Na6(H2O)20(V10O28)·4H2O,a novel polyvanadate(V) with a three‐dimensional framework

The novel title polyvanadate(V), poly[[octa‐μ‐aqua‐dodecaaqua‐μ₄‐octacosaoxidodecavanadato‐hexasodium] tetrahydrate], [Na₆(H₂O)₂₀(V₁₀O₂₈)·4H₂O]_n, contains [V₁₀O₂₈]⁶⁻ anions which lie about inversion centres and have approximate 2/m symmetry and which are linked to [Na₃(H₂O)₁₀]³⁺ cations through two terminal and two μ₂‐bridging O atoms. The structure contains three inequivalent Na⁺ cations, two of which form [Na₂(H₂O)₈]_n chains, which are linked via NaO₆ octahedra involving the third Na⁺ ion, thus forming a three‐dimensional framework.     

Kinetic and mechanistic studies on the electron-transfer reactions between diaquabisethylenediaminecobalt(III) and ethylenediaminetetraacetatocobaltate(III) with promazine in acidic aqueous media

The kinetics of the electron-transfer reactions between promazine (ptz) and [Co(en)₂(H₂O)₂]³⁺ in CF₃SO₃H solution ([Co^III] = (2–6) × 10⁻³ m, [ptz] = 2.5 × 10⁻⁴ m, [H⁺] = 0.02 − 0.05 m, I = 0.1 m (H⁺, K⁺, CF₃SO ₃ ⁻ ), T = 288–308 K) and [Co(edta)]⁻ in aqueous HCl ([Co^III] = (1 − 4) × 10⁻³ m, [ptz] = 1 × 10⁻⁴ m, [H⁺] = 0.1 − 0.5 m, I = 1.0 m (H⁺, Na⁺, Cl⁻), T = 313 − 333 K) were studied under the condition of excess Co^III using u.v.–vis. spectroscopy. The reactions produce a Co^II species and a stable cationic radical. A linear dependence of the pseudo-first-order rate constant (k _obs) on [Co^III] with a non-zero intercept was established for both redox processes. The rate of reaction with the [Co(en)₂(H₂O)₂]³⁺ ion was found to be independent of [H⁺]. In the case of the [Co(edta)]⁻ ion, the k _obs dependence on [H⁺] was linear and the increasing [H⁺] accelerates the rate of the outer-sphere electron-transfer reaction. The activation parameters were calculated as follows: ΔH ^≠ = 105 ± 4 kJ mol⁻¹, ΔS ^≠ = 93 ± 11 J K⁻¹mol⁻¹ for [Co(en)₂(H₂O)₂]³⁺; ΔH ^≠ = 67 ± 9 kJ mol⁻¹, ΔS ^≠ = − 54 ± 28 J K⁻¹mol⁻¹ for [Co(edta)]⁻.     

Hydrate isomerism in [Cu(en)2(H2O)1.935]2[Fe(CN)6]·4H2O

The title compound, bis[di­aqua­bis­(ethyl­enedi­amine‐κ²N,N′)copper(II)­] hexa­cyano­iron(II) tetrahydrate, [Cu(C₂H₈N₂)₂(H₂O)_1.935]₂[Fe(CN)₆]·4H₂O, was crystallized from an aqueous reaction mixture initially containing CuSO₄, K₃[Fe(CN)₆] and ethyl­enedi­amine (en) in a 3:2:6 molar ratio. Its structure is ionic and is built up of two crystallographically different cations, viz. [Cu(en)₂(H₂O)₂]²⁺ and [Cu(en)₂(H₂O)_1.87]²⁺, there being a deficiency of aqua ligands in the latter, [Fe(CN)₆]⁴⁻ anions and disordered solvent water mol­ecules. All the metal atoms lie on centres of inversion. The Cu atom is octahedrally coordinated by two chelate‐bonded en mol­ecules [mean Cu—N = 2.016 (2) Å] in the equatorial plane, and by axial aqua ligands, showing very long distances due to the Jahn–Teller effect [mean Cu—O = 2.611 (2) Å]. In one of the cations, significant underoccupation of the O‐atom site is observed, correlated with the appearance of a non‐coordinated water mol­ecule. This is interpreted as the partial contribution of a hydrate isomer. The [Fe(CN)₆]⁴⁻ anions form quite regular octahedra, with a mean Fe—C distance of 1.913 (2) Å. The dominant intermolecular interactions are cation–anion O—H⋯N hydrogen bonds and these inter­actions form layers parallel to (001).     

Slow Magnetic Relaxation,Antiferromagnetic Ordering,and Metamagnetism in MnII(H2dapsc)-FeIII(CN)6 Chain Complex with Highly Anisotropic Fe-CN-Mn Spin Coupling

Reactions of [Mn(H₂dapsc)Cl₂] ⋅ H₂O (dapsc=2,6- diacetylpyridine bis(semicarbazone)) with K₃[Fe(CN)₆] and (PPh₄)₃[Fe(CN)₆] lead to the formation of the chain polymeric complex {[Mn(H₂dapsc)][Fe(CN)₆][K(H₂O)_3.5]}_n ⋅ 1.5n H₂O ( 1 ) and the discrete pentanuclear complex {[Mn(H₂dapsc)]₃[Fe(CN)₆]₂(H₂O)₂} ⋅ 4 CH₃OH ⋅ 3.4 H₂O ( 2 ), respectively. In the crystal structure of 1 the high-spin [Mn^II(H₂dapsc)]²⁺ cations and low-spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano-bridged chains. The K⁺ ions are located between the chains and are coordinated by oxygen atoms of the H₂dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency-dependent ac magnetic susceptibility, indicating single-chain magnetic behavior with a Mydosh-parameter φ=0.12 and an effective energy barrier (U_eff/k_B) of 36.0 K with τ₀=2.34×10⁻¹¹ s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra-chain spin coupling between [Fe^III(CN)₆]³⁻ and [Mn^II(H₂dapsc)]²⁺ units resulting from orbital degeneracy and unquenched orbital momentum of [Fe^III(CN)₆]³⁻ complexes. The origin of the metamagnetic transition is discussed in terms of strong magnetic anisotropy and weak AF interchain spin coupling.     

Heterometallic compounds with the binuclear complex anion [Cr<Subscript>2</Subscript>(OH)(Ac)(Nta)<Subscript>2</Subscript>]<Superscript>2−</Superscript>: Synthesis and structure

Heterometallic compounds BaCr₂(OH)(Ac)(Nta)₂ · 4H₂O (I) and [Fe(L)₃][Cr₂(OH)(Ac)(Nta)₂] · nH₂O (L is Bipy (II) and Phen (III); Bipy is, αα′-bipyridine, Phen is o,o′-phenanthroline, Ac⁻ is acetate ion, Nta is nitrilotriacetate ion; n = 8 (II) and 6.25 (III)) are synthesized. According to the X-ray diffraction data, compounds II and III have ionic structures built of the isolated complex cations [Fe(L)₃]²⁺, binuclear complex anions [Cr₂(OH)(Ac)(Nta)₂]²⁻, and crystallization water molecules. The magnetic properties of compounds II and III in the interval from 2 to 300 K confirm assumptions on the diamagnetic character of [Fe(L)₃]²⁺ and indicate the antiferromagnetic interaction between the chromium atoms in the dimeric fragment [Cr₂(OH)(Ac)(Nta)₂]²⁻.     

Synthesis and Crystal Structure of a Two-dimensional Silver（Ⅰ）-Iron（Ⅲ） Heteronuclear Coordination Polymer： {[Ag4Fe2（SCN）12（H2O）2] [（inaH）2（H2O）2]}n

The 2‐D heteronuclear coordination polymer {[Ag₄Fe2(SCN)₁₂(H₂O)₂] (inaH)₂(H₂O)₂}_n (1) (inaH is the abbreviation of protonated isonicotinic acid) with chemical formula C₂₄Ag₄Fe₂N₁₄O₈S₁₂ has been synthesized and characterized by single crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The Ag₂S₂ rings connect two kinds of octahedral geometries of Fe(III) ions, [Fe(NCS)₆]^3– and Fe(H₂O)₂(NCS)₄]^? units with bridging thiocyanate ions leading to 2‐D [Ag₄Fe₂(SCN)₁₂(H₂O)₂^2– anion framework. Four kinds of rings including the unprecedented thirty‐two membered Ag₄Fe₄(SCN)₈ rings share comers or edges in the 2‐D anion layer structure. All thiocyanates coordinate to the metal ions according to the HSAB principle with N atoms binding to the Fe(III) ions and with S atoms binding to Ag(I) ions. Pronoated ina cations stabilize the layer structure as counter ions and hydrogen bonds were formed within the pronoated in a cations dimer and between the dimers and the lattice waters. Crystal data: M_r= 1560.44, triclinic, P1, a=0.76082(1) nm, b=0.9234 nm, c= 1.85611(4) nm, a= 103.0170(10)°, β=93.7780(10)°, y=97.4080(10)°, V= 1.25385(3) nm³, Z=1, μ(Mo Kα)=2.650 mm^?1, D_c,=2.067 g · cm^?3, F(000)=758, R₁=0.0412. wR₂=0.1003.     

A series of coordination polymers constructed from flexible bis(benzimidazole)ether ligands and different carboxylates

Six new coordination polymers constructed from two structurally related ligands, 2,2′-bis(2-methylbenzimidazole) ether (L1) and 2,2′-bis(2-ethylbenzimidazole)ether (L2), have been synthesized. They are [Cu(L1)(bz)₂] (1), [Cu(L2)(bz)₂] (2), [Zn₂(L1)(m-bdc)₂] (3), [Cd₂(L2)(m-bdc)₂(H₂O)]₂·H₂O (4), [Zn(L1)(OH-bdc)-(H₂O)] (5) and [Zn₂(L₂)(btca)] (6), where Hbz = benzoic acid, m-H₂bdc = 1,3-benzenedicarboxylic acid, OH-H₂bdc = 5-hydroxyisophthalic acid, and H₄btca = 1,2,4,5-benzenetetracarboxylic acid. In 1 and 2, the bidentate N-donor ligands (L1 and L2) bridge neighboring metal centers to form 1D single chains. The bz anions are attached on both sides of the chains. In 3 and 4, the N-donor ligands (L1 and L2) in cis conformations bridge two metal centers to generate a [M₂(L1)]⁴⁺ unit (M = Zn(II) and Cd(II)). The adjacent [M₂(L1)]⁴⁺ units are further linked via the dicarboxylate anions to form 1D double chain structures. In 5, the Zn(II) cations are bridged by OH-m-bdc anions to form an infinite polymeric chain. The L1 ligands are attached on one side of the chain in a monodentate mode. In 6, two Zn(II) cations are bridged by two L2 ligands to form a [ZnL2]₂ ⁴⁺ ring, which is further linked by btca anions to generate a 2D layer. The luminescent properties of the ligands and 3–6 in the solid state at room temperature were also studied.     

Pivalate Bridged High Spin Manganese(II) and Iron(II) Polymers

Antiferromagnetic Mn(II) polymers of general formula {[L₂Mn(μ-OOCCMe₃)₂][Mn₂(μ-OOCCMe₃)₄]}_n (L = 1,2-phenylenediamine (3) and 4,5-dimethyl-1,2-phenylenediamine (4)) were synthesized from [Mn(μ-OOCCMe₃)₂(HOEt)] _n (1) polymer and arenediamines in MeCN solution. The tetranuclear cluster Fe₄(μ₃-OH)₂(μ-OOCCMe₃)₄(η²-OOCCMe₃)₂(EtOH)₆ (5) was prepared by reacting FeSO₄·7H₂O with KOOCCMe₃ in EtOH and was used as starting pivalate iron(II) agent in further reactions. The thermolysis of 5 in MeCN was shown to result in a ferromagnetic polymer [Fe(μ-OOCCMe₃)₂] _n (6) containing tetrahedral iron(II) atoms. Cluster 5 was found to react with o-phenylenediamine giving rise to ferrimagnetic polymer [Fe(μ-OOCCMe₃)₂(HOEt)]_n (7). The reaction 7 with 2,6-diaminopyridine in MeCN results in binuclear antiferromagnetic complex (2,6-(NH₂)₂C₅H₃N)₂Fe₂(μ-OOCCMe₃)₄· 4MeCN (8). However the reaction of 4,5-dimethyl-1,2-phenylenediamine with polymer 7 yields a polymer {[L₂Fe(μ-OOCCMe₃)₂][Fe₂ (μ-OOCCMe₃)₄]} _n (9), which is an analogue of the manganese polymer 4. All newly synthesized compounds were characterized by the by X-ray diffraction studies and magnetic measurement. Dedicated to Professor Ilya I. Moiseev in recognition of his outstanding contribution to cluster chemistry     

Synthesis, crystal and molecular structure of tetraaquabis(nicotinamide)cobalt(II) phthalate dihydrate

The coordination compound of cobalt(II) with nicotinamide [CoL₂(H₂O)₄][C₆H₄(COO)₂] · 2H₂O (I) (where L stands for nicotinamide) was synthesized and characterized by IR spectroscopy, conductometry, and thermogravimetry. The X-ray structure of complex I was determined. Crystals are monoclinic: a = 15.630(2) ?, b = 7.550(2) ?, c = 21.035(4) ?, β = 100.90(5)°, V = 2437.4(4) ?³, Z = 4, space group C2/c. The structural units of complex I are centrosymmetrical cations [CoL₂(H₂O)₄]²⁺, anions [C₆H₄(COO)₂]²⁻ (lying on axis 2), and molecules of waster of crystallization. Complex cations are packed into layers are alternate with layers containing anions and free H₂O molecules. This is a classical case of π-π-staking interactions that lead to the formation of supramolecular layered assemblies. Original Russian Text ? A.S. Antsyshkina, G.G. Sadikov, T.V. Koksharova, I.S. Gritsenko, V.S. Sergienko, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 8, pp. 1379–1384.     

Chemical Bonding in Homoleptic Carbonyl Cations [M{Fe(CO)5}2]+ (M=Cu,Ag, Au)

Syntheses of the copper and gold complexes [Cu{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] containing the homoleptic carbonyl cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Au) are reported. Structural data of the rare, trimetallic Cu₂Fe, Ag₂Fe and Au₂Fe complexes [Cu{Fe(CO)₅}₂][SbF₆], [Ag{Fe(CO)₅}₂][SbF₆] and [Au{Fe(CO)₅}₂][HOB{3,5-(CF₃)₂C₆H₃}₃] are also given. The silver and gold cations [M{Fe(CO)₅}₂]⁺ (M=Ag, Au) possess a nearly linear Fe-M-Fe’ moiety but the Fe-Cu-Fe’ in [Cu{Fe(CO)₅}₂][SbF₆] exhibits a significant bending angle of 147° due to the strong interaction with the [SbF₆]⁻ anion. The Fe(CO)₅ ligands adopt a distorted square-pyramidal geometry in the cations [M{Fe(CO)₅}₂]⁺, with the basal CO groups inclined towards M. The geometry optimization with DFT methods of the cations [M{Fe(CO)₅}₂]⁺ (M=Cu, Ag, Au) gives equilibrium structures with linear Fe-M-Fe’ fragments and D₂ symmetry for the copper and silver cations and D_4d symmetry for the gold cation. There is nearly free rotation of the Fe(CO)₅ ligands around the Fe-M-Fe’ axis. The calculated bond dissociation energies for the loss of both Fe(CO)₅ ligands from the cations [M{Fe(CO)₅}₂]⁺ show the order M=Au (D_e=137.2 kcal mol⁻¹)>Cu (D_e=109.0 kcal mol⁻¹)>Ag (D_e=92.4 kcal mol⁻¹). The QTAIM analysis shows bond paths and bond critical points for the M−Fe linkage but not between M and the CO ligands. The EDA-NOCV calculations suggest that the [Fe(CO)₅]→M⁺←[Fe(CO)₅] donation is significantly stronger than the [Fe(CO)₅]←M⁺→[Fe(CO)₅] backdonation. Inspection of the pairwise orbital interactions identifies four contributions for the charge donation of the Fe(CO)₅ ligands into the vacant (n)s and (n)p AOs of M⁺ and five components for the backdonation from the occupied (n-1)d AOs of M⁺ into vacant ligand orbitals.     

K6[Fe8.27(HPO3)12]: a new mixed‐valence iron phosphite

The title compound, hexapotassium octairon(II,III) dodecaphosphonate, exhibiting a two‐dimensional structure, is a new mixed alkali/3d metal phosphite. It crystallizes in the space group Rm, with two crystallographically independent Fe atoms occupying sites of m (Fe1) and 3m (Fe2) symmetry. The Fe2 site is fully occupied, whereas the Fe1 site presents an occupancy factor of 0.757 (3). The three independent O atoms, one of which is disordered, are situated on a mirror and all other atoms are located on special positions with 3m symmetry. Layers of formula [Fe₃(HPO₃)₄]²⁻ are observed in the structure, formed by linear Fe₃O₁₂ trimer units, which contain face‐sharing FeO₆ octahedra interconnected by (HPO₃)²⁻ phosphite oxoanions. The partial occupancy of the Fe1 site might be described by the formation of two [Fe(HPO₃)₂]⁻ layers derived from the [Fe₃(HPO₃)₄]²⁻ layer when the Fe1 atom is absent. Fe²⁺ is localized at the Fe1 and Fe2 sites of the [Fe₃(HPO₃)₄]²⁻ sheets, whereas Fe³⁺ is found at the Fe2 sites of the [Fe(HPO₃)₂]⁻ sheets, according to bond‐valence calculations. The K⁺ cations are located in the interlayer spaces, between the [Fe₃(HPO₃)₄]²⁻ layers, and between the [Fe₃(HPO₃)₄]²⁻ and [Fe(HPO₃)₂]⁻ layers.     

Synthesis, structural characterization and properties of a 3D infinitely extended structural rare earth coordination compound of K3{[Sm(H2O)7]2Na[α-SiW11O39Sm(H2O)4]2} · 14 H2O· 14 H2O

A 3D infinitely extended structural rare earth coordination compound with a formula of K₃{[Sm(H₂O)₇]₂Na[α-SiW₁₁O₃₉Sm(H₂O)₄]₂}·14H₂O has been synthesized by reaction of Sm₂O₃, HClO₄, NaOH with α-K₈SiW₁₁O39·nH₂O, and characterized by IR, UV spectra, ICP, TG-DTA, cyclic voltammetry, variable-temperature magnetic susceptibility and X-ray single-crystal diffraction. X-ray single-crystal diffraction indicates that the title compound crystallizes in a triclinic lattice, Pī space group, with a = 1.2462(3) nm, b = 1.2652(3) nm, c = 1.8420(4) nm, α = 87.45(3)°, β = 79.91(3)°, γ= 82.57(3)°, Z = 1, R₁ = 0.0778, wR₂ = 0.1610. Structural analysis reveals that Sm³⁺(1) coordination cation has incorporated into the vacant site of [α-SiW11O₃₉]⁸⁻ entity, forming the [α- SiW₁₁O₃₉Sm(H₂O)₄]⁵⁻ subunit. The two adjacent [α-SiW₁₁O₃9Sm(H₂O)4]⁵⁻ subunits are combined with each other through two Sm(1)-O-W bridges accompanying the formation of dimmer structural unit [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ of the title compound. The neighboring dimmer structural units [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ are linked to form the 1D chainlike structure by means of two Sm³⁺(2) and a Na⁺(1) coordination cations. The K⁺(1) cations connect the 1D packing chains constructing the 2D netlike structure, and adjacent netlike layers are also grafted by K⁺(2) cations to build the novel 3D infinitely extended structure. The result of TG-DTA curves manifests that the decomposition temperature of the title polyanionic framework is 554°C. The cyclic voltammetry measurements show that the title polyanion has the two-step redox processes in aqueous solution with pH = 3.1. Variable temperature magnetic susceptibility indicates the title compound obeys the Cruie-Weiss Law in the higher temperature range from 110 to 300 K, while in the lower temperature range from 2 to 110 K the comparatively strong antiferromagnetism interactions can be observed.     

Mechanistic Studies on the Oxidation of Hydroquinone by an Oxo-bridged Diiron(III,III) Complex in Weakly Acidic Aqueous Media

The kinetics of oxidation of hydroquinone (H₂Q) by a μ-oxo-bridged diiron(III,III) complex, Fe₂(μ-O)(phen)₄(H₂O)₂]⁴⁺ (1) has been investigated in aqueous media at 25.0 °C in presence of an excess of 1,10-phenanthroline (phen). The overall redox rate increases with increase in [H⁺]. The title complex (1) and its conjugate bases, [Fe₂(μ-O)(phen)₄(OH)₂]³⁺(2) and [Fe₂(μ-O)(phen)₄(OH)₂]²⁺ (3), participate in the reaction with H₂Q as the only kinetically reactive reducing species. Rate constants (in dm³ mol⁻¹ s⁻¹) for the parallel reactions (1) + H₂Q → Products, (2) + H₂Q → Products and that for (3) + H₂Q → Products are, respectively, 500 ± 40, 100 ± 6 and 30 ± 2. Substantial rate retardation in D₂O media in comparison to that in H₂O media suggests that electron transfer is coupled with proton movements in the rate-determining step.     

Synthesis and anticancer property of one Fe(II) compound based on 5-(3-pyridyl)tetrazole-2-acetic acid

Abstract

Tetrazole-carboxylate ligands are universally considered as multi-functional candidates for the construction of coordination architectures. A 1-D [Fe(pytza)₂(H₂O)₂]_n·2nH₂O (pytza = 5-(3-pyridyl)tetrazole-acetato) has been prepared. In vitro study on Hela cells show that Hpytza is naturally nontoxic while [Fe(pytza)₂(H₂O)₂]_n·2nH₂O shows high toxicity with a half-maximal inhibitory concentration (IC₅₀) of 6.3?×?10^?5 M. In addition, the compound can effectively inhibit the migration of Hela cells.     

Syntheses,crystal structures and magnetic properties of two cyano-bridged two-dimensional assemblies [Fe(salpn)]2 [Fe(CN)5NO] and [Fe(salpn)]2[Ni(CN)4]

Two cyano-bridged assemblies, [Fe^III(salpn)]₂[Fe^II(CN)₅NO] (1) and [Fe^III (salpn)]₂[Ni^II(CN)₄] (2) [salpn = N, N-1,2-propylenebis(salicylideneiminato)dianion], have been prepared and structurally and magnetically characterized. In each complex, [Fe(CN)₅NO]^2– or [Ni(CN)₄]^2– coordinates with four [Fe(salpn)]⁺ cations using four co-planar CN^– ligands, whereas each [Fe(salpn)]⁺ links two [Fe(CN)₅NO]^2– or [Ni(CN)₄]^2– ions in the trans form, which results in a two-dimensional (2D) network consisting of pillow-like octanuclear [—M^II—CN—Fe^III—NC—]₄ units (M = Fe or Ni). In complex (1), the NO group of [Fe(CN)₅NO]^2– remains monodentate and the bond angle of Fe^II—N—O is 180.0°. The variable temperature magnetic susceptibilities, measured in the 5–300 K range, show weak intralayer antiferromagnetic interactions in both complexes with the intramolecular iron(III)iron(III) exchange integrals of –0.017 cm^–1 for (1) and –0.020 cm^–1 for (2), respectively.     

Synthesis,Crystal Structures,and Properties of Mn(NCS)2 Coordination Compounds with 4-Picoline as Coligand and Crystal Structure of Mn(NCS)2

Reaction of Mn(NCS)₂ with 4-picoline (4-methylpyridine) leads to the formation of [Mn(NCS)₂(4-picoline)₄] · 0.67 · 4-picoline · 0.33 · H₂O ( 1 - Mn ) reported in literature, Mn(NCS)₂(4-picoline)₂(H₂O)₂ ( 2-Mn/H₂O ), and of [Mn(NCS)₂(4-picoline)₂]_n ( 2-Mn/I ). 1-Mn and 2-Mn/H₂O consist of discrete complexes, in which the metal cations are octahedrally coordinated, whereas in 2-Mn/I the metal cations are linked by pairs of μ-1,3-bridging thiocyanate anions into corrugated chains. Measurements using thermogravimetry and differential scanning calorimetry as well as temperature dependent X-ray powder diffraction on 1-Mn and 2-Mn/H₂O reveal that upon heating both compounds transform into [Mn(NCS)₂(4-picoline)]_n ( 3-Mn ) via 2-Mn/I as intermediate. 3-Mn shows a very rare chain topology in which the metal cations are linked by μ-1,3,3 (N,S,S) coordinating anionic ligands which was never observed before with Mn^II. From these investigations there is no hint that a further modification of 2-Mn can be prepared as recently observed for [M(NCS)₂(4-picoline)₂]_n (M = Fe, Cd) and such a form is also not available if the metastable forms of the Fe^II or Cd^II compounds were used as template during thermal decomposition. Magnetic investigations on 2-Mn/H₂O show only paramagnetic behavior, whereas for 2-Mn/I antiferromagnetic ordering is observed. Finally, the crystal structure of Mn(NCS)₂ was determined from XRPD data, which shows that it is strongly related to that of 3-Mn .     

Crystal and molecular structure of tetraaquabarium Di-μ-tartrato-di-μ-hydroxodigermanate(IV) pentahydrate [Ba(H2O)4][Ge2(μ-Tart)2(μ-OH)2] · 5H2O

A new heteronuclear germanium barium complex with D-tartaric acid [Ba(H₂O)₄][Ge₂(μ-Tart)₂(μ-OH)₂]·5H₂O (I) (H₄Tart is tartaric acid) was synthesized. The identity of compound I and its com- position were determined by elemental analysis and X-ray diffraction. The thermal stability of the compound was studied; the coordination centers of the ligand were found from IR spectroscopy. The structure of I was determined by X-ray crystallography. Crystals I are tetragonal: a = 8.5033(2) ?, c = 30.9393(11) ?, V = 2237.10(11) ?³, Z = 4, space group P4₁, R1 = 0.0301 based on 4215 reflections with I > 2σ(I). In crystals I, neutral [Ge₂(μ-Tart)₂] dimers are linked in pairs by double hydroxyl bridges to form {[Ge₂(μ-Tart)₂(μ-OH)₂]²⁻}_∞ polymeric chains. Hydrated Ba²⁺ cations and crystal water molecules are in between the anionic chains. Polymeric complex anions, hydrated barium cations, and H₂O molecules are bound by a system of hydrogen bonds to form a framework.     

Structure and magnetic properties of a dtm-bridged two-dimensional supramolecular complex {[Fe(dtm)2(H2O)2](ClO4)2 · 2H2O} n (dtm = 4,4′-ditriazolemethane)

This work presents the synthesis, crystal structure and magnetic properties of a novel dtm-bridged 2D iron(II) supramolecular complex {[Fe(dtm)₂(H₂O)₂](ClO₄)₂ · 2H₂O} _n (1). The 2D structure of (1) is formed by the incorporation of coordinative linkage and hydrogen-bonding interactions between the oxygen atoms of the anion water cluster [(ClO₄)₂ · 4H₂O]²⁻ and 1D cation complex chain {[Fe(dtm)₂(H₂O)₂]²⁻. The magnetic behavior reveals an antiferromagnetic interaction between Fe(II) ions through hydrogen bonded bridges.     

Phosphodiester hydrolysis promoted by dinuclear iron(III) complexes

We report the reactivity of three binuclear non-heme Fe(III) compounds, namely [Fe₂(bbppnol)(μ-AcO)(H₂O)₂](ClO₄)₂ (1), [Fe₂(bbppnol)(μ-AcO)₂](PF₆) (2), and [Fe₂(bbppnol)(μ-OH)(Cl)₂]·6H₂O (3), where H₃bbppnol = N,N′-bis(2-hydroxybenzyl)-N,N′-bis(2-methylpyridyl)–1,3-propanediamine-2-ol, toward the hydrolysis of bis-(2,4-dinitrophenyl)phosphate as models for phosphoesterase activity. The synthesis and characterization of the new complexes 1 and 3 was also described. The reactivity differences observed for these complexes show that the accessibility of the substrate to the reaction site is one of the key steps that determinate the hydrolysis efficiency.     

Synthesis and crystal structure of tris[(dibenzo-18-crown-6-(tetrahydrofuran)potassium) hexakis(isothiocyanato)ferrate(III) 0.3 hydrate

Abstrac  A new complex [K(Db18C6)(THF)]₃⁺[Fe(NCS)₆]³⁻ · 0.31 H₂O (I) was prepared and studied by X-ray diffraction (space group C2/c, a = 21.954, b = 26.496, c = 15.902 ?, β = 102.24°, Z = 4; direct method, leastsquares refinement in the anisotropic approximation to R = 0.098 for 5944 independent reflections; CAD4 automated diffractometer, λMoK _α). The [Fe(NCS)₆]³⁻ anion (on twofold axis) having a slightly distorted octahedral structure is connected by two K-S bonds with two complex cations connected by a twofold axis. Two independent complex cations [K(Db18C6)(THF)]⁺ are of the host-guest type, one being statistically disordered with respect to the twofold axis with site populations of 0.5. The coordination polyhedra of K⁺ are a distorted hexagonal bipyramid and pyramid. Original Russian Text ? A.N. Chekhlov, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 2, pp. 151–154.