Three Mn(II) complexes with 1,3-bis(4-pyridyl)propane and their supramolecular nets

Three complexes, [Mn(bpp)₄(H₂O)₂](ClO₄)₂?·?1.5H₂O (1), [Mn(bpp)₃Br₂]?·?2H₂O (2), and [Mn(bpp)₂(H₂O)₂](ClO₄)?·?I?·?H₂O?·?bpp (3) (bpp?=?1,3-bis(4-pyridyl)propane), were synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 is mononuclear where M(II) is coordinated to a monodentate TT-bpp, three monodentate TG-bpp, and two water molecules. Complex 2 possesses a single-stranded helical chain formed from MnN₄Br₂ octahedra by a single TT-bpp, with pendant monodentate TG-bpp ligands. Complex 3 consists of a ribbon-type double-stranded chain formed from MnN₄O₂ octahedra by double TG-bpp ligands. 2-D supramolecular architectures of 1–3 are formed by hydrogen bonds. The fluorescence of the three complexes comes from the π*–π transition of the ligand.     

Mercury thiocyanate coordination polymers generated from rigid or flexible organic nitrogen donor-based ligands

Four mercury(II) thiocyanate–organic polymeric complexes, [Hg(μ-4,4-bipy)(SCN)₂]_n (1), [Hg(μ-bpa)(SCN)₂]_n (2), [Hg(μ-bpe)(SCN)₂]_n (3), [Hg(μ-bpp)(SCN)₂]_n (4) {4,4-bipy = 4,4′-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethene and bpp = 1,3-di(4-pyridyl)propane} were prepared from reactions of mercury(II) thiocyanate with four rigid and flexible organic nitrogen donor-based ligands under thermal gradient conditions, brunched tube method. All these compounds were structurally determined by X-ray single-crystal diffraction. The thermal stabilities of compounds 1–4 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Solid state luminescent spectra of compounds 1 and 3 indicate intense fluorescent emissions at 430 and 468 nm, respectively.     

Sonochemical syntheses of a straw-like nano-structure two-dimensional mixed-ligand zinc(II) coordination polymer as precursor for preparation of nano-sized ZnO

Straw-like nano-structure of a new mixed-ligand Zn(II) two-dimensional coordination polymer, {[Zn(μ-4,4′-bipy)(μ-3-bpdb)(H₂O)₂](ClO₄)₂·4,4′-bipy·3-bpdb·H₂O}_n (1) {4,4′-bipy = 4,4′-bipyridine and 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene}, was synthesized by a sonochemical method. The new nano-structure was characterised by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compound 1 was structurally characterised by single crystal X-ray diffraction and consists of two-dimensional polymeric units. ZnO nanoparticles were obtained by calcination of compound 1 at 500 °C under air atmosphere and were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Derivatives of 1,1′-bis(diphenylphosphino)ferrocene (dppf): Electrochemistry, complexation and the X-ray structures of 1,1′-bis(diphenylphosphino)osmocene (dppo) and [PdCl2(dppo)]

The oxidative electrochemistry of 1,1′-bis(diphenylphosphino)osmocene (dppo) and 1,1′-bis(diphenylarsino)ferrocene (dpaf) was studied in dichloromethane with tetrabutylammonium hexafluorophosphate as the supporting electrolyte. The [MCl₂(P^∩P)] (M = Pd or Pt; P^∩P = dppo or 1,1′-bis(diphenylphosphinoindenyl)iron) complexes were prepared, studied electrochemically and the X-ray structures of dppo and [PdCl₂(dppo)] were determined.     

“Wheel-and-axle” binuclear Cu(II) dioximates mediated by 1,2-bis(4-pyridyl)ethane: Synthesis, X-ray study and luminescent properties

The reaction of copper(II) acetate or fluoride with classic dioximes in the presence of 1,2-bis(4-pyridyl)ethane resulted in four novel compounds with the compositions [Cu₂(dmgH)₄bpe] (1), [Cu₂(NioxH)₄bpe] (2), [Cu₂(dpgH)₄bpe] (3), and [Cu₂(dpgH)₄bpe][Cu(dpgH)₂bpe]₂·2DMF (4) (where dmgH₂ = dimethylglyoxime, NioxH₂ = 1,2-cyclohexanedionedioxime, dpgH₂ = diphenylglyoxime, bpe = 1,2-bis(4-pyridyl)ethane, and DMF = N,N′-dimethylformamide), whose crystal structures were determined by single crystal X-ray diffraction. In the binuclear molecules 1-3, as well as in both binuclear and mononuclear molecules in 4 each Cu(II) atom has an identical N₅-environment formulated by four oximic nitrogen atoms of two monodeprotonated ligands in a slightly distorted square planar mode, and the nitrogen atom of the bpe molecule being in the apical position. The new compounds were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Luminescence investigations for 1, 2 and 4 were carried out to clarify whether the guest inclusion in the crystal lattice is accompanied by changes in the emission spectra.     

Thermal,spectroscopic, X-ray powder diffraction,and structural studies on a new Cd(II) mixed-ligand coordination polymer

A new coordination polymer derived from Cd(II) with both rigid and flexible spacer ligands trans-1,2-bis(4-pyridyl)ethane (bpa) and 4,4′-bipyridine (4, 4′-bipy), {[Cd(μ-bpa)(4, 4′-bipy)₂(H₂O)₂] · (ClO₄)₂} _n has been synthesized and characterized by elemental analysis, IR-, ¹H NMR spectroscopy and studied by thermal analyses as well as X-ray crystallography. The single crystal X-ray analysis shows that the complex is a 1-D polymer as a result of bridging 1,3-di(4-pyridyl)propane (bpa). The 1-D chains are further self-assembled into a 3-D network via hydrogen bonding and π–π stacking. In this structure the perchlorates fill the voids. Thermal studies of this polymer show step to step separating of ligands and counter ion at different temperatures.     

Transition metal complexes with squarate anion and the pyridyl-donor ligand 1,3-bis(4-pyridyl)propane (BPP): Synthesis,crystal structure and spectroscopic investigation

Synthesis, crystal structure and the vibrational spectra of coordination polymers with 1,3-bis(4-pyridyl)propane (BPP) and squarate ion ligands and transition metal ions (M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) are described. All compounds are isostructural, and the BPP is not coordinated to metal site since it is in cationic form due to protonation of N atoms from pyridyl rings. The metal is coordinated to two squarate ions and two water molecules in an octahedral distorted geometry. The two water molecules are involved in medium hydrogen bonds with squarate ligands and the average of O?O distance is 2.679(3) Å. Squarate ions adopt the 1,3-bis(monodentate) coordination mode bridging two metal centers giving rise to a 2D arrangement with (4,4) topology. The four-member ring is slightly distorted and the M–M distances are respectively 8.024 and 8.111 Å. The cationic form of BPP molecules are located inside of four-member ring cavity, presenting two different orientations, in which one molecule is inverted comparing to another. Vibrational spectra of all compounds are very similar, in agreement to crystal data. In all infrared spectra of the compounds a medium band at 1640 cm⁻¹ is observed, assigned to the in plane deformation mode of NH bond, indicative of the formation of cationic BPP. In the Raman spectra of the investigated compounds is observed a weak band around 1800 cm⁻¹, assigned to the stretching mode of free CO bond, whereas the medium band observed around 1600 cm⁻¹ is tentatively assigned to coordinated CO stretching mode. At last, a very important achievement of this investigation refers to the coordination geometries of all the investigated compounds, which are governed only by the ligands, independently of the different electronic properties of the metal ions.     

High dimensional coordination polymers based on transition metals, 1,2,4,5-benzenetetracarboxylate anion and 1,3-bis(4-pyridyl)propane nitrogen ligand

The reaction between 1,2,4,5-benzenetetracarboxylic acid (H₄BT) and transition metal ions Mn⁺², Co⁺² and Cu⁺² in the presence of the N-donor co-ligand 1,3-bis(4-pyridyl) propane (BPP) has afforded three new coordination polymers named, {[Mn₄(BT)₂(BPP)₆(H₂O)₆]·4H₂O}_nMnBTBPP, {[Co₂(BT)(BPP)₂(H₂O)₆]·2H₂O}_nCoBTBPP and {[Cu₂(BT)(BPP)₂(H₂O)]·6H₂O}_nCuBTBPP. They were characterized by a combination of analytical, spectroscopic and crystallographic methods. According to the thermal analysis results all the compounds present coordinated and lattice water molecules in the structures. In compounds MnBTBPP and CoBTBPP, the metal centers exhibit octahedral geometry while in compound CuBTBPP, the Cu⁺² ions adopt square-planar and square-pyramidal geometries. In all cases, both BPP and BT ligands are coordinated to the metal sites in the bridging mode extending the polymeric networks. The BT ligand carboxylate groups act in a monodentate coordination mode as indicated by the Raman spectra data through the Δν [ν_asym(COO) − ν_sym(COO)] value.     

Network diversity and supramolecular isomerism in copper(II)/1,2-bis(4-pyridyl)ethane coordination polymers

Reactions of copper(II) sources with 1,2-bis(4-pyridyl)ethane (bpe) yielded metal-organic networks with diverse topologies and dimensionalities. Compounds [Cu(bpe)₂(dmf)₂]_n(ClO₄)_2n·2ndmf (1·2ndmf), [Cu(bpe)₂(dmf)₂]_n(ClO₄)_2n·3.5ndmf (2·3.5ndmf), [Cu(bpe)₂(NO₃)₂]_n·2nH₂O (4·2nH₂O) and [Cu₂(bpe)(O₂CMe)₄]_n·0.7nH₂O (5·0.7nH₂O) have been isolated by altering the copper(II) source, the reaction solvent and the crystallization process. Compounds 1·2ndmf and 2·3.5ndmf consist of cationic [Cu(bpe)₂(dmf)₂]²⁺ repeating units assembled to 1D and 2D (4,4) networks, respectively, and represent supramolecular isomers due to the conformational isomerism of the bridging bpe molecules. Compound 4·2nH₂O consists of neutral mononuclear [Cu(dpe)₂(NO₃)₂] repeating units assembled to inclined interpenetrating (4,4) sheets describing an overall entanglement that is 3D in nature, and compound 5·0.7nH₂O consists of neutral dinuclear repeating units assembled to cross-linked 1D chains.     

Preparation,crystal structures and spectroscopic characterization of oxalate copper(II) complexes containing the nitrogen ligands 4,4′-dimethyl-2,2′-bipyridine and di(2-pyridyl)sulfide

The preparation, crystal structures and spectroscopic characterization of four oxalate copper(II) complexes containing the 4,4′-dimethyl-2,2′-bipyridine (Mebpy) or di(2-pyridyl)sulfide (DPS) nitrogen ligands namely [μ-(ox){Cu(Mebpy)(NO₃)(H₂O)}₂] (1), [μ-(ox){Cu(Mebpy)(ClO₄)(H₂O)}₂] (2), [μ-(ox){Cu(DPS)(H₂O)}₂](ClO₄)₂ (3) and [Cu(DPS)(ox)(H₂O)] · 2H₂O (4) are described. X-ray diffraction measurements have shown that complexes 1–3 are binuclear, in which the oxalate anion bridges two Cu(II) centers, while the complex (4) is mononuclear and the oxalate anion adopts the terminal bidentate chelating coordination mode. In 1 and 2 the Cu(II) sites display a distorted octahedral geometry (4+2 environment) and in compounds 3 and 4 the Cu(II) centers exhibit a slightly distorted square pyramidal geometry. In addition, complexes 1 and 2 present a 2D supramolecular arrangement through hydrogen bonds between coordination water molecules and nitrate or perchlorate anions and π-stacking interaction between the pyridyl rings of Mebpy nitrogen ligands.     

Crystal structures and magnetic properties of three cobalt(II)–organic frameworks with nanoscale channels

Three cobalt(II) coordination polymers, {[Co(nip)(4,4′-bpy)] · 3H₂O} _n (1), [Co(nip)(bpe)] _n (2), and [Co(nip)(bpp)(H₂O)] _n (3), were hydrothermally synthesized by the reaction of cobalt nitrate hexahydrate and nip with 4,4′-bpy, bpe, and bpp [nip = 5-nitro-1,3-benzenedicarboxylato, 4,4′-bpy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane], respectively. Co(II) displays different coordination in the three complexes, resulting in different structures with nanoscale channels. Compounds 1 and 2 form 2-D layer structures, but 3 has a two-fold interpenetrated 3-D framework. The magnetic properties associated with their crystal structures were investigated.     

A series of metal-organic frameworks constructed with arenesulfonates and 4,4′-bipy ligands

Five transition metal compounds containing arenesulfonates and 4,4′-bipy ligands, namely [Zn₂(N,N′-4,4′-bipy)(N-4,4′-bipy)₂(H₂O)₈](bpds)₂ · 5H₂O (1), [Ag₂(N,N′-4,4′-bipy)₂(bpds)] (2), [Cd(N,N′-4,4′-bipy)(H₂O)₄]₂(4-abs)₄ · 5H₂O (3), [Cu(N,N′-4,4′-bipy) (O-bs)₂(H₂O)₂] · 4H₂O (4), and [Zn(N,N′-4,4′-bipy)₂(H₂O)₂](4,4′-bipy)(bs)₂ · 4H₂O (5) (4,4′-bipy = 4,4′-bipyridine, bpds = 4,4′-biphenyldisulfonate, 4-abs = 4-aminobenzenesulfonate, bs = benzenesulfonate), have been synthesized and characterized by X-ray single crystal diffraction, elemental analyses and TG analyses, in order to investigate the coordination chemistry of arenesulfonates and 4,4-bipy, as well as to construct novel coordination frameworks via mixed-ligand strategy. Compounds 2, 4 and 5 could be obtained via hydrothermal or aqueous reactions. Compound 1 forms a binuclear octahedral metal complex. Compounds 2–4 form polymeric chains. Compound 5 consists of 2D square grids with one intercalated 4,4′-bipy molecule. Weak Ag–Ag interactions are observed in compound 2. These complexes show great structural varieties and there are three different coordination modes observed for both the 4,4′-bipy and the sulfonate ligands.     

Ti-catalyzed reactions of 4,4′-bis(trimethylsilyl)bicyclohexyl-2,2′-diene with various electrophiles

Reductive disilylation (Li + Me₃SiCl − THF) of 1,3-cyclohexadiene led to 4,4′-bis(trimethylsilyl)bicyclohexyl-2,2′-diene (1). In the presence of TiCl₄ in dichloromethane, 1 reacted with some acyl chlorides, anhydrides, and aldehydes to give tricyclo[7.4.0.0^3,8]trideca-4,12-diene-2-yl derivatives.     

Synthesis of trifluoromethyl-substituted salicylates by cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one

A formal [3+3] cyclocondensation of 1,3-bis(silyl enol ethers) with the little-known 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one was studied. In contrast to 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one, this α-oxoketene dithioacetal reacts with 1,3-bis(trimethylsilyloxy)-1,3-butadienes in the presence of TiCl₄ to give mainly 6-methylthio-4-(trifluoromethyl)salicylates via 1,2-addition. The scope and limitations of the reaction are discussed.     

Synthesis and crystal structure of a novel Zn(II) 2-D coordination polymer containing 1,3-bis(4-pyridyl)propane ligand and Croconate Violet dianion

From the reaction between Zn(NO₃)₂ · 6H₂O and tetrabutylammonium croconate violet ((NBu₄)₂CV) in the presence of the flexible ligand 1,3-bis(4-pyridyl)propane (BPP) a novel neutral 2-D coordination polymer {[Zn(μ-BPP)(BPP)(CV)(H₂O)] · H₂O}_n (1) was obtained. Compound 1 was characterized by means of elemental analysis, thermogravimetric analysis and vibrational spectroscopy. The crystal structure of 1 reveals that each Zn(II) is coordinated by three nitrogen atoms from two different BPP ligands, two oxygen atoms from one Croconate Violet dianion and one aqua ligand, within a distorted octahedral geometry in a facial arrangement (ZnN₃O₃). One of the BPP ligands adopts a TG (trans–gauche) conformation bridging two zinc centers giving rise to a 1-D polymeric chain along the crystallographic a axis, and the other is coordinated to metal site in a monodentate fashion adopting a TT (trans–trans) conformation. Adjacent 1-D chains are extended into a 2-D coordination network of (4, 4) topology through cooperative hydrogen bonding involving N31, OW2 and OW1 atoms, in direction of the c axis. Two complementary 2-D sheets fit each other exhibiting an interdigitation phenomenon, giving rise to a bilayer supramolecular structure.     

Polarographic behaviour of 1,3-bis[(2-pyridyl)methyleneamino]thiourea (PMAT) in absence and presence of Triton X-100

The polarographic behaviour of 1,3-bis[(2-pyridyl)methyleneamino]thiourea (PMAT) in solutions of varyingpH has been studied both in the absence and presence of Triton X-100 (T.X-100). The mechanism for the reduction process is discussed. The adsorption effect of electrochemically inactive T.X-100 on the polarographic waves ofPMAT has been investigated. The values of the kinetic parameters for the electrode reaction at differentpH values have been computed. The applicability of the polarographic method for determination ofPMAT is also discussed.

---

Das polarographische Verhalten von 1,3-Bis[(2-pyridyl)methylenamino]-thioharnstoff (PMAT) in Anwesenheit und Abwesenheit von Triton X-100. Die polarographische Bestimmung vonPMAT

Zusammenfassung Es wurde das polarographische Verhalten vonPMAT in Lösungen mit verschiedenempH sowohl in Gegenwart als auch ohne Triton X-100 (T.X-100) untersucht. Es wird ein Mechanismus für den Reduktionsprozeß diskutiert. Der Adsorptionseffekt des elektrochemisch inaktiven T.X-100 wurde hinsichtlich der polarographischen Wellen vonPMAT untersucht. Die kinetischen Parameter der Elektrodenreaktion wurden für verschiedenepH-Werte ermittelt. Ebenso wird die Anwendbarkeit der polarographischen Methode für die Bestimmung vonPMAT diskutiert.

     

A New Two-dimensional Zinc Coordination Polymer Constructed by 1,3-Bis(4-pyridyl)-propane and Terephthalate: Synthesis and Crystal Structure

A new zinc coordination polymer, [Zn2(bpp)(tpa)2H2O] 1 (bpp=1,3-bis(4-pyridyl)-propane and tpa=terephthalate) has been hydrothermally synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. X-ray crystal structure analysis reveals that complex 1 crystallizes in monoclinic, space group P2/c with a=18.348(2), b=10.9080(14), c=13.7924(18), β=98.156(2)°, V=2732.5(6)3 , Z=4, C29H24N2O9Zn2 , Mr=675.24, Z=4, F(000)=1376, Dc=1.641 mg/m3 , μ=1.815 mm-1 , the final R=0.0443 and wR=0.0769 for 2715 observed reflections (I>2σ(I)). The title complex exhibits a two-dimensional (4, 4) sheet structure which is further stacked through face-to-face π-π interactions between the monodentately coordinated pyridine ring of bpp ligand and the phenyl ring of terephthalate ligand to form a 3-dimensional supramolecular structure. Thermogravimetric analyses show that the host framework of the complex is thermally stable up to ca. 400 ℃.     

Mercury(II) iodide coordination polymers generated from polyimine ligands

A series of new HgI₂ organic polymeric complexes, [Hg₂(L1)I₄]_n (1), [Hg(L2)I₂]_n (2), [Hg(L3)I₂]_n (3), [Hg₂(L4)I₄]_n (4), [Hg(L5)I₂]_n (5), [Hg(L6)I₃](HL6) (6) {L1 = 1,4-bis(2-pyridyl)-2,3-diaza-1,3-butadiene, L2 = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene, L3 = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, L4 = 2,5-bis(2-pyridyl)-3,4-diaza-2,4-hexadiene, L5 = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene and L6 = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene} was prepared from reactions of mercury(II) iodide with six organic nitrogen donor-based ligands under thermal gradient conditions using the branched tube method. All these compounds were structurally characterized by single-crystal X-ray diffraction. The HgI₂ coordination polymers obtained with the ligands L2, L3 and L5 show one-dimensional zig-zag motifs and in these compounds the HgI₂ units are connected to each other by the ligands L2, L3 and L5 through the pyridyl nitrogen atoms. The L1 and L4 ligands in the compounds 1 and 4 act as both a chelating and bridging group. In the compound 6 the ligand L6 acts as a monodentate ligand, resulting form a discrete compound. The thermal stabilities of compounds 1–6 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA).     

Synthesis,crystal structure and hydrolysis of a dinuclear copper(II) complex constructed by N2O donor Schiff base and 4,4′-bipyridine: Discrete supra-molecular ensembles vs. oligomers

The tridentate Schiff base ligand, 7-amino-4-methyl-5-aza-3-hepten-2-one (HAMAH), prepared by the mono-condensation of 1,2-diaminoethane and acetylacetone, reacts with Cu(BF₄)₂ · 6H₂O to produce initially a dinuclear Cu(II) complex, [{Cu(AMAH)}₂(μ-4,4′-bipy)](BF₄)₂ (1) which undergoes hydrolysis in the reaction mixture and finally produces a linear polymeric chain compound, [Cu(acac)₂(μ-4,4′-bipy)]_n (2). The geometry around the copper atom in compound 1 is distorted square planar while that in compound 2 is essentially an elongated octahedron. On the other hand, the ligand HAMAH reacts with Cu(ClO₄)₂ · 6H₂O to yield a polymeric zigzag chain, [{Cu(acac)(CH₃OH)(μ-4,4′-bipy)}(ClO₄)]_n (3). The geometry of the copper atom in 3 is square pyramidal with the two bipyridine molecules in the cis equatorial positions. All three complexes have been characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. A probable explanation for the different size and shape of the reported polynuclear complexes formed by copper(II) and 4,4′-bipyridine has been put forward by taking into account the denticity and crystal field strength of the blocking ligand as well as the Jahn–Teller effect in copper(II).     

Synthesis and properties of 4,4′-bipyridine based tetracationic carbazolophanes

The precyclophane derived from 3,6-bis(bromomethyl)-9-ethylcarbazole and 5 equiv of 4,4′-bipyridine underwent macrocyclization on quaternization with various dibromides including 3,6-bis(bromomethyl)-9-ethylcarbazole to give carbazole-paraquat, self-complementary, cyclophanes revealing distinct charge-transfer and electrostatic interactions. The macrocyclic carbazolophane 1 was also obtained by a one-pot quaternization technique using equimolar amounts of 3,6-bis(bromomethyl)-9-ethylcarbazole and 4,4′-bipyridine.