungal properties of 2-acetylpyridine4 N-ethylthiosemicarbazone and its metal complexes

Abstract: Spectral and thermal information, as well as activity againstAspergillus niger, have been obtained for 2-acetylpyridine4N-ethylthiosemicarbazone and its iron(III), cobalt(II,III), nickel(II) and copper(II) complexes.

Synthesis and crystal structure of (2-methoxyethyl)-cyclopentadienyl titanium complexes

Abstract: New substituted cyclopentadienyl titanium complexes, Cp'TiCl2 (1), Cp'CpTiCl2 (2) and Cp'TiCl3 (3) (Cp'=(2-methoxyethyl)cyclopentadienyl) have been synthesized; complexes (1) and (3) have been studied by x-ray diffraction. Complex (1) forms red-plate crytals which belong to the monoclinic space group p21/a with unit cell parameters:a 11.431(1),b 7.116(1),c 21.13514 A, β 99.50(1)°, V=1695.5(4)A3 and Z=4. The structure of (1) is refined to the final R of 0.044 for 1833 soserved reflections. The orange octahedral crystals of (3) are monoclinic, space group P21/c with unit cell paranreters:a 7.896(2),b 11.015(5),c 25.213(6)A, β 92.13(2)°, V=2192(1) A3 and Z=8. Refinement for 1714 observed reflections gives the final R of 0.090. The crystal sinceture of (3) shows that the ethereal oxygen atom in the side chain on the Cp ring coordinates with the ratenum atom to form a chelate ring.

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 6. The chemical and antifungal properties of 2-acetylpyridine4N-diethyl- and4N-dipropylthiosemicarbazones and their copper(II) complexes

Abstract: Complexes of stoichiometry [CuLX] where X=Cl, Br and L=2-acetylpyridine4N-diethyl- and4N-dipropylthiosemicarbazone, HL4DE and HL4DP, respectively, have substantially more activity againstAspergillus niger andPaecilomyces variotii than the uncomplexed thiosemicarbazones. Spectral data (i.e., i.r., u.v.vis., and e.s.r) of the complexes are presented along with thermodynamic data for the thiosemicarbazones.

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 8. The chemical and antifungal properties of the nickel(II) complexes of 2-acetylpyridine4N-diethyl- and4N-dipropylthiosemicarbazones

Abstract: Nickel(II) complexes of 2-acetylpyridine4N-diethyl- and4N-dipropylthiosemicarbazone show less activity againstAspercallus niger than the free thiosemicarbazones. However, againstPaecilomyces variotii the nickel(II) complexes possess comparable activity at high concentrations and are more active at lower concentrations. Spectral and thermal information about the nickel(II) complexes, which coordinate the anionic thiosemicarbazone ligands in a tridentate manner, is included.

The chemical and antifungal properties of the copper(II) complexes of 2-acetylpyrazine4 N-methyl-,4 N-dimethyl-, and 3-hexamethyleneiminylthiosemicarbazone

Abstract: Copper(II) complexes of 2-acetylpyrazine2 N-methyl-,4 N-dimethyl- and 3-hexamethyleneiminylthiosemicarbazone have been prepared and characterized. Inhibition of the growth ofAspergillus niger andPaecilomyces bariotii by both the thiosemicarbazones and their copper(II) complexes is included.

Organic oxidations by osmium and ruthenium oxo complexes

Abstract: Un rapide apercu des travaux concernant l'activite oxydante de complexes oxo vis a vis d'amines tertiaires ou d'alcenes.

Synthesis and properties of 7-formyl-8-hydroxyquinoline and its transition metal complexes

Abstract: CoII, NiII, CuII, CdII and HgII complexes of 7-formyl-8-hydroxyquinoline (HFHQ) have been prepared, and characterized by elemental analysis, molar conductivities, electronic and i.r. spectra, and magnetic measurements. It was found that the ligand acts as a neutral monodentate or a monobasic bidentate donor. The CoII, NiII and CuII complexes possess, respectively, tetrahedral, octahedral and square-planar structures based on their magnetic and electronic spectral data. The electrical conductivities of HFHQ and its metal complexes were measured at different temperatures and their activation energies were calculated. The values obtained for the CoII, NiII, CdII and HgII complexes agree fairly well with those reported for semiconductors. The ligand was tested as a corrosion inhibitor for aluminium; the limiting concentration of HFHQ to give maximum efficiency (99.2%) is 10−3 mole dm−3 at 22°C. The metal-ligand ratios and apparent formation constants for the species generated in ethanol solution were determined spectrophotometrically.

Palladium(II) complexes of Schiff bases derived from 5-amino-2,4-(1H, 3H)pyrimidinedione (5-aminouracil) and 1,2-dihydro-1,5-dimethyl-2-phenyl-4-amino-3H-pyrazol-3-one

Abstract: New palladium(II) complexes of Schiff bases, obtained from 5-aminouracil, (AUH), and acetylacetone (AUAcAcH2), benzaldehyde (AUBALH), furan-2-aldehyde (AUFALH), 2-hydroxynaphthaldehyde (AUNALH2), pyridine-2-aldehyde (AUPyALH) or salicylaldehyde (AUSALH2) and from 1,2-dihydro-1,5-dimethyl-2-phenyl-4-amino-3H-pyrazol-3-one (AAPy) and acetylacetone (AAPyAcAcH), 2-hydroxyacetophenone (AAPyAPH), furan-2-aldehyde (AAPyFAL), pytidine-2-aldehyde (AAPyPyAL), or salicylaldehyde (AAPySALH), have been prepared. The complexes, with formulae PdL2Cl2 (L=AUBALH, AUFALH or AUSALH2); PdLCl2 (L=AUAcAcH2, AUNALH2, AUPyALH, AAPyFAL or AAPyPyAL) and PdLCl (L=AAPyAcAc or AAPySAL) were characterized by elemental analysis, i.r. and electronic spectral studies, thermogravimetric analyses and magnetic and conductance measurements. The x-ray powder diffraction pattern of one of the complexes was also examined. The complexes were screened for their possible antitumour activityin vitro.

Ligational behaviour of two biologically active N−S donors towards cobalt(III), iron(III), iron(II) and rhodium(III)

Abstract: The chelating behaviour of two biologically active ligands, pyridine-2-carboxaldehyde(4-phenyl) thiosemicarbazone(L1H) and pyridine-2-carboxaldehyde thiosemicarbazone(LH), towards FeIII, CoIII, FeII and RhIII has been investigated. The ligands act as tridentate N−N−S donors, resulting in the formation of bis-chelate complexes of the type MIII(A)2X·nH2O (A=L1 or L; X=Cl, ClO4; M=CoIII, RhIII, FeIII), FeII(L1H)2SO4·2H2O and FeII(L1)2·H2O. Biological activity of the ligands and the metal complexes in the form ofin vitro antibacterial activities towardsE. coli has been evaluated and the possible reasons for enhancement of the activity of ligands on coordination to metal ion is discussed.

Ligational behaviour of biacetylmonoxime nicotinoyl hydrazone (H2BMNH) towards transition metal ions

Abstract: The synthesis and characterization of MnII, CoII, NiII, CuII, ZnII, CdII UO 2 2+ , CrIII and FeIII complexes of biacetylmonoxime nicotinoyl hydrazone (H2BMNH) are reported. Elemental analysis, molar conductance, magnetic moment and spectral (i.r., visible and n.m.r.) measurements have been used to characterize the complexes. I.r. spectral data show that the ligand behaves in a bidentate and/or tridentate manner. An octahedral structure is proposed for the MnII, NiII, CrIII and FeIII complexes, while a square-planar structure is proposed for both CoII and CuII complexes on the basis of magnetic and spectral measurements.

Activation of dinitrogen at binuclear sites

Abstract: Presentation generale de l'etude structurale et de la reactivite de complexes diazotes homodinucleaires de divers metaux de transition.

The crystal structure of tetraethylammonium aquatetracyanooxorhenate(V)

Abstract: The crystal structure of the tetraethylammonium salt of [ReO(H2O)(CN)4]− has been determined from threedimensional x-ray diffraction data. The light blue crystals are monoclinic, space group P21/m witha=8.760(1),b=9.518(5),c=11.718(1) A, β=102.63(1)o with two molecules per unit cell. The final R value using 2009 observed reflections and anisotropic thermal parameters for all the non-hydrogen atoms was 0.038. The [ReO(H2O)(CN)4]− ion has a distorted octahedral geometry with the rhenium atom displaced by 0.30 A out of the plane formed by the four carbon atoms of the cyano ligands towards the oxo ligand. Bond distances: Re=O=1.667(8), Re−OH2=2.142(7) and Re−C (average)=2.11(1) A.

The structure of binuclear molybdenum(VI) oxocomplexes with dianionic tridentate Schiff bases

Abstract: The new MoVI complex [Mo(O) (μ-O) (SAE)]2 was prepared and characterized by means of spectroscopic (i.r.,1Hn.m.r.) and crystallographic measurements. Crystals of the [Mo(C9H8NO2)(H2O)]2, M=582.3, orthorhombic, space group Pbca,a=13.108(4),b=8.982(2),c=16.842(4) A, v=1982.9 A3, z=4, Dm=1.93(2), Dc=1.95 g cm−3, MoKα γ=0.71069 A, μ=1.3 mm−1, F(000)=1152, T=295K, R=0.035 for 2413 reflections. The crystal structure consists of [Mo(O)(μ-O)(L)]2, in dimeric units. The coordination geometry around each molybdenum atom is distorted octahedral with Mo−O (terminal) and Mo−O (bridge) distances of 1.694(3) and 1.760(3) A, respectively, and with the angle O(1)−Mo−O(2) of 105.6(1)o, typical for manycis-dioxocomplexes of MoVI. The asymmetric bridge is characterized by the following parameters: Mo−O(2)i and Mo−Moi distances equal 2.408(3) and 3.319(3) A, respectively, and the Mo−O(2)−Moi and O(2)−Mo−O(2)i angles equal 104.5(1)o and 75.5(1)o, respectively. The i. r. and Raman spectra of molybdenum complexes with an asymmetric double oxygen bridge display a strong absorption the 800–850 cm−1 range.

The coordination chemistry ofN, N′-ethylenebis(2-acetylpyridine imine) andN, N′-ethylenebis(2-benzoylpyridine imine); two potentially tetradentate ligands containing four nitrogen atoms

Abstract: New complexes of the general formulae [MLA(H2O)2]-Cl2 (M=Ni or Cu), [MLAX2] (M=Co or Cu; X=Cl or Br), [NiLABr2]·H2O, [MLA] [MCl4] (M=Pd or Pt), [NiLB(H2O)2]Cl2·2H2O, [MLBCl2] (M=Co, Ni, Cu, Pd or Pt; X=Cl or Br) and [MLB] [MCl4] (M=Pd or Pt), where LA=N,N′-ethylenebis(2-acetylpyridine imine) and LB=N, N′-ethylenebis(2-benzoylpyridine imine), have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, t.g./d.t.g. methods, magnetic susceptibilities and spectroscopic (i.r., far-i.r., ligand field,1Hn.m.r.) studies. Monomeric pseudo-octahedral stereochemistries for the CoII, NiII and CuII complexes andcis square planar structures for the compounds [MLBX2] (M=Pd or Pt; X=Cl or Br) are assigned in the solid state. The molecules LA and LB behave as tetradentate chelate ligands in the CoII, NiII, CuII and Magnus-type PdII and PtII complexes, bonding through both the pyridine and methine nitrogen atoms. A bidentateN-methine coordination of the Schiff base LB is assigned in the [MLBX2] complexes (M=Pd or Pt; X=Cl or Br). The anomalous magnetic moment values of the CoII complexes are discussed.

Mixed-ligand complexes of copper(I) with heterocyclic thiones

Abstract: Novel mixed-ligand copper(I) complexes of general formula [TPP−Cu−(L)Cl] or [TPPhos−Cu−(L)Cl], where TPP=triphenylphosphine, TPPhos=triphenylphosphate and L=imidazolidine-2-thione [Imt],N-propylimidazolidice-2-thione [PrImt],N-i-propylimidazolidine-2-thione [iPrImt], and 1,3-diazinine-2-thione [Diaz] and bis coniplexes of formula [(L)2CuCl] where L=[PrImt] and [iPrImt] have been prepared and characterized by electronic, vibrational and n.m.r. spectroscopy. The spectral data are consistent with S-donation of thiones. The magnitude of upfield shift in13Cn.m.r. of the thionreide carbon on complexation has been interpreted in terms of coordination geometry around the metal stoms. X-ray structure analysis agrees with the conclusions from the spectroscopic measurements. The structure of [(PrImt)2CuCl] revealed three-coordinated copper(I) with crystal data:a=14.106(4),b=14.380(2),c=19.024(3) A, β=108.8(2)°,z=8 and space group P2/c.

Monodentate substitution reactions of [MO2(CN)4]n− type complexes: The crystal structure of the sodium thiocyanate adduct of tetramethylammonium tetracyanooxothiocyanatotungstate(IV)

Abstract: The crystal structure of (Me4N)3[WO(CN)4(NCS)]·NaNCS was determined from three-dimensional x-ray diffraction data. The dark blue crystals are monoclinic, space group C2/m, with cell dimensions a=13.105(4), b=12.688(2), c=18.871(3) A, β=100.4(8)°, z=4 and D=1.46 g cm−3. Anisotropic refinement of 1333 observed reflections converged to R=0.068. The [WO(CN)4(NCS)]3− ion is a distorted octahedron with the tungsten atom displaced by 0.35 A out of the plane formed by the four cyano ligands, towards the oxo ligand. The coordinated thiocyanate ligand is bonded to the tungsten atomvia the nitrogen atomtrans to the oxo ligand. Bond distances found: W−CNav=2.14(3), W−O=1.61(2) and W−NCS=2.23(2) A. The compound crystallizes as an adduct with an additional thiocyanate anion, ionically bonded to a severely disordered sodium cation. The results correlate with available data from similar complexes.

Nickel(II) chelates of Schiff bases derived from isatin and chromone with amino acids and substituted hydrazines

Abstract: Nickel(II) complexes of the Schiff base derivatives of isatin with glycine, β-alanine, anthranilic acid, S-methyl hydrazine carbodithioate, the ammonium salt of hydrazine carbodithioate, thiosemicarbazide, and benzoyl hydrazine, and nickel(II) complexes of 6-formyl-7-hydroxy-5-methoxy-2-methyl chromonelideneS-methyl hydrazine carbodithioate and benzoyl hydrazone, were prepared and characterized by elemental analysis, i.r., u.v.-vis spectra and magnetic measurements. All the complexes are octahedral.

Cyclometallation ofN, N-dimethyl-3-furancarbothioamide with palladium(II), platinum(II), ruthenium(II) and rhodium(III)

Abstract: N, N-Dimethyl-3-furancarbothioamide (Hbft) was cyclometallated with Li2PdCl4, K2PtCl4, RuCl2(CO)3, and RhCl (PBu3)2 (PBu3=tri-n-butylphosphine) to give, respectively, PdCl(bft), PtCl(bft), RuCl(bft)(CO)2, and RhCl2 (bft)(PBu3)2. These and some of their derivatives were characterized spectroscopically. Cyclometallation occurs regioselectively at position 2 of the furan ring to give a five-membered metallaheterocycle, along with Secoordination of the thioamide group. When the position 2 of the furan ring is blocked by a methyl group,N, N-dimethyl-2-methyl-3-furancarbothioamide (Hmft) is, in similar conditions, cyclopalladated at the N−Me substituout of the thioamide group, the furan ring being left intact. Position 4 of the furan ring of both Hbft and Hmft is unreactive toward cyclometallation.

Transition metal (disubstituted phenylazo)-barbituric and thiobarbituric acid complexes

Abstract: Disubstituted phenylazo-barbituric and thiobarbituric acid complexes derived from CoII, NiII and CuII salts have been prepared. Electronic spectra and magnetic susceptibility measurements prove that the cobalt and nickel complexes have high-spin octahedral and square planar configurations, respectively. The copper-barbituric complexes have distorted octahedral geometry with a possible Cu−Cu interaction, whereas the corresponding thiobarbiturate complexes have square pyramidal distorted octahedral and tetragonal geometries. The room temperature e.s.r. spectra of the copper complexes show anisotropy with axial symmetry in tetragonal geometry, $$d_{x^2 - y^2 } $$ ground state as a result of Cu−Cu interaction. This dimeric structure disappears in DMSO solution. The intradimer super-exchange interaction is temperature dependent indicating a change of the geometry. In some complexes, the azo group coordinates to the metal, in others it does not. The denticity of the ligands has been determined.

Structural studies on cadmium(II), cobalt(II), copper(II), nickel(II) and zinc(II) complexes of 1-malonyl-bis(4-phenylthiosemicarbazide)

Abstract: Several new complexes of the title ligand (H2MPTS) with CoII, NiII, CuII, and CdII have been prepared. Structural assignments of the complexes have been made based on elemental analysis, molar conductivity, magnetic moment and spectral (i.r.,1H n.m.r., reflectance) studies. The compounds are non-conductors in dimethylsulphoxide. The neutral molecule is coordinated to the metal(II) sulphate as a bidentate ligandvia the two carbonyl groups. The ligand reacts with the metal(II) chlorides with the liberation of two hydrogen ions, behaving as a bianionic quadridentate (NONO) donor. Enolization is confirmed by the pH-titration of H2 MPTS and its metal(II) complexes against NaOH. A distorted octahedral structure is proposed for the CuII complex, while a square planar structure is suggested for both CoII and NiII complexes. The stoichiometry of the complexes formed in EtOH and buffer solutions, their apparent formation constants and the ranges for obedience to Beer's law are reported for CoII, NiII and CuII ions. The ligand pK values are calculated. The antimicrobial activity of H2 MPTS and its CoII, NiII, CuII and MnII complexes is demonstrated.

Synthesis, spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of oxalyldihydrazide

Abstract: The new complexes K2[ML2]·2H2O (M=Ni, Cu), K2[PdL2]·H2O, K2[CuL2(H2O)2]·H2O, [Ni(LH2)Cl2]x ·xH2O and [Ni(LH2)Br2]x·1,5xH2O, where LH2= oxalyldihydrazide, have been prepared. Emphasis has been put on determining the conditions for the synthesis of both deprotonated and non-deprotonated NiII complexes. They were characterized by analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and spectroscopic methods like i.r. and far-i.r., diffuse reflectance u.v. vis, and e.s.r. Monomeric square planar and distorted octahedral structures were found for the deprotonated complexes in the solid state while the non-deprotonated NiII complexes appeared to be pseudo-tetrahedral polymers. The doubly deprotonated L2-ion exhibits a bidentate N(amide), N(amide)-coordination, while the neutral LH2 molecule behaves as a N(amino), N(amino)-bidentate ligand forming polymeric structures. Vibrational analysis of the complexes was carried out, using hydrogen and metal isotopic substitution.

Palladium(II) and platinum(II) halide complexes with 2,6-dimethyl-4H-pyran-4-thione

Abstract: 2,6-Dimethyl-4H-pyran-4-thione (DMTP) acts as a sulphur donor towards PtII and PdII halides yielding adducts of general formula [M(DMTP)2X2] (M=Pd or Pt; X=Cl, Br or I). When complex syntheses are performed in benzene, the solvated species [M(DMTP)2X2]·C6H6 (M=Pd or Pt; X=Cl or Br) are obtained. The compounds have been characterized by i.r. and n.m.r. (1H and13C) spectroscopy and by thermogravimetric data. The adduct geometry and the influence of benzene are discussed.

Coordination chemistry of f-block elements with imine acids. Part IV. Synthetic and chiroptical studies on lanthanide(III) complexes of imine acids derived from L-alanine, L-valine, L-tyrosine and L-glutamic acid

Abstract: N-(orthovanillidene)L-alanine (OVAlaH2), N-(salicylidene)L-valine (SValH2), N-(orthovanillidene)L-valine (OVValH2), N-(orthovanillidene)L-tyrosine (OVTyrH3) and N-(salicylidene)L-glutamic acid (SGluH3) react with LaIII, PrIII, NdIII and SmIII to yield new chiral complexes. Their dominant conformers were determined from c.d. spectra supported by1H n.m.r. data, except for the L-glutamic acid derived complexes which were insoluble.

The complexation between iron(III) ion and glycine in nitrate medium

Abstract: In the present work, complex formation between iron(III) ion and glycine was studied by spectrophotometric and enf glass-electrode measurements in a 0.5M NaNO3 medium, at 25°C. The stability constants of iron(III) hydrolytic species were determined in separate experiments and used in the analysis of the iron(III)-glycine system. The experimental data were explained by the following complexes and formation constants: $$\begin{gathered} \left[ {FeGly} \right]^{2 + } \log \beta _{1,0,1} = 8.57 \pm 0.01 \hfill \\ \left[ {FeHGly} \right]^{3 + } \log \beta _{1,1,1} = 11.33 \pm 0.02 \hfill \\ \left[ {Fe_2 \left( {OH} \right)_2 Gly} \right]^{2 + } \log \beta _{2, - 2,2} = 12.32 \pm 0.08 \hfill \\ \end{gathered} $$

Spectral and magnetic studies of polynuclear copper(II) complexes of Schiff base derived from ethylenediamine and ethylacetoacetate

Abstract: The Schiff base (L), prepared by the condensation of two molecules of ethyl acetoacetate and one molecule of ethylenediamine reacts with copper(II) chloride to give poiynuclear complexes of the type Cu3L Cl6, Cu4L Cl8, Cu5L Cl10, Cu6L Cl12, Cu7L Cl14 and Cu8L Cl16. Elemental analyses, molar conductivities, magnetic susceptibilities, x-ray powder diffraction and i.r. spectral studies have been used to characterize the complexes. The i.r. spectra show that the Schiff base binds in a tetradentate manner and the spectral and magnetic studies suggest the presence of a chlorine bridge between the copper atoms. The magnetic susceptibility of the complexes follows the Curie-Weiss law.

New uranyl(VI) complexes with hydrazones derived from aliphatic and aromatic acid hydrazides containing dihydroxo bridges

Abstract: Several new uranyl(VI) complexes of hydrazones, derived from formoyl-, acetoyl-, butroyl-, caproyl-, salicyloyl-, oxaloyldi-, malonoyldi-, and adipolyldi-hydrazines and benzaldehyde or salicylaldehyde have been prepared in absolute EtOH and in the presence or absence of AcONa. The complexes have been characterized by elemental analyses, molar conductivities, spectral (u.v., i.r, n.m.r.,) and magnetic measurements. I.r. spectral data suggest that the ligands coordinate in a bi-, tri- and/or tetradentate fashion in the enol form, and that proton displacement proceedsvia the enolized carbonyl oxygen solely in the benzaldehyde hydrazone complexes and through the OH (phenolic) in the salicylaldehyde hydrazone complexes. Moreover, the spectral data show the existence of dihydroxo bridges for benzaldehyde hydrazone complexes. The role of the OH (phenolic) as well as the presence or absence of NaOAc on the properties of the latter complexes is discussed.

Far infrared spectra (500-50 cm−1) of the 2,2'-bipyridine complexes of palladium and platinum halides

Abstract: The far-i.r. spectra of the title complexes have been examined. Band assignments are based on the shifts induced by ligand deuteration and halide substitution. Deuteration of bipyridine causes large shifts (Δν >10 cm−1) in internal ligand modes, intermediate shifts Δν between 2 and 9 cm−1) in metal-nitrogen stretching and bending modes and small to zero shifts in metal-halide stretching and bending vibrations. Generally, the requirements for square planarC2v synanetry [two ν(M−N) and two ν(M−X) bands] are observed. Previous ambiguities in the assignment of the ν(M−N) bands have been resolved by the isotopic labelling technique employed in this study.

Ligational behaviour of a tetradentate NONS donor ligand towards some transition metal ions

Abstract: The synthesis and characterization of CrII, MnII, FeII, CoII, NiII, PdII, CuII, ZnII, CdII and UO22+ complexes of 1-meotinoyl-4-phenyl-3-thiosemicarbazide (H2NTS) are reported. I.r. spectral data show that the ligand behaves in a bidentate and/or tetradentate manner. An octahedral structure is proposed for the CrII, FeII and NiII complexes; a tetrahedral structure for the MnII, CoII and Cu(NTS)·2H2O complexes; and a square planar structure for the PdII and Cu(HNTS)Cl·H2O complexes. The i.r. data suggest that the FeII complex contains a hydroxo bridge.

Synthetic and structural aspects of hepta-coordinated semicarbazato complexes of oxotungsten(VI)

Abstract: The condensation of aldehydes and ketones, 2-pyridine carbaldehyde, 2-thiophene carbaldehyde, 2-furyl aldehyde, 3-indole carbaldehyde, 3-phenylpropane-1-one, 2-propanone, 4-methyl-2-pentane and 2-phenylethane-2-one, with semicarbazide hydrochloride yields the corresponding Schiff bases which, when subsequently reacted with tungsten oxotetrachloride, yield addition products of the type WOCl4·L (L = ligand). The resulting complexes have been characterized by elemental analysis, molecular weight determination, and by conductivity and magnetic measurements. The bonding mode of the ligands with the metal atom is deduced on the basis of i.r.,1H n.m.r. and13C n.m.r. spectral studies.