Isothiocyanate and selenocyanate complexes of Cu(II), Ni(II), and Co(II) with a pyridylpyrazole-based ligand: synthesis,characterization, and structure

Mononuclear NCS^? containing complexes, [M(NCS)₂L] (L?=?N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)aminomethylpyridine), [Cu(NCS)₂L′] (L′?=?N-(3,5-dimethylpyrazol-1-ylmethyl)aminomethylpyridine), and NCSe^? containing complexes [ML(NCSe)(H₂O)]ClO₄ (M?=?Ni⁺², Co⁺²) have been synthesized and characterized by elemental analysis, spectroscopic, and physico-chemical methods. Structural studies of [Cu(NCS)₂L′] show copper is five coordinate with distorted trigonal bipyramidal geometry with two cis NCS^?. [M(NCS)₂L] and [ML(NCSe)(H₂O)]ClO₄ (M?=?Ni⁺² and Co⁺²) are expected to be octahedral.     

Reactivity of 6-(2-tolyl)- and 6-(2,6-xylyl)-2,2′-bipyridines with palladium(II) derivatives. Selective C(sp)H vs. C(sp)H activation

Two new 6-substituted 2,2′-bipyridines, L, 6-(2-tolyl)bipy, L¹, and 6-(2,6-xylyl)bipy, L², have been synthesized. Their reactions with Na₂[PdCl₄] or {Pd(OAc)₂} afford either 1:1 adducts [Pd(L)X₂] (X=Cl, OAc) or five-membered cyclometallated derivatives [Pd(L¹-H)X] arising from C(sp²)H activation. From the chloro-alkyl intermediates [Pd(L)(Me)Cl], in the presence of Na[BAr′₄] (Ar′=3,5-(CF₃)₂C₆H₃), cationic species [Pd(L)(Me)(S)]⁺ (L=L¹, L²; S=CH₃CN) can be obtained. At variance, in less coordinating solvents, e.g. dichloromethane, unexpected activation of a C(sp³)H bond occurs with loss of methane, to afford 6-membered cyclometallated derivatives. The latter species were isolated as [Pd(L-H)(PPh₃)][BAr′₄].     

Ruthenium(II) and palladium(II) complexes with 2,6-(bispyrazol-1-yl)pyridines

Ruthenium(II) and palladium(II) complexes [Ru(DMSO)(L)Cl₂] and [Pd(L)Cl]Cl, where L = 2,6-bis(pyrazol-1-yl)pyridine (bpp) or 2,6-bis(3,5-dimethylpyrazol-1-yl)pyridine (bdmpp) have been synthesized. All complexes were characterized by elemental analysis, IR, ¹H NMR, UV-Vis, and cyclic voltammetry measurements.     

Chemical characteristics of the products of the complexation reaction between copper(II) and a tetra-aza macrocycle in the presence of chloride ions

The reaction of copper(II) perchlorate with the hydrochloride salt of 3,6,9,15-tetra-azabicyclo[9.3.1]penta-deca-1,11,13-triene (L1) in acetonitrile forms two macrocyclic complexes that can be characterized: [L1Cu^IICl][ClO₄] (1) and [L1Cu^IICl]₂[CuCl₄] (2). The structural, electronic, and redox properties of these complexes were studied using spectroscopy (EPR and UV–visible) and electrochemistry. In addition, the solid-state structure of 1 was obtained using X-ray diffraction. The copper(II) is five-coordinate ligated by four N-atoms of the macrocycle and a chloride atom. EPR studies of 1 both in DMF and aqueous solution indicate the presence of a single copper(II) species. In contrast, EPR studies of 2 performed in frozen DMF and in the solid-state reveal the presence of two spectroscopically distinct copper(II) complexes assigned as [L1Cu^IICl]⁺ and [Cu^IICl₄]^2?. Lastly, electrochemical studies demonstrate that both [L1Cu^IICl]⁺ and [Cu^IICl₄]^2? are redox active. Specifically, the [L1Cu^IICl]⁺ undergoes a quasi-reversible Cu(II)/(I) redox reaction in the absence of excess chloride. In the presence of chloride, however, the chemical irreversibility of this couple becomes evident at concentrations of chloride that exceed 50 mM. As a result, the presence of chloride from the chemical equilibrium of this latter species impedes the reversibility of the reduction of [L1Cu^IICl]⁺ to [L1Cu^ICl]⁰.     

Synthesis and structure of pseudotetrahedral Co(II) zwitterionic complexes: trichloro(1-methylpiperazin-1-ium-N4)cobalt(II) and trichloro(1,4-dimethylpiperazin-1-ium-N4)cobalt(II)

The pseudotetrahedral cobalt(II) zwitterionic complexes, [CoCl₃(H₂Meppz)] (1) [H₂Meppz⁺=1-methylpiperazin-1-ium cation] and [CoCl₃(HMe₂ppz)] (2), [HMe₂ppz⁺=1,4-dimethylpiperazin-1-ium cation] have been synthesized and characterized in the solid state by X-ray single crystal analysis, IR spectra, magnetic measurements and electronic spectra. In both the compounds the cobalt(II) center is coordinated in a distorted tetrahedral fashion by the three chloride ions and by one nitrogen of the piperazine ring that retains the more stable chair conformation. The distorted coordination polyhedron in complex 1 preserves the C_3v symmetry while in complex 2 it retains only the m symmetry. In complex 1, the (H₂Meppz)⁺ cation binds the Co(II) ion in the equatorial position of the piperazine ring using the unmethylated N1–H nitrogen atom that is less hindered than the methylated one. Complex 2, on the contrary, is a novelty being the first example of a Co(II) ion bound in the axial position of a piperazine ring, this produces a long Co(II)–N bond, 2.108(4) Å. Electronic spectra in the solid state are in perfect accordance with the X-ray crystallographic results indicating a C_3v symmetry for complex 1 and a C_s(m) symmetry for complex 2. These complexes present strong two-center and three-center hydrogen bonds of N⁺–H⋯Cl type.     

Co(II), Ni(II), and Cu(II) Complexation with Isatin Aminoguanisone and Nitroaminoguanisone

New complexes of bivalent Co, Ni, and Cu with isatin aminoguanisone (HL) and nitroaminoguanisone (HL¹) of the composition ([Co(HL)₂]Cl₂ (I), [Ni(HL)₂]Cl₂ (II), [Cu(L)Cl] (III), [Co(L¹)₂] (IV), [Ni(L¹)₂] (V), and [Cu(L¹)₂] (VI) are synthesized. Their molecular conductivities and effective magnetic moments are measured and thermal stabilities are studied. The type of the ligand coordination in I–VI is proposed on the basis of IR data. The summary of physicochemical data for I–VI and the energy calculations for their molecules by the molecular mechanics method made it possible to establish stoichiometry of the coordination polyhedra of the complexes.     

Bis(cyclopentadienyl)methan-verbrückte Zweikernkomplexe,V. Heteronukleare Co/Rh-, Co/Ir-, Rh/Ir- und Ti/Ir-Komplexe mit dem Bis(cyclopentadienyl)methan-Dianion als Brückenliganden

Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V^[1]. – Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand^* The lithium and sodium salts of the [C₅H₅CH₂C₅H₄]^- anion, 1 and 2 , react with [Co(CO)₄I], [Rh(CO)₂Cl]₂, and [Ir(CO)₃Cl]n to give predominantly the mononuclear complexes [(C₅H₅-CH₂C₅H₄)M(CO)₂] ( 3, 5, 7 ) together with small amounts of the dinuclear compounds [CH₂(C₅H₄)₂][M(CO)₂]₂ ( 4, 6, 8 ). The ¹H- and ¹³C-NMR spectra of 3, 5 , and 7 prove that the CH₂C₅H₅ substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)₄I], [Rh(CO)₂Cl]₂, and [C₅H₅TiCl₃] the heteronuclear complexes [CH₂(C₅H₄)₂][M(CO)₂][M′(CO)₂] ( 11–13 ) and [CH₂(C₅H₄)₂]-[Ir(CO)₂][C₅H₅TiCl₂] ( 17 ) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH₂(C₅H₄)₂][M(CO)(μ-CO)M′(CO)] ( 14, 15 ). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH₂(C₅H₄)₂][Rh₂(CO)₂(μ-CO)] ( 16 ).     

Synthesis of RuHCl(CO)(Hdmpz)(L)2 (L=PPh3, AsPh3, and Hdmpz=3,5-dimethylpyrazole) and crystal structure of RuHCl(CO)(Hdmpz)(AsPh3)2

Treatment of RuHCl(CO)(L)₃ with a slight excess amount of K[HB(3,5-Me₂pz)₃] in boiling MeOH solution yielded unusual 3,5-dimethylpyrzaole (Hdmpz) complexes, RuHCl(CO)(Hdmpz)(L)₂ (L=PPh₃, 1 or AsPh₃, 2). Unexpectedly the dissociation of the bonds between the boron atom and the nitrogen atoms of the potentially tridentate [HB(3,5-Me₂pz)₃]⁻ ligand during the coordination of the ligand to the Ru^II metal has been observed. In a separate preparation, the RuHCl(CO)(Hdmpz)(PPh₃)₂ complex has also been synthesized from the reaction between RuHCl(CO)(PPh₃)₃ and the monodentate Hdmpz ligand. Complexes 1 and 2 have been characterized by elemental analysis, IR and ¹H NMR spectroscopies. Compound 1 has also been prepared by the reaction between RuHCl(CO)(PPh₃)₃ and K[H₂B(3,5-Me₂pz)₂] in boiling toluene solution. The crystal structure of 2 has been studied by X-ray crystallography. The geometrical structure around Ru^II of 2 is a distorted octahedral structure. The crystal structure of 2 consists of a discrete monomeric compound. It is interesting to find that the sterically-demanding [HB(3,5-Me₂pz)₃]⁻ or [H₂B(3,5-Me₂pz)₂]⁻ ligands break up during the reaction with the Ru^II complexes to form the neutral 3,5-dimethylpyrazole complexes. In contrast to these observations, [H₂Bpz₂]⁻ and [H₂B(4-Brpz)₂]⁻ ligands form very stable Ru^II complexes.     

Cyclopentadienylcobalt Complexes Containing Two Phosphine Ligands

The ionic complexes [C₅H₅Co(L)(Ph₂PMe)I]⁺ [I]^- (L = Ph₃P and Ph₂PMe) were prepared by the reactions of cyclopentadienyl(triphenylphosphine)cobalt and cyclopentadienyl(methyldiphenylphosphine)cobalt diiodides with methyldiphenylphosphine. The treatment of these complexes with sodium tetraphenylborate results in the formation of [C₅H₅Co(L)(Ph₂PMe)I]⁺[BPh₄]^- compounds.     

Dithiocarbamate complexes of cyclopentadienylcobalt(III), [Co(η-C5H5)(L)(S2CNR2)] (L = ligand)

The reactions of [Co(η-C₅H₅)(L)I₂] with Na[S₂CNR₂] (R = alkyl or phenyl) give [Co(η-C₅H₅)(I)(S₂CNR₂)] (I) when L = CO and [Co(η-C₅H₅)(L)(S₂CNR₂)]I (II) when L is a tertiary phosphine, phosphite or stibine, or organo-isocyanide ligand. In similar reactions [Co(η-C₅H₅)(CO)(C₃F₇)I] gives [Co(η-C₅H₅)(C₃F₇)(S₂CNMe₂)] and [Mn(η-MeC₅H₄)(CO)₂(NO)]PF₆ forms [Mn(η-MeC₅H₄)(NO)(S₂CNR₂)]. The iodide ligands in I may be displaced by L, to give II, or by other ligands such as [CN]^?, [NCS]^?, H₂O or pyridine whilst SnCl₂ converts it to SnCl₂I. The iodide counter-anion in II may be replaced by others to give [BPh₄]^?, [Co(CO)₄]^? or [NO₃]^? salts. However [CN]^? acts differently and displaces (PhO)₃P from [Co(η-C₅H₅){P(OPh)₃}(S₂CNMe)]I to give [Co(η-C₅H₅)(CN)(S₂CNMe₂)] which may be alkylated reversibly by MeI and irreversibly by MeSO₃F to [Co(η-C₅H₅)(CNMe)(S₂CNMe₂)]⁺ salts. Conductivity measurements suggest that solutions of I in donor solvents are partially ionized with the formation of [Co(η-C₅H₅)(solvent)(S₂CNR₂)]⁺ I^? species. The IR and ¹H NMR spectra of the various complexes are reported. They are consistent with pseudo-octahedral “pianostool” molecular structures in which the bidentate dithiocarbamate ligands are coordinated to the metal atoms through both sulphur atoms.     

Structurally rigid bis(pyrazolyl)pyridine Zn(II) and Cu(II) complexes: Structures and kinetic studies in ring‐opening polymerization of ε‐caprolactone

Four bis(pyrazolyl)pyridine Zn(II) and Cu(II) carboxylate complexes have been structurally elucidated and used as initiators in the ring‐opening polymerization (ROP) of ε‐carprolactone (ε‐CL). Reactions of bis(3,5‐dimethyl‐pyrazol‐1‐yl)pyridine ( L1 ) with the appropriate Zn(II) and Cu(II) carboxylates afforded the corresponding complexes; [Zn(L1)(C₆H₅COO)₂] ( 1 ), [Zn(L1)(2‐Cl‐C₆H₄COO)₂] ( 2 ), [Zn(L1)(OAc)₂] ( 3 ) and [Cu(L1)(OAc)₂] ( 4 ) in moderate to good yields. Molecular structures of compounds 1 , 2 , 3 confirmed the presence of one tridentate bound ligand L1 in the metal coordination sphere and two carboxylate anions to give five coordination number around Zn(II) and Cu(II) atoms. Complexes 1 , 2 , 3 , 4 initiated the ROP of ε‐CL at 110 °C to give polymers of moderate molecular weights. Kinetic analyses of the ROP reactions indicate pseudo ‐first‐order dependency on ε‐CL monomer and initiator. ¹H NMR and mass spectral data established a coordination insertion mechanistic pathway and behaviour of 1 , 2 , 3 , 4 as initiators in the ROP of ε‐CL. Copyright © 2016 John Wiley & Sons, Ltd.     

Hexamethylphosphorsäuretriamid als Ligand, 2. Mitt.: Umsetzungen von [Co(HMPT)4]2+ mit Chlorid-, Bromid- und Jodidionen

Zusammenfassung Folgende Koordinationsformen entstehen aus [Co(HMPT)₄]²⁺ bei Zusatz von Halogenidionen in Hexamethylphosphorsäuretriamid (HMPT): [Co(HMPT)₃Cl]⁺, [Co(HMPT)₂Cl₂], [Co(HMPT)Cl₃]^–, [CoCl₄]^2–, [Co(HMPT)₃Br]⁺, [Co(HMPT)₂Br₂] und [Co(HMPT)₃J]⁺.

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Hexamethylphosphoric triamide as a ligand II: Reactions of Co(HMPT)₄ ²⁺ with chloride, bromide, and iodide ions

The following coordination species are formed from [Co(HMPT)₄]²⁺, by addition of halide ions in hexamethylphosphoric triamide (HMPT): [Co(HMPT)₃Cl]⁺, [Co(HMPT)₂Cl₂], [Co(HMPT)Cl₃]^–, [CoCl₄]^2–, [Co(HMPT)₃Br]⁺, [Co(HMPT)₂Br₂] and [Co(HMPT)₃J]⁺.

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Mit 7 Abbildungen

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V. Gutmann, A. Weisz undW. Kerber, 1. Mitt., Mh. Chem.100, 2096 (1969).     

Novel 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone and Zn(II), Cu(II), Ni(II) and Co(III) complexes: Synthesis,characterization, crystal structure,antioxidant, antimicrobial and antiproliferative activity

New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)₂]I₂ (1) , [Cu (HL)Cl₂] (2) , [Cu (HL)Br₂] (3) , [Cu (HL)(H₂O)₂](ClO₄)₂ (4) , [Ni (HL)₂]I₂·H₂O (5) , [Co(L)₂]Cl (6) , [Co(L)₂]NO₃ (7) , [Co(L)₂]I·[Co(L)₂](I₃) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (¹H and ¹³C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity.     

Effects of solvation on charge distribution of 1,2-semiquinonato/catecholatocobalt complexes containing bis(3-pyridyl) phenylvinylsilane

Recrystallization of [Co(3,5-dbbq)₂(L)₂] (3,5-dbbq?=?3,5-di-tert-butyl-1,2-benzoquinone; L?=?bis(3-pyridyl)phenylvinylsilane) from diethyl ether at ?20?°C produces trans-[Co(3,5-dbbq)₂(L)₂] while the recrystallization from toluene at ?20?°C gives trans-[Co(3,5-dbbq)₂(L)₂]·2PhMe. The complex exists as trans-[Co^III(3,5-dbsq)(3,5-dbcat)(L)₂] (3,5-dbsq?=?3,5-di-tert-butyl-1,2-semiquinonato; 3,5-dbcat?=?3,5-di-tert-butylcatecholato) in the solid state at 173?K. Differences in charge distribution between trans-[Co(3,5-dbbq)₂(L)₂] and trans-[Co(3,5-dbbq)₂(L)₂]·2PhMe have been observed based on the effective magnetic moments and IR spectra of the complexes along with their X-ray crystal structures.     

Novel cyclohexyl‐based aminophosphine ligands and use of their Ru(II) complexes in transfer hydrogenation of ketones

Two new aminophosphines – furfuryl‐(N‐dicyclohexylphosphino)amine, [Cy₂PNHCH₂–C₄H₃O] ( 1 ) and thiophene‐(N‐dicyclohexylphosphino)amine, [Cy₂PNHCH₂–C₄H₃S] ( 2 ) – were prepared by the reaction of chlorodicyclohexylphosphine with furfurylamine and thiophene‐2‐methylamine. Reaction of the aminophosphines with [Ru(η⁶‐p‐cymene)(μ‐Cl)Cl]₂ or [Ru(η⁶‐benzene)(μ‐Cl)Cl]₂ gave corresponding complexes [Ru(Cy₂PNHCH₂–C₄H₃O)(η⁶‐p‐cymene)Cl₂] ( 1a ), [Ru(Cy₂PNHCH₂–C₄H₃O)(η⁶‐benzene)Cl₂] ( 1b ), [Ru(Cy₂PNHCH₂–C₄H₃S)(η⁶‐p‐cymene)Cl₂] ( 2a ) and [Ru(Cy₂PNHCH₂–C₄H₃S)(η⁶‐benzene)Cl₂] ( 2b ), respectively, which are suitable catalyst precursors for the transfer hydrogenation of ketones. In particular, [Ru(Cy₂PNHCH₂–C₄H₃S)(η⁶‐benzene)Cl₂] acts as a good catalyst, giving the corresponding alcohols in 98–99% yield in 30 min at 82 °C (up to time of flight ≤ 588 h^?1). Copyright © 2014 John Wiley & Sons, Ltd.     

13C, 31P and 1H NMR Investigations of Rh(I)-(2S,4S)-2,4-Bis(Diphenylphosphino)Pentane (Bdpp)-Diene Complexes

Abstract

Although transition metal-phosphine-diene complexes can be conveniently studied by ³¹P NMR occationally other nuclei such as ¹³C or ¹H can provide more valuable information. Here we report on the liquid state stereostructure and conformational behaviour of [Rh(NED(S,S-BDPP)]⁺, [Rh(COD)(S,S-BOPP)]⁺ and [Rh(NBO)(S,S-BDPP)Cl] complexes. Thc stereochemistry of these precursors is of interest Prom the point of homogenous catalytic reactions such as hydrogenation. In the square-planar cationic complexes the phnsphine chelate show C₂ symmetry whereas in the spectra of the five-coordinated neutral species this symmetry is 1ost when recorded in aromatic solvents (C₆D₆, toluene-d₆) or at lower temperatirra (³¹P, CO₂Cl₂ 195 K). At the same time the ¹H and ¹³C spectra indicate pairwise non-identity of the diene atoms.     

Ruthenafuran Complexes Supported by the Bipyridine-Bis(diphenylphosphino)methane Ligand Set: Synthesis and Cytotoxicity Studies

Mononuclear and dinuclear Ru(II) complexes cis-[Ru(κ²-dppm)(bpy)Cl₂] (1), cis-[Ru(κ²-dppe)(bpy)Cl₂] (2) and [Ru₂(bpy)₂(μ-dpam)₂(μ-Cl)₂](Cl)₂ ([3](Cl)₂) were prepared from the reactions between cis(Cl), cis(S)-[Ru(bpy)(dmso-S)₂Cl₂] and diphosphine/diarsine ligands (bpy = 2,2′-bipyridine; dppm = 1,1-bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphosphino)ethane; dpam = 1,1-bis(diphenylarsino)methane). While methoxy-substituted ruthenafuran [Ru(bpy)(κ²-dppe)(C^O)]⁺ ([7]⁺; C^O = anionic bidentate [C(OMe)CHC(Ph)O]⁻ chelate) was obtained as the only product in the reaction between 2 and phenyl ynone HC≡C(C=O)Ph in MeOH, replacing 2 with 1 led to the formation of both methoxy-substituted ruthenafuran [Ru(bpy)(κ²-dppm)(C^O)]⁺ ([4]⁺) and phosphonium-ring-fused bicyclic ruthenafuran [Ru(bpy)(P^C^O)Cl]⁺ ([5]⁺; P^C^O = neutral tridentate [(Ph)₂PCH₂P(Ph)₂CCHC(Ph)O] chelate). All of these aforementioned metallafuran complexes were derived from Ru(II)–vinylidene intermediates. The potential applications of these metallafuran complexes as anticancer agents were evaluated by in vitro cytotoxicity studies against cervical carcinoma (HeLa) cancer cell line. All the ruthenafuran complexes were found to be one order of magnitude more cytotoxic than cisplatin, which is one of the metal-based anticancer agents being widely used currently.     

Synthesis,structural studies and bio-activity of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with p -amino acetophenone salicyloyl hydrazone

Complexes of the type [M(pash)Cl] and [M(Hpash)(H₂O)SO₄] (M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpash = p-amino acetophenone salicyloyl hydrazone) have been synthesized and characterized by elemental analyses, molar electrical conductance, magnetic moments, electronic, ESR and IR spectra, thermal studies and X-ray powder diffraction. All the complexes are insoluble in common organic solvents and are non-electrolytes. The magnetic moment values and electronic spectra indicate a square-planar geometry for Co(II), Ni(II) and Cu(II) chloride complexes and spin-free octahedral geometry for the sulfato complexes. The ligand coordinates through >C=N–,–NH₂ and a deprotonated enolate group in all the chloro complexes, and through >C=N–, >C=O and–NH₂ in the sulfato complexes. Thermal analyses (TGA and DTA) of [Cu(pash)Cl] show a multi-step exothermic decomposition pattern. ESR spectral parameters of Cu(II) complexes in solid state at room temperature suggest the presence of the unpaired electron in d _{x ² ? y ²} . X-ray powder diffraction parameters for [Cu(pash)Cl] and [Ni(Hpash)(H₂O)SO₄] correspond to tetragonal and orthorhombic crystal lattices, respectively. The complexes show a fair degree of antifungal activity against Aspergillus sp., Stemphylium sp. and Trichoderma sp. and moderate antibacterial activity against E. coli and Clostridium sp.     

Electrocarboxylation of chloroacetonitrile mediated by electrogenerated cobalt(I) phenanthroline

The electrocarboxylation of chloroacetonitrile mediated by [Co(II)(phen)₃]²⁺ has been investigated. Cyclic voltammetry studies of [Co(II)(phen)₃]²⁺ have shown that [Co(I)(phen)₃]⁺, an 18 electron complex, activates chloroacetonitrile by an oxidative addition through the loss of a phenanthroline ligand to give [RCo(III)(phen)₂Cl]⁺. The unstable one-electron-reduced complex underwent Co–C bond cleavage. In carbon dioxide saturated solution, CO₂ insertion proceeds after reduction of the alkylcobalt complex. A catalytic current is observed which corresponds to the electrocarboxylation of chloroacetonitrile into cyanoacetic acid. Electrolyses confirmed the process and gave faradic yield of 62% in cyanoacetic acid at potentials that are about 0.3 V less cathodic than the one required for Ni(salen).