Crystal structures of chiral (R/S) (C<Subscript>8</Subscript>H<Subscript>11</Subscript>N)<Subscript>2</Subscript> · Zn(OAc)<Subscript>2</Subscript>

Two opposite configuration (R/S) of chiral complexes (C₈H₁₁N)₂ · Zn(OAc)₂ (Ia and Ib—L-(−)-) and D-(+)-isomer) were synthesized by a simple one-pot method. The crystal structures of Ia and ib determined by X-ray crystallography.     

(Indenyl)iridacarborane (η<Superscript>5</Superscript>-indenyl)Ir(η-7,8-C<Subscript>2</Subscript>B<Subscript>9</Subscript>H<Subscript>11</Subscript>): synthesis,structure, and bonding

A reaction of iodide [(η⁵-indenyl)IrI₂]_n (1) with thallium dicarbollide Tl[Tl(η-7,8-C₂B₉H₁₁)] leads to (indenyl)iridacarborane (η⁵-indenyl)Ir(η-7,8-C₂B₉H₁₁) (2) in 32% yield. The X-ray diffraction study showed that in the structure of 2, the five-membered rings C₅ and C₂B₃ have a cisoid conformation, in which the bridgehead carbon atoms of the indenyl ligand are arranged opposite to the carborane cage carbon atoms. The DFT calculations showed that the Ir—indenyl bond in compound 2 is weaker than the Ir—Cp bond in the complex (η-7,8-C₂B₉H₁₁)IrCp.     

Pyrazolate-bridged binuclear zinc complexes Zn<Subscript>2</Subscript>(μ-dmpz)<Subscript>2</Subscript>(Hdmpz)<Subscript>2</Subscript>(OOCR)<Subscript>2</Subscript> (R = Me,Ph; Hdmpz = 3,5-dimethylpyrazole)

Triethylamine reacts with aqueous zinc acetate and the product of its thermolysis in the presence of benzoic acid to yield the complexes [Zn₇(μ₄-O)(μ-OOCMe)₁₀][η-OC(Me)OHNEt₃]₂ (1) and [Zn₂(μOOCPh)₄][η-OC(Me)OHNEt₃]₂ (2), respectively. The reactions of 1 and 2 with 3,5-dimethylpyrazole at room temperature in benzene yield pyrazolate-bridged binuclear complexes Zn₂(μdmpz)₂(Hdmpz)₂(OOCR)₂ (R = Me (3), Ph (4)). The structures of complexes 1–4 have been determined by X-ray crystallography.     

Bis(4‐picoline‐κN)gold(I) dibromidoaurate(I) and bis(4‐picoline‐κN)gold(I) dichloridoaurate(I): space‐group ambiguity?

Bis(4‐picoline‐κN)gold(I) dibromidoaurate(I), [Au(C₆H₇N)₂][AuBr₂], (I), crystallizes in the monoclinic space group P2₁/n, with two half cations and one general anion in the asymmetric unit. The cations, located on centres of inversion, assemble to form chains parallel to the a axis, but there are no significant contacts between the cations. Cohesion is provided by flanking anions, which are connected to the cations by short Au...Au contacts and C—H...Br hydrogen bonds, and to each other by Br...Br contacts. The corresponding chloride derivative, [Au(C₆H₇N)₂][AuCl₂], (II), is isotypic. A previous structure determination of (II), reported in the space group P with very similar axis lengths to those of (I) [Lin et al. (2008). Inorg. Chem. 47 , 2543–2551], might be identical to the structure presented here, except that its γ angle of 88.79 (7)° seems to rule out a monoclinic cell. No phase transformation of (II) could be detected on the basis of data sets recorded at 100, 200 and 295 K.     

Thermodynamic characteristics of europium pivalate binuclear complexes Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> and [Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> · (Phen)<Subscript>2</Subscript>]

Sublimation of europium pivalate binuclear complexes Eu₂(Piv)₆ and [Eu₂(Piv)₆ · (Phen)₂] (Piv = (CH₃)₃CCOO, Phen = C₁₂H₈N₂) in the temperature range of 383–660 K is studied by the Knudsen effusion method with mass-spectrometric analysis of the gas phase. The vaporization of Eu₂(Piv)₆ is shown to be accompanied by polymerization and the formation of Eu₂(Piv)₆ and Eu₄(Piv)₁₂ molecules. The saturated vapor over the mixed-ligand complex of europium pivalate with o-phenanthroline consists of Phen, Eu₂(Piv)₆, and Eu₄(Piv)₁₂ molecules. The partial pressures of the gas components, as well as the standard enthalpies of sublimation and dissociation of the reaction proceeding with removal of phenanthroline have been determined.     

Erbium(III) and lutecium(III) complexes [Ln(H<Subscript>2</Subscript>O)<Subscript>8</Subscript>][Cr(NCS)<Subscript>6</Subscript>] · 5H<Subscript>2</Subscript>O: Synthesis and crystal structure

[Ln(H₂O)₈][Cr(NCS)₆] · 5H₂O aqua complexes, where Ln = Er (1), Lu (2), have been found in an aqueous solution instead of binary complex salts with an organic ligand in their cation, when crystal products of the reaction between Ln(NO₃)₃ · 6H₂O (Ln = Er, Lu), K₃[Cr(NCS)₆] · 4H₂O, and 8-oxyquinoline (C₉H₇NO) were studied by X-ray diffraction. Crystals of complexes 1 and 2 are isostructural and crystallize in triclinic system, space group P\(\bar 1\), Z = 2. For complex 1: a = 9.0677(4) Å, b = 9.3115(4) Å, c = 16.9595 Å, α = 81.526(2)°, β = 86.153(2)°, γ = 83.879(2)°, V = 1406.33(10) ų, ρ_calc = 1.894 g/cm³; for complex 2: a = 9.0438(3) Å, b = 9.2880(3) Å, c = 16.9181(3) Å, α = 81.7250(10)°, β = 86.1600(10)°, γ = 83.8850(10)°, V = 1396.38(7) ų, ρ_calc = 1.926 g/cm³.     

A review on green Lewis acids: zirconium(IV) oxydichloride octahydrate (ZrOCl<Subscript>2</Subscript>·8H<Subscript>2</Subscript>O) and zirconium(IV) tetrachloride (ZrCl<Subscript>4</Subscript>) in organic chemistry

Lewis acids are important and interesting catalysts in most organic transformations. Among different Lewis acids, Zr(IV) species such as ZrCl₄ and ZrOCl₂·8H₂O are allocated special attention because of their low toxicity, availability and handling, moisture stability, and low cost in comparison to some of their corresponding compounds. During recent decades, Lewis acids have been used to promote different types of organic reactions because they naturally possess mild acidity properties and, as such, can catalyze reactions selectively. This means that in the presence of various functional groups, they can operate on a specific group to produce the objective product. In this review we have focused on the reactions which have been progressed in the presence of ZrCl₄ and ZrOCl₂·8H₂O. The study has been ordered based on the number of the reaction components and their solvent media.     

<Emphasis Type="Italic">catena</Emphasis>-(μ<Subscript>3</Subscript>-Bromo)di(μ<Subscript>2</Subscript>-bromo)bromo(18-crown-6)dilead(II): Synthesis and crystal structure

A new polymeric complex, catena-(μ₃-bromo)di(μ₂-bromo)bromo(18-crown-6)dilead(II), [Pb₂Br(μ₂-Br)₂(μ₃-Br)(18-crown-6)] _n (I), is synthesized, and its crystal structure is studied using X-ray diffraction analysis (space group P \(\bar 1\), a = 7.970, b = 16.048, c = 19.153 Å, α = 72.75°, β = 88.57°, γ = 87.92°, Z = 4, direct method, full-matrix least-squares method in the anisotropic approximation, R = 0.076 for 6093 independent reflections, CAD4 automated diffractometer, λMoK_α radiation). The crystal structure of complex I contains infinite chains of the PbBr₆ octahedra along the x axis with the bridging Br^? anions as common edges. The [PbBr(18-crown-6)]⁺ host-guest complex fragments are attached through weak Pb-Br bonds to these chains on the side. In two independent terminal fragments, the coordination polyhedra of the Pb²⁺ cations are distorted hexagonal bipyramids with bases of six O atoms of the crown ligand and two Br^? anions in the axial vertices. Two Pb²⁺ cations from the [PbBr₃] _n ^? infinite polymer chain have a distorted octahedral coordination.     

Synthesis and Characterization of the Face-Centered Cubic Clusters [(Me<Subscript>3</Subscript>tacn)<Subscript>8</Subscript>M<Subscript>8</Subscript>Pt<Subscript>6</Subscript>(CN)<Subscript>24</Subscript>]<Superscript>12+</Superscript> (M = Cr,Mo)

Incorporation of a 5d transition metal into the face-centered cubic metal-cyanide cluster geometry is accomplished for the first time with the isolation of a series of compounds featuring [(Me₃tacn)₈M₈Pt₆(CN)₂₄]¹²⁺ (M = Cr, Mo) clusters. Reaction of [(Me₃tacn)Cr(CN)₃] and K₂[PtCl₄] in a boiling aqueous solution generates [(Me₃tacn)₈Cr₈Pt₆(CN)₂₄]Cl₁₂ · 27H₂O (1), wherein Pt^II centers reside at the face-centering sites and the cyanide ligands have reoriented to give Pt^II–C≡N–Cr^III linkages. The cyclic voltammogram obtained for a solution of 1 in DMSO exhibits a quasireversible reduction event centered at E _1/2 = ?1.59 V versus Cp₂Fe^0/1+. Reaction of 1 with K₂[Pt(CN)₄] in aqueous solution affords [(Me₃tacn)₈Cr₈Pt₆(CN)₂₄][Pt(CN)₄]₆ · 6H₂O (2), in which each face of the cubic cluster is capped by a staggered tetracyanoplatinate anion with a Pt–Pt separation of 3.1552(7) Å. Attempts to perform analogous cluster-forming reactions with [(Me₃tacn)Mo(CN)₃] revealed a tendency toward cluster decomposition to give mixtures of insoluble products, including [(Me₃tacn)₈Mo₈Pt₆(CN)₂₄][Pt(CN)₄]₆ · 46H₂O (3) and [(Me₃tacn)₈Mo₈Pt₆(CN)₂₄][Pt(CN)₄]_2.5[Pt(CN)₃Br]₂Br₃ · 6H₂O (4). Crystallographic analyses revealed these compounds to contain the anticipated [(Me₃tacn)₈Mo₈Pt₆(CN)₂₄]¹²⁺ cluster in fully- and partially-capped forms, respectively. Unfortunately, the insolubility of these molybdenum-containing products precluded characterization of the cluster by cyclic voltammetry.     

Oxidation of Fe(III) to Fe(VI) by the Fe(CN)<Stack><Subscript>6</Subscript><Superscript>3−</Superscript></Stack> ion in strong solution of alkalis

Ferricyanide ions oxidize Fe(III) up to Fe(VI) in 7–11 M KOH solutions and 10–16 M NaOH solutions. The completeness of the oxidation increases with increasing alkali and ferricyanide concentrations. The presence of KNO₂, KAc, and K₂C₂O₄ in 7 M KOH solution increases the Fe(VI) yield. Potassium fluoride in the concentration of 0.02 M does not hinder Fe(VI) formation, but in the concentration of 0.1 M completely suppresses Fe(III) oxidation. The attempt to oxidize Fe(VI) up to Fe(VIII) by the disproportionation of Fe(VI) or by the action of Fe(CN)₆³⁻ and ozone was unsuccessful due to a high oxidation potential of the Fe(VIII)/(VI) couple.     

Two crystalline modifications of Pd<Subscript>2</Subscript>(μ-ac)<Subscript>2</Subscript>(acac)<Subscript>2</Subscript>

Crystal structures of two modifications of a binuclear Pd₂(μ-ac)₂(acac)₂ complex are studied at 150 K and 297 K (ac = acetate; acac = acetylacetonate). It is demonstrated that in both cases, the packing of the complexes can be considered as pseudohexagonal, the molecules forming infinite chains by interactions between chelate rings with the shortest contacts Pd...C _γ ～ 3.3 Å.     

π-Complex of Cu(I) Chloride with 1-Allyloxybenzotriazole CuCl · C<Subscript>6</Subscript>H<Subscript>4</Subscript>N<Subscript>3</Subscript>(OC<Subscript>3</Subscript>H<Subscript>5</Subscript>)

Single crystals of CuCl · C₆H₄N₃(OC₃H₅)(I) are synthesized by ac electrochemical method from Cu(II) chloride and 1-allyloxybenzotriazole in ethanol solution and their unit cell parameters are determined: space group P2₁/a a=11.583(4) , b=11.443(7) , c=8.620(4) , =108.77(3)°, V=1082(2) ³, R(F)=0.0366, R _w (F)=0.0396 for 1095 reflections. In the structure of -complex I, inorganic fragment Cu₂Cl₂ forms centrocymmetric parallelogram. A molecule of 1-allyloxybenzotriazole acts as a bridge, which is bonded to the Cu atoms of two inorganic dimers through the C=C bond of the allyl group and to the N atom of a triazole ring. Owing to this bridging function, the ligand molecules form zigzag organometallic layers. The trigonal-pyramidal coordination sphere of a metal atom includes two Cl atoms and the C=C group. The structural motif of complex I significantly differs from that of the previously studied 2CuCl · C₆H₄N₃(OC₃H₅) and resembles the motif of a bromide analog Cu₂Br₂ · [C₆H₄N₃(OC₃H₅)]₂.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 364–369.Original Russian Text Copyright © 2005 by Goreshnik, Myskiv.     

Synthesis and structure of trinuclear pyrazolate-bridged acetates M<Subscript>3</Subscript>(μ-dmpz)<Subscript>4</Subscript>(Hdmpz)<Subscript>2</Subscript>(OOCMe)<Subscript>2</Subscript> (M = Zn or Co; Hdmpz = 3,5-dimethylpyrazole)

We discovered that reactions of hydrous cobalt and zinc acetates with 3,5-dimethylpyrazole (Hdmpz) in boiling xylene or toluene or upon the thermolysis of solid precursors (150°C) yield trinuclear pyrazolate-bridged complexes M₃ (μ-dmpz)₄(Hdmpz)₂ (OOCMe)₂(M = Zn or Co). Depending on the crystallization conditions, these complexes contain various solvating molecules (benzene, toluene, or Hdmpz), which influences the character of intramolecular and intermolecular hydrogen bonding, as shown by X-ray crystallography.     

Synthesis,structure, and some reactions of the cluster complex [(μ-H)<Subscript>2</Subscript>Fe<Subscript>5</Subscript>(μ<Subscript>3</Subscript>-Se)<Subscript>2</Subscript>(CO)<Subscript>14</Subscript>]

In the reaction of Na₂Se with [Fe(CO)₅] in isopropanol with subsequent acidification with HCl, which is used to synthesize [(μ-H)₂Fe₃(μ₃-Se)(CO)₉] (II), the cluster [(μ-H)₂Fe₅(μ₃-Se)₂(CO)₁₄] (I) was detected. In assumption that compound I could serve as a suitable synthon for preparing the bulky heterometallic clusters, its reactions with the Rh-containing complexes were studied. The reaction of I with [Rh(CO)₂Cp*] (Cp* is pentamethylcyclopentadienyl) was found to give a mixture of the products. The main reaction products were isolated and their structures were determined: [Fe₂Rh(μ₃-Se)₂(CO)₆Cp*], [Fe₂Rh(μ₃-Se)(μ₃-CO)(CO)₆Cp*], [FeRh₂(μ₃-Se)(μ-CO)(CO)₃Cp ₂ ^* ], [Fe₂Rh₂(μ₄-Se)(μ-CO)₄(CO)₂Cp ₂ ^* ]. Potassium hydride treatment of II with subsequent addition of [Cp*Rh(CH₃CN)₃](CF₃SO₃)₂ leads to the well-known cluster complex [Fe₃Rh(μ₄-Se)(CO)₉Cp*]. A set of the reaction products indicates that the {Fe₅Se₂} core cannot be used as one-piece “building block” in the synthesis of heterometallic clusters.     

Synthesis and spectral studies on NiS<Subscript>4</Subscript>, NiS<Subscript>2</Subscript>PN,NiS<Subscript>2</Subscript>P<Subscript>2</Subscript> chromophores: Single-crystal X-ray structure of [Ni(dbpdtc)<Subscript>2</Subscript>] (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate)

Three complexes of a dithiocarbamate ligand (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate), namely [Ni(dbpdtc)₂] (1), [Ni(dbpdtc)(NCS)(PPh₃)] (2) and [Ni(dbpdtc)(PPh₃)₂]ClO₄ (3) have been prepared. The complexes were characterized by IR, electronic spectroscopy and cyclic voltammetry. A single-crystal X-ray structural analysis was carried out for complex 1 and showed that the nickel is in a distorted square planar environment with a NiS₄ chromophore. For the two mixed ligand complexes, the thioureide ν _C–N values were shifted to higher wavenumbers compared to [Ni(dbpdtc)₂], suggesting increased strength of the thioureide bond due to the presence of the π-accepting phosphine. Electronic spectral studies suggest square planar geometries for the complexes. Cyclic voltammetry showed easier reduction of nickel(II) to nickel(I) in the mixed ligand complexes compared to [Ni(dbpdtc)₂].     

Crystal structure and spectroscopic properties of ciprofloxacinium pentachloroantimonate(III) monohydrate (C<Subscript>17</Subscript>H<Subscript>19</Subscript>N<Subscript>3</Subscript>O<Subscript>3</Subscript>F)SbCl<Subscript>5</Subscript> · H<Subscript>2</Subscript>O

Synthesis, X-ray diffraction, IR and luminescence spectroscopic studies of the monohydrate of pentachloroantimonate(III) of doubly protonated ciprofloxacin (C₁₇H₁₉N₃O₃F)SbCl₅ · H₂O (I) were performed. The structure of I is formed by SbCl₆ octahedra combined into polymeric chains [SbCl₅] _n ^2n? through common vertices, ciprofloxacinium cations (CfH₃)²⁺, and water molecules linked by hydrogen bonds. CfH is protonated at the carbonyl oxygen atom and the terminal nitrogen atom of the piperazinyl group. The electronic and geometric aspects determining the luminescence properties of I and of related compounds are discussed.     

Crystal structure and solid–solid phase transition of the complex (C<Subscript>11</Subscript>H<Subscript>18</Subscript>NO)<Subscript>2</Subscript>CuCl<Subscript>4</Subscript>(s)

The complex (C₁₁H₁₈NO)₂CuCl₄(s) was synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were used to characterize the structure and composition of the complex. Low-temperature heat-capacities of the compound were measured by an adiabatic calorimeter in the temperature range from 77 to 400 K. A phase transition of the compound took place in the region of 297–368 K. Experimental molar heat-capacities were fitted to two polynomial equations of heat-capacities as a function of the reduced temperature by least square method. The peak temperature, molar enthalpy, and entropy of phase transition of the compound were calculated to be T _trs = 354.214 ± 0.298 K, Δ_trs H _m = 76.327 ± 0.328 kJ mol⁻¹, and Δ_trs S _m = 51.340 ± 0.164 J K⁻¹ mol⁻¹.     

Synthesis and Structure of Cobalt(III) α-Dimethylglyoximate [Co(DH)<Subscript>2</Subscript>(Py)<Subscript>2</Subscript>][H<Subscript>2</Subscript>F<Subscript>3</Subscript>]

The [Co(DH)₂(Py)₂][H₂F₃] complex (DH^? is the dimethylglyoxime residue) is synthesized and studied by X-ray diffraction analysis. Structural units of the crystal are complex cations [Co(DH)₂(Py)₂]⁺ and anions [H₂F₃]^?. Two residues of α-dimethylglyoxime linked by intramolecular hydrogen bonds O-H?O lie in the equatorial plane of the octahedral Co(III) complex, and two pyridine molecules occupy the apical positions. The H₂F ₃ ^? anion is formed due to the association of the F^? ion with two HF molecules through hydrogen bonds F-H?F. Weak intermolecular interactions C-H?F and C-H?O are observed in the crystal. The problem of the influence of these interactions on the packing of the complexes in crystal is discussed.     

Crystal structure of <Emphasis Type="Italic">N</Emphasis>-(3-hydroxypropyl)-β-alanine and Bis(<Emphasis Type="Italic">N</Emphasis>-(3-hydroxypropyl)-β-alaninato)dicopper(II) [Cu<Subscript>2</Subscript> (Pro-ala)<Subscript>2</Subscript>]

N-(3-Hydroxypropyl)-β-alanine was synthesized by the reacti on of 3-aminopropanol with acrylic acid. From this ligand and basic copper carbonate, bis(N-(3-hydroxypropyl)-β-alaninato)dicopper(II) [Cu₂ (C₆H₁₁NO₃)₂] was obtained. The structures of the chelating agent and the copper complex were studied by X-ray diffraction. The Cu(II) coordination polyhedron is a distorted square pyramid. Each ligand forms six-membered β-alaninate and propanolamine chelate rings. The propoxy group functions as a bridge. In the crystal structure, the molecules form intermolecular coordination bonds C=O→Cu, which are perpendicular to the layers. The EPR signal typical of dimeric copper complexes is not observed due to low occupancy of the excited paramagnetic triplet state. The weak paramagnetic signal from monomeric copper complex allowed recording of the ¹H NMR spectrum of [Cu₂ (Pro-ala) ₂] with characteristic line broadening and contact shift. It follows from the obtained data that on dissolution, the complex dissociates by 40% to give monomeric copper complexes.     

Crystal structure of Mg pivalate hydrate Mg(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>(Piv)<Subscript>2</Subscript> · 3H<Subscript>2</Subscript>O

Single crystals of Mg pivalate hydrate, Mg(H₂O)₆(Piv)₂ · 3H₂O (HPiv = (CH₃)₃CCOOH) are synthesized and their structure is determined by X-ray diffraction method. The crystals are rhombic: a = 10.917(2) Å, b = 12.625(2) Å, c = 31.394(8) Å, Z = 8, space group Pbca, R ₁ = 0.0525. The Mg atom has octahedral surrounding of the O atoms of water molecules (Mg-O 2.044–2.137 Å). The cationic chains of [Mg(H₂O)₆] _∞ ²⁺ lie in the voids of doubled network anionic layers of [(H₂O)₃(Piv)₂] _∞∞ ^2? . Inside the layer, the pivalate anions alternate with water molecules in the xy plane, being bonded to them by hydrogen bonds. The cationic chains and the anionic layers are united into layered packs by hydrogen bonds between coordinated water molecules and pivalate anions and between coordinated and crystal hydrate water molecules.