Crystal structure and magnetic properties of a three-dimensional complex constructed from [CuL]2+ and [Fe(CN)6]3− precursors

Self-assembly of the precursor [Cu(L)]²⁺ (L = 3,10-dipropyl-1,3,5,8,10,12-hexaazacyclotetradecane) with hexacyanometalate [Fe(CN)₆]³⁻ produces a 3-D cyano-bridged Cu(II)–Fe(III) bimetallic assembly, [CuL]₂[Fe(CN)₆]ClO₄ · H₂O (1), characterized by single-crystal X-ray diffraction studies, and magnetic measurements. The crystallographic determination reveals that each hexacyanoferromate(III) ion connects four copper(II) ions using four co-planar CN⁻ groups which axially coordinate to the copper ion in a trans fashion forming trans-CuL(N≡C)₂ moieties in (1). Magnetic studies reveal that (1) displays a ferromagnetic interaction between Cu(II) and Fe(III) through the CN linkage.     

Investigation of phase transitions of a pseudo-hexagonal phase of [Rh(NH3)5Cl]2[Re6S8(CN)6]·3H2O during thermal decomposition

A general motif of the crystal structure of [Rh(NH₃)₅Cl]₂[Re₆S₈(CN)₆]·3H₂O is examined, and the cluster anions are found to form a pseudo-hexagonal sublattice. The thermal decomposition of [Rh(NH₃)₅Cl]₂[Re₆S₈(CN)₆]·3H₂O is studied, and it is shown that in helium atmosphere thermolysis occurs through the formation of intermediate amorphous phases. The final product obtained at 1200°C is a disordered single-phase solid solution of Re_0.75Rh_0.25 based on the structure of rhenium. Powder X-ray diffraction data for solid solutions in the system of Rh-Re are surveyed. It is demonstrated that the data for phases prepared by the thermal decomposition of coordination compounds better match the theoretical state diagram than the experimental one. The dependence of atomic volume on the composition of solid solutions of Re_xRh_1−x is derived. Original Russian Text Copyright ? 2007 by S. A. Gromilov, K. V. Yusenko, and E. A. Shusharina __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No.5, pp.957–962, September–October, 2007.     

Electronic Structure and Molecular Properties of the Mixed Rhenium–Molybdenum [Re6−x Mo x S8(CN)6]q−, (x = 0 to 6) Clusters

Relativistic density functional calculations including scalar and spin-orbit effects via the ZORA approximation and including solvent effects were carried out on the [Re₆S₈(CN)₆]⁴⁻, [Re₅MoS₈(CN)₆]⁵⁻, [Re₄Mo₂S₈(CN)₆]⁵⁻, [Re₃Mo₃S₈(CN)₆]⁵⁻, [Re₂Mo₄S₈(CN)₆]⁵⁻, [ReMo₅S₈(CN)₆]⁵⁻ and [Mo₆S₈(CN)₆]⁶⁻ clusters. By increasing the replacement of each Re atom with Mo atoms we find that for x > 2 the HOMO–LUMO gap decreases significantly. The calculated gap of the [Re₃Mo₃S₈(CN)₆]⁵⁻, [Re₂Mo₄S₈(CN)₆]⁵⁻ and [ReMo₅S₈(CN)₆]⁵⁻ clusters is similar to the calculated and observed gap of the superconducting PbMo₆S₈ Chevrel phases. The current calculations also indicates that the electronic similarities of the lowest excited states of the semiconducting 24e [Re₅MoS₈(CN)₆]⁵⁻ and 23e [Re₄Mo₂S₈(CN)₆]⁵⁻ clusters with the strongly luminescent 24e [Re₆S₈(CN)₆]⁴⁻ cluster, suggest that these mixed metal clusters might be luminescent.     

Die Kristallstrukturen der Cyanidofluoridoborate K[BFx(CN)4–x], x = 0–4

The crystal structure of K[BF₃(CN)] (Pbcn (Nr. 60) with a = 13.3486(15) b = 6.5239(7) c = 10.0085(11) Å, and eight formula units per unit cell) has been determined and the one of K[BF₂(CN)₂] was confirmed and improved. The different networks in the complete series of borates K[BF_x(CN)_4–x], x = 0–4 are compared and discussed.     

Low-dimensional Compounds Containing Cyano Groups. XIII. Structural–spectral Correlation of Copper Dicyanoargentates

The new mixed-valence mixed-metal complex Cu(py)₆Cu₂Ag₂(CN)₆ (py = pyridine) possesses a three dimensional polymeric crystal structure. The Cu(I) atom is tetrahedrally coordinated by two nitrogen atoms of pyridine molecules, by one nitrogen atom of the dicyanoargentate anion and by one carbon atom of the cyano group. Both the dicyanoargentate anion and the cyano group bridge the Cu(I) atom with neighboring Cu(II) atoms. These are hexacoordinated in the form of an elongated tetragonal bipyramid. The equatorial plane is formed by two nitrogen atoms from two pyridine molecules and two nitrogen atoms from bridging cyano groups. Axial positions are occupied by nitrogen atoms of the bridging [Ag(CN₂]⁻ anions. Correlation between structures of the title compound and seven other dicyanoargentates with their i.r. spectra has been studied. The coordination mode of [Ag(CN₂]⁻ anions in compounds Cu_8-xAg_x(tn)₃(CN)₁₀ x = 0.25, Cu(3-Mepy)₂Ag₂(CN)₄, Cu(py)₂Ag₂(CN)₄ and Cu(py)₄Ag₂(CN)₄ (tn is 1,3-diaminopropane, 3-Mepy is 3-methylpyridine) is predicted based on this correlation.     

Crystal structure of barium trans (O)- cis (CN)-Bis(2-picolinato)dicyanocobaltate(III) hydrate [Ba(H2O)4][Co(Pic)2(CN)2]2 · 4.41H2O

In the crystals of [Ba(H₂O)₄][Co(Pic)₂(CN)₂]₂ · 4.41H₂O (tetragonal system, a = b = 10.9390(4) ?, c = 31.7624(15) ?, Z = 4, space group P4₃), the trans(O)-cis(CN)-[Co(Pic)₂(CN)₂]⁻ anions are incorporated into cellular infinite layers whose sites contain Ba²⁺ ions, which are connected to four neighboring complexes through the oxygen atoms of the carboxy groups of the 2-picolinate ions. Four O atoms of the water molecules complete the Ba coordination polyhedron to a distorted square antiprism. Original Russian Text ? M. Zabel, V.I. Pavlovskii, A.L. Poznyak, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 3, pp. 417–420.     

Free electron model in cluster structure theory. Electronic structures of [Mo6S8(CN)6]6?, [Mo6Se8(CN)6]6?, [Re6S8(CN)6]4?, and Rh6(CO)16 clusters

The results of quantum chemical calculations of the electronic structure and geometry of octahedral clusters [Mo₆S₈(CN)₆]⁶⁻, [Mo₆Se₈(CN)₆]⁶⁻, [Re₆S₈(CN)₆]⁴⁻, and Rh₆(CO)₁₆ by the ab initio SCF (RHF) and DFT (B3LYP) methods with various basis sets are presented. The electronic states of the clusters under study in ideal spherically symmetric potential were classified in the orbital quantum number l (1s, 1p, 1d, 1f, 1g, 1h, 1i), l = 0–6. In real crystal field with O_h symmetry these states are split. The calculated new electronic states were matched to the irreducible representations of the point symmetry group O_h. The polarizabilities of the compounds considered are 55–65 ų. A new model for the electronic structure of octahedral clusters containing M₆ groups was proposed. The model is based on the idea of free electrons moving in spherically symmetric potential field. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2617–2624, December, 2005.     

Carbon supported electrocatalysts prepared by the sol–gel method and their utilization for the oxidation of methanol in acid media

One of the key objectives in fuel-cell technology is to improve the performance of the anode catalyst for the alcohol oxidation and reduce Pt loading. Here, we show the use of six different electrocatalysts synthesized by the sol–gel method on carbon powder to promote the oxidation of methanol in acid media. The catalysts Pt–PbO _x and Pt–(RuO₂–PbO _x ) with 10% of catalyst load exhibited significantly enhanced catalytic activity toward the methanol oxidation reaction as compared to Pt–(RuO₂)/C and Pt/C electrodes. Cyclic voltammetry studies showed that the electrocatalysts Pt–PbO _x /C and Pt–(RuO₂–PbO _x )/C started the oxidation process at extremely low potentials and that they represent a good novelty to oxidize methanol. Furthermore, quasi-stationary polarization experiments and cronoamperometry studies showed the good performance of the Pt–PbO _x , Pt–(RuO₂–PbO _x )/C and Pt–(RuO₂–IrO₂)/C catalysts during the oxidation process. Thus, the addition of metallic Pt and PbO _x onto high-area carbon powder, by the sol–gel route, constitutes an interesting way to prepare anodes with high catalytic activity for further applications in direct methanol fuel cell systems.     

Synthesis and Characterization of Polyoxometalate–Polyamino Dendritic Hybrid Compounds

Organic–inorganic hybrid compounds were prepared by the reaction of a tin chloride-substituted polyoxometalate, [PSn(Cl)W₁₁O₃₉]⁴⁻ with tris(2-aminoethyl)amine, and poly(propylene)imine (DAB-Am) tetraamine and octaamine dendrimers. Translational diffusion coefficients of the hybrid compounds were measured in DMSO-d ₆ by the stimulated echo diffusion (STE) NMR technique. Molecular radii were derived from the diffusion coefficients by the Stokes–Einstein equation and appeared to be incorrect because of fast exchange on the NMR time scale of the counter cation in the solution, which led to an averaging of the NMR signal and high diffusion coefficients. An effective hydrodynamic diameter of the [PSn(Cl)W₁₁O₃₉]⁴⁻–polypropylenimine octaamine hybrid adduct was measured in a light scattering experiment.     

Multiple-layer heterometallic MnII–AgI coordination polymers constructed from [Ag 2I (CN)3]? and [AgI(CN)2]? units

Two multiple-layer heterometallic Mn^II–Ag^I coordination polymers, {Mn^II(ampyz)(H₂O)[Ag₂^I(CN)₃][Ag^I(CN)₂]·ampyz} _n (1) and {[Mn^II(benzim)₂[Ag^I(CN)₂]₂][(benzim)Ag^I(CN)]·H₂O} _n (2) where ampyz = 2-aminopyrazine and benzim = benzimidazole, have been prepared and structurally characterized. Compound 1 reveals a multiple-layer two-dimensional network with strong hexanuclear argentophilic interactions leading to an infinite three-dimensional framework. Compound 2 has an unprecedented double-layer two-dimensional squared grid-type network with (4,4) topology through Ag^I···Ag^I and π–π interactions between two adjacent squared layers. These double-layer networks of 2 are linked to others by π–π interactions, leading to a three-dimensional framework.     

Crystal structure of a tetrahedral cluster complex [Zn2(NH3)6(μ-OH)][Zn(NH3)4]0.5[Re4Te4(CN)12]·5H2O

A cluster complex of the composition [Zn₂(NH₃)₆(μ-OH)][Zn(NH₃)₄]_0.5[Re₄Te₄(CN)₁₂]·5H₂O is obtained by the interaction of an aqueous solution of K₄[Re₄Te₄(CN)₁₂]·5H₂O with an aqueous ammonia solution of ZnCl₂. The compound crystallizes in the C2/m (12) monoclinic space group with unit cell parameters a = 23.233(2) ?, b = 14.5906(16) ?, c = 14.3825(15) ?, β = 125.169(1)°, V = 3985.5(7) ?³, Z = 4, d _x = 3.290 g/cm³. The structure is built from cluster [Re₄Te₄(CN)₁₂]⁴⁻ anions and complex [Zn₂(NH₃)₆(μ-OH)]³⁺ and [Zn(NH₃)₄]²⁺ cations; the latter is disordered over two positions.     

Crystal structures of [Hg(<Emphasis Type="Italic">N</Emphasis>-ethylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>] and [Hg(<Emphasis Type="Italic">N</Emphasis>-propylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>]

Two mercury(II) cyanide complexes of N-ethylthiourea (Ettu) and N-propylthiourea (Prtu) ligands, [Hg(Ettu)₂(CN)₂] (1) and [Hg(Prtu)₂(CN)₂] (2), were prepared and their crystal structures were determined by X-ray crystallography. In both structures, the mercury atom is coordinated to two sulfur atoms of thioureas and two cyanide carbon atoms in a pseudo-tetrahedral mode with the bond angles in the range of 90.52(11)–162.2(3)°. The structures are stabilized by N-H—S, N-H—N, and C-H—N intramolecular and intermolecular hydrogen bonds.     

Synthesis and application of novel fluoroalkyl end-capped cooligomers having adamantane as a pendant group

Fluoroalkyl end-capped cooligomers having adamantane as a pendant group [R_F-(Ad-HAc) _x –(Co-M) _y -R_F] were prepared by the reactions of fluoroalkanoyl peroxide with 3-hydroxy-1-adamantylacrylate (Ad-HAc) and comonomers (Co-M) such as acrylic acid (ACA), N,N-dimethylacrylamide (DMAA), and acryloylmorpholine (ACMO) under mild conditions. Thermogravimetric analyses (TGA) showed that thermal stability of R_F-(Ad-HAc) _x –(Co-M) _y -R_F was superior to that of the corresponding fluoroalkyl end-capped cooligomers having adamantane in the main chains [R_F-(Ad) _x –(Co-M) _y -R_F] and the fluoroalkyl end-capped homooligomers possessing no adamantyl segments [R_F-(M) _n -R_F]. It is interesting to note that fluoroalkyl end-capped Ad-Hac–DMAA cooligomer [R_F-(Ad-HAc) _x –(DMAA) _y -R_F] was found to form the nanometer size-controlled cooligomeric aggregates which consist of around 16 fluorinated cooligomeric molecules in methanol/water mixed solvents. Furthermore, these fluorinated cooligomeric aggregate could occupy around 320 ADMDD [5-(2-adamantylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione] molecules as guest molecules per aggregate core, although ADMDD could not be encapsulated into the R_F-(Ad) _x –(Co-M) _y -R_F cooligomeric and R_F-(M) _n -R_F homooligomeric aggregate cores under similar conditions.     

Analysis of Solvent–Solvent Interactions in Mixed Isosteric Solvents by Inverse Gas Chromatography

The Flory–Huggins interaction parameter, χ ₂₃, characterizing the interaction between solvents in a mixed stationary phase has been calculated using inverse gas chromatography (IGC). The χ ₂₃ parameters for four mixed solvent systems formed by mixing a non-polar branched alkane, 19, 24-dioctadecyldotetracontane (C78), with four different polar solvents are analysed as a function of temperature. Two of the polar solvents are formed by replacing one of the –CH₃ groups of C78 by –OH (POH) group and –CN (PCN) group and the other two polar solvents are formed by replacing all the four –CH₃ groups of C78 by four –CF₃ (TTF) groups and four –OCH₃ (TMO) groups. The five solvents have similar structures and nearly the same molar volume and in mixtures, they form regular solutions. For the mixture, C78 + POH, χ ₂₃ was calculated at two compositions and for the remaining three mixtures χ ₂₃ was calculated at equimolar composition. Eight solute probes representing all possible chemical structures and polarity were used under conditions approaching infinite dilution. The effects of temperature, concentration of the mixed solvent and probe solute on χ ₂₃ are presented and discussed. The probe-independent χ ₂₃ values were also calculated by linear regression analysis using the retention data of all the solute probes. In all the mixed solvents considered here the χ ₂₃ values are probe-dependent and decrease with increase of temperature.     

Novel Three-Dimensional Coordination Polymers Based on [Mo6Se8(CN)6]7− Anions and Mn2+ Cations

Three novel coordination polymers K₅[MnMo₆Se₈(CN)₆] · 8H₂O (1), (Me₄N)₄[{Mn(H₂O)₂}_1.5Mo₆Se₈(CN)₆] · 4H₂O (2), and K₃[{Mn₂(H₂O)₄}Mo₆Se₈(CN)₆] · 7H₂O (3) have been synthesized by layering of a methanol solution of [Mn(salen)]CH₃COO (salen–N,N′-bis(salicylidene)ethylenediamine) on an aqueous solution of K₇[Mo₆Se₈(CN)₆] · 8H₂O. The compounds have been characterized by single-crystal X-ray diffraction analysis. All structures are based on negatively charged porous polymer frameworks where CN groups of [Mo₆Se₈(CN)₆]⁷⁻ cluster complexes are coordinated to Mn²⁺ cations. Cavities in the frameworks are filled by additional cations and solvate water molecules.     

Synthesis, structures, and properties of molybdenum and tungsten chalcogenide cubane complexes (NH4)6[M4Q4(CN)12]·6H2O (M=Mo or W; Q=S or Se)

Four new chalcogenide molybdenum and tungsten cubane clusters (NH₄)₆[M₄Q₄(CN)₁₂]·6H₂O (M=Mo or W; Q=S or Se) were prepared by high-temperature reactions of the triangular M₃O₇Br₄ complexes with KCN at 430 °C followed by crystallization from aqueous solutions of ammonium acetate. The molecular and crystal structures of (NH₄)₆[Mo₄S₄(CN)₁₂]·6H₂O, (NH₄)₆[W₄S₄(CN)₁₂]·6H₂O, and (NH₄)₆[W₄Se₄(CN)₁₂]·6H₂O were established by X-ray diffraction analysis. The mixed-valence cubane clusters are diamagnetic and isostructural and have the symmetryT _d . The clusters were characterized by IR and electronic spectroscopy. The data of cyclic voltammetry demonstrated that the [M₄Q₄(CN)₁₂] ⁿ⁻ clusters exist in three oxidation states from the most oxidized (n=6; 10 cluster electrons) to the most reduced electron-precise 12-electron species (n=8). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 18–24, January, 2000.     

Hetarylamidines derived from PtIV-mediated coupling of nitriles with aminoheterocycles

The trans-[PtCl₄(EtCN)₂] complex is involved in coupling reactions (CH₂Cl₂, 30–35 °C, 10–15 min) with 2-amino derivatives of heterocyclic compounds (2-NH₂Het, where Het is pyridyl, 4-methylpyridyl, 5-methylpyridyl, 6-methylpyridyl, or thiazolyl) to form the trans-[PtCl₄{ N(H)=C(Et)NHHet}₂] complexes (1–5) with κ¹(N)-coordinated hetarylamidine ligands. The reaction with the use of 2-aminopyrimidine (2-NH₂Pym) produces the [PtCl₄(₂-NH₂Pym)₂] complex (6) as a result of complete replacement of the nitrile ligands in the [PtCl₄(EtCN)₂] complex. The compositions and structures of compounds 1–6 were confirmed by elemental analysis (C, H, N), IR spectroscopy, ¹H, ¹³C{1H}, and ¹⁹⁵Pt{¹H} NMR spectroscopy, and FAB mass spectrometry. Complex 1 was additionally characterized by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1572–1576, September, 2006.     

Synthesis and structure of [Ni(dien)2]3[W4S4(CN)2]·20H2O and [Cu(dien)(Hdien)]2[W4S4(CN)12]·8H2O

[Ni(dien)₂]₃[W₄S₄(CN)₁₂]·20H₂O and [Cu(dien)(Hdien)]₂[W₄S₄(CN)₁₂]·8H₂O were obtained by evaporating water-ammonia solutions containing K₆[W₄S₄(CN)₁₂]·2H₂O·2CH₃OH, diethylene triamine, and NiCl₂·6H₂O or CuCl₂·6H₂O. The crystals of the complex compounds were obtained within 3 days. The complex compounds were characterized by IR spectroscopy and by XRD and elemental analysis. XRD data for the complex [Ni(dien)₂]₃[W₄S₄(CN)₁₂]·20H₂O are: triclinic system, , a = 14.671(2) Å, b = 16.448(3) Å, c = 19.814(3) Å, α = 67.841(3)°, β = 68.996(3)°, γ = 67.527(3)°, V = 3961.6(11) ų, Z = 2; for the complex [Cu(dien)(Hdien)]₂[W₄S₄(CN)₁₂]·8H₂O: monoclinic system, C2/c, a = 37.4290(1) Å, b = 17.7370(1) Å, c = 25.7370(2) Å, β = 105.3840(2)°, V = 16474.02(16) ų, Z = 12. Original Russian Text Copyright ? 2005 by I. V. Kalinina, D. G. Samsonenko, Z. A. Starikova, A. A. Korlyukov, J. Lipkowski, V. P. Fedin, and M. Yu. Antipin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 1, pp. 139–148, January–February, 2005.     

Low-dimensional compounds containing cyano groups. III: a structural,spectral and thermal study of dicyanoargentates containing 4-methylpyridine

The complexes Cu^II(4-Mepy)₂Ag₂(CN)₄ (1) and Cu^II(4-Mepy)₃Ag_2–x Cu^I _x (CN)₄ (2) (4-Mepy = 4-methylpyridine, x = 0.07) were isolated from a reaction mixture containing 4-Mepy, K[Ag(CN)₂] and CuSO₄. I.r. spectra indicated the presence of both monodentate and bridging cyano groups in (1) and (2), confirmed by their known structures, both consisting of neutral zigzag chains. Two neighbouring chains in (2) are linked by argentophilic interactions between Ag atoms of bridging dicyanoargentate anions, whose positions are partly occupied by Cu^I ions to the extent of 7 at.%, with an unusually short Ag...Ag distance of 2.9264(5) Å, to form a ladder. Individual ladders are tied together as sheets by weaker argentophilic interactions between silver atoms of interdigitated monodentate dicyanoargentate anions of two different ladders. Thermal decomposition of (2) occurs in two separated stages. In the first stage, three 4-Mepy molecules are liberated from the formula unit and, in the second stage, redox decomposition of the cyano groups occurs. The thermal decomposition of (1) is more complicated as the release of two 4-Mepy molecules is overlapped by decomposition of one cyano group followed by further redox decomposition of the remaining cyano groups.