Cobalt(II) complexes with pyridine and 5-[(E)-2-(aryl)-1-diazenyl]-quinolin-8-olates: synthesis,electrochemistry and X-ray structural characterization

Abstract

Nine new cobalt(II) compounds, trans-[Co(L^PAQ)₂(Py)₂] (1), trans-[Co(L^PAQ)₂(3-MePy)₂] (2), trans-[Co(L^MeAQ)₂(Py)₂] (3), trans-[Co(L^OMeAQ)₂(Py)₂] (4), trans-[Co(L^OEtAQ)₂(Py)₂]·2(H₂O) (5), trans-[Co(L^CAQ)₂(Py)₂] (6), trans-[Co(L^BAQ)₂(Py)₂] (7), cis-[Co(L^BAQ)₂(3-MePy)₂] (8a) and trans-[Co(L^BAQ)₂(3-MePy)₂]·2(3-MePy) (8b) (primary ligand: L^XAQ?=?substituted 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olate; secondary ligands: Py?=?pyridine, 3-MePy = 3-methylpyridine), have been synthesized and characterized by elemental analysis, IR and UV-vis spectroscopy. Magnetic measurements of the cobalt compounds were performed in solution by ¹H NMR spectroscopy using the Evans’ method while their redox properties were studied by cyclic voltammetry. Single-crystal X-ray diffraction analysis of the compounds revealed their octahedral geometries and trans configuration, except for 8a, which has a cis configuration. Intermolecular noncovalent interactions were detected, π···π interactions in 5, C?–?H···π interactions in 2 and C?–?H···π edge-to-face (T-shaped) arrangements in 3, 4, 6, and 7.     

Coordination-driven synthesis of Ag(I) compounds based on a double emission ligand consisting of 1,3,4-oxadiazole and cyclotriphosphazene units

A new ligand (L) which consists of cyclotriphosphazene and 1,3,4-oxadiazole units is reported. Two new Ag(I) coordination compounds {[Ag(L)SO₃CF₃] _n (1) and Ag₂L₂(NO₃)₂ (2)} based on L and Ag(I) salts are obtained. Compound 1 features a 1-D chain, in which the ligand L adopts a divergent trans-conformation, whereas 2 is a discrete binuclear Ag(I) molecule in which L adopts convergent cis-conformation. Compounds 1 and 2 are fully characterized by ¹H-NMR, Infrared, elemental analysis, X-ray powder, and single-crystal diffraction. Luminescent properties of 1 and 2 are investigated.     

Potentiometric sensors based on poly(3,4-ethylenedioxythiophene) (PEDOT) doped with sulfonated calix[4]arene and calix[4]resorcarenes

Potentiometric ion sensors have been prepared by galvanostatic electrosynthesis of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with p-sulfonated calix[4]arene (C[4]S) and p-methylsulfonated calix[4]resorcarenes (R_n[4]S) with alkyl substituents of different chain length (R₁=CH₃; R₂=C₂H₅; R₃=C₆H₁₃). The bowl-shape of these doping ions makes them suitable as ionic recognition sites, and their bulky character is expected to prevent them from leaching out of the conducting polymer membrane. For comparison, sensors based on PEDOT doped with poly(styrene sulfonate) (PSS) and poly(vinyl sulfonate) (PVS) were also constructed. The resulting GC/PEDOT electrodes were conditioned in 0.01 mol L^–1 AgNO₃ and their performance as Ag⁺ ion-selective electrodes (ISEs) studied. Results reveal that selectivity and lifetime of the electrodes is affected by the doping anion structure, although all electrodes show selectivity towards Ag⁺ ions. Interaction of Ag⁺ with sulfur atoms present in the conducting polymer backbone is considered to be the main reason for this behavior. A second set of electrodes was constructed and conditioned in 0.1 mol L^–1 KCl. These electrodes were tested in chloride solutions of quaternary ammonium cations, showing that C[4]S and R₂[4]S exhibit significant sensitivity towards pyridinium.Dedicated to Professor György Horányi on the occasion of his 70th birthday in recognition of his outstanding contributions to electrochemistry     

Synthesis and Crystal Structures of S 2 O 2 Macrocycle L, and its Silver(I) and Platinum(II) Complexes (Where L = 5,8-dioxa-2,11-dithia-[12]-o-cyclophane)

The S₂O₂-donor macrocycle, L(5,8-dioxa-2,11-dithia-[12]-o-cyclophane or 3,4-benzo-1,6-dithia-9,12-dioxocyclo-tetradecane-3-ene) was synthesized by ring closure reaction of 2,2'-(ethylenedioxy)diethanethiol with ,'-dibromo-o-xyleneunder high dilution and crystallized from methanol. The X-ray structure of L has a C₂ axis and is shown to have two S atoms oriented exodentate and two O atoms positionedendodentate to the ring cavity. Reaction of AgNO₃ with L affords monomeric [Ag(L)(NO₃)], (1)in which the Ag atom is in a distorted trigonal plane coordinated by two S atoms in a ring and to one O atom from the NO₃ ^- ion. The behavior of complex 1 in solution was also characterized by NMR titration. Reaction between K₂PtCl₄ and L affords [Pt(L)Cl₂], (2) in which the Pt atom has a distorted square-planar environment, coordinated to two S atoms of Land to two Cl^- ions in a cis arrangement.     

Silver(I) and Silver(II) Complexes with Some Tetraazamacrocyclic Ligands in Aqueous Solutions

The reactions of silver(I) with isocyclam, scorpiand,trans-Me₂[14]anN₄, cis-Me₆[14]anN₄,(N-Me)Me₂py[14]anN₄ and py[12]anN₄ were investigated.The stability constant of the Ag(I) complex with py[12]anN₄ was determined. The aqueous solutions of the silver(II) complexes with the 14-membered ligands were obtained, and characterized by means of UV-VIS and CVA measurements. The Ag²⁺ ion does not form a five-coordinate complex with scorpiand. The formal potentials of the Ag(II)/Ag(I) system in the presence of scorpiand, trans-Me₂[14]anN₄, cis-Me₆[14]anN₄ and(N-Me)Me₂py[14]anN₄ were determined. The mechanism is also proposedfor the electroreduction of the silver(II) complexes with these compounds on a platinum electrode in aqueous solution.     

Silver(I)-selective membrane potentiometric sensor based on two recently synthesized ionophores containing calix[4]arene

Two new PVC membrane electrodes that are highly selective to Ag(I) ions were prepared using (L₁) calyx[4]arene (L₂) as two suitable neutral carriers. The silver(I) ion selective electrodes exhibit a good response for silver ion over a wide concentration range of 1.0 × 10⁻¹ to 4.2 × 10⁻⁶ M (L₁) and 1.0 × 10⁻¹ to 6.5 × 10⁻⁶ M (L₂) with a Nernstian slope of 60 mV per decade (L₁) and 58 mV per decade (L₂) at 25°C, and was found to be very selective, precise, and usable within the pH range 4.0–8.0. They have a response time of <15 s and can be used for at least 3 months without any measurable divergence in potential. The proposed sensors show a fairly good discriminating ability towards Ag⁺ ion in comparison to some hard and soft metal ions. The electrodes were used as indicator electrodes in the potentiometric titration of silver ion and in the determination of Ag⁺ in photographic emulsion and radiographic and photographic films. Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 7, pp. 862–868. The article is published in the original.     

Silver(I) complexes with halo-substituted cyanoanilines: synthesis,characterization and antibacterial activity

Four Ag(I) complexes, [Ag(L₁)₂](NO₃) (1), [Ag(L₂)(NO₃)] (2), [Ag(L₃)₃](NO₃) (3), and [Ag(L₄)₂](NO₃) (4), with ligands derived from halo-containing cyanoanilines (L₁ = 4-amino-3fluorobenzonitrile, L₂ = 4-amino-3-chlorobenzonitrile, L₃ = 4-amino-3-bromobenzonitrile, L₄ = 4-amino-2-bromobenzonitrile) were synthesized and characterized by C, H, and N elemental analysis, IR and ¹H NMR spectroscopy and single crystal X-ray diffraction. Complexes 1–4 crystallized in the triclinic space group C2/c, P2(1)/n, P-1 and C2/c, respectively. In 1 and 4, Ag⁺ is four-coordinate with L₁ or L₄ to form 1-D _∞{[Ag(L₁/L₄)₂]⁺} polymeric cations. In 2, Ag⁺ is three-coordinate by two L₂ ligands and one NO₃^? ligand to form a 1-D _∞{[Ag(L₂)(NO₃)]} zigzag chain. In 3, Ag⁺ is four-coordinate by L₃ to form a dinuclear [Ag(L₃)₃]⁺ cation. The NO₃^? is a 4-connector bridging group in 1 and 3 and a 5-connector bridging group in 2 and 4. The intermolecular hydrogen bonds and Ag?O weak interactions play important roles in forming 3-D networks of 1–4. The antibacterial activities for 1–4 were evaluated against Bacillus subtilis, Staphylococcus aureus and Escherichia coli with MTT method. The antibacterial results indicated that 2 showed the best inhibitory activity against the test bacterial strains, and was as potent as chloramphenicol.     

Heterocalixarenes. Part 2. Calix[m]uracil[n]benzimidazol-2(1H)-one[3] arenes: Synthesis and Binding Characteristics

The reactions of uracil/benzimidazol-2(1H)-one with 1,3-bis(bromomethyl)benzene provide respectively1 3-bis[(3-bromomethylbenzene)methyl]uracil/benzimidazol-2(1H)-onewhich on subsequent cyclization with1,3-bis[(uracil-1-yl/benzimidazol-2(1H)-one-1-yl)methyl]benzenederivatives provide respectively calix[m]uracil[n]benzimidazoI-2(1H)-one[3]arenes[m =3, n = 0 (9); m = 2, n = 1 (10);m = 1, n = 2 (11) and m = 0, n = 3 (12)]. The heterocalixarenes 9–12, both in liquid–liquid and solid–liquid extraction experiments, selectively extract ammonium picrates over the similarly sized K⁺ picrate. The selectivity is much more pronounced in the case of solid-liquid extractions. Both in L-L and S-L extractions, 10 exhibits the highest order oft-BuNH₃ ⁺/K⁺ selectivity.     

Synthesis and metal complexation studies of [2n]thiacalix[m]arene[m]pyrazine

Novel [2_n]thiacalixarenepyrazine and [2_n]thiacalixarenetriazine systems were synthesised by one-pot S_NAr reactions. A screening of the metal-complexing ability of [2₆]hexathiacalix[3]arene[3]pyrazine revealed its affinity for Cu^I, Cu^II and Ag^I metal salts.     

Preparation and Properties of trans-[CoCl2(tmd>)2]Cl,and trans- and cis-[Co(NCS)2(tmd)2]NO3 (tmd: Tetramethylenediamine)

The cobalt(III) complexes [CoX₂(tmd)₂]⁺ (X: Cl^? or NCS^?, tmd: tetramethylenediamine), in which tmd forms a seven-membered chelate ring, have been prepared. Trans-[CoCl₂(tmd)₂]Cl was derived from [Co(NO₂)₂(tmd)₂]NO₃ in a fairly good yield. Two geometrical isomers, trans and cis, of [Co(NCS)₂-(tmd)₂]NO₃ were independently synthesized from trans-[CoCl₂(tmd)₂]Cl by different methods. The geometrical configurations of the isomeric pair of the NCS complex have been determined based on chromatographic behavior, electronic absorption spectra, and vibrational spectra. The d-d and CT absorption maxima of the NCS complex (18.7 x 10³cm^?1 (ε = 275) and 30.9 x 10³cm^?1 (ε = 3630) for the trans isomer, 19.3 x 10³cm^?1 (ε = 302) and 31.0 x 10³cm^?1 (ε = 4070) for the cis isomer) and the Co-N(amine) stretching frequency of trans-[CoCl₂(tmd)₂]Cl (418 cm^?1) have been compared with those of the corresponding ethylenediamine and trimethylenediamine complexes.     

Synthesis and characterization of the [Cu(Cin2bda)2]ClO4 and [Cu(Ncin2bda)2]ClO4 complexes: Crystal structure of [Cu(Ncin2bda)2]ClO4

Two copper(I) complexes [Cu(Cin₂bda)₂]ClO₄ (I) and [Cu(Ncin₂bda)₂]ClO₄ (II) have been prepared by the reaction of the ligands N²,N²′-bis(3-phenylallylidene)biphenyl-2,2′-diamine (L¹) and N²,N²′-bis[3-(2-nitrophenyl)allylidene]biphenyl-2,2′-diamine (L²) and copper(I) salt. These compounds were characterized by CHN analyses, ¹H NMR, IR, and UV-Vis spectroscopy. The C=N stretching frequency in the copper(I) complexes shows a shift to a lower frequency relative to the free ligand due to the coordination of the nitrogen atoms. The crystal and molecular structure of II was determined by X-ray single-crystal crystallography. The coordination polyhedron about the copper(I) center in the complex is best described as a distorted tetrahedron. A quasireversible redox behavior was observed for complexes I and II. The article is published in the original.     

Mono Halogen Substituted Calix[4]pyrroles: Fine-tuning the Anion Binding Properties of Calix[4]pyrrole

Abstract

Single halogen atom (i. e. I, Br, Cl and F) substituted calix[4]pyrroles, compounds 2, 3, 4 and 5, were synthesized. Studies of these systems reveal that replacement of a single β-pyrrolic hydrogen atom can increase the anion binding ability of calix[4]pyrroles for a variety of anions (e. g. Cl^?, Br^?, H₂PO₄ ^? and HSO^? ₄) relative to normal non-halogen substituted calix[4]pyrrole 1. In the case of chloride anion, the expected relative affinity sequence of 5 > 4 > 3 > 2 was observed. This was not found to be true for Br^?, H²PO^? ₄, and HSO^? ₄. Here, the chlorine substituted calix[4]pyrrole 4 was found to display a slightly higher affinity in the case of each anion than the fluorine-bearing derivative 5. This was rationalized in terms of intermolecular NH … F hydrogen bonding interactions being present in CD₂Cl₂ solutions of 5. Support for this latter conclusion came from concentration and temperature-dependent NMR spectroscopic studies.

A matched set of mono halogen substituted calix[4]pyrroles was used to study in detail, the extent to which halogen substituents may be used to fine-tune the anion binding properties of calix[4]pyrroles.     

Coordination behavior of chromone Schiff bases towards the [ReVO]3+ and [ReI(CO)3]+ cores

Herein, we describe the coordination behavior of chromone Schiff bases towards [Re^VO]³⁺ and [Re^I(CO)₃]⁺. The reaction between 2-(2-thiolphenyliminomethyl)-4H-chromen-4-one (Htch) and [Re(CO)₅Cl] led to fac-[Re(CO)₃(bsch)Cl] (1) (bsch = 2-benzothiazole-4H-chromen-4-one). The square pyramidal [ReO(Hns)] (2) {H₂ns=bis-[(2-phenylthiolate)iminomethyl]-methyl-1-(2-hydroxyphenyl)prop-2-en-1-one} and octahedral [ReO(OCH₃)(PPh₃)(Huch)] (3) complexes were isolated from reactions of trans-[Re^VOBr₃(PPh₃)₂] with Htch and H₃uch [(5Z)-5-((4-hydroxy-2-methoxy-2H-chromen-3-yl)methyleneamino)-6-amino-1,3-dimethylpyrimidine-2,4(1H, 3H)-dione], respectively. The chromone Schiff bases and their metal complexes were fully characterized via NMR-, IR- and UV–Vis spectroscopy, single crystal XRD analysis and conductivity measurements. In addition, DFT studies were conducted to compare selected optimized and experimental parameters of the complexes.     

Ruthenium(II) ligated to tetradentate diaminodithioethers: synthesis,characterisation and electrochemistry

Ruthenium(II) complexes containing two tetradentate ligands, 1,2-bis(o-aminophenylthio)ethane (L¹) and 1,2-(oaminophenylthio)xylene (L²), have been prepared. The complexes, which are of the type Ru(L)Cl₂ [L = L¹ (1);/L² (2)], [Ru(L)(PPh₃)Cl]Cl [L = L¹ (3); L² (4)] and [Ru(L)(bpy)](PF₆)₂ [L = L¹ (5);/L² (6)], were characterised by elemental analysis, i.r., u.v.-vis. and n.m.r. spectroscopy and their electrochemical behaviour has been examined by cyclic voltammetry using a glassy carbon working electrode and an Ag/AgCl electrode as the reference electrode. This revised version was published online in June 2006 with corrections to the Cover Date.     

Four silver-containing coordination polymers based on bis(imidazole) ligands

Four coordination polymers, [Ag(L¹)](m-Hbdc) (1), [Ag(L¹)]₂(p-bdc)?·?8H₂O (2), [Ag(Hbtc)(L¹)][Ag(L¹)]?·?2H₂O (3) and [Ag₂(L²)₂](OH-bdc)₂?·?4H₂O (4), where L¹?=?1,1′-(1,4-butanediyl)bis(imidazole), L²?=?1,2-bis(imidazol-1-ylmethyl)benzene, m-H₂bdc?=?1,3-benzenedicarboxylic acid, p-H₂bdc?=?1,4-benzenedicarboxylic acid, H₃btc?=?1,3,5-benzenetricarboxylic acid, and OH–H₂bdc?=?5-hydroxisophthalic acid, were synthesized under hydrothermal conditions. Compound 1 contains a–Ag-L¹–Ag-L¹–chain and a hydrogen-bonding interaction induced–(m-Hbdc)-(m-Hbdc)–chain. Compound 2 consists of two independent–Ag-L¹–Ag-L¹–chains. P-bdc anions are not coordinated. Hydrogen bonds form a 3D supramolecular structure. A novel (H₂O)₁₆ cluster is formed by lattice water molecules in 2. Compound 3 contains a–Ag-L¹–Ag-L¹–and a–Ag(Hbtc)-L¹–Ag(Hbtc)-L¹–chain. The packing diagram shows a 2D criss-cross supramolecular structure, with?π?···?π?and C–H ···?π?interactions stabilizing the framework. Compound 4 contains a [Ag₂(L²)₂]²⁺ dimer with hydrogen-bonding,?π?··· π, and Ag ··· O interactions forming a 3D supramolecular framework. The luminescent properties for these compounds in the solid state are discussed.     

Synthesis and physico-chemical characterization of coordination compounds of 3d metals with bis(hydroxylammonium)bicyclo[2.2.1]-hept-5-en-endo-2,3-cis-dicarboxylate

Summary The reaction of aqueous solutions of 3d metal salts with bis(hydroxylammonium) bicyclo[2.2.1]-hept-5-en-endo-2,3-cis-dicarboxylate in a 12 mole ratio yielded complexes of the general formula [MⁿL₂(NH₃OH)₂]·nH₂O and [Fe^IIIL₂(NH₃OH)H₂O]·H₂O, where M^II=Mn, Fe, Co, Ni, Cu and Zn, and L=bicyclo[2.2.1]-hept-5-en-endo-2,3-cis-dicarboxylate dianion.The compounds were characterized by i.r. spectra and thermal analysis. For all complexes, an octahedral structure is proposed which is formed bytrans coordination of two bidentate (OO) ligands (L) and two NH₃OH⁺ cations attrans positions, coordinated also through oxygen atoms; and similarlytrans positions for NH₃OH⁺ and H₂O in the case of the Fe^III complex.     

High potential isomeric dihalobis[2-(arylazo)pyridine] osmium(III) perchlorate monohydrate

Summary The preparation of isomeric complexes [Os^IIIX₂L₂]ClO₄· H₂O [{(4)} and (5): X = Cl or Br, L(1) = 2-(phenylazo)-pyridine (L¹) or 2-(m-tolylazo)pyridine(L²)] via stereo-retentive oxidation of the corresponding osmium(II) precursors [(2) and (3), respectively] is described. The complexes were characterized using spectroscopic and electrochemical methods. The low-spin (idealized t _2g ⁵ ; S = 1/2) paramagnetic complex ions display characteristic osmium(III) e.p.r. spectra in frozen (-196° C) MeCNPhMe. In dry MeCN solution, the OsX₂N₄ unit exhibits irreversible [OsX₂L₂]²⁺/[OsX₂L₂]⁺ and reversible [OsX₂L₂]⁺/[OsX₂L₂] couples at ca. 1.8 and 1.0 V versus saturated calomel electrode (s.c.e.), respectively. The use of (4)/(5) as an oxidant is noted.     

Synthesis and characterization of [Cu(Phca2en)(PPh3)X] (X=Cl, Br, I, NCS, N3) complexes: crystal structures of [Cu(Phca2en)(PPh3)Br] and [Cu(Phca2en)(PPh3)I]

New mixed-ligand copper(I) complexes, [Cu(Phca₂en)(PPh₃)X], [Phca₂en = N,N′-bis(β-phenylci-nnamaldehyde)-1,2-diiminoethane and X=Cl (1), Br (2), I (3), NCS (4), N₃ (5)] have been synthesized and characterized by various techniques. ¹H and ¹³C-NMR and IR spectral data of these copper(I) complexes are compared with the free ligand to elucidate some structural features. The structures of [Cu(Phca₂en)(PPh₃)Br] (2) and [Cu(Phca₂en)(PPh₃)I] (3) have been determined from single-crystal data showing that the coordination geometry around copper atom is a distorted tetrahedron. Furthermore, these Cu(I) complexes exhibit supramolecular motifs of the type multiple phenyl embraces resulting from attractive interactions between phenyl rings of PPh₃ moieties. The presence of the C–H…Cu weak intramolecular hydrogen bonds, due to the trapping of C–H bonds in the vicinity of the metal atoms, is also reported.     

Potassium thiocyanate argentates: K3[Ag(SCN)4], K4[Ag2(SCN)6] and K[Ag(SCN)2]

The anions of the title compounds contain [Ag(SCN)₄] units, with the S atoms coordinating to Ag⁺ in a tetrahedral arrangement. Whereas in the isolated anions of tripotassium tetra­thio­cyanatoargentate(I), K₃[Ag(SCN)₄], (I), all SCN^? groups are bonded as terminal ligands, in tetrapotassium di‐μ‐thio­cyanato‐S:S‐bis­[dithio­cyanato­argentate(I)], K₄[Ag₂(SCN)₆], (II), two AgS₄ tetrahedra share one common edge. In poly[potassium [argentate(I)‐di‐μ‐thio­cyanato‐S:S]], K[Ag(SCN)₂], (III), edge‐ and vertex‐sharing of AgS₄ tetrahedra results in infinite [Ag(SCN)₂]^? layers.     

Synthesis and characterization of the substituted products from the reaction of a bulky phosphite with [Os3(CO)12]

Reaction of (acetonitrile)-undeca(carbonyl)-tri-osmium and tris(2,4-di-tert-butylphenyl) phosphite yielded the phosphite clusters [Os₃(CO)₁₁L] (4) and [Os₃(CO)₁₀L₂] (5) [L = P(O-2,4- ^t Bu₂C₆H₃)₃]. These compounds were characterized spectroscopically and the molecular structure of 5 was determined by single crystal X-ray diffraction, the first reported structural analysis of a tri-osmium cluster containing aromatic phosphite ligands. Compound 5 crystallized in the triclinic space group P 1, and revealed an equatorial trans–trans position of the bulky phosphite ligands.