Intramolecular self-alkylation reaction of an iron(II) dichloroclathrochelate caused cyclization–demethylation in its chelate ribbed fragment

Nucleophilic substitution of an iron(II) dichloroclathrochelate precursor FeBd₂(Cl₂Gm)(BF)₂ (where Bd^2 − and Gm are α-benzildioxime dianion and glyoxime residue, respectively) with 3-dimethylaminopropylamine unexpectedly afforded the macrobicyclic product of an intramolecular cyclization followed by a demethylation reaction with elimination of CH₃Cl. The molecular structure of this clathrochelate was unambiguously confirmed both in solution and in solid state using multinuclear NMR spectroscopy and by single crystal X-ray diffraction, respectively.     

The first P–N containing RuCl3NO complex: fac-[RuCl3(NO)(P–N)] (P–N = [o-(N,N-dimethylamino)phenyl]diphenylphosphine)

Complex fac-[RuCl₃(NO)(P–N)] was synthesized from [RuCl₃(H₂O)₂(NO)] in methanol solution under reflux. The orange solid obtained was characterized by NMR (³¹P{¹H}, ¹H, ¹³C) and, cyclic voltammetry, ESI-MS, IR, elemental analysis and X-ray diffraction structure determination. The ³¹P{¹H} reveals the presence of singlet at 36 ppm. IR N–O stretching as KBr pellets or CH₂Cl₂ solution presented 1866 cm⁻¹ and 1872 cm⁻¹, respectively.     

Adsorption of MCPA pesticide by MgAl-layered double hydroxides

In the present study, the adsorption characteristics of the herbicide MCPA (4-chloro-2-methylphenoxyacetic acid) on layered double hydroxides (LDHs) were evaluated under laboratory conditions with particular attention to the effect of layer charge, original interlayer anion and morphology. The final objective is the use of LDHs and modified LDH materials as recyclable adsorbents and heterogeneous catalysts for the treatment of contaminated waste waters.The anionic clays tested were [Mg_1−xAl_x(OH)₂]^x+[X_x/m^m−·nH₂O] materials. The MCPA adsorption capacity was determined from adsorption isotherms and a kinetic study. We looked at the influence of the pH, the Mg²⁺/Al³⁺ ratio, i.e. the anion exchange capacity, the nature of the intercalated anion X (CO₃²⁻, NO₃⁻, Cl⁻) and the morphology of the adsorbent on the extent of adsorption. The adsorption isotherms, described by Freundlich model, are of S-type with tendency to L-type for high MCPA equilibrium concentration. Furthermore, the adsorption capacity increases with the layer charge density. Hence, MCPA adsorption on LDHs occurs by anion exchange in two steps, an external exchange followed by an interlayer exchange, which explain these changes of type within the same isotherm. Besides, the adsorption capacity depends on the nature of the starting anions, following the affinity order (NO₃⁻<Cl⁻<CO₃²⁻) proposed by Miyata and increases with the specific surface area.     

Synthesis, crystal structure and NMR of [Na(DB18C6)(CH3CN)]3[α-AsM12O40] (M = Mo/W)

Two super-molecular complexes [Na(DB18C6)(CH₃CN)]₃[α-AsM₁₂O₄₀] (M = Mo/W) were obtained by solvothermal reaction and characterized by IR,¹H ¹³C and gUMBC NMR, X-ray. The result reveals that the complex consists of a [α-AsM₁₂O₄₀]³⁻ (M = Mo/W) anion with α-Keggin structure, and three complex [Na (DB18C6)(CH₃CN)]⁺ cations in which every sodium ion is located in the cavity of dibenzo-18-crown-6 with 6 Na–O bonds and coordinated with one of the terminal O atom of [α-AsM₁₂O₄₀]³⁻ (M = Mo/W) and the N atom of CH₃CN from two sides of the distorted DB18C6 plane, respectively. The three terminal O atoms linked with sodium ion are from a single M₃O₁₃ (M = Mo/W) triplet of the α-Keggin metalatoarsenate anion, and M–O_b (M = Mo/W) bonds exhibit alternating single–double bond character.     

Structure and magnetic properties of a copper malonate/dipyridylamine layered coordination polymer with both syn–anti and anti–anti copper carboxylate chains

The novel 2-D copper metal–organic layered coordination polymer {[Cu₂(malonate)₂(dpa)(H₂O)₂] · H₂O} (1, dpa = 4,4′-dipyridylamine) has been prepared and characterized by single-crystal X-ray diffraction, IR and thermogravimetric analysis. The structure of compound 1 consists of alternating syn–anti and anti–anti copper malonate 1-D chains linked into a (6,3) herringbone layer motif through tethering dpa ligands. Variable temperature magnetic studies indicate weak ferromagnetic coupling through the 1-D copper malonate chains with J = 0.64(1) cm⁻¹ and g = 2.033(4).     

Bimetallic nickel complexes of trimethyl phenyl linked salicylaldimine ligands: Synthesis, structure and their ethylene polymerization behaviors

Bimetallic salicylaldimine-nickel complexes, 2,4,6-Me₃-1,3-{[NCH–(3′-R-5′-Y-2′-O–C₆H₃)-κ²-N,O]Ni(Ph) (PPh₃)}₂ [R = tert-Bu, Y = Me, 1b; R = Ph, Y = H, 2b] were prepared and their catalytic behaviors of ethylene polymerization were investigated. The bimetallic complex 2b shows higher activities (2.9 × 10⁵ g PE mol⁻¹ Ni h⁻¹) for ethylene polymerization and affords polymer with high molecular weight (M_w = 1.41 × 10⁵) and broad molecular weight distribution (M_w/M_n = 6.1) than its mononuclear matrix, {[(2,6-Me₂C₆H₃)–NCH–(3′-Ph-2′-O–C₆H₃)-κ²-N,O]Ni(Ph)(PPh₃)} (3) (Activity = 5.5 × 10⁴ g PE mol⁻¹ Ni h⁻¹; M_w = 1.86 × 10⁴; M_w/M_n = 2.8).     

The dipeptide H-Aib-l-Ala-OH ligand in copper(II) chemistry: Variation of product identity as a function of pH

A systematic investigation of the influence of “pH” on the product identity from the Cu^II/H-Aib-l-Ala-OH (LH) reaction system is described, where H-Aib-l-Ala-OH is α-aminoisobutyryl-l-alanine. The pH variation has led to the synthesis of two discrete complexes, the structures of which have been determined by single-crystal X-ray crystallography. The “low pH” complex {[CuClL](H₂O)_2.5}_n (1) is a 3D coordination polymer, in which the dipeptide monoanion L⁻ behaves as a η¹:η¹:η¹:μ₂ ligand binding one Cu^II atom through its amino nitrogen and neutral peptide oxygen, and an adjacent Cu^II atom through one of its carboxylate oxygen. The “higher pH” complex {[Cu(H₋₁L)(EtOH)](EtOH)}_n (2) is a chain (1D) compound, in which the dipeptide dianion H₋₁L²⁻ uses its amino nitrogen, deprotonated peptide nitrogen and both carboxylate oxygens to bridge two metal centres.     

Ten-vertex osmamonocarbaboranes via arachno and nido {CB9} monocarbaboranes. Polyhedral contraction promoted by [OsCl2(PPh3)3] in MeOH and the crystal and molecular structure of [1-H-1,1-(PPh3)2-2-Ph-3-(OMe)-isocloso-1,2-OsCB8H7]

Reactions of [OsCl₂(PPh₃)₃] 1 with the [NEt₄]⁺ salts of the [6-Ph-nido-6-CB₉H₁₁]⁻ anion 2 and the [arachno-6-CB₉H₁₄]⁻ anion 3 each proceed selectively in methanol solution with the elimination of one boron-containing fragment from the starting cluster polyhedron, yielding together a short series of three novel 10-vertex hydridoosmamonocarbaboranes of isocloso {OsCB₈} cluster geometry.     

Polymeric ternary metal thiols I. Products from reaction of Cu(II) with MoS4

The black, polymeric, product isolated from the reaction of Cu(II) salts with MoS₄²⁻ has been shown to have some unexpected and unusual properties, i.e. a stoichiometry of Cu_1.6MOS₄X_y (X = Cl⁻, Br⁻, y ≈ 1; X = SO₄²⁻, y ≈ 0.5), reduction of the metal centres to Cu(I) and Mo(V), the presence of S radical centres, and the absorption of ca. 2 mol O₂. EXAFS spectra have also been recorded. The W anion WS₄²⁻ behaves identically.     

The Beauty and Complexity of the Mixed-Ligand Pd(II)-containing Monomers,Oligomers and Polymers Built upon Diphosphines and 1,8-Diisocyano-<Emphasis Type="Italic">p</Emphasis>-menthane

The starting materials Pd(diphos)Cl₂ where diphos = bis(diphenylphosphino)ethane (dppe), bis(diphenylphosphino)propane (dppp), bis(diphenylphosphino)butane (dppb), and Pd₂(diphos′)₂Cl₄ where diphos′ = bis(diphenylphosphino)pentane (dpppen) and bis(diphenylphosphino)hexane (dpph) were reacted with the bridging ligand 1,8-diisocyano-p-menthane (dmb) to form species of the type {Pd₂(diphos)₂(dmb) ₂ ⁴⁺ } _n and {Pd(diphos′)₂(dmb) ₂ ⁴⁺ } _n . Except for Pd₂(dppe)₂(dmb) ₂ ⁴⁺ , which was characterized by X-ray crystallography, the identity of the other weakly soluble dmb-containing materials were exhaustively characterized in solution and in the solid state by ³¹P NMR (Magic Angle Spinning), chemical analyses, MALDI-TOF, DSC, TGA, IR and T ₁/NOE (³¹P NMR spin-lattice relaxation time and nuclear overhauser enhancement constant measurements). Model compounds such as Pd(diphos)(CN-tBu) ₂ ²⁺ (diphos = dppe, dppp, dppb) and Pd₂(diphos′)₂(CN-tBu) ₄ ⁴⁺ (diphos′ = dpppen, dpph; as BF ₄ ⁻ or PF ₆ ⁻ salts), were prepared and also characterized by X-ray crystallography. Evidence for mono- (model complexes only of the type dppe, dppp, and dppb) and dinuclear complexes, as well as oligomers and polymers, are obtained for most cases, as well as the presence of monomer–oligomer (or polymer) equilibrium. During the course of this study, the complexes [Pd(dppp)(CN-tBu)₂](TCNQ)(Cl), [Pd₂(dpppen)₂(CN-tBu)₂(Cl)₂](PF₆)₂, and [Pd₂(dpppen)₂(CN-tBu)₂(CN)₂](TCNQ)₂ (TCNQ⁻ = tetraquinodimethane anion) were isolated and characterized by X-ray crystallography.This paper is dedicated to Professor Richard J. Puddephatt.     

A novel 3D double helix cobalt(II) coordination polymer: Synthesis, crystal structures and third-order non-linear optical properties

One new metal-organic complex formulated as {[Co(bipy)₃][Co₂(μ₂–ox)₃]}_n 1 (bipy = 2,2′-bipyridyl; ox = oxalate) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and UV–visible spectra. The complex 1 contains helical chains composed of left-handed and right-handed helices interlaced in pairs. The third-order non-linear optical (NLO) properties of the 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 5.75 × 10⁻³⁰ esu for 1 in a 2.36 × 10⁻⁴ mol dm⁻³ DMF solution.     

Ferromagnetic mixed tribridged dinuclear copper(II) complex [Cu2(OAc)2(OH)(dpa)2]PF6 · H2O (dpa = 2,2′-dipyridylamine): 3D superstructure based on hydrogen bond and π…π interaction

A new dinuclear complex [Cu₂(OAc)₂(OH)(dpa)₂] PF₆ · H₂O (1) is prepared and structurally and magneto-structurally characterized. The monocationic core contains one acetate in familiar bidentate η¹:η¹:μ₂-bridge and another in the rare monoatomic bridge along with one hydroxo intermediary. 1 packs through N–H…O and O–H…O hydrogen bonds and π…π interaction resulting a 3D supramolecular continuum and displays high-energy intraligand ¹(π − π^*) fluorescence and intraligand ³(π − π^*) phosphorescence in glassy solution.     

Switching on the photochemical reactivity in heterodimetallic Os–Ru bipyridyl complexes containing a bis(bidentate) phosphine

For the first time the excited states of the RuP₂N₄ moiety belonging to a new heterodimetallic Os^II–Ru^II bipyridyl complex are successfully designed in order to introduce photochemical reactivity. This dramatic effect is achieved via the use of the sterically demanding bis(bidentate) phosphine cis, trans, cis-1,2,3,4-tetrakis(diphenylphosphino)cyclobutane (dppcb). Thus, the temperature dependence of the luminescence lifetimes ranging from 77 to 298 K for the novel homodimetallic species meso-(ΔΛ/ΛΔ)-[Os₂(dppcb)(bpy)₄](PF₆)₄ (1) and rac-(ΔΔ/ΛΛ)-[Os₂(dppcb)(bpy)₄](PF₆)₄ (2) clearly indicates that the d–d state responsible for photochemistry is not populated. By contrast, the analogous temperature dependence for the new heterodimetallic species ΔΛ/ΛΔ-[Os(bpy)₂(dppcb)Ru(bpy)₂](PF₆)₄ (3) and ΔΔ/ΛΛ-[Os(bpy)₂(dppcb)Ru(bpy)₂](PF₆)₄ (4) unequivocally shows that as a consequence of the population of the d–d state the photochemical reactivity is switched on. Since single crystal X-ray structure analyses are a major clue to the understanding of photophysical and photochemical properties, also the X-ray structures of 1–3 are given.     

Layered double hydroxides pillared by macropolyoxometalates

Pillared derivatives of Mg_1−xAl_x layered double hydroxides (LDHs) were prepared by anion exchange reaction of a synthetic meixnerite precursor, [Mg₃Al(OH)₂](OH), with macromolecular polyoxometalate ions. The intercalated polyoxometalates included the lacunary Dawson ion (α-P₂W₁₇O₆₁)¹⁰⁻, the Finke (Zn₄(H₂O)₂(AsW₉O₃₄)₂)¹⁰⁻ and (WZn₃(H₂O)₂(ZnW₉O₃₄)₂)¹²⁻ ions, the doubled Dawson (P₄W₃₀Zn₄(H₂O)₂O₁₁₂)¹⁶⁻ and the polyoxocryptates (NaSb₉W₂₁O₈₆)¹⁸⁻ and (NaP₅W₃₀O₁₁₀)¹⁴⁻. Anion exchange reaction of [Zn₂Al(OH)₂](NO₃⁻) with (NaP₅W₃₀O₁₁₀)¹⁴⁻ also resulted in a crystalline pillared product. The intercalates exhibited gallery heights up to 16.6 Å and thermal stabilities to 200°C. Nitrogen adsorption/desorption studies for the LDH intercalates showed that access to the gallery micropores was achieved upon POM intercalation. All of the intercalates contained a salt-like impurity phase, as indicated by XRD. The Zn₂Al–(NaP₅W₃₀O₁₁₀)¹⁴⁻ LDH was investigated as a catalyst for the peroxide oxidation of cyclohexene. A comparison of the reactivities of three samples containing different fractions of the salt-like impurity suggested that the impurity phase contributes significantly to the observed activity.     

Reaction between the diaqua form of cisplatin and 2-methylsulfanylphenylphosphonic acid yields a dinuclear phosphonato-bridged complex via NH3 elimination

Reaction between cis-[Pt(NH₃)₂(H₂O)₂]²⁺ and (2-methylsulfanyl)phenyl phosphonic acid (H₂mspp) did not yield the expected cis-diammine [(2-methylsulfanylphenyl)phosphonato]platinum(II) but the dimeric compound [{Pt(mspp)(NH₃)}₂]·6H₂O in which the dianionic mspp²⁻ ligand acts both as chelator and bridging ligand. Thus, the high trans-effect of the sulfanyl group apparently leads to elimination of one NH₃ ligand. An X-ray crystal structure analysis of the dimeric complex is reported.     

A zirconium-containing sandwich-type dimer based on trivacant α- and β-[GeW9O34] units, [Zr3O(OH)2(α-GeW9O34)(β-GeW9O34)]

A new zirconium-containing sandwich-type dimer based on trivacant α- and β-[GeW₉O₃₄]¹⁰⁻ units, [Zr₃O(OH)₂(α-GeW₉O₃₄)(β-GeW₉O₃₄)]¹²⁻, was synthesized and characterized by IR spectroscopy, UV electronic spectroscopy and single crystal X-ray diffraction. The central bent of the polyanion contains three oxygen atoms alternating with the three zirconium atoms. The polyanion represents a rare example of the sandwich POMs containing two different isomer subunits.     

Synthesis, structure and magnetism of a μ3-carbonato bridged nickel(II) complex with 2,2′,2″-tris(2-aminoethyl)amine ligand: a new coordination mode of carbonato bridge

A novel bridged Ni(II) complex with tris(2-aminoethyl)amine (tren), [Ni₃(tren)₃(H₂O)₂(μ₃-CO₃)](ClO₄)₄ · 2H₂O, was obtained by bubbling CO₂ into an aqueous solution of μ₂-OH bridged Ni(II) complex. The X-ray structure analysis of the title complex shows that the three nickel atoms are asymmetrically bridged by one tetradentate carbonato ligand, which presents a new bridge mode. The further magnetochemistry study exhibits a strong antiferromagnetic coupling between nickel(II) ions with J₁ = −11.03 cm⁻¹, J₂ = −80.27 cm⁻¹ in the title compound.     

Synthesis, structural characterization and third-order non-linear optical property of new three-dimensional metal-organic polymer [Fe2(μ10-btc)0.5(μ2-ox)0.5(μ2-O)1.5]n

One new metal-organic polymer formulated as [Fe₂(μ₁₀-btc)_0.5(μ₂-ox)_0.5(μ₂-O)_1.5]_n 1 (btc = 1,2,4,5-benzenetetracarboxylate, pyramellitate; ox = oxalate) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, TGA, IR spectra and UV–visible spectra. Complex 1 presents the first 3D coordination network structure constructed by bridging btc, ox and O mixed ligands. In 1, carboxyl groups of btc are all deprotonated and they have a new type of μ₁₀-btc coordination mode. The third-order non-linear optical (NLO) properties of the title compound 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 5.98 × 10⁻³⁰ esu for 1 in a 7.45 × 10⁻⁴ mol dm⁻³ DMF solution.     

An oxide chain constructed from octamolybdate, a Keggin anion and a copper (II) – Tetrapyridylpyrazine binuclear unit

The hydrothermal reaction of MoO₃, CuSO₄·5H₂O, tetra-4-pyridylpyrazine (tpyprz), and diphenyldiarsonic acid in water at 140 °C for 48 h yielded the one-dimensional material [{Cu₂(tpyprz)(H₂O)₃}₂{Mo₈O₂₆}{Mo₁₂O₃₆(AsO₄)}]·8H₂O (1·8H₂O). The chain structure of 1·8H₂O is constructed from alternating β-octamolybdate clusters and molybdoarsonate Keggin clusters linked through {Cu₂(tpyprz)(H₂O)₃}⁴⁺ binuclear subunits. The Cu(II) sites are inequivalent with one copper bonding to two pyridyl donors and a pyrazine nitrogen of one terminus of the tpyprz ligand, two aqua ligands and an oxo-group of the cluster while the second copper site coordinates to the nitrogen donors of the other terminus of the tpyprz ligand, an aqua group, a terminal oxo-group of the cluster and a terminal oxo-group of the mixed valence {Mo₁₁^VIMo^VO₃₆(AsO₄)}⁴⁻ cluster. Crystal data: C₄₈H₆₀AsCu₄Mo₂₀N₁₂O₈₀: FW = 4332.96 Triclinic , a = 12.5087(5) Å, b = 13.6681(6) Å, c = 14.8980(6) Å, α = 92.196(1)°, β = 97.046(1)°, γ = 97.751(1)°, Z = 1, D_calc = 2.877 g cm⁻³; structure solution and refinement based on 12,333 reflections (Mo K_α, λ = 0.71073 Å) converged at R₁ = 0.0540 and wR₂ = 0.1115.     

Novel Hg and Mn supramolecular complexes with a versatile building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiolate involving in situ ligand formation

Reaction of potassium N′-(pyridine-4-carbonyl)-hydrazinecarbodithioate ([K⁺(H₂L)⁻]) with Hg^II or Mn^II inorganic salt in the presence of 1,10-phenanthroline (phen) or 4,4′-bipyridine (bipy), yields complexes [Hg(pyt)₂(phen)] (1) and {[Mn(pyt)₂(H₂O)₂]·(bipy)·(H₂O)₂}_n (2), in which the pyt ligand (Hpyt = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol) is obtained by in situ ligand formation from the acyclic precursor [K⁺(H₂L)⁻]. Single crystal X-ray diffraction suggests that the pyt anionic ligands in 1 and 2 behave as thiolate and thione isomers, respectively, and display S- and μ-N_pyridyl, N_oxadiazole-binding fashions. Complex 1 shows a 1-D fishbone-like supramolecular array via strong aromatic stacking interactions between the discrete mononuclear coordination motifs, whereas 2 has a 2-D layered host coordination framework with the inclusion of bipy and water guests in the cavities.