Benzoyl hydrazone derivatives of niobium(V) and tantalum(V) ethoxides

Summary Niobium(V) and tantalum(V) pentaethoxides react with monofunctional benzoyl hydrazones (BHy) in refluxing benzene to give products of the type, M(OEt)_5–n(BHy)_n (where M=Nb or Ta and n=1, 2 or 3). The complexes have been characterised on the basis of elemental analysis, spectral (i.r. and n.m.r.) and molecular weight data.     

Ditolyldithiophosphato derivatives of phosphorus(III) and phosphorus(V)

O,O′-Ditolylphosphorodithioates of phosphorus(III), [(o-, m-, or p-CH₃C₆H₄O)₂PS₂] _n PCl_3−n , and phosphorus(V), [(o-, m-, or p-CH₃C₆H₄O)₂-PS₂] _n POCl_3−n , (n = 1, 2, and 3) were isolated as colorless viscous liquids by the reaction of PCl₃ and POCl₃ with sodium ditolylphosphorodithioate, (o-, m-, or p-CH₃C₆H₄O)₂PS₂Na, in 1:1, 1:2, and 1:3 molar ratios in toluene. These compounds were characterized by elemental analyses, molecular weight measurements, IR, and NMR (¹H, ³¹P, and ¹³C) spectroscopic studies, which indicated a less common monodentate linkage of dithiophosphate moieties in both phosphorus(III) and phosphorus(V) derivatives leading to a tetrahedral geometry around the phosphorus atom.     

Doubly-bridged binuclear complexes of oxomolybdenum(V) and oxotungsten(V) containing sexadentate ligands

Binuclear oxomolybdenum(V) and oxotungsten(V) complexes of the type, [M ₂(O)₂(-X)(-X ¹)], where M=Mo, W;X.X ¹=O, S; L=edta, pdta (n=2-), tpen, tppn (n=2+) (edta^4– =ethylenediaminetetraacetate(4–), pdta=R- orR,S-propylenediaminetetraacetate(4–), tpen=N,N,N ¹,N¹-tetrakis(2-pyridyhnethyl)-ethylenediamine, and tppn=R- orR,S-N,N,N ¹,N¹-tetrakis(2-pyridylmethyl)-propylenediami ne) are reviewed with respect to their preparation, structure, spectroscopic properties, reactivities, and in particular asymmetric distortion around the bicyclo [4.1.1 ] type core and stereoselectivity related to this distortion,Dedicated to Professor Jiaxi Lu on the occasion of his 80th birthday and in recognition of his pioneering contributions.     

Ditolyldithiophosphato derivatives of phosphorus(III) and phosphorus(V)

O,O′-Ditolylphosphorodithioates of phosphorus(III), [(o-, m-, or p-CH₃C₆H₄O)₂PS₂] _n PCl_3−n , and phosphorus(V), [(o-, m-, or p-CH₃C₆H₄O)₂-PS₂] _n POCl_3−n , (n = 1, 2, and 3) were isolated as colorless viscous liquids by the reaction of PCl₃ and POCl₃ with sodium ditolylphosphorodithioate, (o-, m-, or p-CH₃C₆H₄O)₂PS₂Na, in 1:1, 1:2, and 1:3 molar ratios in toluene. These compounds were characterized by elemental analyses, molecular weight measurements, IR, and NMR (¹H, ³¹P, and ¹³C) spectroscopic studies, which indicated a less common monodentate linkage of dithiophosphate moieties in both phosphorus(III) and phosphorus(V) derivatives leading to a tetrahedral geometry around the phosphorus atom. Correspondence: Sushil K. Pandey, Department of Chemistry, University of Jammu, Baba Saheb Ambedkar Road, Jammu 180 006 (J & K), India.     

Complex Formation of Rhenium (V) with Benzimidazole in Acidic Media

Rhenium(V) complexes of 1H-benzimidazole (L), isolated from acidic media: (HL)₂[ReOX₅]·(H₂O) _n and [ReOL _x X _y (H₂O) _z ](H₂O) _n (HL and L are protonated and deprotonated forms of benzimidazole; X = Cl^-, Br^-) were studied by means of IR spectroscopy, ¹H NMR spectroscopy, and thermal analysis.     

Alkali metal (Na and K)-mediated supramolecular assembly of oxovanadium(V) complexes: Synthesis and structural characterization

The syntheses and characterization of alkali metal complexes [{VO₂L}M(H₂O}_n] (1 and 2) [M = Na⁺ (1), K⁺ (2)] of anionic cis-dioxovanadium(V) species (LVO₂⁻) of the Schiff base 2-hydroxybenzoylhydrazone of 2-hydroxybenzaldehyde have been reported. The number of coordinated water molecules in [{VO₂L}M(H₂O}_n] decreases as the charge density of the alkali metal ion decreases (n = 5 for Na⁺ and 1 for K⁺). These compounds represented M⁺-mediated supramolecular assembly [{VO₂L}M(H₂O}_n]_∝ with an infinite polymeric structure containing an alternating array of cis-dioxo vanadium(V), [VO₂L]⁻, units and aquated metal ion centres, as confirmed by X-ray crystallographic investigation of both. All the compounds are characterized by elemental analysis, IR, UV–Vis and NMR spectroscopy.     

The extraction of niobium (V) and Tantalum (V) by Octylarsinic acid in chloroform

Dioctylarsinic acid (HDOAA) in chloroform solution extracts Nb(V) and Ta(V) efficiently from solutions containing oxalate and oxalic acid at hydrochloric acid concentrations greater than 1M.The extraction coefficients are 92.5 at 7M hydrochloric acid and 251 at 6M hydrochloric acid for niobium and tantalum, respectively. These metals can be extracted even more efficiently from sulfuric acid solutions. The results of the reagent- and pH-dependence studies suggested that a trimeric, monobasic oxoacid of niobium, associated with ten HDOAA molecules, is extracted. Tantalum appears to be present in the organic phase as (H₂DOAA)⁺ [Ta(C₂O₄)₃ (HDOAA_n] (n=l or 2).     

Monooxovanadium(V) 2-phenylphenoxides: synthesis,characterization, and antimicrobial potential

Monooxovanadium(V) complexes of the composition VOCl_{3? n} (L) _n (where L = 2-phenylphenoxide ion; n = 1–3) (1–3) have been synthesized in quantitative yields by the reaction of VOCl₃ with 2-phenylphenol in toluene. The characterization of the complexes has been accomplished by elemental analysis, molar conductance measurements, IR, ¹H-NMR, electronic, mass spectral, and thermal studies. The ligands as well as the complexes have been screened for their in vitro antimicrobial activity against the pathogenic bacteria Escherichia coli and Staphylococcus aureus and fungi Candida albicans, Aspergillus niger, and Fusarium oxysporum by a twofold serial dilution. An increase in the biocidal activity was observed for the vanadium complexes. The minimum inhibitory concentration (MIC) values were 6.25–25 µg mL^?1 for complexes, relative to that of the free ligand of 25–50 µg mL^?1.     

Thermolyse von Phosphor(V)-Schwefel(VI)-nitridhalogeniden

Thermolysis of Phosphorus(V) Sulfur(VI) Nitride Halides Thermolysis of compounds of the type R₂PCl = N–SO₂X (R = Cl, CH₃, C₆H₅; X = F, Cl) results in the formation of the compounds R₂P(O)Cl and [NS(O)X]_n. Pyrolysis of the title compounds with longer chains yields, among others, the cyclic compounds III and IX. IX is also one of the decomposition products of a sulfamide derivative (XXI). Finally the thermal behaviour of carbon containing phosphorus(V) sulfur(VI) nitride chlorides has been investigated.     

Untersuchungen an Wasseraddukten des Antimon(V)-chlorids

Studies on Water Adducts of Antimony(V) Chloride Antimony(V) chloride gives four solid adducts of sbCl₅ · nH₂O I-IV (n = 1, 2, 3, 4) at room temperature. In the solid state I is oligomer by hydrogen bridges. In II, III, and IV are besides the adducts ionic products of the constitution H⁺(H₂O)_n] SbCl₅OH^? (n = 1, 2, 3). I and II reacts with sodium chloride to yield sodium hexachloroantimonate(V) · 1 resp. 2 H₂O. The vibrational spectra were discussed.     

The reduction of chromium(V) in non-aqueous media: The preparation of mixed ligand complexes of chromium(III) from [bipyH2][CrOCl5] (bipy = 2,2′-bipyridyl)

Summary The chromium(V) complex [bipyH₂][CrOCl₅] reacts with MeCN to yield the octahedral chromium(III) complex [CrCl₃(bipy)(NCMe)], the nitrile ligand of which can be replaced by other ligands to give [CrCl₃(bipy)L] complexes (L = py, pyO, and Ph₃PO). However, reactions of [bipyH₂]-[CrOCl₅] with higher nitriles RCN (R = Et, n-Pr, Ph, or PhCH₂) or with MeNO₂ all lead to the isolation of [CrCl₃(bipy)]_n (n most probably being 2), which may also be prepared by thermal decomposition of [CrCl₃(bipy)(NCMe)].     

Fluorooxoperoxo complexes of vanadium(V)

Substances crystallizing under various conditions from the MVO₃(MF, HF)H₂O₂H₂O (M = NH₄, K) systems have been characterized by elemental analysis, infrared and Raman spectra and X-ray powder patterns. Besides the known M₂[VO(O₂)₂F] complexes, complexes of two new types have been obtained: M₃[HV₂O₂(O₂)₃F₄·2H₂O and (NH₄)₃[V₂O₂(O₂)₄F]·nH₂O (n≈2). Vibrational spectra of new complexes are consistent with the presence of dimeric anions containing V(μ₂O₂)V and VFV bridges, respectively.     

Pulse radiolysis and voltammetry of bis(diamine)dioxorhenium(V) complexes

The Re(V) complexes [Re(L)₂O₂]⁺ [L = en (1,2-diaminoethane) or pn (1,3-diaminopropane)] are reduced irreversibly near −1.5 V (SCE) in a neutral or basic aqueous solution, but protonation causes a significant anodic shift of ≈ + 1 V. No oxidation is observed in aqueous solution before the solvent limit (≈ + 1 V) at solid electrodes but oxidation of [Re(en)₂O₂]⁺ with OH in pulse radiolysis experiments generates a Re(VI) intermediate which decays by first-order kinetics (k_d 2.5 × 10⁴ s⁻¹), apparently by rate-determining ligand loss. Reduction with e⁻_aq likewise forms transient d³-Re(IV) complexes which show first-order decay (6 × 10³ s⁻¹ for en, 9 × 10³ s⁻ for pn), ultimately to ReO₂. Transient intermediates were characterized by their electronic spectra, which for d³-Re(IV) complexes are qualitatively similar to Cr(III) and known octahedral Re(IV) complexes with different donor ligands.     

Adducts of niobium(V) and tantalum(V) halides. XIV. Structure and relative stability of the adducts with some phosphoryl compounds

The adducts of niobium(V) and tantalum(V) halides with some phosphoryl compounds have been studied in chloroform solution by ¹H- and ¹⁹F-FT-NMR. spectroscopy. These octahedral adducts of general formula MX₅ · L (M = Nb, Ta; X = F, Cl, Br; L = phosphoryl ligand) are monomeric and neutral. Their relative stability constants have been determined at ?60°. The stabilities are controlled by electronic effects of substituents on the phosphoryl group.     

Synthesis and Spectroscopic Characterisation of Six-Coordinate Complexes of Oxovanadium(V)

Complexes of the types VO(L)(R-deaH), VO(R-dea)(LH), and VO(L)(OGOH)[L = deprotonated form of N-(1-hydroxyethyl) naphthaldimine; R-dea = deprotonated form of a N-substituted diethanolamine, with R = H or Ph; G = CH₂CH₂, CHMeCHMe, CMe₂CMe₂, CHMeCH₂CMe₂, CMe₂CH₂CH₂CMe₂] have been prepared by the equimolar reactions of VO(OPr ⁱ )₃, LH₂, and an appropriate diethanolamine or glycol in benzene. All of these coloured solid complexes have been characterised by elemental (C, H, N, and V) analyses and by spectroscopic (i.r., electronic, ¹H-, ⁵¹V-n.m.r) studies. The relative lability of the hydroxy group(s) of N-(1-hydroxyethyl)naphthaldiamine, diethanolamine, and glycol has also been investigated.     

I-substituted imidazolemanganese(II) complexes

Summary A series of manganese(II) spin-free complexes of the type: MnL_n Cl₂ [L =N-Methylimidazole (MeIm), n = 1,2,3,6; L =_N-ethylimidazole (EtIm), n = 4], MnL_nBr₂ (L = MeIm, n = 2, 4, 6; L = EtIm, n = 4, 6), MnL_nI₂ (L = MeIm, n = 4, 6; L = EtIm, n = 6), MnL_n(NCS)₂ (L = MeIm, n = 3, 4; L = EtIm, n = 4), MnL₆X₂ (L = MeIm, EtIm; X = NO₃, ClO₄, BF₄); (Me₄N)(MnLCl₃)(L = MeIm, EtIm); (Et₄N)[Mn(MeIm)Br₃] and Mn(MeIm)₂(N₃)₂ · 5 H₂O were prepared and characterized. The complexes have either octahedral, distorted octahedral, polymeric octahedral or tetrahedral structures.     

Reactivity of Schiff base rhenium(V) complexes with dimethylphenylphosphine

Summary The ReOX₂L(PPh₃) complexes (X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate) react with dimethylphenylphosphine (PMe₂Ph) to give ReOX₂L(PMe₂Ph) initially by displacement of the phosphine ligand and then the ReX₂L(PMe₂Ph)₂ complexes with reduction of rhenium(V) to rhenium(III). The complexes were characterized by elemental analysis, magnetic susceptibility measurements and i.r. and¹H n.m.r. spectra.     

Molybdenum(VI), (V) and (IV) complexes with chiral benzoin thiosemicarbazone

The chiral (ONS) dianionic Schiff base ligand benzoin thiosemicarbazone (H₂L) reacts with MoO₂(acac)₂ to give the polymeric complex [(MoO₂L) _n ] (1) (Type 1). The reaction of MoO₂L with pyridine (py), 3-picoline (3-pic) or 4-picoline (4-pic) gives [Mo^VIO₂LD] (D = py, 3-pic or 4-pic) (Type 1). Further, the reaction of [MoO₂L] or [MoO₂LD] with PPh₃ or reaction of [MoO₂L] with PPh₃ (plus bpy or phen, D) in the presence of donor reagents D gives [Mo^IVOL] or [Mo^IVOLD] (Type 2). On the other hand, the reaction of [MoO₂L] with hydrazides (zdhH₃) such as benzoylhydrazine (bhH₃), isonicotinoylhydrazine (inhH₃), nicotinoylhydrazine (nhH₃), salicyloylhydrazine (slhH₃) and thiosemicarbazide (tscH₃) produced non-oxo–diazenido complexes [MoL(zdh)] (Type 3). The complexes have been characterized by elemental analyses, molar conductance, magnetic moment, electronic, i.r. and e.s.r. spectroscopic measurements.     

Rapid and simple chromatographic separation of V(V) and V(IV) using KH-phthalate and their determination by flame atomic absorption spectrometry

A method was developed for the chromatographic separation of V(V) and V(IV) based on the different sorption forces of these vanadium species in C18 columns in presence of KH-phthalate. The vanadium species were detected with a flame atomic absorption spectrometer with acetylene/N₂O flame. The detection limits (3σ) of V(V) and V(IV) were 0.18 μg/mL and 0.15 μg/mL, respectively. The relative standard deviations (N = 5) are 4.2% and 3.4% for 20–20 μg/mL V(V) and V(IV), respectively. The sampling frequency is 75/h. Because of the special interaction occurring between phthalate and V(IV) on the C18 column and the acetylene/N₂O flame atomic absorption detection, practically no interferences can be detected even in large inorganic matrix. Received: 20 February 1997 / Revised: 2 June 1997 / Accepted: 7 June 1997