Air-stable Complex Research Articles

N,N,O Ligands Based on Triazoles and Transition Metal Complexes Thereof

AbstractThe reaction of 2H‐benzotriazole (1) with dichloroacetic acid leads to the symmetric bis(2H‐benzotriazol‐2‐yl)methane (2c) in 40 % yield. Deprotonation of 2c at the bridging methylene group and subsequent carboxylation with CO2 yielded the new tripodal N,N,O ligand bis(2H‐benzotriazol‐2‐yl)acetic acid Hbbta (3). The sterically less demanding sodium 3,3‐bis(1H‐1,2,4‐triazol‐1‐yl)propionate Na[btp] (5) was obtained by saponification of methyl 3,3‐bis(1H‐1,2,4‐triazol‐1‐yl)propionate (4). The heteroscorpionate ligand 3 was treated with [MnBr(CO)5] and [RuCl2(PPh3)3] to form the manganese tricarbonyl complex [Mn(bbta)(CO)3] (6) and the air stable ruthenium complex [Ru(bbta)Cl(PPh3)2] (7). DFT calculations and the IR spectra of the carbonyl complex 6 reveal ligand 3 to be a less electron‐donating ligand compared to the bis(1H‐pyrazol‐1‐yl)acetic acid Hbpza. In case of the 1H‐1,2,4‐triazole‐based ligand 5 formation of coordination polymers were observed as proven by the synthesis of [Zn(btp)2]∞ (8) and [Mn(btp)2]∞ (9). Polymer 8 crystallises in linear chains of zinc atoms bridged by two molecules of ligand 5 each. These polymer chains show an interesting π‐stacking interaction between uncoordinated triazole residues of the ligands. Deposition of the coordination polymer on highly ordered pyrolytic graphite (HOPG) was successful and was analysed by scanning tunnelling microscopy (STM). Reaction of Na[btp] (5) with MnSO4·H2O resulted in a metal organic framework (MOF) [Mn(btp)2]∞ (9).

ChemInform Abstract: An Air Stable Moisture Resistant Titanium Triflate Complex as a Lewis Acid Catalyst for C—C Bond Forming Reactions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An Air Stable Moisture Resistant Titanium Triflate Complex as a Lewis Acid Catalyst for CC Bond Forming Reactions

An air and moisture stable C(3)-symmetric titanium(IV) triflate, supported by a tripodal amine-(tris-phenolate) ligand, has been synthesized and characterized by X-ray crystallography and shown to be a good Lewis acid catalyst for a range of aza-Diels-Alder, Diels-Alder, syn aldol, allylation, and alkylation reactions.

Synthesis and Reactivity of Catecholate Complexes Containing Quadruply Bonded Metal Ions

Quadruply bonded metal complexes of rhenium and molybdenum have been prepared with tetrachlorocatechol. Structural characterization on the [Re(2)(Cl(4)Cat)(4)](2-) anion has shown that it consists of distorted square-planar Re(Cl(4)Cat)(2) units linked by a short (2.2067 A) quadruple Re-Re bond. The addition of tetrachlorocatechol to molybdenum acetate was used to prepare the isoelectronic molybdenum analogue "[Mo(2)(Cl(4)Cat)(4)](4-)". This complex was found to be far more reactive than the rhenium dimer. A dimer containing a Mo-Mo double bond, [(Cl(4)Cat)(2)Mo(mu-O)(mu-OCH(3))Mo(Cl(4)Cat)(2)](3-), was obtained as the methanolysis product of the complex formed initially, and the oxomolybdenum(V) monomer [MoO(Cl(4)Cat)(2)](-) was formed under more oxidative conditions. Both complexes are oxygen-sensitive, giving [MoO(2)(Cl(4)Cat)(2)](2-) as the final air-stable complex product.

Syntheses and structures of the tetra-phosphine complexes trans-MCl2(PH3)4 (M = Ru, Os)

The air stable tetra-phosphine complexes trans-MCl(2)(PH(3))(4) (M = Ru, Os) are formed in high yield from reactions of MCl(3).3H(2)O with PH(3) in MeOH.

Synthesis of Bi2S3 Nanostructures from Bismuth(III) Thiourea and Thiosemicarbazide Complexes

Rod-shaped nanostructures of Bi2S3 were synthesized by the solution decomposition of the two new bismuth(III) complexes [Bi6(pydc)8(Hpydc)2(tu)8] (1) and {[Bi2(pydc)3(tsc)(H2O)2]·H2O}∞ (2) (H2pydc = 2,6-pyridinedicarboxylic acid also known as dipicolinic acid; tu = thiourea, tsc = thiosemicarbazide). They were obtained by treatment of Bi2O3 with dipicolinic acid in the presence of the sulfur-containing ligands. The complexes were characterized with the aid of elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. The dipicolinate anions behave as tridentate ligands toward Bi(III), but two modes of coordination are found. In both cases the ligand serves as a pincer ligand O,N,O-bonded to one bismuth(III) center, but it can also function as a bridging ligand through one carboxylate group that assembles into hexanuclear molecules (1) or a polymeric chain (2). The air-stable complexes 1 and 2 have been used as starting materials in the preparation of bismuth sulfide nanoparticles (NPs) in the presence of different surfactants. Decomposition of 1 and 2 gave Bi2S3 in all cases, but addition of a small amount of 1-dodecanethiol (DT) or 1-octadecanethiol (OT) at 120 °C resulted in better crystallite growth with the observation of nanorods up to several hundreds of nanometers in length. These were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The influence of various reaction conditions on the shape and size of the nanocrystals is discussed. The high resolution (HR) TEM images reveal a number of linear and planar crystal defects and atomic distortions that account for the splitting of bismuth sulfide nanocrystals as observed previously. The growth mechanism is believed to involve decomposition of the precursors and formation of Bi2S3 seeds, followed by the preferential [001] growth of larger particles. Crystal splitting caused by defects and atomic distortions as well as Ostwald ripening processes play important roles in shaping the morphologies of the final Bi2S3 nanostructures.

Inhibition of Electrocatalytic O2 Reduction of Functional CcO Models by Competitive, Non-Competitive, and Mixed Inhibitors

Electrocatalytic reduction of O(2) by functional cytochrome C Oxidase (CcO) models is studied in the presence of several known inhibitors like CO, N(3)(-), CN(-), and NO(2)(-). These models successfully reproduce the inhibitions observed in CcO at similar concentrations reported for these inhibitors. Importantly, the data show very different electrochemical responses depending on the nature of the inhibitor, that is, competitive, non-competitive and mixed. Chemical models have been provided for these observed differences in the electrochemical behavior. Using the benchmark electrochemical behaviors for known inhibitors, the inhibition by NO(2)(-) is investigated. Electrochemical data suggests that NO(2)(-) acts as a competitive inhibitor at high concentrations. Spectroscopic data suggests that NO released during oxidation of the reduced catalyst in presence of excess NO(2)(-) is the source of the competitive inhibition by NO(2)(-). Presence of the distal Cu(B) lowers the inhibitory effect of CN(-) and NO(2)(-). While for CN(-) it weakens its binding affinity to the reduced complex by approximately 4.5 times, for NO(2)(-), it allows regeneration of the active catalyst from a catalytically inactive, air stable ferrous nitrosyl complex via a proposed superoxide mediated pathway.

A Comparative Study on (NHC)Pd(acac)Cl Complexes (NHC = N-heterocyclic carbene): Indications for the Origin of the Different Reactivity of Saturated and Unsaturated NHC in Cross-Coupling Reactions

The synthesis of the new well-defined and air-stable complex (SIPr)Pd(acac)Cl (SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) is described, and the catalytic activity of this new complex has been tested in the α-arylation of ketones and in Buchwald−Hartwig amination reactions. The significant differences in catalytic performance when compared to the previously reported, unsaturated counterpart (IPr)Pd(acac)Cl (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) are discussed by means of X-ray crystallography and on the basis of their varying solution dynamics, observed by 1H NMR spectroscopy.

Ambient Synthesis and Characterization of High-Quality CdSe Quantum Dots by an Aqueous Route

Herein, we report the ambient synthesis of CdSe nanoparticles of widely tunable particle size by a solution route. The proposed protocol uses hydrazine hydrate to form an air-stable complex of selenium. These nanoparticles are characterized by X-ray diffraction, FTIR, optical absorption, photoluminescence, and transmission electron microcopy measurements. By varying the molarities of Cd(2+) and Se(2-) ions in solution with 3-mercaptopropionic acid as the capping ligand, the method permits us to synthesize nanoparticles of size ranging from 1.58 to 3.42 nm (estimated from optical absorption edge measurements) by controlling the annealing time of the starting colloid at 100 degrees C. The extracted quantum dots are of high quality (40% photoluminescence quantum yield) and exhibit colors ranging from deep blue to red. The resulting colloids are very stable, and no precipitate is observed over a period of 6 months. Thus, the method is simple and easily scalable to synthesize fluorescent CdSe nanoparticles.

Water‐Soluble (Phosphane)gold(I) Complexes – Applications as Recyclable Catalysts in a Three‐Component Coupling Reaction and as Antimicrobial and Anticancer Agents

Water-soluble compounds of the type [AuCl(PR3)] with alkyl-bis-(m-sulfonated-phenyl)-(mC6H4SO3Na)2 and dialkyl-(m-sulfonated-phenyl)-(mC6H4SO3Na) (R = nBu, Cp) phosphanes have been prepared. Dialkyl-phosphane compounds generate water-soluble nanoparticles of 10-15 nm radius when dissolved in water. These air-stable complexes have been evaluated as catalysts in the synthesis of propargylamines via a three-component coupling reaction of aldehydes, amines and alkynes in water. The antimicrobial activity of the new complexes against Gram-positive and Gram-negative bacteria and yeast has been evaluated. The new compounds display moderate to high antibacterial activity. The more lipophilic compounds are also potent against fungi. Their cytotoxic properties have been analyzed in vitro utilizing human Jurkat T-cell acute lymphoblastic leukemia cells. Compounds with dialkyl-(m-sulfonated-phenyl)-(mC6H4SO3Na) phosphanes displayed moderate to high cytotoxicity on this cell line. Death cell mechanism occurs mainly by early apoptosis. The catalytic/biological activity of the previously described compound with commercial m-trisulfonated-triphenylphosphine [AuCl(TPPTS)] (6) has been also evaluated to compare the effects of the higher basicity and lipophilicity of the alkyl- and di-alkyl-(m-sulfonated-phenyl) phosphanes on these new compounds.

Synthesis and characterization amino-salicylaldimine palladium-based complexes and their Suzuki coupling reaction study

A series of palladium (II) complexes bearing new amino-salicylaldimine ligands have been synthesized and structurally characterized. These palladium complexes showed the high catalytic activity for the Suzuki reaction of activated aryl chlorides with phenylboronic acid in DMF under air atmosphere A series of amino-salicylaldimine ligands, 5-R-3-morpholinomethyl-salicylaldimine (R = t-Bu, CH 3 , Br) have been synthesized and structurally analyzed. These tridentate ligands add to palladium (II) to give high yields of air-stable complexes that are characterized by IR, 1 H NMR and elemental analysis. Crystal structure details of complex 1 are presented. These Pd (II) complexes with amino-salicylaldimine ligands are versatile and efficient Suzuki catalysts towards cross-coupling of a variety of aryl chlorides with phenylboronic acid using DMF as solvent.

Mono‐ and Dinuclear Palladium(II) N,S‐Heterocyclic Carbene Complexes with N Spacers and their Suzuki Coupling Activities

Mixed-ligand N,S-heterocyclic carbene (NSHC) complexes, trans-[PdBr(2)(NSHC)(Py)] (NSHC=3-benzyl- or 3-propyl-benzothiazolin-2-ylidene), have been obtained from bridge-cleavage reactions of the dinuclear complex, [Pd(mu-Br)Br(NSHC)](2), in pyridine at room temperature. Use of neutral N-bidentate donors (L=pyrazine, 1,2-bis(4-pyridyl)ethane, 4,4'-bipyridine and trans-1,2-bis(4-pyridyl)ethylene) yields the dinuclear spacer-bridged [Pd(2)Br(4)(NSHC)(2)(mu-L)] complexes. The X-ray single-crystal structures of the pyridyl, bridging pyrazine and 1,2-bis(4-pyridyl)ethane complexes are reported. These air-stable complexes are active in the Suzuki-Miyaura coupling reactions of selected aryl bromides. The dinuclear complexes are generally more active than their mononuclear pyridyl analogues. The benzyl derivatives consistently outperform the n-propyl counterparts.

An 18-member dinucleating unsymmetrical [N10] macrocycle and its bimetallic complexes M2LCl2(ClO4) (M=Co, Ni, Cu, Zn, Cd or Hg)

The 18-member unsymmetrical dinucleating Shiff-base decaaza [N10] macrocyclic ligand, 2,8,11,17-tetramethyl-3,5,7,12,14,16-hexaphenyl-[1,3,5,7,9,10,12,14,16,18] decaazaoctadeca-2,8,11,17-tetraene dihydroperchlorate (L · 2HClO4) was obtained as a cream colored solid from reaction of N-acetylaniline and hydrazine in the presence of HClO4 followed by cyclization (capping) using aniline and excess HCHO in methanol at RT. Reactions of L · 2HClO4 with MCl2 and [M(Ph3P)2Cl2] afforded air stable complexes, M2LCl4(ClO4)2 (M = Co, Ni, Cu, Zn or Cd). The compounds have been characterized by physico-chemical and spectroscopic studies. FAB–Mass spectral data support bimetallic coordination by the macrocycle. IR studies confirm coordination/encapsulation of metal ions involving unsymmetrical aza sites. Magnetic susceptibility and UV–Visible data indicate a low-spin, five-coordinate geometry for Co(II) and Ni(II) complexes. The anisotropic EPR signals (g ∥ > g ⊥) for Cu2+ complex suggest an axial type tetragonality. Molecular model computations have been employed for a theoretical perspective of the ligand and complexes. The important bond lengths and bond angles have been estimated using CS Chem-3D software. The ionic association constant (K 1) and thermodynamic free energy change (ΔG) were evaluated from the conductometric data of the complexes, which indicate presence of a strong ion-pair even in solution. Cyclic voltametric studies on solutions of M2LCl4(ClO4)2 (M = Co, Ni or Cu) in DMSO indicate reversible and quasi-reversible redox couples.

Synthesis and structural characterization of a coordinatively unsaturated ruthenium complex, Cp ∗Ru(Ph 2nacnac), and its CO adduct

Two new half sandwich ruthenium complexes with 2- N-phenylamino-4- N-phenylimino-2-pentene (Ph 2nacnac) ligands have been synthesized and characterized. Single crystal X-ray diffraction analysis reveals the monomeric, highly air sensitive complex Cp ∗Ru(Ph 2nacnac) ( 4) has a coordinatively unsaturated structure and the coordination environment around Ru(II) is effectively a triangle made up of Ct(Cp ∗)–N(1)–N(2). An air stable complex Cp ∗Ru(Ph 2nacnac)(CO) ( 5) is prepared by reaction of 4 with CO, and has a pseudo-tetrahedral geometry around the Ru(II) center, made up of Ct(Cp ∗)–N(1)–N(2)–C(28).

Oxo‐ and Imidovanadium Complexes Incorporating Methylene‐ and Dimethyleneoxa‐Bridged Calix[3]‐ and ‐[4]arenes: Synthesis, Structures and Ethylene Polymerisation Catalysis

Reaction of [V(X)(OR)3] (X=O, Np-tolyl; R=Et, nPr or tBu) with p-tert-butylhexahomotrioxacalix[3]areneH3, LH3, affords the air-stable complexes [{V(X)L}n] (X=O, n=1 (1); X=Np-tolyl, n=2 (2)). Alternatively, 1 is readily available either from interaction of [V(mes)3THF] with LH3, and subsequent oxidation with O2 or upon reaction of LLi3 with [VOCl3]. Reaction of [V(Np-tolyl)(OtBu)3] with 1,3-dimethylether-p-tert-butylcalix[4]areneH2, Cax(OMe)2(OH)2, afforded [{VO(OtBu)}2(mu-O)Cax(OMe)2(O)2].2 MeCN (42 MeCN), in which two vanadium atoms are bound to just one calix[4]arene ligand; the n-propoxide analogue of 4, namely [{VO(OnPr)}2(mu-O)Cax(OMe)2(O)2].1.5 MeCN (51.5 MeCN), has also been isolated from a similar reaction using [V(O)(OnPr)3]. Reaction of [VOCl3], LiOtBu, (Me3Si)2O and Cax(OMe)2(OH)2 gave [{VO(OtBu)Cax(OMe)2(O)2}2Li4O2].8 MeCN (68 MeCN), in which an Li4O4 cube (two of the oxygen atoms are derived from the calixarene ligands) is sandwiched between two Cax(OMe)2(O)2. The reaction between [V(Np-tolyl)(OtBu)3] and Cax(OMe)2(OH)2, afforded [V(Np-tolyl)(OtBu)2Cax(OMe)2(O)(OH)]5 MeCN (75 MeCN), in which two tert-butoxide groups remain bound to the tetrahedral vanadium atom, which itself is bound to the calix[4]arene through only one phenolic oxygen atom. Reaction of p-tert-butylcalix[4]areneH4, Cax(OH)4 and [V(Np-tolyl)(OnPr)3] led to loss of the imido group and formation of the dimeric complex [{VCax(O)4(NCMe)}2].6 MeCN (86 MeCN). Monomeric vanadyl oxo- and imidocalix[4]arene complexes [V(X)Cax(O)3(OMe)(NCMe)] (X=O (11), Np-tolyl (12)) were obtained by the reaction of the methylether-p-tert-butylcalix[4]areneH3, Cax(OMe)(OH)3, and [V(X)(OR)3] (R=Et or nPr). Vanadyl calix[4]arene fragments can be linked by the reaction of 2,6-bis(bromomethyl)pyridine with Cax(OH)4 and subsequent treatment with [VOCl3] to afford the complex [{VOCax(O)4}2(mu-2,6-(CH2)2C5H3N)].4 MeCN (134 MeCN). The compounds 1-13 have been structurally characterised by single-crystal X-ray diffraction. Upon activation with methylaluminoxane, these complexes displayed poor activities, however, the use of dimethylaluminium chloride and the reactivator ethyltrichloroacetate generates highly active, thermally stable catalysts for the conversion of ethylene to, at 25 degrees C, ultra-high-molecular-weight (>5, 500,000), linear polyethylene, whilst at higher temperature (80 degrees C), the molecular weight of the polyethylene drops to about 450,000. Using 1 and 2 at 25 degrees C for ethylene/propylene co-polymerisation (50:50 feed) leads to ultra-high-molecular-weight (>2,900,000) polymer with about 14.5 mol% propylene incorporation. The catalytic systems employing the methyleneoxa-bridged complexes 1 and 2 are an order of magnitude more active than the bimetallic complexes 5 and 13, which, in turn, are an order of magnitude more active than pro-catalysts 8, 11 and 12. These differences in activity are discussed in terms of the structures of each class of complex.

Asymmetric Ni Phosphite Catalyzed Trialkylaluminum Addition to Aldehydes

Novel methods of catalytic asymmetric C-C bond formation are among the most actively studied areas of enantioselective catalysis. The asymmetric addition of trialkylaluminum compounds is of special interest, as they are available in industrial scale from olefins and aluminum hydride. This is one of the first reports of a really practical method for the addition of AlR3 (R = Alk) to aldehydes, using relatively low amounts of a phosphorus catalyst. The chiral phosphite, used as a ligand, is available in three steps from d-glucose. Very high enantioselectivities were achieved with only 1 mol% of the resulting Ni catalyst. A safe and air-stable complex of DABCO with AlMe3 (DABAL-Me3) was used for the introduction of a methyl group.

Bis(acetylacetonato)ruthenium(ii) complexes containing alkynyldiphenylphosphines. Formation and redox behaviour of [Ru(acac)2(Ph2PCCR)2] (R = H, Me, Ph) complexes and the binuclear complex cis-[{Ru(acac)2}2(µ-Ph2PCCPPh2)}2

Two equivalents of Ph(2)PC triple bond CR (R=H, Me, Ph) react with thf solutions of cis-[Ru(acac)(2)(eta(2)-alkene)(2)] (acac=acetylacetonato; alkene=C(2)H(4), 1; C(8)H(14), 2) at room temperature to yield the orange, air-stable compounds trans-[Ru(acac)(2)(Ph(2)PC triple bond CR)(2)] (R=H, trans-3; Me=trans-4; Ph, trans-5) in isolated yields of 60-98%. In refluxing chlorobenzene, trans-4 and trans-5 are converted into the yellow, air-stable compounds cis-[Ru(acac)(2)(Ph(2)PC triple bond CR)(2)] (R=Me, cis-4; Ph, cis-5), isolated in yields of ca. 65%. From the reaction of two equivalents of Ph(2)PC triple bond CPPh(2) with a thf solution of 2 an almost insoluble orange solid is formed, which is believed to be trans-[Ru(acac)(2)(micro-Ph(2)PC triple bond CPPh(2))](n) (trans-6). In refluxing chlorobenzene, the latter forms the air-stable, yellow, binuclear compound cis-[{Ru(acac)(2)(micro-Ph(2)PC triple bond CPPh(2))}(2)] (cis-6). Electrochemical studies indicate that cis-4 and cis-5 are harder to oxidise by ca. 300 mV than the corresponding trans-isomers and harder to oxidise by 80-120 mV than cis-[Ru(acac)(2)L(2)] (L=PPh(3), PPh(2)Me). Electrochemical studies of cis-6 show two reversible Ru(II/III) oxidation processes separated by 300 mV, the estimated comproportionation constant (K(c)) for the equilibrium cis-6(2+) + cis6 <=> 2(cis-6(+)) being ca. 10(5). However, UV-Vis spectra of cis-6(+) and cis-6(2+), generated electrochemically at -50 degrees C, indicate that cis-6(+) is a Robin-Day Class II mixed-valence system. Addition of one equivalent of AgPF(6) to trans-3 and trans-4 forms the green air-stable complexes trans-3 x PF(6) and trans-4 x PF(6), respectively, almost quantitatively. The structures of trans-4, cis-4, trans-4 x PF(6) and cis-6 have been confirmed by X-ray crystallography.

A novel stable CuI complex based on an unconjugated bisanthryl-tethered diimine ligand with tri-coordinate mode

The first air-stable mononuclear CuI complex (1) based on an unconjugated bisanthryl-tethered diimine ligand has been synthesized and characterized by elemental analysis, ESI-MS, UV-vis, FT-IR spectra and TGA analysis. X-ray diffraction analysis at room temperature reveals that complex 1 crystallizes in a monoclinic system, space group P21/c with a=15.611(3) A, b=24.412 (5) A, c=15.430 (6) A, β=114.49 (3)°, V=5351.3 (19) A3, ρ calc=1.359 g cm−3, μ=0.472 mm−1 and Z=4. The crystal structure of 1 features a mononuclear tricoordinated complex with a distorted triagonal planar geometry. The CuI center is coordinated to three imine N atoms of two Schiff base ligands, while the remaining one imine N atom keeps uncoordinated. UV-vis absorption and emission spectra indicate that the complexation of metal ion has slight influence on the electronic structure of the ligand. TGA analysis confirms that complex 1 is stable up to 253°C.

Synthesis and Application of Chiral N‐Heterocyclic Carbene–Oxazoline Ligands: Iridium‐Catalyzed Enantioselective Hydrogenation

Two libraries of enantiomerically pure imidazolium salts bearing an oxazoline unit were synthesized. Deprotonation of the imidazolium salts and complexation of the resulting oxazoline-carbene ligands to iridium(I) was achieved in one step by mixing the imidazolium salts with NaOtBu and [(eta(4)-cod)IrCl](2) in THF at room temperature. The air-stable complexes were purified by flash chromatography. All complexes were analyzed by two-dimensional (2D) NMR methods and one compound from each family was characterized by X-ray structure analysis. The two libraries of iridium complexes were successfully tested in the asymmetric hydrogenation of unfunctionalized and functionalized olefins. Enantioselectivities of up to 90 % ee were obtained with trans-alpha-methylstilbene. Upon complexation of imidazolium salt 15 p with R(1) = phenyl, C-H bond activation of the phenyl ring gave rise to iridium(III) complex 17, which was fully characterized by NMR spectroscopy and X-ray structure analysis. Complex 17 proved to be catalytically inactive in the hydrogenation.

Synthesis, spectral and antifungal studies of some iron(II,III) and cobalt(II) complexes of 4-amino-3-ethyl-5-mercapto-S-triazole

4-Amino-3-ethyl-5-mercapto-S-trizole forms some air stable complexes with Fe II,III and Co II ions. All complexes are characterized through elemental analysis, molar conductance, magnetic susceptibility, electronic and infra red spectral studies. All complexes are six coordinated and tentatively octahedral structures has been assigned. 10 Dq, B' and β values for Co II complexes indicate the strong ligand nature in spectrochemical series. All complexes have been screened against Aspergillus flavus and all exhibits significant antifungal activities.